Android - An Open Handset Alliance Project

java.net
public class

java.net.URLClassLoader

java.lang.Object
	java.lang.ClassLoader
		java.security.SecureClassLoader
			java.net.URLClassLoader

This class loader is responsible for loading classes and resources from a list of URLs which can refer to either directories or JAR files. Classes loaded by this URLClassLoader are granted permission to access the URLs contained in the URL search list.

Summary

Public Constructors

					URLClassLoader(URL[] urls)
					Constructs a new instance of this class.
					URLClassLoader(URL[] urls, ClassLoader parent)
					Constructs a new instance of this class.
					URLClassLoader(URL[] searchUrls, ClassLoader parent, URLStreamHandlerFactory factory)
					Constructs a new instance of this class.

Public Methods

	URL	findResource(String name)
		Answers a URL referencing the specified resource or null if no resource could be found.
	Enumeration	findResources(String name)
		Answers an enumeration of URLs that contain the specified resource.
	URL[]	getURLs()
		Answers the search list of this URLClassLoader
static	URLClassLoader	newInstance(URL[] urls, ClassLoader parentCl)
		Answers an instance of `URLClassLoader`.
static	URLClassLoader	newInstance(URL[] urls)
		Answers an instance of `URLClassLoader`.

Protected Methods

				void	addURL(URL url)
					Adds the specified URL to the search list.
				Package	definePackage(String packageName, Manifest manifest, URL url)
					Define a new Package using information extracted from the specified Manifest.
				Class	findClass(String clsName)
					Locates and loads the specified class, searching this URLClassLoader's list of URLS.
				PermissionCollection	getPermissions(CodeSource codesource)
					Answers the permissions for the given code source.

Methods inherited from class java.security.SecureClassLoader

defineClass, defineClass, getPermissions

Methods inherited from class java.lang.ClassLoader

		void	clearAssertionStatus()
			Clears the default, package and class assertion status of a classloader
final		Class	defineClass(byte[] classRep, int offset, int length)
			This method is deprecated. Use defineClass(String, byte[], int, int)
final		Class	defineClass(String name, ByteBuffer b, ProtectionDomain protectionDomain)
			Defines a new class for the name, bytecodes in the byte buffer and the protection domain.
final		Class	defineClass(String className, byte[] classRep, int offset, int length, ProtectionDomain protectionDomain)
			Constructs a new class from an array of bytes containing a class definition in class file format and assigns the new class to the specified protection domain.
final		Class	defineClass(String className, byte[] classRep, int offset, int length)
			Constructs a new class from an array of bytes containing a class definition in class file format.
		Package	definePackage(String name, String specTitle, String specVersion, String specVendor, String implTitle, String implVersion, String implVendor, URL sealBase)
			Define a new Package using the specified information.
		Class	findClass(String className)
			Overridden by subclasses, by default throws ClassNotFoundException.
		String	findLibrary(String libName)
			Answers the absolute path of the file containing the library associated with the given name, or null.
final		Class	findLoadedClass(String className)
			Attempts to find and return a class which has already been loaded by the virtual machine.
		URL	findResource(String resName)
			Answers an URL which can be used to access the resource described by resName, using the class loader's resource lookup algorithm.
		Enumeration	findResources(String resName)
			Answers an Enumeration of URL which can be used to access the resources described by resName, using the class loader's resource lookup algorithm.
final		Class	findSystemClass(String className)
			Attempts to load a class using the system class loader.
		Package	getPackage(String name)
			Attempt to locate the requested package.
		Package[]	getPackages()
			Return all the packages known to this class loader.
final		ClassLoader	getParent()
			Returns the specified ClassLoader's parent.
		URL	getResource(String resName)
			Answers an URL which can be used to access the resource described by resName, using the class loader's resource lookup algorithm.
		InputStream	getResourceAsStream(String resName)
			Answers a stream on a resource found by looking up resName using the class loader's resource lookup algorithm.
		Enumeration	getResources(String resName)
			Answers an Enumeration of URL which can be used to access the resources described by resName, using the class loader's resource lookup algorithm.
	static	ClassLoader	getSystemClassLoader()
			Returns the system class loader.
	static	URL	getSystemResource(String resName)
			Answers an URL specifying a resource which can be found by looking up resName using the system class loader's resource lookup algorithm.
	static	InputStream	getSystemResourceAsStream(String resName)
			Answers a stream on a resource found by looking up resName using the system class loader's resource lookup algorithm.
	static	Enumeration	getSystemResources(String resName)
			Answers an Enumeration of URLs containing all resources which can be found by looking up resName using the system class loader's resource lookup algorithm.
		Class	loadClass(String className)
			Invoked by the Virtual Machine when resolving class references.
		Class	loadClass(String className, boolean resolve)
			Loads the class with the specified name, optionally linking the class after load.
final		void	resolveClass(Class clazz)
			Forces a class to be linked (initialized).
		void	setClassAssertionStatus(String cname, boolean enable)
			Sets the assertion status of a class.
		void	setDefaultAssertionStatus(boolean enable)
			Sets the default assertion status of a classloader
		void	setPackageAssertionStatus(String pname, boolean enable)
			Sets the assertion status of a package.
final		void	setSigners(Class c, Object[] signers)
			Sets the signers of a class.

Methods inherited from class java.lang.Object

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

	Object	clone()
		Answers a new instance of the same class as the receiver, whose slots have been filled in with the values in the slots of the receiver.
	boolean	equals(Object o)
		Compares the argument to the receiver, and answers true if they represent the same object using a class specific comparison.
	void	finalize()
		Called by the virtual machine when there are no longer any (non-weak) references to the receiver.
final	Class	getClass()
		Answers the unique instance of java.lang.Class which represents the class of the receiver.
	int	hashCode()
		Answers an integer hash code for the receiver.
final	void	notify()
		Causes one thread which is `wait` ing on the receiver to be made ready to run.
final	void	notifyAll()
		Causes all threads which are `wait` ing on the receiver to be made ready to run.
	String	toString()
		Answers a string containing a concise, human-readable description of the receiver.
final	void	wait(long time, int frac)
		Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by `notify` or `notifyAll`) or the expiration of the timeout.
final	void	wait(long time)
		Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by `notify` or `notifyAll`) or the expiration of the timeout.
final	void	wait()
		Causes the thread which sent this message to be made not ready to run pending some change in the receiver (as indicated by `notify` or `notifyAll`).

Details

Public Constructors

public URLClassLoader(URL[] urls)

Constructs a new instance of this class. The newly created instance will have the system ClassLoader as its parent. URLs that end with "/" are assumed to be directories, otherwise they are assumed to be Jar files.

Parameters

urls	the URLs to search

Throws

SecurityException	if a security manager exists and its checkCreateClassLoader method doesn't allow creation of new ClassLoaders

public URLClassLoader(URL[] urls, ClassLoader parent)

Constructs a new instance of this class. The newly created instance will have the specified ClassLoader as its parent. URLs that end with "/" are assumed to be directories, otherwise they are assumed to be Jar files.

Parameters

urls	the URLs to search
parent	the ClassLoader to assign as this loader's parent.

Throws

SecurityException	if a security manager exists and its checkCreateClassLoader method doesn't allow creation of new ClassLoaders

public URLClassLoader(URL[] searchUrls, ClassLoader parent, URLStreamHandlerFactory factory)

Constructs a new instance of this class. The newly created instance will have the specified ClassLoader as its parent and use the specified factory to create stream handlers. URLs that end with "/" are assumed to be directories, otherwise they are assumed to be Jar files.

Parameters

searchUrls	java.net.URL[] the URLs that will be searched in the order they were specified for resource
parent	ClassLoader the ClassLoader name of the resource to find.
factory	java.net.URLStreamHandlerFactory the factory that will used to create stream (protocol) handlers

Throws

SecurityException	if a security manager exists and its checkCreateClassLoader method doesn't allow creation of new ClassLoaders

Public Methods

public URL findResource(String name)

Answers a URL referencing the specified resource or null if no resource could be found.

Parameters

name	java.lang.String the name of the requested resource

Returns

URL URL for the resource.

public Enumeration findResources(String name)

Answers an enumeration of URLs that contain the specified resource.

Parameters

name	java.lang.String the name of the requested resource

Returns

Enumeration the enumeration of URLs that contain the specified resource.

Throws

IOException	thrown if an IO Exception occurs while attempting to connect

public URL[] getURLs()

Answers the search list of this URLClassLoader

Returns

java.net.URL[]

public static URLClassLoader newInstance(URL[] urls, ClassLoader parentCl)

Answers an instance of URLClassLoader. loadClass() of the new instance will call security manager's checkPackageAccess() before loading a class.

Parameters

urls	URL[] the list of URLs that is passed to the new `URLClassloader`
parentCl	ClassLoader the parent class loader that is passed to the new `URLClassloader`

Returns

URLClassLoader the new instance of URLClassLoader

public static URLClassLoader newInstance(URL[] urls)

Answers an instance of URLClassLoader. loadClass() of the new instance will call the SecurityManager's checkPackageAccess() before loading a class.

Parameters

urls	java.net.URL[] a list of URLs that is passed to the new URLClassloader

Returns

java.net.URLClassLoader the new instance of URLClassLoader

Protected Methods

protected void addURL(URL url)

Adds the specified URL to the search list.

Parameters

url	java.net.URL the new URL

protected Package definePackage(String packageName, Manifest manifest, URL url)

Define a new Package using information extracted from the specified Manifest.

Parameters

packageName	The name of the package
manifest	The Manifest for the Package
url	The code source for the Package

Returns

The Package created

Throws

IllegalArgumentException	if the Package already exists

protected Class findClass(String clsName)

Locates and loads the specified class, searching this URLClassLoader's list of URLS.

Parameters

clsName	String the name of the class.

Returns

Class the class that has been loaded.

Throws

ClassNotFoundException	if the class cannot be loaded

protected PermissionCollection getPermissions(CodeSource codesource)

Answers the permissions for the given code source. First this method retrieves the permissions from the system policy. If the protocol is "file:/" then a new permission, FilePermission, granting the read permission to the file is added to the permission collection. Otherwise, connecting to and accepting connections from the URL is granted.

Parameters

codesource	CodeSource

Returns

PermissionCollection

final	Class	defineClass(String name, ByteBuffer b, CodeSource cs)
final	Class	defineClass(String name, byte[] b, int off, int len, CodeSource cs)
	PermissionCollection	getPermissions(CodeSource codesource)


e.g. "intent" or "activity"

Android - An Open Handset Alliance Project

Documentation

Goodies

java.net.URLClassLoader

Summary

Public Constructors

Public Methods

Protected Methods

Methods inherited from class java.security.SecureClassLoader

Methods inherited from class java.lang.ClassLoader

Methods inherited from class java.lang.Object

Details

Public Constructors

public URLClassLoader(URL[] urls)

Parameters

Throws

public URLClassLoader(URL[] urls, ClassLoader parent)

Parameters

Throws

public URLClassLoader(URL[] searchUrls, ClassLoader parent, URLStreamHandlerFactory factory)

Parameters

Throws

Public Methods

public URL findResource(String name)

Parameters

Returns

public Enumeration findResources(String name)

Parameters

Returns

Throws

public URL[] getURLs()

Returns

public static URLClassLoader newInstance(URL[] urls, ClassLoader parentCl)

Parameters

Returns

public static URLClassLoader newInstance(URL[] urls)

Parameters

Returns

Protected Methods

protected void addURL(URL url)

Parameters

protected Package definePackage(String packageName, Manifest manifest, URL url)

Parameters

Returns

Throws

protected Class findClass(String clsName)

Parameters

Returns

Throws

protected PermissionCollection getPermissions(CodeSource codesource)

Parameters

Returns