org.apache.catalina.loader
Class StandardClassLoader

java.lang.Object
  |
  +--java.lang.ClassLoader
        |
        +--java.security.SecureClassLoader
              |
              +--java.net.URLClassLoader
                    |
                    +--org.apache.catalina.loader.StandardClassLoader

All Implemented Interfaces:

Reloader

public class StandardClassLoader

extends java.net.URLClassLoader

implements Reloader

Subclass implementation of java.net.URLClassLoader that knows how to load classes from disk directories, as well as local and remote JAR files. It also implements the Reloader interface, to provide automatic reloading support to the associated loader.

In all cases, URLs must conform to the contract specified by URLClassLoader - any URL that ends with a "/" character is assumed to represent a directory; all other URLs are assumed to be the address of a JAR file.

IMPLEMENTATION NOTE - Local repositories are searched in the order they are added via the initial constructor and/or any subsequent calls to addRepository().

IMPLEMENTATION NOTE - At present, there are no dependencies from this class to any other Catalina class, so that it could be used independently.

Version:

$Revision: 1.24.2.1 $ $Date: 2001/11/16 01:21:51 $

Author:

Craig R. McClanahan, Remy Maucherat

Field Summary

protected java.util.ArrayList	available The set of optional packages (formerly standard extensions) that are available in the repositories associated with this class loader.
protected java.util.HashMap	classCache The cache of ClassCacheEntries for classes we have loaded locally, keyed by class name.
protected int	debug The debugging detail level of this component.
protected boolean	delegate Should this class loader delegate to the parent class loader before searching its own repositories (i.e. the usual Java2 delegation model)?
protected java.net.URLStreamHandlerFactory	factory URL stream handler for additional protocols.
protected java.lang.String[]	repositories The list of local repositories, in the order they should be searched for locally loaded classes or resources.
protected java.util.ArrayList	required The set of optional packages (formerly standard extensions) that are required in the repositories associated with this class loader.

Constructor Summary

StandardClassLoader()
Construct a new ClassLoader with no defined repositories and no parent ClassLoader.

StandardClassLoader(java.lang.ClassLoader parent)
Construct a new ClassLoader with no defined repositories and the specified parent ClassLoader.

StandardClassLoader(java.lang.ClassLoader parent, java.net.URLStreamHandlerFactory factory)
Construct a new ClassLoader with no defined repositories and the specified parent ClassLoader.

StandardClassLoader(java.lang.String[] repositories)
Construct a new ClassLoader with the specified repositories and no parent ClassLoader.

StandardClassLoader(java.lang.String[] repositories, java.lang.ClassLoader parent)
Construct a new ClassLoader with the specified repositories and parent ClassLoader.

StandardClassLoader(java.net.URL[] repositories, java.lang.ClassLoader parent)
Construct a new ClassLoader with the specified repositories and parent ClassLoader.

StandardClassLoader(java.net.URLStreamHandlerFactory factory)
Construct a new ClassLoader with no defined repositories and no parent ClassLoader, but with a stream handler factory.

Method Summary

void	addRepository(java.lang.String repository) Add a new repository to the set of places this ClassLoader can look for classes to be loaded.
protected void	addRepositoryInternal(java.lang.String repository) Add a repository to our internal array only.
protected static java.net.URL[]	convert(java.lang.String[] input) Convert an array of String to an array of URL and return it.
protected static java.net.URL[]	convert(java.lang.String[] input, java.net.URLStreamHandlerFactory factory) Convert an array of String to an array of URL and return it.
Extension[]	findAvailable() Return a list of "optional packages" (formerly "standard extensions") that have been declared to be available in the repositories associated with this class loader, plus any parent class loader implemented with the same class.
java.lang.Class	findClass(java.lang.String name) Find the specified class in our local repositories, if possible.
protected java.io.InputStream	findLoadedResource(java.lang.String name) Finds the resource with the given name if it has previously been loaded and cached by this class loader, and return an input stream to the resource data.
java.lang.String[]	findRepositories() Return a String array of the current repositories for this class loader.
Extension[]	findRequired() Return a list of "optional packages" (formerly "standard extensions") that have been declared to be required in the repositories associated with this class loader, plus any parent class loader implemented with the same class.
java.net.URL	findResource(java.lang.String name) Find the specified resource in our local repository, and return a URL refering to it, or null if this resource cannot be found.
java.util.Enumeration	findResources(java.lang.String name) Return an enumeration of URLs representing all of the resources with the given name.
int	getDebug() Return the debugging detail level for this component.
boolean	getDelegate() Return the "delegate first" flag for this class loader.
protected java.security.PermissionCollection	getPermissions(java.security.CodeSource codeSource) Get the Permissions for a CodeSource.
java.net.URL	getResource(java.lang.String name) Find the resource with the given name.
java.io.InputStream	getResourceAsStream(java.lang.String name) Find the resource with the given name, and return an input stream that can be used for reading it.
java.lang.Class	loadClass(java.lang.String name) Load the class with the specified name.
java.lang.Class	loadClass(java.lang.String name, boolean resolve) Load the class with the specified name, searching using the following algorithm until it finds and returns the class.
boolean	modified() Have one or more classes or resources been modified so that a reload is appropriate?
protected static java.lang.String	parseProtocol(java.lang.String spec) Parse URL protocol.
void	setDebug(int debug) Set the debugging detail level for this component.
void	setDelegate(boolean delegate) Set the "delegate first" flag for this class loader.
void	setPermissions(java.lang.String path) If there is a Java SecurityManager create a read FilePermission or JndiPermission for the file directory path.
void	setPermissions(java.net.URL url) If there is a Java SecurityManager add a read FilePermission or JndiPermission for URL.
java.lang.String	toString() Render a String representation of this object.

Methods inherited from class java.net.URLClassLoader

addURL, definePackage, getURLs, newInstance, newInstance

Methods inherited from class java.security.SecureClassLoader

defineClass

Methods inherited from class java.lang.ClassLoader

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

Methods inherited from class java.lang.Object

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

Field Detail

available

protected java.util.ArrayList available

The set of optional packages (formerly standard extensions) that are available in the repositories associated with this class loader. Each object in this list is of type org.apache.catalina.loader.Extension.

classCache

protected java.util.HashMap classCache

The cache of ClassCacheEntries for classes we have loaded locally, keyed by class name.

debug

protected int debug

The debugging detail level of this component.

delegate

protected boolean delegate

Should this class loader delegate to the parent class loader before searching its own repositories (i.e. the usual Java2 delegation model)? If set to false, this class loader will search its own repositories first, and delegate to the parent only if the class or resource is not found locally.

repositories

protected java.lang.String[] repositories

The list of local repositories, in the order they should be searched for locally loaded classes or resources.

required

protected java.util.ArrayList required

The set of optional packages (formerly standard extensions) that are required in the repositories associated with this class loader. Each object in this list is of type org.apache.catalina.loader.Extension.

factory

protected java.net.URLStreamHandlerFactory factory

URL stream handler for additional protocols.

Constructor Detail

StandardClassLoader

public StandardClassLoader()

Construct a new ClassLoader with no defined repositories and no parent ClassLoader.

StandardClassLoader

public StandardClassLoader(java.net.URLStreamHandlerFactory factory)

Construct a new ClassLoader with no defined repositories and no parent ClassLoader, but with a stream handler factory.

Parameters:

factory - the URLStreamHandlerFactory to use when creating URLs

StandardClassLoader

public StandardClassLoader(java.lang.ClassLoader parent)

Construct a new ClassLoader with no defined repositories and the specified parent ClassLoader.

Parameters:

parent - The parent ClassLoader

StandardClassLoader

public StandardClassLoader(java.lang.ClassLoader parent,
                           java.net.URLStreamHandlerFactory factory)

Construct a new ClassLoader with no defined repositories and the specified parent ClassLoader.

Parameters:

parent - The parent ClassLoader

factory - the URLStreamHandlerFactory to use when creating URLs

StandardClassLoader

public StandardClassLoader(java.lang.String[] repositories)

Construct a new ClassLoader with the specified repositories and no parent ClassLoader.

Parameters:

repositories - The initial set of repositories

StandardClassLoader

public StandardClassLoader(java.lang.String[] repositories,
                           java.lang.ClassLoader parent)

Construct a new ClassLoader with the specified repositories and parent ClassLoader.

Parameters:

repositories - The initial set of repositories

parent - The parent ClassLoader

StandardClassLoader

public StandardClassLoader(java.net.URL[] repositories,
                           java.lang.ClassLoader parent)

Construct a new ClassLoader with the specified repositories and parent ClassLoader.

Parameters:

repositories - The initial set of repositories

parent - The parent ClassLoader

Method Detail

getDebug

public int getDebug()

Return the debugging detail level for this component.

setDebug

public void setDebug(int debug)

Set the debugging detail level for this component.

Parameters:

debug - The new debugging detail level

getDelegate

public boolean getDelegate()

Return the "delegate first" flag for this class loader.

setDelegate

public void setDelegate(boolean delegate)

Set the "delegate first" flag for this class loader.

Parameters:

delegate - The new "delegate first" flag

setPermissions

public void setPermissions(java.lang.String path)

If there is a Java SecurityManager create a read FilePermission or JndiPermission for the file directory path.

Parameters:

path - file directory path

setPermissions

public void setPermissions(java.net.URL url)

If there is a Java SecurityManager add a read FilePermission or JndiPermission for URL.

Parameters:

url - URL for a file or directory on local system

addRepository

public void addRepository(java.lang.String repository)

Add a new repository to the set of places this ClassLoader can look for classes to be loaded.

Specified by:

addRepository in interface Reloader

Parameters:

repository - Name of a source of classes to be loaded, such as a directory pathname, a JAR file pathname, or a ZIP file pathname

Throws:

java.lang.IllegalArgumentException - if the specified repository is invalid or does not exist

findAvailable

public Extension[] findAvailable()

Return a list of "optional packages" (formerly "standard extensions") that have been declared to be available in the repositories associated with this class loader, plus any parent class loader implemented with the same class.

findRepositories

public java.lang.String[] findRepositories()

Return a String array of the current repositories for this class loader. If there are no repositories, a zero-length array is returned.

Specified by:

findRepositories in interface Reloader

findRequired

public Extension[] findRequired()

Return a list of "optional packages" (formerly "standard extensions") that have been declared to be required in the repositories associated with this class loader, plus any parent class loader implemented with the same class.

modified

public boolean modified()

Have one or more classes or resources been modified so that a reload is appropriate?

IMPLEMENTATION NOTE - We assume that anything loaded from a JAR file will never need to be reloaded unless the JAR file itself has been updated. Unpacked classes or resources loaded from a directory are checked individually.

Specified by:

modified in interface Reloader

toString

public java.lang.String toString()

Render a String representation of this object.

Overrides:

toString in class java.lang.Object

findClass

public java.lang.Class findClass(java.lang.String name)
                          throws java.lang.ClassNotFoundException

Find the specified class in our local repositories, if possible. If not found, throw ClassNotFoundException.

Overrides:

findClass in class java.net.URLClassLoader

Parameters:

name - Name of the class to be loaded

Throws:

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

findResource

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

Find the specified resource in our local repository, and return a URL refering to it, or null if this resource cannot be found.

Overrides:

findResource in class java.net.URLClassLoader

Parameters:

name - Name of the resource to be found

findResources

public java.util.Enumeration findResources(java.lang.String name)
                                    throws java.io.IOException

Return an enumeration of URLs representing all of the resources with the given name. If no resources with this name are found, return an empty enumeration.

Overrides:

findResources in class java.net.URLClassLoader

Parameters:

name - Name of the resources to be found

Throws:

java.io.IOException - if an input/output error occurs

getResource

public java.net.URL getResource(java.lang.String name)

Find the resource with the given name. A resource is some data (images, audio, text, etc.) that can be accessed by class code in a way that is independent of the location of the code. The name of a resource is a "/"-separated path name that identifies the resource. If the resource cannot be found, return null.

This method searches according to the following algorithm, returning as soon as it finds the appropriate URL. If the resource cannot be found, returns null.

• If the delegate property is set to true, call the getResource() method of the parent class loader, if any.
• Call findResource() to find this resource in our locally defined repositories.
• Call the getResource() method of the parent class loader, if any.

Overrides:

getResource in class java.lang.ClassLoader

Parameters:

name - Name of the resource to return a URL for

getResourceAsStream

public java.io.InputStream getResourceAsStream(java.lang.String name)

Find the resource with the given name, and return an input stream that can be used for reading it. The search order is as described for getResource(), after checking to see if the resource data has been previously cached. If the resource cannot be found, return null.

Overrides:

getResourceAsStream in class java.lang.ClassLoader

Parameters:

name - Name of the resource to return an input stream for

loadClass

public java.lang.Class loadClass(java.lang.String name)
                          throws java.lang.ClassNotFoundException

Load the class with the specified name. This method searches for classes in the same manner as loadClass(String, boolean) with false as the second argument.

Overrides:

loadClass in class java.lang.ClassLoader

Parameters:

name - Name of the class to be loaded

Throws:

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

loadClass

public java.lang.Class loadClass(java.lang.String name,
                                 boolean resolve)
                          throws java.lang.ClassNotFoundException

Load the class with the specified name, searching using the following algorithm until it finds and returns the class. If the class cannot be found, returns ClassNotFoundException.

• Call findLoadedClass(String) to check if the class has already been loaded. If it has, the same Class object is returned.
• If the delegate property is set to true, call the loadClass() method of the parent class loader, if any.
• Call findClass() to find this class in our locally defined repositories.
• Call the loadClass() method of our parent class loader, if any.

If the class was found using the above steps, and the resolve flag is true, this method will then call resolveClass(Class) on the resulting Class object.

Overrides:

loadClass in class java.lang.ClassLoader

Parameters:

name - Name of the class to be loaded

resolve - If true then resolve the class

Throws:

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

getPermissions

protected final java.security.PermissionCollection getPermissions(java.security.CodeSource codeSource)

Get the Permissions for a CodeSource. If this instance of StandardClassLoader is for a web application context, add read FilePermissions for the base directory (if unpacked), the context URL, and jar file resources.

Overrides:

getPermissions in class java.net.URLClassLoader

Returns:

PermissionCollection for CodeSource

parseProtocol

protected static java.lang.String parseProtocol(java.lang.String spec)

Parse URL protocol.

Returns:

String protocol

addRepositoryInternal

protected void addRepositoryInternal(java.lang.String repository)

Add a repository to our internal array only.

Parameters:

repository - The new repository

Throws:

java.lang.IllegalArgumentException - if the manifest of a JAR file cannot be processed correctly

convert

protected static java.net.URL[] convert(java.lang.String[] input)

Convert an array of String to an array of URL and return it.

Parameters:

input - The array of String to be converted

convert

protected static java.net.URL[] convert(java.lang.String[] input,
                                        java.net.URLStreamHandlerFactory factory)

Convert an array of String to an array of URL and return it.

Parameters:

input - The array of String to be converted

factory - Handler factory to use to generate the URLs

findLoadedResource

protected java.io.InputStream findLoadedResource(java.lang.String name)

Finds the resource with the given name if it has previously been loaded and cached by this class loader, and return an input stream to the resource data. If this resource has not been cached, return null.

Parameters:

name - Name of the resource to return