Configuration (Apache Hadoop Main 3.1.3 API)

java.lang.Object
- org.apache.hadoop.conf.Configuration

All Implemented Interfaces:

Iterable<Map.Entry<String,String>>, Writable

Direct Known Subclasses:

JobConf, YarnConfiguration
```
@InterfaceAudience.Public
 @InterfaceStability.Stable
public class Configuration
extends Object
implements Iterable<Map.Entry<String,String>>, Writable
```
Provides access to configuration parameters.
Resources

Configurations are specified by resources. A resource contains a set of name/value pairs as XML data. Each resource is named by either a String or by a Path. If named by a String, then the classpath is examined for a file with that name. If named by a Path, then the local filesystem is examined directly, without referring to the classpath.
Unless explicitly turned off, Hadoop by default specifies two resources, loaded in-order from the classpath:
1. core-default.xml: Read-only defaults for hadoop.
2. core-site.xml: Site-specific configuration for a given hadoop installation.
Applications may add additional resources, which are loaded subsequent to these resources in the order they are added.
Final Parameters

Configuration parameters may be declared final. Once a resource declares a value final, no subsequently-loaded resource can alter that value. For example, one might define a final parameter with:
```
 <property>
 <name>dfs.hosts.include</name>
 <value>/etc/hadoop/conf/hosts.include</value>
 <final>true</final>
 </property>
```
Administrators typically define parameters as final in core-site.xml for values that user applications may not alter.
Variable Expansion

Value strings are first processed for variable expansion. The available properties are:
1. Other properties defined in this Configuration; and, if a name is undefined here,
2. Environment variables in System.getenv() if a name starts with "env.", or
3. Properties in System.getProperties().
For example, if a configuration resource contains the following property definitions:
```
 <property>
 <name>basedir</name>
 <value>/user/${user.name}</value>
 </property>
 
 <property>
 <name>tempdir</name>
 <value>${basedir}/tmp</value>
 </property>

 <property>
 <name>otherdir</name>
 <value>${env.BASE_DIR}/other</value>
 </property>
 
```
When conf.get("tempdir") is called, then ${basedir} will be resolved to another property in this Configuration, while ${user.name} would then ordinarily be resolved to the value of the System property with that name.
When conf.get("otherdir") is called, then ${env.BASE_DIR} will be resolved to the value of the ${BASE_DIR} environment variable. It supports ${env.NAME:-default} and ${env.NAME-default} notations. The former is resolved to "default" if ${NAME} environment variable is undefined or its value is empty. The latter behaves the same way only if ${NAME} is undefined.
By default, warnings will be given to any deprecated configuration parameters and these are suppressible by configuring log4j.logger.org.apache.hadoop.conf.Configuration.deprecation in log4j.properties file.
Tags

Optionally we can tag related properties together by using tag attributes. System tags are defined by hadoop.system.tags property. Users can define there own custom tags in hadoop.custom.tags property.
For example, we can tag existing property as:
```
 <property>
 <name>dfs.replication</name>
 <value>3</value>
 <tag>HDFS,REQUIRED</tag>
 </property>

 <property>
 <name>dfs.data.transfer.protection</name>
 <value>3</value>
 <tag>HDFS,SECURITY</tag>
 </property>
 
```
Properties marked with tags can be retrieved with conf .getAllPropertiesByTag("HDFS") or conf.getAllPropertiesByTags (Arrays.asList("YARN","SECURITY")).

Constructor Summary

Constructors
Constructor and Description
`Configuration()` A new configuration.
`Configuration(boolean loadDefaults)` A new configuration where the behavior of reading from the default resources can be turned off.
`Configuration(Configuration other)` A new configuration with the same settings cloned from another.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods Deprecated Methods
Modifier and Type	Method and Description
`static void`	`addDefaultResource(String name)` Add a default resource.
`static void`	`addDeprecation(String key, String newKey)` Adds the deprecated key to the global deprecation map when no custom message is provided.
`static void`	`addDeprecation(String key, String[] newKeys)` Deprecated. use `addDeprecation(String key, String newKey)` instead
`static void`	`addDeprecation(String key, String[] newKeys, String customMessage)` Deprecated. use `addDeprecation(String key, String newKey, String customMessage)` instead
`static void`	`addDeprecation(String key, String newKey, String customMessage)` Adds the deprecated key to the global deprecation map.
`static void`	`addDeprecations(org.apache.hadoop.conf.Configuration.DeprecationDelta[] deltas)` Adds a set of deprecated keys to the global deprecations.
`void`	`addResource(Configuration conf)` Add a configuration resource.
`void`	`addResource(InputStream in)` Add a configuration resource.
`void`	`addResource(InputStream in, boolean restrictedParser)`
`void`	`addResource(InputStream in, String name)` Add a configuration resource.
`void`	`addResource(InputStream in, String name, boolean restrictedParser)`
`void`	`addResource(Path file)` Add a configuration resource.
`void`	`addResource(Path file, boolean restrictedParser)`
`void`	`addResource(String name)` Add a configuration resource.
`void`	`addResource(String name, boolean restrictedParser)`
`void`	`addResource(URL url)` Add a configuration resource.
`void`	`addResource(URL url, boolean restrictedParser)`
`void`	`clear()` Clears all keys from the configuration.
`static void`	`dumpConfiguration(Configuration config, String propertyName, Writer out)` Writes properties and their attributes (final and resource) to the given `Writer`.
`static void`	`dumpConfiguration(Configuration config, Writer out)` Writes out all properties and their attributes (final and resource) to the given `Writer`, the format of the output would be,
`static void`	`dumpDeprecatedKeys()`
`String`	`get(String name)` Get the value of the `name` property, `null` if no such property exists.
`String`	`get(String name, String defaultValue)` Get the value of the `name`.
`Properties`	`getAllPropertiesByTag(String tag)` Get all properties belonging to tag.
`Properties`	`getAllPropertiesByTags(List<String> tagList)` Get all properties belonging to list of input tags.
`boolean`	`getBoolean(String name, boolean defaultValue)` Get the value of the `name` property as a `boolean`.
`Class<?>`	`getClass(String name, Class<?> defaultValue)` Get the value of the `name` property as a `Class`.
`<U> Class<? extends U>`	`getClass(String name, Class<? extends U> defaultValue, Class<U> xface)` Get the value of the `name` property as a `Class` implementing the interface specified by `xface`.
`Class<?>`	`getClassByName(String name)` Load a class by name.
`Class<?>`	`getClassByNameOrNull(String name)` Load a class by name, returning null rather than throwing an exception if it couldn't be loaded.
`Class<?>[]`	`getClasses(String name, Class<?>... defaultValue)` Get the value of the `name` property as an array of `Class`.
`ClassLoader`	`getClassLoader()` Get the `ClassLoader` for this job.
`InputStream`	`getConfResourceAsInputStream(String name)` Get an input stream attached to the configuration resource with the given `name`.
`Reader`	`getConfResourceAsReader(String name)` Get a `Reader` attached to the configuration resource with the given `name`.
`double`	`getDouble(String name, double defaultValue)` Get the value of the `name` property as a `double`.
`<T extends Enum<T>> T`	`getEnum(String name, T defaultValue)` Return value matching this enumerated type.
`File`	`getFile(String dirsProp, String path)` Get a local file name under a directory named in dirsProp with the given path.
`Set<String>`	`getFinalParameters()` Get the set of parameters marked final.
`float`	`getFloat(String name, float defaultValue)` Get the value of the `name` property as a `float`.
`<U> List<U>`	`getInstances(String name, Class<U> xface)` Get the value of the `name` property as a `List` of objects implementing the interface specified by `xface`.
`int`	`getInt(String name, int defaultValue)` Get the value of the `name` property as an `int`.
`int[]`	`getInts(String name)` Get the value of the `name` property as a set of comma-delimited `int` values.
`Path`	`getLocalPath(String dirsProp, String path)` Get a local file under a directory named by dirsProp with the given path.
`long`	`getLong(String name, long defaultValue)` Get the value of the `name` property as a `long`.
`long`	`getLongBytes(String name, long defaultValue)` Get the value of the `name` property as a `long` or human readable format.
`char[]`	`getPassword(String name)` Get the value for a known password configuration element.
`protected char[]`	`getPasswordFromConfig(String name)` Fallback to clear text passwords in configuration.
`char[]`	`getPasswordFromCredentialProviders(String name)` Try and resolve the provided element name as a credential provider alias.
`Pattern`	`getPattern(String name, Pattern defaultValue)` Get the value of the `name` property as a `Pattern`.
`String[]`	`getPropertySources(String name)` Gets information about why a property was set.
`protected Properties`	`getProps()`
`Map<String,String>`	`getPropsWithPrefix(String confPrefix)` Constructs a mapping of configuration and includes all properties that start with the specified configuration prefix.
`org.apache.hadoop.conf.Configuration.IntegerRanges`	`getRange(String name, String defaultValue)` Parse the given attribute as a set of integer ranges
`String`	`getRaw(String name)` Get the value of the `name` property, without doing variable expansion.If the key is deprecated, it returns the value of the first key which replaces the deprecated key and is not null.
`URL`	`getResource(String name)` Get the `URL` for the named resource.
`InetSocketAddress`	`getSocketAddr(String name, String defaultAddress, int defaultPort)` Get the socket address for `name` property as a `InetSocketAddress`.
`InetSocketAddress`	`getSocketAddr(String hostProperty, String addressProperty, String defaultAddressValue, int defaultPort)` Get the socket address for `hostProperty` as a `InetSocketAddress`.
`double`	`getStorageSize(String name, double defaultValue, org.apache.hadoop.conf.StorageUnit targetUnit)` Gets storage size from a config file.
`double`	`getStorageSize(String name, String defaultValue, org.apache.hadoop.conf.StorageUnit targetUnit)` Gets the Storage Size from the config, or returns the defaultValue.
`Collection<String>`	`getStringCollection(String name)` Get the comma delimited values of the `name` property as a collection of `String`s.
`String[]`	`getStrings(String name)` Get the comma delimited values of the `name` property as an array of `String`s.
`String[]`	`getStrings(String name, String... defaultValue)` Get the comma delimited values of the `name` property as an array of `String`s.
`long`	`getTimeDuration(String name, long defaultValue, TimeUnit unit)` Return time duration in the given time unit.
`long`	`getTimeDuration(String name, long defaultValue, TimeUnit defaultUnit, TimeUnit returnUnit)` Return time duration in the given time unit.
`long`	`getTimeDuration(String name, String defaultValue, TimeUnit unit)`
`long`	`getTimeDuration(String name, String defaultValue, TimeUnit defaultUnit, TimeUnit returnUnit)`
`long`	`getTimeDurationHelper(String name, String vStr, TimeUnit unit)` Return time duration in the given time unit.
`long[]`	`getTimeDurations(String name, TimeUnit unit)`
`String`	`getTrimmed(String name)` Get the value of the `name` property as a trimmed `String`, `null` if no such property exists.
`String`	`getTrimmed(String name, String defaultValue)` Get the value of the `name` property as a trimmed `String`, `defaultValue` if no such property exists.
`Collection<String>`	`getTrimmedStringCollection(String name)` Get the comma delimited values of the `name` property as a collection of `String`s, trimmed of the leading and trailing whitespace.
`String[]`	`getTrimmedStrings(String name)` Get the comma delimited values of the `name` property as an array of `String`s, trimmed of the leading and trailing whitespace.
`String[]`	`getTrimmedStrings(String name, String... defaultValue)` Get the comma delimited values of the `name` property as an array of `String`s, trimmed of the leading and trailing whitespace.
`Map<String,String>`	`getValByRegex(String regex)` get keys matching the the regex
`static boolean`	`hasWarnedDeprecation(String name)` Returns whether or not a deprecated name has been warned.
`static boolean`	`isDeprecated(String key)` checks whether the given `key` is deprecated.
`boolean`	`isPropertyTag(String tagStr)` Get Property tag Enum corresponding to given source.
`Iterator<Map.Entry<String,String>>`	`iterator()` Get an `Iterator` to go through the list of `String` key-value pairs in the configuration.
`static void`	`main(String[] args)` For debugging.
`boolean`	`onlyKeyExists(String name)` Return existence of the `name` property, but only for names which have no valid value, usually non-existent or commented out in XML.
`void`	`readFields(DataInput in)` Deserialize the fields of this object from `in`.
`void`	`reloadConfiguration()` Reload configuration from previously added resources.
`static void`	`reloadExistingConfigurations()` Reload existing configuration instances.
`void`	`set(String name, String value)` Set the `value` of the `name` property.
`void`	`set(String name, String value, String source)` Set the `value` of the `name` property.
`void`	`setAllowNullValueProperties(boolean val)` Set Configuration to allow keys without values during setup.
`void`	`setBoolean(String name, boolean value)` Set the value of the `name` property to a `boolean`.
`void`	`setBooleanIfUnset(String name, boolean value)` Set the given property, if it is currently unset.
`void`	`setClass(String name, Class<?> theClass, Class<?> xface)` Set the value of the `name` property to the name of a `theClass` implementing the given interface `xface`.
`void`	`setClassLoader(ClassLoader classLoader)` Set the class loader that will be used to load the various objects.
`void`	`setDeprecatedProperties()` Sets all deprecated properties that are not currently set but have a corresponding new property that is set.
`void`	`setDouble(String name, double value)` Set the value of the `name` property to a `double`.
`<T extends Enum<T>> void`	`setEnum(String name, T value)` Set the value of the `name` property to the given type.
`void`	`setFloat(String name, float value)` Set the value of the `name` property to a `float`.
`void`	`setIfUnset(String name, String value)` Sets a property if it is currently unset.
`void`	`setInt(String name, int value)` Set the value of the `name` property to an `int`.
`void`	`setLong(String name, long value)` Set the value of the `name` property to a `long`.
`void`	`setPattern(String name, Pattern pattern)` Set the given property to `Pattern`.
`void`	`setQuietMode(boolean quietmode)` Set the quietness-mode.
`void`	`setRestrictSystemProperties(boolean val)`
`static void`	`setRestrictSystemPropertiesDefault(boolean val)`
`void`	`setRestrictSystemProps(boolean val)`
`void`	`setSocketAddr(String name, InetSocketAddress addr)` Set the socket address for the `name` property as a `host:port`.
`void`	`setStorageSize(String name, double value, org.apache.hadoop.conf.StorageUnit unit)` Sets Storage Size for the specified key.
`void`	`setStrings(String name, String... values)` Set the array of string values for the `name` property as as comma delimited values.
`void`	`setTimeDuration(String name, long value, TimeUnit unit)` Set the value of `name` to the given time duration.
`int`	`size()` Return the number of keys in the configuration.
`String`	`toString()`
`void`	`unset(String name)` Unset a previously set property.
`InetSocketAddress`	`updateConnectAddr(String name, InetSocketAddress addr)` Set the socket address a client can use to connect for the `name` property as a `host:port`.
`InetSocketAddress`	`updateConnectAddr(String hostProperty, String addressProperty, String defaultAddressValue, InetSocketAddress addr)` Set the socket address a client can use to connect for the `name` property as a `host:port`.
`void`	`write(DataOutput out)` Serialize the fields of this object to `out`.
`void`	`writeXml(OutputStream out)` Write out the non-default properties in this configuration to the given `OutputStream` using UTF-8 encoding.
`void`	`writeXml(String propertyName, Writer out)` Write out the non-default properties in this configuration to the given `Writer`.
`void`	`writeXml(Writer out)`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.lang.Iterable
forEach, spliterator

- Constructor Detail
 - Configuration
```
public Configuration()
```
 A new configuration.
 - Configuration
```
public Configuration(boolean loadDefaults)
```
 A new configuration where the behavior of reading from the default resources can be turned off. If the parameter loadDefaults is false, the new instance will not load resources from the default files.
 
 Parameters:
 
 loadDefaults - specifies whether to load from the default files
 - Configuration
```
public Configuration(Configuration other)
```
 A new configuration with the same settings cloned from another.
 
 Parameters:
 
 other - the configuration from which to clone settings.
- Method Detail
 - addDeprecations
```
public static void addDeprecations(org.apache.hadoop.conf.Configuration.DeprecationDelta[] deltas)
```
 Adds a set of deprecated keys to the global deprecations. This method is lockless. It works by means of creating a new DeprecationContext based on the old one, and then atomically swapping in the new context. If someone else updated the context in between us reading the old context and swapping in the new one, we try again until we win the race.
 
 Parameters:
 
 deltas - The deprecations to add.
 - addDeprecation
```
@Deprecated
public static void addDeprecation(String key,
 String[] newKeys,
 String customMessage)
```
 Deprecated. use addDeprecation(String key, String newKey, String customMessage) instead
 
 Adds the deprecated key to the global deprecation map. It does not override any existing entries in the deprecation map. This is to be used only by the developers in order to add deprecation of keys, and attempts to call this method after loading resources once, would lead to UnsupportedOperationException If a key is deprecated in favor of multiple keys, they are all treated as aliases of each other, and setting any one of them resets all the others to the new value. If you have multiple deprecation entries to add, it is more efficient to use #addDeprecations(DeprecationDelta[] deltas) instead.
 
 Parameters:
 
 key -
 
 newKeys -
 
 customMessage -
 - addDeprecation
```
public static void addDeprecation(String key,
 String newKey,
 String customMessage)
```
 Adds the deprecated key to the global deprecation map. It does not override any existing entries in the deprecation map. This is to be used only by the developers in order to add deprecation of keys, and attempts to call this method after loading resources once, would lead to UnsupportedOperationException If you have multiple deprecation entries to add, it is more efficient to use #addDeprecations(DeprecationDelta[] deltas) instead.
 
 Parameters:
 
 key -
 
 newKey -
 
 customMessage -
 - addDeprecation
```
@Deprecated
public static void addDeprecation(String key,
 String[] newKeys)
```
 Deprecated. use addDeprecation(String key, String newKey) instead
 
 Adds the deprecated key to the global deprecation map when no custom message is provided. It does not override any existing entries in the deprecation map. This is to be used only by the developers in order to add deprecation of keys, and attempts to call this method after loading resources once, would lead to UnsupportedOperationException If a key is deprecated in favor of multiple keys, they are all treated as aliases of each other, and setting any one of them resets all the others to the new value. If you have multiple deprecation entries to add, it is more efficient to use #addDeprecations(DeprecationDelta[] deltas) instead.
 
 Parameters:
 
 key - Key that is to be deprecated
 
 newKeys - list of keys that take up the values of deprecated key
 - addDeprecation
```
public static void addDeprecation(String key,
 String newKey)
```
 Adds the deprecated key to the global deprecation map when no custom message is provided. It does not override any existing entries in the deprecation map. This is to be used only by the developers in order to add deprecation of keys, and attempts to call this method after loading resources once, would lead to UnsupportedOperationException If you have multiple deprecation entries to add, it is more efficient to use #addDeprecations(DeprecationDelta[] deltas) instead.
 
 Parameters:
 
 key - Key that is to be deprecated
 
 newKey - key that takes up the value of deprecated key
 - isDeprecated
```
public static boolean isDeprecated(String key)
```
 checks whether the given key is deprecated.
 
 Parameters:
 
 key - the parameter which is to be checked for deprecation
 
 Returns:
 
 true if the key is deprecated and false otherwise.
 - setDeprecatedProperties
```
public void setDeprecatedProperties()
```
 Sets all deprecated properties that are not currently set but have a corresponding new property that is set. Useful for iterating the properties when all deprecated properties for currently set properties need to be present.
 - reloadExistingConfigurations
```
public static void reloadExistingConfigurations()
```
 Reload existing configuration instances.
 - addDefaultResource
```
public static void addDefaultResource(String name)
```
 Add a default resource. Resources are loaded in the order of the resources added.
 
 Parameters:
 
 name - file name. File should be present in the classpath.
 - setRestrictSystemPropertiesDefault
```
public static void setRestrictSystemPropertiesDefault(boolean val)
```
 - setRestrictSystemProperties
```
public void setRestrictSystemProperties(boolean val)
```
 - addResource
```
public void addResource(String name)
```
 Add a configuration resource. The properties of this resource will override properties of previously added resources, unless they were marked final.
 
 Parameters:
 
 name - resource to be added, the classpath is examined for a file with that name.
 - addResource
```
public void addResource(String name,
 boolean restrictedParser)
```
 - addResource
```
public void addResource(URL url)
```
 Add a configuration resource. The properties of this resource will override properties of previously added resources, unless they were marked final.
 
 Parameters:
 
 url - url of the resource to be added, the local filesystem is examined directly to find the resource, without referring to the classpath.
 - addResource
```
public void addResource(URL url,
 boolean restrictedParser)
```
 - addResource
```
public void addResource(Path file)
```
 Add a configuration resource. The properties of this resource will override properties of previously added resources, unless they were marked final.
 
 Parameters:
 
 file - file-path of resource to be added, the local filesystem is examined directly to find the resource, without referring to the classpath.
 - addResource
```
public void addResource(Path file,
 boolean restrictedParser)
```
 - addResource
```
public void addResource(InputStream in)
```
 Add a configuration resource. The properties of this resource will override properties of previously added resources, unless they were marked final. WARNING: The contents of the InputStream will be cached, by this method. So use this sparingly because it does increase the memory consumption.
 
 Parameters:
 
 in - InputStream to deserialize the object from. In will be read from when a get or set is called next. After it is read the stream will be closed.
 - addResource
```
public void addResource(InputStream in,
 boolean restrictedParser)
```
 - addResource
```
public void addResource(InputStream in,
 String name)
```
 Add a configuration resource. The properties of this resource will override properties of previously added resources, unless they were marked final.
 
 Parameters:
 
 in - InputStream to deserialize the object from.
 
 name - the name of the resource because InputStream.toString is not very descriptive some times.
 - addResource
```
public void addResource(InputStream in,
 String name,
 boolean restrictedParser)
```
 - addResource
```
public void addResource(Configuration conf)
```
 Add a configuration resource. The properties of this resource will override properties of previously added resources, unless they were marked final.
 
 Parameters:
 
 conf - Configuration object from which to load properties
 - reloadConfiguration
```
public void reloadConfiguration()
```
 Reload configuration from previously added resources. This method will clear all the configuration read from the added resources, and final parameters. This will make the resources to be read again before accessing the values. Values that are added via set methods will overlay values read from the resources.
 - get
```
public String get(String name)
```
 Get the value of the name property, null if no such property exists. If the key is deprecated, it returns the value of the first key which replaces the deprecated key and is not null. Values are processed for variable expansion before being returned.
 
 Parameters:
 
 name - the property name, will be trimmed before get value.
 
 Returns:
 
 the value of the name or its replacing property, or null if no such property exists.
 - setAllowNullValueProperties
```
public void setAllowNullValueProperties(boolean val)
```
 Set Configuration to allow keys without values during setup. Intended for use during testing.
 
 Parameters:
 
 val - If true, will allow Configuration to store keys without values
 - setRestrictSystemProps
```
public void setRestrictSystemProps(boolean val)
```
 - onlyKeyExists
```
public boolean onlyKeyExists(String name)
```
 Return existence of the name property, but only for names which have no valid value, usually non-existent or commented out in XML.
 
 Parameters:
 
 name - the property name
 
 Returns:
 
 true if the property name exists without value
 - getTrimmed
```
public String getTrimmed(String name)
```
 Get the value of the name property as a trimmed String, null if no such property exists. If the key is deprecated, it returns the value of the first key which replaces the deprecated key and is not null Values are processed for variable expansion before being returned.
 
 Parameters:
 
 name - the property name.
 
 Returns:
 
 the value of the name or its replacing property, or null if no such property exists.
 - getTrimmed
```
public String getTrimmed(String name,
 String defaultValue)
```
 Get the value of the name property as a trimmed String, defaultValue if no such property exists. See @{Configuration#getTrimmed} for more details.
 
 Parameters:
 
 name - the property name.
 
 defaultValue - the property default value.
 
 Returns:
 
 the value of the name or defaultValue if it is not set.
 - getRaw
```
public String getRaw(String name)
```
 Get the value of the name property, without doing variable expansion.If the key is deprecated, it returns the value of the first key which replaces the deprecated key and is not null.
 
 Parameters:
 
 name - the property name.
 
 Returns:
 
 the value of the name property or its replacing property and null if no such property exists.
 - set
```
public void set(String name,
 String value)
```
 Set the value of the name property. If name is deprecated or there is a deprecated name associated to it, it sets the value to both names. Name will be trimmed before put into configuration.
 
 Parameters:
 
 name - property name.
 
 value - property value.
 - set
```
public void set(String name,
 String value,
 String source)
```
 Set the value of the name property. If name is deprecated, it also sets the value to the keys that replace the deprecated key. Name will be trimmed before put into configuration.
 
 Parameters:
 
 name - property name.
 
 value - property value.
 
 source - the place that this configuration value came from (For debugging).
 
 Throws:
 
 IllegalArgumentException - when the value or name is null.
 - unset
```
public void unset(String name)
```
 Unset a previously set property.
 - setIfUnset
```
public void setIfUnset(String name,
 String value)
```
 Sets a property if it is currently unset.
 
 Parameters:
 
 name - the property name
 
 value - the new value
 - get
```
public String get(String name,
 String defaultValue)
```
 Get the value of the name. If the key is deprecated, it returns the value of the first key which replaces the deprecated key and is not null. If no such property exists, then defaultValue is returned.
 
 Parameters:
 
 name - property name, will be trimmed before get value.
 
 defaultValue - default value.
 
 Returns:
 
 property value, or defaultValue if the property doesn't exist.
 - getInt
```
public int getInt(String name,
 int defaultValue)
```
 Get the value of the name property as an int. If no such property exists, the provided default value is returned, or if the specified value is not a valid int, then an error is thrown.
 
 Parameters:
 
 name - property name.
 
 defaultValue - default value.
 
 Returns:
 
 property value as an int, or defaultValue.
 
 Throws:
 
 NumberFormatException - when the value is invalid
 - getInts
```
public int[] getInts(String name)
```
 Get the value of the name property as a set of comma-delimited int values. If no such property exists, an empty array is returned.
 
 Parameters:
 
 name - property name
 
 Returns:
 
 property value interpreted as an array of comma-delimited int values
 - setInt
```
public void setInt(String name,
 int value)
```
 Set the value of the name property to an int.
 
 Parameters:
 
 name - property name.
 
 value - int value of the property.
 - getLong
```
public long getLong(String name,
 long defaultValue)
```
 Get the value of the name property as a long. If no such property exists, the provided default value is returned, or if the specified value is not a valid long, then an error is thrown.
 
 Parameters:
 
 name - property name.
 
 defaultValue - default value.
 
 Returns:
 
 property value as a long, or defaultValue.
 
 Throws:
 
 NumberFormatException - when the value is invalid
 - getLongBytes
```
public long getLongBytes(String name,
 long defaultValue)
```
 Get the value of the name property as a long or human readable format. If no such property exists, the provided default value is returned, or if the specified value is not a valid long or human readable format, then an error is thrown. You can use the following suffix (case insensitive): k(kilo), m(mega), g(giga), t(tera), p(peta), e(exa)
 
 Parameters:
 
 name - property name.
 
 defaultValue - default value.
 
 Returns:
 
 property value as a long, or defaultValue.
 
 Throws:
 
 NumberFormatException - when the value is invalid
 - setLong
```
public void setLong(String name,
 long value)
```
 Set the value of the name property to a long.
 
 Parameters:
 
 name - property name.
 
 value - long value of the property.
 - getFloat
```
public float getFloat(String name,
 float defaultValue)
```
 Get the value of the name property as a float. If no such property exists, the provided default value is returned, or if the specified value is not a valid float, then an error is thrown.
 
 Parameters:
 
 name - property name.
 
 defaultValue - default value.
 
 Returns:
 
 property value as a float, or defaultValue.
 
 Throws:
 
 NumberFormatException - when the value is invalid
 - setFloat
```
public void setFloat(String name,
 float value)
```
 Set the value of the name property to a float.
 
 Parameters:
 
 name - property name.
 
 value - property value.
 - getDouble
```
public double getDouble(String name,
 double defaultValue)
```
 Get the value of the name property as a double. If no such property exists, the provided default value is returned, or if the specified value is not a valid double, then an error is thrown.
 
 Parameters:
 
 name - property name.
 
 defaultValue - default value.
 
 Returns:
 
 property value as a double, or defaultValue.
 
 Throws:
 
 NumberFormatException - when the value is invalid
 - setDouble
```
public void setDouble(String name,
 double value)
```
 Set the value of the name property to a double.
 
 Parameters:
 
 name - property name.
 
 value - property value.
 - getBoolean
```
public boolean getBoolean(String name,
 boolean defaultValue)
```
 Get the value of the name property as a boolean. If no such property is specified, or if the specified value is not a valid boolean, then defaultValue is returned.
 
 Parameters:
 
 name - property name.
 
 defaultValue - default value.
 
 Returns:
 
 property value as a boolean, or defaultValue.
 - setBoolean
```
public void setBoolean(String name,
 boolean value)
```
 Set the value of the name property to a boolean.
 
 Parameters:
 
 name - property name.
 
 value - boolean value of the property.
 - setBooleanIfUnset
```
public void setBooleanIfUnset(String name,
 boolean value)
```
 Set the given property, if it is currently unset.
 
 Parameters:
 
 name - property name
 
 value - new value
 - setEnum
```
public <T extends Enum<T>> void setEnum(String name,
 T value)
```
 Set the value of the name property to the given type. This is equivalent to set(<name>, value.toString()).
 
 Parameters:
 
 name - property name
 
 value - new value
 - getEnum
```
public <T extends Enum<T>> T getEnum(String name,
 T defaultValue)
```
 Return value matching this enumerated type. Note that the returned value is trimmed by this method.
 
 Parameters:
 
 name - Property name
 
 defaultValue - Value returned if no mapping exists
 
 Throws:
 
 IllegalArgumentException - If mapping is illegal for the type provided
 - setTimeDuration
```
public void setTimeDuration(String name,
 long value,
 TimeUnit unit)
```
 Set the value of name to the given time duration. This is equivalent to set(<name>, value + <time suffix>).
 
 Parameters:
 
 name - Property name
 
 value - Time duration
 
 unit - Unit of time
 - getTimeDuration
```
public long getTimeDuration(String name,
 long defaultValue,
 TimeUnit unit)
```
 Return time duration in the given time unit. Valid units are encoded in properties as suffixes: nanoseconds (ns), microseconds (us), milliseconds (ms), seconds (s), minutes (m), hours (h), and days (d).
 
 Parameters:
 
 name - Property name
 
 defaultValue - Value returned if no mapping exists.
 
 unit - Unit to convert the stored property, if it exists.
 
 Throws:
 
 NumberFormatException - If the property stripped of its unit is not a number
 - getTimeDuration
```
public long getTimeDuration(String name,
 String defaultValue,
 TimeUnit unit)
```
 - getTimeDuration
```
public long getTimeDuration(String name,
 long defaultValue,
 TimeUnit defaultUnit,
 TimeUnit returnUnit)
```
 Return time duration in the given time unit. Valid units are encoded in properties as suffixes: nanoseconds (ns), microseconds (us), milliseconds (ms), seconds (s), minutes (m), hours (h), and days (d). If no unit is provided, the default unit is applied.
 
 Parameters:
 
 name - Property name
 
 defaultValue - Value returned if no mapping exists.
 
 defaultUnit - Default time unit if no valid suffix is provided.
 
 returnUnit - The unit used for the returned value.
 
 Returns:
 
 time duration in given time unit
 
 Throws:
 
 NumberFormatException - If the property stripped of its unit is not a number
 - getTimeDuration
```
public long getTimeDuration(String name,
 String defaultValue,
 TimeUnit defaultUnit,
 TimeUnit returnUnit)
```
 - getTimeDurationHelper
```
public long getTimeDurationHelper(String name,
 String vStr,
 TimeUnit unit)
```
 Return time duration in the given time unit. Valid units are encoded in properties as suffixes: nanoseconds (ns), microseconds (us), milliseconds (ms), seconds (s), minutes (m), hours (h), and days (d).
 
 Parameters:
 
 name - Property name
 
 vStr - The string value with time unit suffix to be converted.
 
 unit - Unit to convert the stored property, if it exists.
 - getTimeDurations
```
public long[] getTimeDurations(String name,
 TimeUnit unit)
```
 - getStorageSize
```
public double getStorageSize(String name,
 String defaultValue,
 org.apache.hadoop.conf.StorageUnit targetUnit)
```
 Gets the Storage Size from the config, or returns the defaultValue. The unit of return value is specified in target unit.
 
 Parameters:
 
 name - - Key Name
 
 defaultValue - - Default Value -- e.g. 100MB
 
 targetUnit - - The units that we want result to be in.
 
 Returns:
 
 double -- formatted in target Units
 - getStorageSize
```
public double getStorageSize(String name,
 double defaultValue,
 org.apache.hadoop.conf.StorageUnit targetUnit)
```
 Gets storage size from a config file.
 
 Parameters:
 
 name - - Key to read.
 
 defaultValue - - The default value to return in case the key is not present.
 
 targetUnit - - The Storage unit that should be used for the return value.
 
 Returns:
 
 - double value in the Storage Unit specified.
 - setStorageSize
```
public void setStorageSize(String name,
 double value,
 org.apache.hadoop.conf.StorageUnit unit)
```
 Sets Storage Size for the specified key.
 
 Parameters:
 
 name - - Key to set.
 
 value - - The numeric value to set.
 
 unit - - Storage Unit to be used.
 - getPattern
```
public Pattern getPattern(String name,
 Pattern defaultValue)
```
 Get the value of the name property as a Pattern. If no such property is specified, or if the specified value is not a valid Pattern, then DefaultValue is returned. Note that the returned value is NOT trimmed by this method.
 
 Parameters:
 
 name - property name
 
 defaultValue - default value
 
 Returns:
 
 property value as a compiled Pattern, or defaultValue
 - setPattern
```
public void setPattern(String name,
 Pattern pattern)
```
 Set the given property to Pattern. If the pattern is passed as null, sets the empty pattern which results in further calls to getPattern(...) returning the default value.
 
 Parameters:
 
 name - property name
 
 pattern - new value
 - getPropertySources
```
@InterfaceStability.Unstable
public String[] getPropertySources(String name)
```
 Gets information about why a property was set. Typically this is the path to the resource objects (file, URL, etc.) the property came from, but it can also indicate that it was set programmatically, or because of the command line.
 
 Parameters:
 
 name - - The property name to get the source of.
 
 Returns:
 
 null - If the property or its source wasn't found. Otherwise, returns a list of the sources of the resource. The older sources are the first ones in the list. So for example if a configuration is set from the command line, and then written out to a file that is read back in the first entry would indicate that it was set from the command line, while the second one would indicate the file that the new configuration was read in from.
 - getRange
```
public org.apache.hadoop.conf.Configuration.IntegerRanges getRange(String name,
 String defaultValue)
```
 Parse the given attribute as a set of integer ranges
 
 Parameters:
 
 name - the attribute name
 
 defaultValue - the default value if it is not set
 
 Returns:
 
 a new set of ranges from the configured value
 - getStringCollection
```
public Collection<String> getStringCollection(String name)
```
 Get the comma delimited values of the name property as a collection of Strings. If no such property is specified then empty collection is returned.
 This is an optimized version of getStrings(String)
 
 Parameters:
 
 name - property name.
 
 Returns:
 
 property value as a collection of Strings.
 - getStrings
```
public String[] getStrings(String name)
```
 Get the comma delimited values of the name property as an array of Strings. If no such property is specified then null is returned.
 
 Parameters:
 
 name - property name.
 
 Returns:
 
 property value as an array of Strings, or null.
 - getStrings
```
public String[] getStrings(String name,
 String... defaultValue)
```
 Get the comma delimited values of the name property as an array of Strings. If no such property is specified then default value is returned.
 
 Parameters:
 
 name - property name.
 
 defaultValue - The default value
 
 Returns:
 
 property value as an array of Strings, or default value.
 - getTrimmedStringCollection
```
public Collection<String> getTrimmedStringCollection(String name)
```
 Get the comma delimited values of the name property as a collection of Strings, trimmed of the leading and trailing whitespace. If no such property is specified then empty Collection is returned.
 
 Parameters:
 
 name - property name.
 
 Returns:
 
 property value as a collection of Strings, or empty Collection
 - getTrimmedStrings
```
public String[] getTrimmedStrings(String name)
```
 Get the comma delimited values of the name property as an array of Strings, trimmed of the leading and trailing whitespace. If no such property is specified then an empty array is returned.
 
 Parameters:
 
 name - property name.
 
 Returns:
 
 property value as an array of trimmed Strings, or empty array.
 - getTrimmedStrings
```
public String[] getTrimmedStrings(String name,
 String... defaultValue)
```
 Get the comma delimited values of the name property as an array of Strings, trimmed of the leading and trailing whitespace. If no such property is specified then default value is returned.
 
 Parameters:
 
 name - property name.
 
 defaultValue - The default value
 
 Returns:
 
 property value as an array of trimmed Strings, or default value.
 - setStrings
```
public void setStrings(String name,
 String... values)
```
 Set the array of string values for the name property as as comma delimited values.
 
 Parameters:
 
 name - property name.
 
 values - The values
 - getPassword
```
public char[] getPassword(String name)
 throws IOException
```
 Get the value for a known password configuration element. In order to enable the elimination of clear text passwords in config, this method attempts to resolve the property name as an alias through the CredentialProvider API and conditionally fallsback to config.
 
 Parameters:
 
 name - property name
 
 Returns:
 
 password
 
 Throws:
 
 IOException
 - getPasswordFromCredentialProviders
```
public char[] getPasswordFromCredentialProviders(String name)
 throws IOException
```
 Try and resolve the provided element name as a credential provider alias.
 
 Parameters:
 
 name - alias of the provisioned credential
 
 Returns:
 
 password or null if not found
 
 Throws:
 
 IOException
 - getPasswordFromConfig
```
protected char[] getPasswordFromConfig(String name)
```
 Fallback to clear text passwords in configuration.
 
 Parameters:
 
 name -
 
 Returns:
 
 clear text password or null
 - getSocketAddr
```
public InetSocketAddress getSocketAddr(String hostProperty,
 String addressProperty,
 String defaultAddressValue,
 int defaultPort)
```
 Get the socket address for hostProperty as a InetSocketAddress. If hostProperty is null, addressProperty will be used. This is useful for cases where we want to differentiate between host bind address and address clients should use to establish connection.
 
 Parameters:
 
 hostProperty - bind host property name.
 
 addressProperty - address property name.
 
 defaultAddressValue - the default value
 
 defaultPort - the default port
 
 Returns:
 
 InetSocketAddress
 - getSocketAddr
```
public InetSocketAddress getSocketAddr(String name,
 String defaultAddress,
 int defaultPort)
```
 Get the socket address for name property as a InetSocketAddress.
 
 Parameters:
 
 name - property name.
 
 defaultAddress - the default value
 
 defaultPort - the default port
 
 Returns:
 
 InetSocketAddress
 - setSocketAddr
```
public void setSocketAddr(String name,
 InetSocketAddress addr)
```
 Set the socket address for the name property as a host:port.
 - updateConnectAddr
```
public InetSocketAddress updateConnectAddr(String hostProperty,
 String addressProperty,
 String defaultAddressValue,
 InetSocketAddress addr)
```
 Set the socket address a client can use to connect for the name property as a host:port. The wildcard address is replaced with the local host's address. If the host and address properties are configured the host component of the address will be combined with the port component of the addr to generate the address. This is to allow optional control over which host name is used in multi-home bind-host cases where a host can have multiple names
 
 Parameters:
 
 hostProperty - the bind-host configuration name
 
 addressProperty - the service address configuration name
 
 defaultAddressValue - the service default address configuration value
 
 addr - InetSocketAddress of the service listener
 
 Returns:
 
 InetSocketAddress for clients to connect
 - updateConnectAddr
```
public InetSocketAddress updateConnectAddr(String name,
 InetSocketAddress addr)
```
 Set the socket address a client can use to connect for the name property as a host:port. The wildcard address is replaced with the local host's address.
 
 Parameters:
 
 name - property name.
 
 addr - InetSocketAddress of a listener to store in the given property
 
 Returns:
 
 InetSocketAddress for clients to connect
 - getClassByName
```
public Class<?> getClassByName(String name)
 throws ClassNotFoundException
```
 Load a class by name.
 
 Parameters:
 
 name - the class name.
 
 Returns:
 
 the class object.
 
 Throws:
 
 ClassNotFoundException - if the class is not found.
 - getClassByNameOrNull
```
public Class<?> getClassByNameOrNull(String name)
```
 Load a class by name, returning null rather than throwing an exception if it couldn't be loaded. This is to avoid the overhead of creating an exception.
 
 Parameters:
 
 name - the class name
 
 Returns:
 
 the class object, or null if it could not be found.
 - getClasses
```
public Class<?>[] getClasses(String name,
 Class<?>... defaultValue)
```
 Get the value of the name property as an array of Class. The value of the property specifies a list of comma separated class names. If no such property is specified, then defaultValue is returned.
 
 Parameters:
 
 name - the property name.
 
 defaultValue - default value.
 
 Returns:
 
 property value as a Class[], or defaultValue.
 - getClass
```
public Class<?> getClass(String name,
 Class<?> defaultValue)
```
 Get the value of the name property as a Class. If no such property is specified, then defaultValue is returned.
 
 Parameters:
 
 name - the class name.
 
 defaultValue - default value.
 
 Returns:
 
 property value as a Class, or defaultValue.
 - getClass
```
public  Class<? extends U> getClass(String name,
 Class<? extends U> defaultValue,
 Class xface)
```
 Get the value of the name property as a Class implementing the interface specified by xface. If no such property is specified, then defaultValue is returned. An exception is thrown if the returned class does not implement the named interface.
 
 Parameters:
 
 name - the class name.
 
 defaultValue - default value.
 
 xface - the interface implemented by the named class.
 
 Returns:
 
 property value as a Class, or defaultValue.
 - getInstances
```
public  List getInstances(String name,
 Class xface)
```
 Get the value of the name property as a List of objects implementing the interface specified by xface. An exception is thrown if any of the classes does not exist, or if it does not implement the named interface.
 
 Parameters:
 
 name - the property name.
 
 xface - the interface implemented by the classes named by name.
 
 Returns:
 
 a List of objects implementing xface.
 - setClass
```
public void setClass(String name,
 Class<?> theClass,
 Class<?> xface)
```
 Set the value of the name property to the name of a theClass implementing the given interface xface. An exception is thrown if theClass does not implement the interface xface.
 
 Parameters:
 
 name - property name.
 
 theClass - property value.
 
 xface - the interface implemented by the named class.
 - getLocalPath
```
public Path getLocalPath(String dirsProp,
 String path)
 throws IOException
```
 Get a local file under a directory named by dirsProp with the given path. If dirsProp contains multiple directories, then one is chosen based on path's hash code. If the selected directory does not exist, an attempt is made to create it.
 
 Parameters:
 
 dirsProp - directory in which to locate the file.
 
 path - file-path.
 
 Returns:
 
 local file under the directory with the given path.
 
 Throws:
 
 IOException
 - getFile
```
public File getFile(String dirsProp,
 String path)
 throws IOException
```
 Get a local file name under a directory named in dirsProp with the given path. If dirsProp contains multiple directories, then one is chosen based on path's hash code. If the selected directory does not exist, an attempt is made to create it.
 
 Parameters:
 
 dirsProp - directory in which to locate the file.
 
 path - file-path.
 
 Returns:
 
 local file under the directory with the given path.
 
 Throws:
 
 IOException
 - getResource
```
public URL getResource(String name)
```
 Get the URL for the named resource.
 
 Parameters:
 
 name - resource name.
 
 Returns:
 
 the url for the named resource.
 - getConfResourceAsInputStream
```
public InputStream getConfResourceAsInputStream(String name)
```
 Get an input stream attached to the configuration resource with the given name.
 
 Parameters:
 
 name - configuration resource name.
 
 Returns:
 
 an input stream attached to the resource.
 - getConfResourceAsReader
```
public Reader getConfResourceAsReader(String name)
```
 Get a Reader attached to the configuration resource with the given name.
 
 Parameters:
 
 name - configuration resource name.
 
 Returns:
 
 a reader attached to the resource.
 - getFinalParameters
```
public Set<String> getFinalParameters()
```
 Get the set of parameters marked final.
 
 Returns:
 
 final parameter set.
 - getProps
```
protected Properties getProps()
```
 - size
```
public int size()
```
 Return the number of keys in the configuration.
 
 Returns:
 
 number of keys in the configuration.
 - clear
```
public void clear()
```
 Clears all keys from the configuration.
 - iterator
```
public Iterator<Map.Entry<String,String>> iterator()
```
 Get an Iterator to go through the list of String key-value pairs in the configuration.
 
 Specified by:
 
 iterator in interface Iterable<Map.Entry<String,String>>
 
 Returns:
 
 an iterator over the entries.
 - getPropsWithPrefix
```
public Map<String,String> getPropsWithPrefix(String confPrefix)
```
 Constructs a mapping of configuration and includes all properties that start with the specified configuration prefix. Property names in the mapping are trimmed to remove the configuration prefix.
 
 Parameters:
 
 confPrefix - configuration prefix
 
 Returns:
 
 mapping of configuration properties with prefix stripped
 - writeXml
```
public void writeXml(OutputStream out)
 throws IOException
```
 Write out the non-default properties in this configuration to the given OutputStream using UTF-8 encoding.
 
 Parameters:
 
 out - the output stream to write to.
 
 Throws:
 
 IOException
 - writeXml
```
public void writeXml(@Nullable
 Writer out)
 throws IOException
```
 Throws:
 
 IOException
 - writeXml
```
public void writeXml(@Nullable
 String propertyName,
 Writer out)
 throws IOException,
 IllegalArgumentException
```
 Write out the non-default properties in this configuration to the given Writer.
 - When property name is not empty and the property exists in the configuration, this method writes the property and its attributes to the Writer.
 - When property name is null or empty, this method writes all the configuration properties and their attributes to the Writer.
 - When property name is not empty but the property doesn't exist in the configuration, this method throws an IllegalArgumentException.

Parameters:: out - the writer to write to.
Throws:: IOException; IllegalArgumentException

dumpConfiguration

public static void dumpConfiguration(Configuration config,
                                     String propertyName,
                                     Writer out)
                              throws IOException

Writes properties and their attributes (final and resource) to the given Writer.

When propertyName is not empty, and the property exists in the configuration, the format of the output would be,

  {
    "property": {
      "key" : "key1",
      "value" : "value1",
      "isFinal" : "key1.isFinal",
      "resource" : "key1.resource"
    }
  }

When propertyName is null or empty, it behaves same as dumpConfiguration(Configuration, Writer), the output would be,

  { "properties" :
      [ { key : "key1",
          value : "value1",
          isFinal : "key1.isFinal",
          resource : "key1.resource" },
        { key : "key2",
          value : "value2",
          isFinal : "ke2.isFinal",
          resource : "key2.resource" }
       ]
   }

When propertyName is not empty, and the property is not found in the configuration, this method will throw an IllegalArgumentException.

Class Configuration

Resources

Final Parameters

Variable Expansion

Tags

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface java.lang.Iterable

Constructor Detail

Configuration

Configuration

Configuration

Method Detail

addDeprecations

addDeprecation

addDeprecation

addDeprecation

addDeprecation

isDeprecated

setDeprecatedProperties

reloadExistingConfigurations

addDefaultResource

setRestrictSystemPropertiesDefault

setRestrictSystemProperties

addResource

addResource

addResource

addResource

addResource

addResource

addResource

addResource

addResource

addResource

addResource

reloadConfiguration

get

setAllowNullValueProperties

setRestrictSystemProps

onlyKeyExists

getTrimmed

getTrimmed

getRaw

set

set

unset

setIfUnset

get

getInt

getInts

setInt

getLong

getLongBytes

setLong

getFloat

setFloat

getDouble

setDouble

getBoolean

setBoolean

setBooleanIfUnset

setEnum

getEnum

setTimeDuration

getTimeDuration

getTimeDuration

getTimeDuration

getTimeDuration

getTimeDurationHelper

getTimeDurations

getStorageSize

getStorageSize

setStorageSize

getPattern

setPattern

getPropertySources

getRange

getStringCollection

getStrings