JavaTM 2 Platform
Std. Ed. v1.3.1

java.security
Class SecureClassLoader

java.lang.Object
  |
  +--java.lang.ClassLoader
        |
        +--java.security.SecureClassLoader
Direct Known Subclasses:
URLClassLoader

public class SecureClassLoader
extends ClassLoader

This class extends ClassLoader with additional support for defining classes with an associated code source and permissions which are retrieved by the system policy by default.


Constructor Summary
protected SecureClassLoader()
          Creates a new SecureClassLoader using the default parent class loader for delegation.
protected SecureClassLoader(ClassLoader parent)
          Creates a new SecureClassLoader using the specified parent class loader for delegation.
 
Method Summary
protected  Class defineClass(String name, byte[] b, int off, int len, CodeSource cs)
          Converts an array of bytes into an instance of class Class, with an optional CodeSource.
protected  PermissionCollection getPermissions(CodeSource codesource)
          Returns the permissions for the given CodeSource object.
 
Methods inherited from class java.lang.ClassLoader
defineClass, defineClass, defineClass, definePackage, findClass, findLibrary, findLoadedClass, findResource, findResources, findSystemClass, getPackage, getPackages, getParent, getResource, getResourceAsStream, getResources, getSystemClassLoader, getSystemResource, getSystemResourceAsStream, getSystemResources, loadClass, loadClass, resolveClass, setSigners
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

SecureClassLoader

protected SecureClassLoader(ClassLoader parent)
Creates a new SecureClassLoader using the specified parent class loader for delegation.

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.

Parameters:
parent - the parent ClassLoader
Throws:
SecurityException - if a security manager exists and its checkCreateClassLoader method doesn't allow creation of a class loader.
See Also:
SecurityManager.checkCreateClassLoader()

SecureClassLoader

protected SecureClassLoader()
Creates a new SecureClassLoader using the default parent class loader for delegation.

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.

Throws:
SecurityException - if a security manager exists and its checkCreateClassLoader method doesn't allow creation of a class loader.
See Also:
SecurityManager.checkCreateClassLoader()
Method Detail

defineClass

protected final Class defineClass(String name,
                                  byte[] b,
                                  int off,
                                  int len,
                                  CodeSource cs)
Converts an array of bytes into an instance of class Class, with an optional CodeSource. Before the class can be used it must be resolved.

If a non-null CodeSource is supplied and a Policy provider is installed, Policy.getPermissions() is invoked in order to associate a ProtectionDomain with the class being defined.

Parameters:
name - the name of the class
b - the class bytes
off - the start offset of the class bytes
len - the length of the class bytes
cs - the associated CodeSource, or null if none
Returns:
the Class object created from the data, and optional CodeSource.

getPermissions

protected PermissionCollection getPermissions(CodeSource codesource)
Returns the permissions for the given CodeSource object. The default implementation of this method invokes the java.security.Policy.getPermissions method to get the permissions granted by the policy to the specified CodeSource.

This method is invoked by the defineClass method which takes a CodeSource as an argument when it is constructing the ProtectionDomain for the class being defined.

The constructed ProtectionDomain is cached by the SecureClassLoader. The contents of the cache persist for the lifetime of the SecureClassLoader instance. This persistence inhibits Policy.refresh() from influencing the protection domains already in the cache for a given CodeSource.

Parameters:
codesource - the codesource.
Returns:
the permissions granted to the codesource.

JavaTM 2 Platform
Std. Ed. v1.3.1

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For further API reference and developer documentation, see Java 2 SDK SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.

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