org.apache.hadoop.registry.client.binding

Class JsonSerDeser<T>

java.lang.Object

org.apache.hadoop.registry.client.binding.JsonSerDeser<T>

Type Parameters:

T - Type to marshal.

Direct Known Subclasses:

RegistryUtils.ServiceRecordMarshal

@InterfaceAudience.Private
@InterfaceStability.Evolving
public class JsonSerDeser<T>
extends Object

Support for marshalling objects to and from JSON.

It constructs an object mapper as an instance field. and synchronizes access to those methods which use the mapper

Field Summary

Fields

Modifier and Type	Field and Description
static String	E_DATA_TOO_SHORT
static String	E_MISSING_MARKER_STRING
static String	E_NO_DATA

Constructor Summary

Constructors

Constructor and Description
JsonSerDeser(Class<T> classType) Create an instance bound to a specific type

Method Summary

Methods

Modifier and Type	Method and Description
T	fromBytes(String path, byte[] bytes) Deserialize from a byte array
T	fromBytes(String path, byte[] bytes, String marker) Deserialize from a byte array, optionally checking for a marker string.
T	fromFile(File jsonFile) Convert from a JSON file
T	fromInstance(T instance) clone by converting to JSON and back again.
T	fromJson(String json) Convert from JSON
T	fromResource(String resource) Convert from a JSON file
String	getName() Get the simple name of the class type to be marshalled
T	load(org.apache.hadoop.fs.FileSystem fs, org.apache.hadoop.fs.Path path) Load from a Hadoop filesystem
void	save(org.apache.hadoop.fs.FileSystem fs, org.apache.hadoop.fs.Path path, T instance, boolean overwrite) Save a cluster description to a hadoop filesystem
byte[]	toBytes(T instance) Convert JSON To bytes
String	toJson(T instance) Convert an instance to a JSON string
String	toString(T instance) Convert an instance to a string form for output.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

E_NO_DATA

public static final String E_NO_DATA

See Also:

Constant Field Values

E_DATA_TOO_SHORT

public static final String E_DATA_TOO_SHORT

See Also:

Constant Field Values

E_MISSING_MARKER_STRING

public static final String E_MISSING_MARKER_STRING

See Also:

Constant Field Values

Constructor Detail

JsonSerDeser

public JsonSerDeser(Class<T> classType)

Create an instance bound to a specific type

Parameters:

classType - class to marshall

Method Detail

getName

public String getName()

Get the simple name of the class type to be marshalled

Returns:

the name of the class being marshalled

fromJson

public T fromJson(String json)
           throws IOException,
                  org.codehaus.jackson.JsonParseException,
                  org.codehaus.jackson.map.JsonMappingException

Convert from JSON

Parameters:

json - input

Returns:

the parsed JSON

Throws:

IOException - IO

org.codehaus.jackson.map.JsonMappingException - failure to map from the JSON to this class

org.codehaus.jackson.JsonParseException

fromFile

public T fromFile(File jsonFile)
           throws IOException,
                  org.codehaus.jackson.JsonParseException,
                  org.codehaus.jackson.map.JsonMappingException

Convert from a JSON file

Parameters:

jsonFile - input file

Returns:

the parsed JSON

Throws:

IOException - IO problems

org.codehaus.jackson.map.JsonMappingException - failure to map from the JSON to this class

org.codehaus.jackson.JsonParseException

fromResource

public T fromResource(String resource)
               throws IOException,
                      org.codehaus.jackson.JsonParseException,
                      org.codehaus.jackson.map.JsonMappingException

Convert from a JSON file

Parameters:

resource - input file

Returns:

the parsed JSON

Throws:

IOException - IO problems

org.codehaus.jackson.map.JsonMappingException - failure to map from the JSON to this class

org.codehaus.jackson.JsonParseException

fromInstance

public T fromInstance(T instance)
               throws IOException

clone by converting to JSON and back again. This is much less efficient than any Java clone process.

Parameters:

instance - instance to duplicate

Returns:

a new instance

Throws:

IOException - problems.

load

public T load(org.apache.hadoop.fs.FileSystem fs,
     org.apache.hadoop.fs.Path path)
       throws IOException,
              org.codehaus.jackson.JsonParseException,
              org.codehaus.jackson.map.JsonMappingException

Load from a Hadoop filesystem

Parameters:

fs - filesystem

path - path

Returns:

a loaded CD

Throws:

IOException - IO problems

EOFException - if not enough bytes were read in

org.codehaus.jackson.JsonParseException - parse problems

org.codehaus.jackson.map.JsonMappingException - O/J mapping problems

save

public void save(org.apache.hadoop.fs.FileSystem fs,
        org.apache.hadoop.fs.Path path,
        T instance,
        boolean overwrite)
          throws IOException

Save a cluster description to a hadoop filesystem

Parameters:

fs - filesystem

path - path

overwrite - should any existing file be overwritten

Throws:

IOException - IO exception

toBytes

public byte[] toBytes(T instance)
               throws IOException

Convert JSON To bytes

Parameters:

instance - instance to convert

Returns:

a byte array

Throws:

IOException

fromBytes

public T fromBytes(String path,
          byte[] bytes)
            throws IOException,
                   InvalidRecordException

Deserialize from a byte array

Parameters:

path - path the data came from

bytes - byte array

Throws:

IOException - all problems

EOFException - not enough data

InvalidRecordException - if the parsing failed -the record is invalid

fromBytes

public T fromBytes(String path,
          byte[] bytes,
          String marker)
            throws IOException,
                   NoRecordException,
                   InvalidRecordException

Deserialize from a byte array, optionally checking for a marker string.

If the marker parameter is supplied (and not empty), then its presence will be verified before the JSON parsing takes place; it is a fast-fail check. If not found, an InvalidRecordException exception will be raised

Parameters:

path - path the data came from

bytes - byte array

marker - an optional string which, if set, MUST be present in the UTF-8 parsed payload.

Returns:

The parsed record

Throws:

IOException - all problems

EOFException - not enough data

InvalidRecordException - if the JSON parsing failed.

NoRecordException - if the data is not considered a record: either it is too short or it did not contain the marker string.

toJson

public String toJson(T instance)
              throws IOException,
                     org.codehaus.jackson.JsonGenerationException,
                     org.codehaus.jackson.map.JsonMappingException

Convert an instance to a JSON string

Parameters:

instance - instance to convert

Returns:

a JSON string description

Throws:

org.codehaus.jackson.JsonParseException - parse problems

org.codehaus.jackson.map.JsonMappingException - O/J mapping problems

IOException

org.codehaus.jackson.JsonGenerationException

toString

public String toString(T instance)

Convert an instance to a string form for output. This is a robust operation which will convert any JSON-generating exceptions into error text.

Parameters:

instance - non-null instance

Returns:

a JSON string