Package org.elasticsearch.xcontent.internal

Class EmbeddedImplClassLoader

java.lang.Object

java.lang.ClassLoader

java.security.SecureClassLoader

org.elasticsearch.xcontent.internal.EmbeddedImplClassLoader

public final class EmbeddedImplClassLoader
extends SecureClassLoader

A class loader that is responsible for loading implementation classes and resources embedded within an archive.

This loader facilitates a scenario whereby an API can embed its implementation and dependencies all within the same archive as the API itself. The archive can be put directly on the class path, where it's API classes are loadable by the application class loader, but the embedded implementation and dependencies are not. When locating a concrete provider, the API can create an instance of an EmbeddedImplClassLoader to locate and load the implementation.

The archive typically consists of two disjoint logically groups: 1. the top-level classes and resources, 2. the embedded classes and resources

The top-level classes and resources are typically loaded and located, respectively, by the parent of an EmbeddedImplClassLoader loader. The embedded classes and resources, are located by the parent loader as pure resources with a provider specific name prefix, and classes are defined by the EmbeddedImplClassLoader. The list of prefixes is determined by reading the entries in the MANIFEST.TXT.

For example, the structure of the archive named x-content:

  /org/elasticsearch/xcontent/XContent.class
  /IMPL-JARS/x-content/LISTING.TXT - contains list of jar file names, newline separated
  /IMPL-JARS/x-content/x-content-impl.jar/xxx
  /IMPL-JARS/x-content/dep-1.jar/abc
  /IMPL-JARS/x-content/dep-2.jar/xyz
 

Method Summary

Modifier and Type	Method	Description
Class<?>	findClass(String name)
protected URL	findResource(String name)
protected Enumeration<URL>	findResources(String name)

Methods inherited from class java.security.SecureClassLoader

defineClass, defineClass, getPermissions

Methods inherited from class java.lang.ClassLoader

clearAssertionStatus, defineClass, defineClass, defineClass, defineClass, definePackage, findClass, findLibrary, findLoadedClass, findResource, findSystemClass, getClassLoadingLock, getDefinedPackage, getDefinedPackages, getName, getPackage, getPackages, getParent, getPlatformClassLoader, getResource, getResourceAsStream, getResources, getSystemClassLoader, getSystemResource, getSystemResourceAsStream, getSystemResources, getUnnamedModule, isRegisteredAsParallelCapable, loadClass, loadClass, registerAsParallelCapable, resolveClass, resources, setClassAssertionStatus, setDefaultAssertionStatus, setPackageAssertionStatus, setSigners

Methods inherited from class java.lang.Object

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

Method Details

findClass

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

Overrides:

findClass in class ClassLoader

Throws:

ClassNotFoundException

findResource

protected URL findResource(String name)

Overrides:

findResource in class ClassLoader

findResources

protected Enumeration<URL> findResources(String name)
                                  throws IOException

Overrides:

findResources in class ClassLoader

Throws:

IOException