- java.lang.Object
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- java.lang.ClassLoader
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- java.security.SecureClassLoader
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- java.net.URLClassLoader
 
 
 
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- All Implemented Interfaces:
- Closeable,- AutoCloseable
 - Direct Known Subclasses:
- MLet
 
 public class URLClassLoader extends SecureClassLoader implements Closeable This class loader is used to load classes and resources from a search path of URLs referring to both JAR files and directories. Anyjar:scheme URL (seeJarURLConnection) is assumed to refer to a JAR file. Anyfile: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-release JAR 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. - Since:
- 1.2
 
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Constructor SummaryConstructors Constructor Description URLClassLoader(String name, URL[] urls, ClassLoader parent)Constructs a new namedURLClassLoaderfor the specified URLs.URLClassLoader(String name, URL[] urls, ClassLoader parent, URLStreamHandlerFactory factory)Constructs a new namedURLClassLoaderfor the specified URLs, parent class loader, and URLStreamHandlerFactory.URLClassLoader(URL[] urls)Constructs a new URLClassLoader for the specified URLs using the default delegation parentClassLoader.URLClassLoader(URL[] urls, ClassLoader parent)Constructs a new URLClassLoader for the given URLs.URLClassLoader(URL[] urls, ClassLoader parent, URLStreamHandlerFactory factory)Constructs a new URLClassLoader for the specified URLs, parent class loader, and URLStreamHandlerFactory.
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Method SummaryAll Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description protected voidaddURL(URL url)Appends the specified URL to the list of URLs to search for classes and resources.voidclose()Closes this URLClassLoader, so that it can no longer be used to load new classes or resources that are defined by this loader.protected PackagedefinePackage(String name, Manifest man, URL url)Defines a new package by name in thisURLClassLoader.protected Class<?>findClass(String name)Finds and loads the class with the specified name from the URL search path.URLfindResource(String name)Finds the resource with the specified name on the URL search path.Enumeration<URL>findResources(String name)Returns an Enumeration of URLs representing all of the resources on the URL search path having the specified name.protected PermissionCollectiongetPermissions(CodeSource codesource)Returns the permissions for the given codesource object.InputStreamgetResourceAsStream(String name)Returns an input stream for reading the specified resource.URL[]getURLs()Returns the search path of URLs for loading classes and resources.static URLClassLoadernewInstance(URL[] urls)Creates a new instance of URLClassLoader for the specified URLs and default parent class loader.static URLClassLoadernewInstance(URL[] urls, ClassLoader parent)Creates a new instance of URLClassLoader for the specified URLs and parent class loader.- 
Methods declared in class java.security.SecureClassLoaderdefineClass, defineClass
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Methods declared in class java.lang.ClassLoaderclearAssertionStatus, defineClass, defineClass, defineClass, defineClass, definePackage, findClass, findLibrary, findLoadedClass, findResource, findSystemClass, getClassLoadingLock, getDefinedPackage, getDefinedPackages, getName, getPackage, getPackages, getParent, getPlatformClassLoader, getResource, getResources, getSystemClassLoader, getSystemResource, getSystemResourceAsStream, getSystemResources, getUnnamedModule, isRegisteredAsParallelCapable, loadClass, loadClass, registerAsParallelCapable, resolveClass, resources, setClassAssertionStatus, setDefaultAssertionStatus, setPackageAssertionStatus, setSigners
 
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Constructor Detail- 
URLClassLoaderpublic URLClassLoader(URL[] urls, ClassLoader parent) Constructs a new URLClassLoader for the given URLs. The URLs will be searched in the order specified for classes and resources after first searching in the specified parent class loader. Anyjar:scheme URL is assumed to refer to a JAR file. Anyfile: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 downloaded and opened as needed.If there is a security manager, this method first calls the security manager's checkCreateClassLoadermethod to ensure creation of a class loader is allowed.- Parameters:
- urls- the URLs from which to load classes and resources
- parent- the parent class loader for delegation
- Throws:
- SecurityException- if a security manager exists and its- checkCreateClassLoadermethod doesn't allow creation of a class loader.
- NullPointerException- if- urlsor any of its elements is- null.
- See Also:
- SecurityManager.checkCreateClassLoader()
 
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URLClassLoaderpublic URLClassLoader(URL[] urls) Constructs a new URLClassLoader for the specified URLs using the default delegation parentClassLoader. The URLs will be searched in the order specified for classes and resources after first searching in the parent class loader. Any 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 downloaded and opened as needed.If there is a security manager, this method first calls the security manager's checkCreateClassLoadermethod to ensure creation of a class loader is allowed.- Parameters:
- urls- the URLs from which to load classes and resources
- Throws:
- SecurityException- if a security manager exists and its- checkCreateClassLoadermethod doesn't allow creation of a class loader.
- NullPointerException- if- urlsor any of its elements is- null.
- See Also:
- SecurityManager.checkCreateClassLoader()
 
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URLClassLoaderpublic URLClassLoader(URL[] urls, ClassLoader parent, URLStreamHandlerFactory factory) 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.If there is a security manager, this method first calls the security manager's checkCreateClassLoadermethod to ensure creation of a class loader is allowed.- Parameters:
- urls- the URLs from which to load classes and resources
- parent- the parent class loader for delegation
- factory- the URLStreamHandlerFactory to use when creating URLs
- Throws:
- SecurityException- if a security manager exists and its- checkCreateClassLoadermethod doesn't allow creation of a class loader.
- NullPointerException- if- urlsor any of its elements is- null.
- See Also:
- SecurityManager.checkCreateClassLoader()
 
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URLClassLoaderpublic URLClassLoader(String name, URL[] urls, ClassLoader parent) Constructs a new namedURLClassLoaderfor 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. Any 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 downloaded and opened as needed.- Parameters:
- name- class loader name; or- nullif not named
- urls- the URLs from which to load classes and resources
- parent- the parent class loader for delegation
- Throws:
- IllegalArgumentException- if the given name is empty.
- NullPointerException- if- urlsor any of its elements is- null.
- SecurityException- if a security manager exists and its- SecurityManager.checkCreateClassLoader()method doesn't allow creation of a class loader.
- Since:
- 9
 
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URLClassLoaderpublic URLClassLoader(String name, URL[] urls, ClassLoader parent, URLStreamHandlerFactory factory) Constructs a new namedURLClassLoaderfor 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.- Parameters:
- name- class loader name; or- nullif not named
- urls- the URLs from which to load classes and resources
- parent- the parent class loader for delegation
- factory- the URLStreamHandlerFactory to use when creating URLs
- Throws:
- IllegalArgumentException- if the given name is empty.
- NullPointerException- if- urlsor any of its elements is- null.
- SecurityException- if a security manager exists and its- checkCreateClassLoadermethod doesn't allow creation of a class loader.
- Since:
- 9
 
 
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Method Detail- 
getResourceAsStreampublic InputStream getResourceAsStream(String name) Returns an input stream for reading the specified resource. If this loader is closed, then any resources opened by this method will be closed.The search order is described in the documentation for ClassLoader.getResource(String).- Overrides:
- getResourceAsStreamin class- ClassLoader
- Parameters:
- name- The resource name
- Returns:
- An input stream for reading the resource, or nullif the resource could not be found
- Throws:
- NullPointerException- If- nameis- null
- Since:
- 1.7
 
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closepublic void close() throws IOExceptionCloses this URLClassLoader, 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: and file: URLs, it also closes any files that were opened by it. If another thread is loading a class when the closemethod is invoked, then the result of that load is undefined.The method makes a best effort attempt to close all opened files, by catching IOExceptions internally. Unchecked exceptions and errors are not caught. Calling close on an already closed loader has no effect.- Specified by:
- closein interface- AutoCloseable
- Specified by:
- closein interface- Closeable
- 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.
- SecurityException- if a security manager is set, and it denies- RuntimePermission- ("closeClassLoader")
- Since:
- 1.7
 
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addURLprotected void addURL(URL url) Appends the specified URL to the list of URLs to search for classes and resources.If the URL specified is nullor is already in the list of URLs, or if this loader is closed, then invoking this method has no effect.- Parameters:
- url- the URL to be added to the search path of URLs
 
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getURLspublic URL[] getURLs() Returns the search path of URLs for loading classes and resources. This includes the original list of URLs specified to the constructor, along with any URLs subsequently appended by the addURL() method.- Returns:
- the search path of URLs for loading classes and resources.
 
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findClassprotected Class<?> findClass(String name) throws ClassNotFoundException Finds and loads the class with the specified name from the URL search path. Any URLs referring to JAR files are loaded and opened as needed until the class is found.- Overrides:
- findClassin class- ClassLoader
- Parameters:
- name- the name of the class
- Returns:
- the resulting class
- Throws:
- ClassNotFoundException- if the class could not be found, or if the loader is closed.
- NullPointerException- if- nameis- null.
 
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definePackageprotected Package definePackage(String name, Manifest man, URL url) Defines a new package by name in thisURLClassLoader. The attributes contained in the specifiedManifestwill be used to obtain package version and sealing information. For sealed packages, the additional URL specifies the code source URL from which the package was loaded.- Parameters:
- name- the package name
- man- the- Manifestcontaining package version and sealing information
- url- the code source url for the package, or null if none
- Returns:
- the newly defined Packageobject
- Throws:
- IllegalArgumentException- if the package name is already defined by this class loader
 
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findResourcepublic URL findResource(String name) Finds the resource with the specified name on the URL search path.- Overrides:
- findResourcein class- ClassLoader
- Parameters:
- name- the name of the resource
- Returns:
- a URLfor the resource, ornullif the resource could not be found, or if the loader is closed.
 
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findResourcespublic Enumeration<URL> findResources(String name) throws IOException Returns an Enumeration of URLs representing all of the resources on the URL search path having the specified name.- Overrides:
- findResourcesin class- ClassLoader
- Parameters:
- name- the resource name
- Returns:
- An EnumerationofURLs. If the loader is closed, the Enumeration contains no elements.
- Throws:
- IOException- if an I/O exception occurs
 
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getPermissionsprotected PermissionCollection getPermissions(CodeSource codesource) Returns the permissions for the given codesource object. The implementation of this method first calls super.getPermissions and then adds permissions based on the URL of the codesource.If the protocol of this URL is "jar", then the permission granted is based on the permission that is required by the URL of the Jar file. If the protocol is "file" and there is an authority component, then permission to connect to and accept connections from that authority may be granted. If the protocol is "file" and the path specifies a file, then permission to read that file is granted. If protocol is "file" and the path is a directory, permission is granted to read all files and (recursively) all files and subdirectories contained in that directory. If the protocol is not "file", then permission to connect to and accept connections from the URL's host is granted. - Overrides:
- getPermissionsin class- SecureClassLoader
- Parameters:
- codesource- the codesource
- Returns:
- the permissions granted to the codesource
- Throws:
- NullPointerException- if- codesourceis- null.
 
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newInstancepublic static URLClassLoader newInstance(URL[] urls, ClassLoader parent) Creates a new instance of URLClassLoader for the specified URLs and parent class loader. If a security manager is installed, theloadClassmethod of the URLClassLoader returned by this method will invoke theSecurityManager.checkPackageAccessmethod before loading the class.- Parameters:
- urls- the URLs to search for classes and resources
- parent- the parent class loader for delegation
- Returns:
- the resulting class loader
- Throws:
- NullPointerException- if- urlsor any of its elements is- null.
 
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newInstancepublic static URLClassLoader newInstance(URL[] urls) Creates a new instance of URLClassLoader for the specified URLs and default parent class loader. If a security manager is installed, theloadClassmethod of the URLClassLoader returned by this method will invoke theSecurityManager.checkPackageAccessbefore loading the class.- Parameters:
- urls- the URLs to search for classes and resources
- Returns:
- the resulting class loader
- Throws:
- NullPointerException- if- urlsor any of its elements is- null.
 
 
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