org.apache.catalina.loader
Class WebappClassLoader

java.lang.Object
  java.lang.ClassLoader
      java.security.SecureClassLoader
          java.net.URLClassLoader
              org.apache.catalina.loader.WebappClassLoader

All Implemented Interfaces:

Lifecycle

public class WebappClassLoader
extends java.net.URLClassLoader
implements Lifecycle

Specialized web application class loader.

This class loader is a full reimplementation of the URLClassLoader from the JDK. It is desinged to be fully compatible with a normal URLClassLoader, although its internal behavior may be completely different.

IMPLEMENTATION NOTE - This class loader faithfully follows the delegation model recommended in the specification. The system class loader will be queried first, then the local repositories, and only then delegation to the parent class loader will occur. This allows the web application to override any shared class except the classes from J2SE. Special handling is provided from the JAXP XML parser interfaces, the JNDI interfaces, and the classes from the servlet API, which are never loaded from the webapp repository.

IMPLEMENTATION NOTE - Due to limitations in Jasper compilation technology, any repository which contains classes from the servlet API will be ignored by the class loader.

IMPLEMENTATION NOTE - The class loader generates source URLs which include the full JAR URL when a class is loaded from a JAR file, which allows setting security permission at the class level, even when a class is contained inside a JAR.

IMPLEMENTATION NOTE - Local repositories are searched in the order they are specified in the JarRepository.

IMPLEMENTATION NOTE - No check for sealing violations or security is made unless a security manager is present.

Version:

$Revision: 1237 $ $Date: 2009-11-03 02:55:48 +0100 (Tue, 03 Nov 2009) $

Author:

Remy Maucherat, Craig R. McClanahan

Nested Class Summary

protected class

WebappClassLoader.PrivilegedFindResource

Field Summary

protected java.security.Permission	allPermission All permission.
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)?
static boolean	ENABLE_CLEAR_REFERENCES
protected java.io.File	loaderDir Path where resources loaded from JARs will be extracted.
protected java.util.HashMap	loaderPC The PermissionCollection for each CodeSource for a web application context.
protected static org.jboss.logging.Logger	log
protected boolean	needConvert need conversion for properties files
protected java.util.Map<java.lang.String,java.lang.Object>	notFoundResources The list of not found resources.
protected static java.lang.String[]	packageTriggers Set of package names which are not allowed to be loaded from a webapp class loader without delegating first.
protected java.lang.ClassLoader	parent The parent class loader.
protected java.util.ArrayList	permissionList A list of read File and Jndi Permission's required if this loader is for a web application context.
protected JarRepository	repository Associated Jar repository.
protected java.net.URL[]	repositoryURLs Repositories URLs, used to cache the result of getURLs.
protected java.util.Map<java.lang.String,ResourceEntry>	resourceEntries The cache of ResourceEntry for classes and resources we have loaded, keyed by resource name.
protected java.lang.SecurityManager	securityManager Instance of the SecurityManager installed.
protected static StringManager	sm The string manager for this package.
protected boolean	started Has this component been started?
protected java.lang.ClassLoader	system The system class loader.
static boolean	SYSTEM_CL_DELEGATION
protected static java.lang.String[]	triggers The set of trigger classes that will cause a proposed repository not to be added if this class is visible to the class loader that loaded this factory class.
protected static java.lang.Object	VALUE

Fields inherited from interface org.apache.catalina.Lifecycle

AFTER_START_EVENT, AFTER_STOP_EVENT, BEFORE_START_EVENT, BEFORE_STOP_EVENT, DESTROY_EVENT, INIT_EVENT, PERIODIC_EVENT, START_EVENT, STOP_EVENT

Constructor Summary

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

WebappClassLoader(java.lang.ClassLoader parent)
Construct a new ClassLoader with no defined repositories and no parent ClassLoader.

Method Summary

void	addLifecycleListener(LifecycleListener listener) Add a lifecycle event listener to this component.
void	addPermission(java.security.Permission permission) If there is a Java SecurityManager create a Permission.
void	addPermission(java.lang.String path) If there is a Java SecurityManager create a read FilePermission or JndiPermission for the file directory path.
void	addPermission(java.net.URL url) If there is a Java SecurityManager create a read FilePermission or JndiPermission for URL.
protected void	clearReferences() Clear references.
protected static void	deleteDir(java.io.File dir) Delete the specified directory, including all of its contents and subdirectories recursively.
protected boolean	filter(java.lang.String name) Filter classes.
java.lang.Class	findClass(java.lang.String name) Find the specified class in our local repositories, if possible.
protected java.lang.Class	findClassInternal(java.lang.String name) Find specified class in local repositories.
LifecycleListener[]	findLifecycleListeners() Get the lifecycle listeners associated with this lifecycle.
protected java.lang.Class	findLoadedClass0(java.lang.String name) Finds the class with the given name if it has previously been loaded and cached by this class loader, and return the Class object.
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.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.
protected ResourceEntry	findResourceInternal(java.io.File file, java.lang.String path) Find specified resource in local repositories.
protected ResourceEntry	findResourceInternal(java.lang.String name, java.lang.String path) Find specified resource in local repositories.
java.util.Enumeration	findResources(java.lang.String name) Return an enumeration of URLs representing all of the resources with the given name.
boolean	getAntiJARLocking()
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.
JarRepository	getRepository()
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.
protected java.net.URL	getURI(java.io.File file) Get URL.
protected java.net.URL	getURL(java.io.File file, boolean encoded) Get URL.
java.net.URL[]	getURLs() Returns the search path of URLs for loading classes and resources.
protected boolean	isPackageSealed(java.lang.String name, java.util.jar.Manifest man) Returns true if the specified package name is sealed according to the given manifest.
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.
protected boolean	loadedByThisOrChild(java.lang.Class clazz) Determine whether a class was loaded by this class loader or one of its child class loaders.
protected void	nullInstance(java.lang.Object instance)
protected void	refreshPolicy() Refresh the system policy file, to pick up eventual changes.
void	removeLifecycleListener(LifecycleListener listener) Remove a lifecycle event listener from this component.
void	setAntiJARLocking(boolean antiJARLocking)
void	setDelegate(boolean delegate) Set the "delegate first" flag for this class loader.
protected void	setParentClassLoader(java.lang.ClassLoader pcl) Utility method for use in subclasses.
void	setRepository(JarRepository repository)
void	setWorkDir(java.io.File workDir) Change the work directory.
void	start() Start the class loader.
void	stop() Stop the class loader.
java.lang.String	toString() Render a String representation of this object.
protected boolean	validate(java.lang.String name) Validate a classname.
protected boolean	validateJarFile(java.io.File jarfile) Check the specified JAR file, and return true if it does not contain any of the trigger classes.

Methods inherited from class java.net.URLClassLoader

addURL, definePackage, newInstance, newInstance

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, getPackage, getPackages, getParent, getResources, getSystemClassLoader, getSystemResource, getSystemResourceAsStream, getSystemResources, loadClass, resolveClass, setClassAssertionStatus, setDefaultAssertionStatus, setPackageAssertionStatus, setSigners

Methods inherited from class java.lang.Object

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

Field Detail

log

protected static org.jboss.logging.Logger log

ENABLE_CLEAR_REFERENCES

public static final boolean ENABLE_CLEAR_REFERENCES

SYSTEM_CL_DELEGATION

public static final boolean SYSTEM_CL_DELEGATION

triggers

protected static final java.lang.String[] triggers

The set of trigger classes that will cause a proposed repository not to be added if this class is visible to the class loader that loaded this factory class. Typically, trigger classes will be listed for components that have been integrated into the JDK for later versions, but where the corresponding JAR files are required to run on earlier versions.

packageTriggers

protected static final java.lang.String[] packageTriggers

Set of package names which are not allowed to be loaded from a webapp class loader without delegating first.

sm

protected static final StringManager sm

The string manager for this package.

repository

protected JarRepository repository

Associated Jar repository.

resourceEntries

protected java.util.Map<java.lang.String,ResourceEntry> resourceEntries

The cache of ResourceEntry for classes and resources we have loaded, keyed by resource name.

notFoundResources

protected java.util.Map<java.lang.String,java.lang.Object> notFoundResources

The list of not found resources.

VALUE

protected static final java.lang.Object VALUE

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.

repositoryURLs

protected java.net.URL[] repositoryURLs

Repositories URLs, used to cache the result of getURLs.

permissionList

protected java.util.ArrayList permissionList

A list of read File and Jndi Permission's required if this loader is for a web application context.

loaderDir

protected java.io.File loaderDir

Path where resources loaded from JARs will be extracted.

loaderPC

protected java.util.HashMap loaderPC

The PermissionCollection for each CodeSource for a web application context.

securityManager

protected java.lang.SecurityManager securityManager

Instance of the SecurityManager installed.

parent

protected java.lang.ClassLoader parent

The parent class loader.

system

protected java.lang.ClassLoader system

The system class loader.

started

protected boolean started

Has this component been started?

needConvert

protected boolean needConvert

need conversion for properties files

allPermission

protected java.security.Permission allPermission

All permission.

Constructor Detail

WebappClassLoader

public WebappClassLoader()

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

WebappClassLoader

public WebappClassLoader(java.lang.ClassLoader parent)

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

Method Detail

getRepository

public JarRepository getRepository()

setRepository

public void setRepository(JarRepository repository)

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

getAntiJARLocking

public boolean getAntiJARLocking()

Returns:

Returns the antiJARLocking.

setAntiJARLocking

public void setAntiJARLocking(boolean antiJARLocking)

Parameters:

antiJARLocking - The antiJARLocking to set.

addPermission

public void addPermission(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

addPermission

public void addPermission(java.net.URL url)

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

Parameters:

url - URL for a file or directory on local system

addPermission

public void addPermission(java.security.Permission permission)

If there is a Java SecurityManager create a Permission.

Parameters:

permission - The permission

setWorkDir

public void setWorkDir(java.io.File workDir)

Change the work directory.

setParentClassLoader

protected void setParentClassLoader(java.lang.ClassLoader pcl)

Utility method for use in subclasses. Must be called before Lifecycle methods to have any effect.

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,
                                    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 java.security.PermissionCollection getPermissions(java.security.CodeSource codeSource)

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

Overrides:

getPermissions in class java.net.URLClassLoader

Parameters:

codeSource - where the code was loaded from

Returns:

PermissionCollection for CodeSource

getURLs

public java.net.URL[] getURLs()

Returns 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.

Overrides:

getURLs in class java.net.URLClassLoader

Returns:

the search path of URLs for loading classes and resources.

addLifecycleListener

public void addLifecycleListener(LifecycleListener listener)

Add a lifecycle event listener to this component.

Specified by:

addLifecycleListener in interface Lifecycle

Parameters:

listener - The listener to add

findLifecycleListeners

public LifecycleListener[] findLifecycleListeners()

Get the lifecycle listeners associated with this lifecycle. If this Lifecycle has no listeners registered, a zero-length array is returned.

Specified by:

findLifecycleListeners in interface Lifecycle

removeLifecycleListener

public void removeLifecycleListener(LifecycleListener listener)

Remove a lifecycle event listener from this component.

Specified by:

removeLifecycleListener in interface Lifecycle

Parameters:

listener - The listener to remove

start

public void start()
           throws LifecycleException

Start the class loader.

Specified by:

start in interface Lifecycle

Throws:

LifecycleException - if a lifecycle error occurs

stop

public void stop()
          throws LifecycleException

Stop the class loader.

Specified by:

stop in interface Lifecycle

Throws:

LifecycleException - if a lifecycle error occurs

clearReferences

protected void clearReferences()

Clear references.

nullInstance

protected void nullInstance(java.lang.Object instance)

loadedByThisOrChild

protected boolean loadedByThisOrChild(java.lang.Class clazz)

Determine whether a class was loaded by this class loader or one of its child class loaders.

findClassInternal

protected java.lang.Class findClassInternal(java.lang.String name)
                                     throws java.lang.ClassNotFoundException

Find specified class in local repositories.

Returns:

the loaded class, or null if the class isn't found

Throws:

java.lang.ClassNotFoundException

findResourceInternal

protected ResourceEntry findResourceInternal(java.io.File file,
                                             java.lang.String path)

Find specified resource in local repositories. This block will execute under an AccessControl.doPrivilege block.

Returns:

the loaded resource, or null if the resource isn't found

findResourceInternal

protected ResourceEntry findResourceInternal(java.lang.String name,
                                             java.lang.String path)

Find specified resource in local repositories.

Returns:

the loaded resource, or null if the resource isn't found

isPackageSealed

protected boolean isPackageSealed(java.lang.String name,
                                  java.util.jar.Manifest man)

Returns true if the specified package name is sealed according to the given manifest.

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

findLoadedClass0

protected java.lang.Class findLoadedClass0(java.lang.String name)

Finds the class with the given name if it has previously been loaded and cached by this class loader, and return the Class object. If this class has not been cached, return null.

Parameters:

name - Name of the resource to return

refreshPolicy

protected void refreshPolicy()

Refresh the system policy file, to pick up eventual changes.

filter

protected boolean filter(java.lang.String name)

Filter classes.

Parameters:

name - class name

Returns:

true if the class should be filtered

validate

protected boolean validate(java.lang.String name)

Validate a classname. As per SRV.9.7.2, we must restict loading of classes from J2SE (java.*) and classes of the servlet API (javax.servlet.*). That should enhance robustness and prevent a number of user error (where an older version of servlet.jar would be present in /WEB-INF/lib).

Parameters:

name - class name

Returns:

true if the name is valid

validateJarFile

protected boolean validateJarFile(java.io.File jarfile)
                           throws java.io.IOException

Check the specified JAR file, and return true if it does not contain any of the trigger classes.

Parameters:

jarfile - The JAR file to be checked

Throws:

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

getURL

protected java.net.URL getURL(java.io.File file,
                              boolean encoded)
                       throws java.net.MalformedURLException

Get URL.

Throws:

java.net.MalformedURLException

getURI

protected java.net.URL getURI(java.io.File file)
                       throws java.net.MalformedURLException

Get URL.

Throws:

java.net.MalformedURLException

deleteDir

protected static void deleteDir(java.io.File dir)

Delete the specified directory, including all of its contents and subdirectories recursively.

Parameters:

dir - File object representing the directory to be deleted