URLClassLoader class in Java

java.net.URLClassLoader

This class loader is used to load classes and resources from a search path of URLs referring to both JAR files and directories. Any jar: scheme URL is assumed to refer to the JAR file. Any file: scheme URL that ends with a '/' is assumed to refer to a directory. Otherwise, the URL is assumed to refer to a JAR file which will be opened as needed.

This class loader supports the loading of classes and resources from the contents of a multi-releaseJAR file that is referred to by a given URL.

The AccessControlContext of the thread that created the instance of URLClassLoader will be used when subsequently loading classes and resources.

The classes that are loaded are by default granted permission only to access the URLs specified when the URLClassLoader was created.

Some methods of URLClassLoader class

URLClassLoader(URL[]): This method constructs a new URLClassLoader for the specified URLs using the default delegation parent ClassLoader.

URLClassLoader(URL[], ClassLoader): This method constructs a new URLClassLoader for the given URLs.

URLClassLoader(String, URL[], ClassLoader): This method constructs a new named URLClassLoader for the specified URLs.The URLs will be searched in the order specified for classes and resources after first searching in the specified parent class loader.

URLClassLoader(URL[], ClassLoader, URLStreamHandlerFactory): This method constructs a new URLClassLoader for the specified URLs, parent class loader, and URLStreamHandlerFactory. The parent argument will be used as the parent class loader for delegation. The factory argument will be used as the stream handler factory to obtain protocol handlers when creating new jar URLs.

URLClassLoader(String, URL[], ClassLoader, URLStreamHandlerFactory): This method constructs a new named URLClassLoader for the specified URLs, parent class loader, and URLStreamHandlerFactory.

close(): This method closes this URLClassLoader so that it can no longer be used to load new classes or resources that are defined by this loader. 

findResource(String): This method finds the resource with the specified name on the URL search path.

findResources(String):  This method returns an Enumeration of URLs representing all of the resources on the URL search path having the specified name.

getResourceAsStream(String): This method returns an input stream for reading the specified resource. If this loader is closed, any resources this method opens will be closed.

getURLs(): This method returns the search path of URLs for loading classes and resources.