public class URLClassLoader extends SecureClassLoader implements Closeable
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.
| Constructor and Description |
|---|
URLClassLoader(URL[] urls)
Constructs a new URLClassLoader for the specified URLs using the
default delegation parent
ClassLoader. |
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.
|
| Modifier and Type | Method and Description |
|---|---|
protected void |
addURL(URL url)
Appends the specified URL to the list of URLs to search for
classes and resources.
|
void |
close()
Closes this URLClassLoader, so that it can no longer be used to load
new classes or resources that are defined by this loader.
|
protected Package |
definePackage(String name,
Manifest man,
URL url)
Defines a new package by name in this ClassLoader.
|
protected Class<?> |
findClass(String name)
Finds and loads the class with the specified name from the URL search
path.
|
URL |
findResource(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 PermissionCollection |
getPermissions(CodeSource codesource)
Returns the permissions for the given codesource object.
|
InputStream |
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 URLClassLoader |
newInstance(URL[] urls)
Creates a new instance of URLClassLoader for the specified
URLs and default parent class loader.
|
static URLClassLoader |
newInstance(URL[] urls,
ClassLoader parent)
Creates a new instance of URLClassLoader for the specified
URLs and parent class loader.
|
defineClass, defineClassclearAssertionStatus, defineClass, defineClass, defineClass, defineClass, definePackage, findLibrary, findLoadedClass, findSystemClass, getClassLoadingLock, getPackage, getPackages, getParent, getResource, getResources, getSystemClassLoader, getSystemResource, getSystemResourceAsStream, getSystemResources, loadClass, loadClass, registerAsParallelCapable, resolveClass, setClassAssertionStatus, setDefaultAssertionStatus, setPackageAssertionStatus, setSignerspublic URLClassLoader(URL[] urls, ClassLoader parent)
If there is a security manager, this method first
calls the security manager's checkCreateClassLoader method
to ensure creation of a class loader is allowed.
urls - the URLs from which to load classes and resourcesparent - the parent class loader for delegationSecurityException - if a security manager exists and its
checkCreateClassLoader method doesn't allow
creation of a class loader.NullPointerException - if urls is null.SecurityManager.checkCreateClassLoader()public URLClassLoader(URL[] urls)
ClassLoader. 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 checkCreateClassLoader method
to ensure creation of a class loader is allowed.
urls - the URLs from which to load classes and resourcesSecurityException - if a security manager exists and its
checkCreateClassLoader method doesn't allow
creation of a class loader.NullPointerException - if urls is null.SecurityManager.checkCreateClassLoader()public URLClassLoader(URL[] urls, ClassLoader parent, URLStreamHandlerFactory factory)
If there is a security manager, this method first
calls the security manager's checkCreateClassLoader method
to ensure creation of a class loader is allowed.
urls - the URLs from which to load classes and resourcesparent - the parent class loader for delegationfactory - the URLStreamHandlerFactory to use when creating URLsSecurityException - if a security manager exists and its
checkCreateClassLoader method doesn't allow
creation of a class loader.NullPointerException - if urls is null.SecurityManager.checkCreateClassLoader()public InputStream getResourceAsStream(String name)
The search order is described in the documentation for ClassLoader.getResource(String).
getResourceAsStream in class ClassLoadername - The resource namenull
if the resource could not be foundpublic void close()
throws IOException
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 close method 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.
close in interface Closeableclose in interface AutoCloseableIOException - 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")protected void addURL(URL url)
If the URL specified is null or is already in the
list of URLs, or if this loader is closed, then invoking this
method has no effect.
url - the URL to be added to the search path of URLspublic URL[] getURLs()
protected Class<?> findClass(String name) throws ClassNotFoundException
findClass in class ClassLoadername - the name of the classClassNotFoundException - if the class could not be found,
or if the loader is closed.NullPointerException - if name is null.protected Package definePackage(String name, Manifest man, URL url) throws IllegalArgumentException
name - the package nameman - the Manifest containing package version and sealing
informationurl - the code source url for the package, or null if noneIllegalArgumentException - if the package name duplicates
an existing package either in this class loader or one
of its ancestorspublic URL findResource(String name)
findResource in class ClassLoadername - the name of the resourceURL for the resource, or null
if the resource could not be found, or if the loader is closed.public Enumeration<URL> findResources(String name) throws IOException
findResources in class ClassLoadername - the resource nameEnumeration of URLs
If the loader is closed, the Enumeration will be empty.IOException - if an I/O exception occursprotected PermissionCollection getPermissions(CodeSource 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.
getPermissions in class SecureClassLoadercodesource - the codesourceNullPointerException - if codesource is null.public static URLClassLoader newInstance(URL[] urls, ClassLoader parent)
loadClass method of the URLClassLoader
returned by this method will invoke the
SecurityManager.checkPackageAccess method before
loading the class.urls - the URLs to search for classes and resourcesparent - the parent class loader for delegationNullPointerException - if urls is null.public static URLClassLoader newInstance(URL[] urls)
loadClass method of the URLClassLoader
returned by this method will invoke the
SecurityManager.checkPackageAccess before
loading the class.urls - the URLs to search for classes and resourcesNullPointerException - if urls is null. Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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