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Class java.net.URLClassLoader

java.lang.Object
    |
    +----java.lang.ClassLoader
            |
            +----java.security.SecureClassLoader
                    |
                    +----java.net.URLClassLoader

public class URLClassLoader

extends SecureClassLoader

URLClassLoader(URL[])

Constructs a new URLClassLoader for the specified URLs.

URLClassLoader(URL[], ClassLoader)

checkPackageDefinition(String)

This method can be overridden to throw a SecurityException if the calling thread is not allowed to define classes in the package specified by the argument.

definePackage(String, Attributes, URL)

Defines a package by name in this ClassLoader.

findLocalClass(String)

Finds and loads the class with the specified name from the URL search path.

getExtClassLoader()

Returns the shared instance of ClassLoader used to load classes and resources from installed extensions.

getLocalResource(String)

Finds the resource with the specified name on the URL search path.

getLocalResources(String)

Returns an Enumeration of URLs representing all of the resources with the given name that could be found on the URL search path.

invokeClass(String, String[])

Invokes an application given the name of the application's main class and an array of arguments.

public URLClassLoader(URL[] urls)

Constructs a new URLClassLoader for the specified URLs. The URLs will be searched in the order specified after looking for classes and resources in installed extensions.

Parameters:

urls - the URLs from which to load classes and resources

public URLClassLoader(URL[] urls,
                      ClassLoader parent)

protected Class findLocalClass(String name)

Finds and loads the class with the specified name from the URL search path. The base URLs are opened and expanded as needed until the class is found.

Parameters:

name - the name of the class

Returns:

the resulting class, or null if not found

Throws: SecurityException

if a package sealing violation has occurred

Overrides:

findLocalClass in class ClassLoader

protected Package definePackage(String name,
                                Attributes attr,
                                URL sealBase)

Defines a package by name in this ClassLoader. The specification and implementation titles, names, and vendors are obtained from the given Attributes object.

Parameters:

name - the package name

attr - the package Attributes

sealBase - if specified then this package is sealed with respect to the given code base URL

Throws: IllegalArgumentException

if the package name duplicates an existing package either in this class loader or the parent class loader

protected void checkPackageDefinition(String name) throws SecurityException

This method can be overridden to throw a SecurityException if the calling thread is not allowed to define classes in the package specified by the argument. By default, the calling thread is allowed to define classes in any package.

Parameters:

name - the package name

Throws: SecurityException

if the caller cannot define classes in the specified package

public URL getLocalResource(String name)

Finds the resource with the specified name on the URL search path. Returns a URL for the resource, or null if the resource could not be found.

Parameters:

name - the name of the resource

Overrides:

getLocalResource in class ClassLoader

public Enumeration getLocalResources(String name) throws IOException

Returns an Enumeration of URLs representing all of the resources with the given name that could be found on the URL search path. XXX: Why does this need to throw IOException?

Parameters:

name - the resource name

Returns:

an Enumeration of resource URLs

Overrides:

getLocalResources in class ClassLoader

public void invokeClass(String name,
                        String[] args) throws ClassNotFoundException, NoSuchMethodException, InvocationTargetException

Invokes an application given the name of the application's main class and an array of arguments. The class must define define a static method "main" which takes an array of String arguments and is of return type "void".

Parameters:

name - the name of the application's main class

args - the arguments to pass to the application

Throws: ClassNotFoundException

if the specified class could not be found

Throws: NoSuchMethodException

if the specified class does not define a "main" method

Throws: InvocationTargetException

if the application raised an exception

public static ClassLoader getExtClassLoader()

Returns the shared instance of ClassLoader used to load classes and resources from installed extensions. By default, new instances of URLClassLoader will delegate to this class loader. XXX Use a Reference object here

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