com.netphantom.common

Class JarClassLoader

java.lang.Object

java.lang.ClassLoader

java.security.SecureClassLoader

com.netphantom.common.JarClassLoader

All Implemented Interfaces:

Closeable, AutoCloseable

public class JarClassLoader
extends SecureClassLoader
implements Closeable

This class handles one Jar or several Jar file(s) (already loaded), typically NpJarFile or MemoryJarFile's.

Please note that this class is NOT thread safe for adding additional Jars and subdirectories. This should be done PRIOR to using the class loader. This way, the code does not use any synchronization and is therefore faster.

Author:

Christopher Mindus

Constructor Summary

Constructors

Constructor and Description
JarClassLoader(ClassLoader parent, JarFilePath... jarFilePaths) Creates the Jar file class loader using the default parent class loader for delegation.
JarClassLoader(IJarFile jar) Creates the Jar file class loader using the default parent class loader for delegation.
JarClassLoader(IJarFile jar, ClassLoader parent) Creates the Jar file class loader with a specified parent class loader for delegation.
JarClassLoader(IJarFile jar, String subDirectory, ClassLoader parent) Creates the Jar file class loader using the default parent class loader for delegation.

Method Summary

Modifier and Type	Method and Description
void	add(File directory) Adds a new Directory entry to the class loader.
void	add(IJarFile jar) Adds a new jar with root as subdirectory to the class loader.
void	add(IJarFile jar, String subDirectory) Adds a new jar with subdirectory to the class loader.
void	add(JarFilePath jarFilePath) Adds a new JarFilePath entry to the class loader.
void	close() Closes this class loader, so that it can no longer be used to load new classes or resources that are defined by this loader.
Class<?>	findClass(String name) Finds the class with the specified binary name.
URL	findResource(String name) Finds the resource with the given name.
Enumeration<URL>	findResources(String name) Returns an enumeration of URL objects representing all the resources with the given name.
InputStream	getResourceAsStream(String name) Open for reading, a resource of the specified name from the search path used to load classes.
void	initialize() Initializes the class loader by defining all packages.

Methods inherited from class java.security.SecureClassLoader

defineClass, defineClass, getPermissions

Methods inherited from class java.lang.ClassLoader

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

Methods inherited from class java.lang.Object

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

Constructor Detail

JarClassLoader

public JarClassLoader(IJarFile jar)

Creates the Jar file class loader using the default parent class loader for delegation.

It is IMPORTANT to call initialize() before using the class loader.

Parameters:

jar - The Jar file for the class path.

JarClassLoader

public JarClassLoader(IJarFile jar,
                      ClassLoader parent)

Creates the Jar file class loader with a specified parent class loader for delegation.

It is IMPORTANT to call initialize() before using the class loader.

Parameters:

jar - The Jar file for the class path.

parent - The Parent class loader.

JarClassLoader

public JarClassLoader(IJarFile jar,
                      String subDirectory,
                      ClassLoader parent)
               throws IllegalArgumentException

Creates the Jar file class loader using the default parent class loader for delegation.

It is IMPORTANT to call initialize() before using the class loader.

Parameters:

jar - The Jar file for the class path.

subDirectory - Path inside the Jar file, e.g. System/classpath/bin/, or null for the entire JarFile. If an entry is not ending with a "/", it will be appended.

parent - The Parent class loader.

Throws:

IllegalArgumentException - If the subDirectory is not found in the Jar file.

JarClassLoader

public JarClassLoader(ClassLoader parent,
                      JarFilePath... jarFilePaths)
               throws IllegalArgumentException

Creates the Jar file class loader using the default parent class loader for delegation.

It is IMPORTANT to call initialize() before using the class loader.

Parameters:

parent - The Parent class loader.

jarFilePaths - Jar file and paths list or array.

Throws:

IllegalArgumentException - If the subDirectory is not found in the Jar file.

Method Detail

add

public final void add(IJarFile jar)

Adds a new jar with root as subdirectory to the class loader. Please note that this call must be done prior to using the class loader as it is not thread safe.

Parameters:

jar - The Jar file for the class path.

Throws:

IllegalStateException - If class loader already is initialized or has been closed.

add

public final void add(IJarFile jar,
                      String subDirectory)

Adds a new jar with subdirectory to the class loader. Please note that this call must be done prior to using the class loader as it is not thread safe.

Parameters:

jar - The Jar file for the class path.

subDirectory - Path inside the Jar file, e.g. System/classpath/bin/, or null for the entire JarFile. If an entry is not ending with a "/", it will be appended.

Throws:

IllegalStateException - If class loader already is initialized or has been closed.

add

public final void add(JarFilePath jarFilePath)

Adds a new JarFilePath entry to the class loader. Please note that this call must be done prior to using the class loader as it is not thread safe.

Parameters:

jarFilePath - The Jar file for the class path.

Throws:

IllegalStateException - If class loader already is initialized or has been closed.

add

public final void add(File directory)
               throws IOException

Adds a new Directory entry to the class loader. Please note that this call must be done prior to using the class loader as it is not thread safe.

Parameters:

directory - The directory for the class path.

Throws:

IOException - If the directory is not found or refers to a non-directory.

IllegalStateException - If class loader already is initialized or has been closed.

initialize

public final void initialize()
                      throws IOException

Initializes the class loader by defining all packages.

Throws:

IOException - For I/O errors or if there is a sealing problem in the Jar file.

IllegalStateException - If class loader already is initialized or has been closed.

close

public void close()
           throws IOException

Closes this class loader, so that it can no longer be used to load new classes or resources that are defined by this loader. Classes and resources defined by any of this loader's parents in the delegation hierarchy are still accessible. Also, any classes or resources that are already loaded, are still accessible.

In the case of jar:, file:, npjar: and memjar: URLs, it also closes any files that were opened by it. If another thread is loading a class when the close method is invoked, then the result of that load is undefined.

The method makes a best effort attempt to close all opened files, by catching IOException's internally. Unchecked exceptions and errors are not caught. Calling close on an already closed loader has no effect.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Throws:

IOException - If closing any file opened by this class loader resulted in an IOException. Any such exceptions are caught internally. If only one is caught, then it is re-thrown. If more than one exception is caught, then the second and following exceptions are added as suppressed exceptions of the first one caught, which is then re-thrown.

findClass

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

Finds the class with the specified binary name. This method is overridden by this class loader implementations that follow the delegation model for loading classes, and will be invoked by the loadClass method after checking the parent class loader for the requested class.

Overrides:

findClass in class ClassLoader

Parameters:

name - The binary name of the class

Returns:

The resulting Class object

Throws:

ClassNotFoundException - If the class could not be found.

IllegalStateException - If class loader is not initialized.

See Also:

ClassLoader.findClass(java.lang.String)

findResource

public final URL findResource(String name)

Finds the resource with the given name. Class loader implementations should override this method to specify where to find resources.

Overrides:

findResource in class ClassLoader

Parameters:

name - The resource name.

Returns:

An URL object for reading the resource, or null if the resource could not be found.

Throws:

IllegalStateException - If class loader is not initialized.

findResources

public final Enumeration<URL> findResources(String name)

Returns an enumeration of URL objects representing all the resources with the given name. Class loader implementations should override this method to specify where to load resources from.

Overrides:

findResources in class ClassLoader

Parameters:

name - The resource name.

Returns:

An enumeration of URL objects for the resources.

Throws:

IllegalStateException - If class loader is not initialized.

getResourceAsStream

public final InputStream getResourceAsStream(String name)

Open for reading, a resource of the specified name from the search path used to load classes. This method locates the resource through the system class loader (see getSystemClassLoader()).

Overrides:

getResourceAsStream in class ClassLoader

Parameters:

name - the name of the resource.

Returns:

An input stream for reading the resource, or null if the resource could not be found.

Throws:

IllegalStateException - If class loader is not initialized.

See Also:

ClassLoader.getResourceAsStream(java.lang.String)