Class URLClassLoader
- All Implemented Interfaces:
- Closeable,- AutoCloseable
jar:
 scheme URL (see JarURLConnection) is assumed to refer to a
 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-release JAR file that is referred to by a given URL.
- Since:
- 1.2
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Constructor SummaryConstructorsConstructorDescriptionURLClassLoader(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 SummaryModifier and TypeMethodDescriptionprotected voidAppends 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<?> Finds and loads the class with the specified name from the URL search path.findResource(String name) Finds the resource with the specified name on the URL search path.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 an empty Permission collection.getResourceAsStream(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, defineClassMethods 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 Details- 
URLClassLoaderConstructs 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.- Parameters:
- urls- the URLs from which to load classes and resources
- parent- the parent class loader for delegation
- Throws:
- NullPointerException- if- urlsor any of its elements is- null.
 
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URLClassLoaderConstructs 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.- Parameters:
- urls- the URLs from which to load classes and resources
- Throws:
- NullPointerException- if- urlsor any of its elements is- null.
 
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URLClassLoaderConstructs 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.- 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:
- NullPointerException- if- urlsor any of its elements is- null.
 
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URLClassLoaderConstructs 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.
- Since:
- 9
 
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URLClassLoaderConstructs 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.
- Since:
- 9
 
 
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Method Details- 
getResourceAsStreamReturns 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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closeCloses 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.
- Since:
- 1.7
 
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addURLAppends 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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getURLsReturns 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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findClassFinds 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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definePackageDefines 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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findResourceFinds 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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findResourcesReturns 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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getPermissionsReturns an empty Permission collection.- Overrides:
- getPermissionsin class- SecureClassLoader
- Parameters:
- codesource- the- CodeSource
- Returns:
- an empty Permission collection
- Throws:
- NullPointerException- if- codesourceis- null.
 
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newInstanceCreates a new instance of URLClassLoader for the specified URLs and parent class loader.- 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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newInstanceCreates a new instance of URLClassLoader for the specified URLs and default parent class loader.- 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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