org.apache.hadoop.util

Class ApplicationClassLoader

java.lang.Object

java.lang.ClassLoader

java.security.SecureClassLoader

java.net.URLClassLoader

org.apache.hadoop.util.ApplicationClassLoader

All Implemented Interfaces:

Closeable, AutoCloseable

Direct Known Subclasses:

ApplicationClassLoader

@InterfaceAudience.Public
@InterfaceStability.Unstable
public class ApplicationClassLoader
extends URLClassLoader

A URLClassLoader for application isolation. Classes from the application JARs are loaded in preference to the parent loader.

Field Summary

Fields

Modifier and Type	Field and Description
static String	SYSTEM_CLASSES_DEFAULT Default value of the system classes if the user did not override them.

Constructor Summary

Constructors

Constructor and Description
ApplicationClassLoader(String classpath, ClassLoader parent, List<String> systemClasses)
ApplicationClassLoader(URL[] urls, ClassLoader parent, List<String> systemClasses)

Method Summary

Methods

Modifier and Type	Method and Description
URL	getResource(String name)
static boolean	isSystemClass(String name, List<String> systemClasses) Checks if a class should be included as a system class.
Class<?>	loadClass(String name)
protected Class<?>	loadClass(String name, boolean resolve)

Methods inherited from class java.net.URLClassLoader

addURL, close, definePackage, findClass, findResource, findResources, getPermissions, getResourceAsStream, getURLs, newInstance, newInstance

Methods inherited from class java.security.SecureClassLoader

defineClass, defineClass

Methods inherited from class java.lang.ClassLoader

clearAssertionStatus, defineClass, defineClass, defineClass, defineClass, definePackage, findLibrary, findLoadedClass, findSystemClass, getClassLoadingLock, getPackage, getPackages, getParent, getResources, getSystemClassLoader, getSystemResource, getSystemResourceAsStream, getSystemResources, registerAsParallelCapable, resolveClass, setClassAssertionStatus, setDefaultAssertionStatus, setPackageAssertionStatus, setSigners

Methods inherited from class java.lang.Object

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

Field Detail

SYSTEM_CLASSES_DEFAULT

public static final String SYSTEM_CLASSES_DEFAULT

Default value of the system classes if the user did not override them. JDK classes, hadoop classes and resources, and some select third-party classes are considered system classes, and are not loaded by the application classloader.

Constructor Detail

ApplicationClassLoader

public ApplicationClassLoader(URL[] urls,
                      ClassLoader parent,
                      List<String> systemClasses)

ApplicationClassLoader

public ApplicationClassLoader(String classpath,
                      ClassLoader parent,
                      List<String> systemClasses)
                       throws MalformedURLException

Throws:

MalformedURLException

Method Detail

getResource

public URL getResource(String name)

Overrides:

getResource in class ClassLoader

loadClass

public Class<?> loadClass(String name)
                   throws ClassNotFoundException

Overrides:

loadClass in class ClassLoader

Throws:

ClassNotFoundException

loadClass

protected Class<?> loadClass(String name,
                 boolean resolve)
                      throws ClassNotFoundException

Overrides:

loadClass in class ClassLoader

Throws:

ClassNotFoundException

isSystemClass

public static boolean isSystemClass(String name,
                    List<String> systemClasses)

Checks if a class should be included as a system class. A class is a system class if and only if it matches one of the positive patterns and none of the negative ones.

Parameters:

name - the class name to check

systemClasses - a list of system class configurations.

Returns:

true if the class is a system class