org.apache.commons.vfs2.impl

Class VFSClassLoader

java.lang.Object

java.lang.ClassLoader

java.security.SecureClassLoader

org.apache.commons.vfs2.impl.VFSClassLoader

public class VFSClassLoader
extends java.security.SecureClassLoader

A class loader that can load classes and resources from a search path.

The search path can consist of VFS FileObjects referring both to folders and JAR files. Any FileObject of type FileType.FILE is assumed to be a JAR and is opened by creating a layered file system with the "jar" scheme.

TODO - Test this with signed Jars and a SecurityManager.

See Also:

FileSystemManager.createFileSystem(org.apache.commons.vfs2.FileObject)

Field Summary

Fields

Modifier and Type	Field and Description
private java.util.ArrayList<FileObject>	resources

Constructor Summary

Constructors

Constructor and Description
VFSClassLoader(FileObject[] files, FileSystemManager manager) Constructors a new VFSClassLoader for the given files.
VFSClassLoader(FileObject[] files, FileSystemManager manager, java.lang.ClassLoader parent) Constructors a new VFSClassLoader for the given FileObjects.
VFSClassLoader(FileObject file, FileSystemManager manager) Constructors a new VFSClassLoader for the given file.
VFSClassLoader(FileObject file, FileSystemManager manager, java.lang.ClassLoader parent) Constructors a new VFSClassLoader for the given file.

Method Summary

Modifier and Type	Method and Description
private void	addFileObjects(FileSystemManager manager, FileObject[] files) Appends the specified FileObjects to the list of FileObjects to search for classes and resources.
protected void	copyPermissions(java.security.PermissionCollection src, java.security.PermissionCollection dest) Copies the permissions from src to dest.
private java.lang.Class<?>	defineClass(java.lang.String name, Resource res) Loads and verifies the class with name and located with res.
private java.lang.Package	definePackage(java.lang.String name, Resource res) Reads attributes for the package and defines it.
protected java.lang.Class<?>	findClass(java.lang.String name) Finds and loads the class with the specified name from the search path.
protected java.net.URL	findResource(java.lang.String name) Finds the resource with the specified name from the search path.
protected java.util.Enumeration<java.net.URL>	findResources(java.lang.String name) Returns an Enumeration of all the resources in the search path with the specified name.
FileObject[]	getFileObjects() Provide access to the file objects this class loader represents.
protected java.security.PermissionCollection	getPermissions(java.security.CodeSource cs) Calls super.getPermissions both for the code source and also adds the permissions granted to the parent layers.
private boolean	isSealed(Resource res) Returns true if the we should seal the package where res resides.
private Resource	loadResource(java.lang.String name) Searches through the search path of for the first class or resource with specified name.
private FileObject	lookupFileObject(java.lang.String name) Does a reverse lookup to find the FileObject when we only have the URL.

Methods inherited from class java.security.SecureClassLoader

defineClass, defineClass

Methods inherited from class java.lang.ClassLoader

clearAssertionStatus, defineClass, defineClass, defineClass, defineClass, definePackage, findLibrary, findLoadedClass, findSystemClass, getClassLoadingLock, getPackage, getPackages, getParent, getResource, getResourceAsStream, getResources, getSystemClassLoader, getSystemResource, getSystemResourceAsStream, getSystemResources, loadClass, loadClass, registerAsParallelCapable, resolveClass, setClassAssertionStatus, setDefaultAssertionStatus, setPackageAssertionStatus, setSigners

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

resources

private final java.util.ArrayList<FileObject> resources

Constructor Detail

VFSClassLoader

public VFSClassLoader(FileObject file,
                      FileSystemManager manager)
               throws FileSystemException

Constructors a new VFSClassLoader for the given file.

Parameters:

file - the file to load the classes and resources from.

manager - the FileManager to use when trying create a layered Jar file system.

Throws:

FileSystemException - if an error occurs.

VFSClassLoader

public VFSClassLoader(FileObject file,
                      FileSystemManager manager,
                      java.lang.ClassLoader parent)
               throws FileSystemException

Constructors a new VFSClassLoader for the given file.

Parameters:

file - the file to load the classes and resources from.

manager - the FileManager to use when trying create a layered Jar file system.

parent - the parent class loader for delegation.

Throws:

FileSystemException - if an error occurs.

VFSClassLoader

public VFSClassLoader(FileObject[] files,
                      FileSystemManager manager)
               throws FileSystemException

Constructors a new VFSClassLoader for the given files. The files will be searched in the order specified.

Parameters:

files - the files to load the classes and resources from.

manager - the FileManager to use when trying create a layered Jar file system.

Throws:

FileSystemException - if an error occurs.

VFSClassLoader

public VFSClassLoader(FileObject[] files,
                      FileSystemManager manager,
                      java.lang.ClassLoader parent)
               throws FileSystemException

Constructors a new VFSClassLoader for the given FileObjects. The FileObjects will be searched in the order specified.

Parameters:

files - the FileObjects to load the classes and resources from.

manager - the FileManager to use when trying create a layered Jar file system.

parent - the parent class loader for delegation.

Throws:

FileSystemException - if an error occurs.

Method Detail

getFileObjects

public FileObject[] getFileObjects()

Provide access to the file objects this class loader represents.

Returns:

An array of FileObjects.

Since:

2.0

addFileObjects

private void addFileObjects(FileSystemManager manager,
                            FileObject[] files)
                     throws FileSystemException

Appends the specified FileObjects to the list of FileObjects to search for classes and resources.

Parameters:

manager - The FileSystemManager.

files - the FileObjects to append to the search path.

Throws:

FileSystemException - if an error occurs.

findClass

protected java.lang.Class<?> findClass(java.lang.String name)
                                throws java.lang.ClassNotFoundException

Finds and loads the class with the specified name from the search path.

Overrides:

findClass in class java.lang.ClassLoader

Throws:

java.lang.ClassNotFoundException - if the class is not found.

defineClass

private java.lang.Class<?> defineClass(java.lang.String name,
                                       Resource res)
                                throws java.io.IOException

Loads and verifies the class with name and located with res.

Throws:

java.io.IOException

isSealed

private boolean isSealed(Resource res)
                  throws FileSystemException

Returns true if the we should seal the package where res resides.

Throws:

FileSystemException

definePackage

private java.lang.Package definePackage(java.lang.String name,
                                        Resource res)
                                 throws FileSystemException

Reads attributes for the package and defines it.

Throws:

FileSystemException

getPermissions

protected java.security.PermissionCollection getPermissions(java.security.CodeSource cs)

Calls super.getPermissions both for the code source and also adds the permissions granted to the parent layers.

Overrides:

getPermissions in class java.security.SecureClassLoader

Parameters:

cs - the CodeSource.

Returns:

The PermissionCollections.

copyPermissions

protected void copyPermissions(java.security.PermissionCollection src,
                               java.security.PermissionCollection dest)

Copies the permissions from src to dest.

Parameters:

src - The source PermissionCollection.

dest - The destination PermissionCollection.

lookupFileObject

private FileObject lookupFileObject(java.lang.String name)

Does a reverse lookup to find the FileObject when we only have the URL.

findResource

protected java.net.URL findResource(java.lang.String name)

Finds the resource with the specified name from the search path. This returns null if the resource is not found.

Overrides:

findResource in class java.lang.ClassLoader

Parameters:

name - The resource name.

Returns:

The URL that matches the resource.

findResources

protected java.util.Enumeration<java.net.URL> findResources(java.lang.String name)
                                                     throws java.io.IOException

Returns an Enumeration of all the resources in the search path with the specified name.

Gets called from ClassLoader.getResources(String) after parent class loader was questioned.

Overrides:

findResources in class java.lang.ClassLoader

Parameters:

name - The resources to find.

Returns:

An Enumeration of the resources associated with the name.

Throws:

FileSystemException - if an error occurs.

java.io.IOException

loadResource

private Resource loadResource(java.lang.String name)
                       throws FileSystemException

Searches through the search path of for the first class or resource with specified name.

Parameters:

name - The resource to load.

Returns:

The Resource.

Throws:

FileSystemException - if an error occurs.