org.apache.tools.ant
Class AntClassLoader

java.lang.Object
  |
  +--java.lang.ClassLoader
        |
        +--org.apache.tools.ant.AntClassLoader
All Implemented Interfaces:
BuildListener, java.util.EventListener, SubBuildListener
Direct Known Subclasses:
AntClassLoader2

public class AntClassLoader
extends java.lang.ClassLoader
implements SubBuildListener

Used to load classes within ant with a different classpath from that used to start ant. Note that it is possible to force a class into this loader even when that class is on the system classpath by using the forceLoadClass method. Any subsequent classes loaded by that class will then use this loader rather than the system class loader.


Constructor Summary
AntClassLoader()
          Create an Ant Class Loader
AntClassLoader(java.lang.ClassLoader parent, boolean parentFirst)
          Creates an empty class loader.
AntClassLoader(java.lang.ClassLoader parent, Project project, Path classpath, boolean parentFirst)
          Creates a classloader for the given project using the classpath given.
AntClassLoader(Project project, Path classpath)
          Creates a classloader for the given project using the classpath given.
AntClassLoader(Project project, Path classpath, boolean parentFirst)
          Creates a classloader for the given project using the classpath given.
 
Method Summary
 void addJavaLibraries()
          add any libraries that come with different java versions here
 void addLoaderPackageRoot(java.lang.String packageRoot)
          Adds a package root to the list of packages which must be loaded using this loader.
 void addPathElement(java.lang.String pathElement)
          Adds an element to the classpath to be searched.
protected  void addPathFile(java.io.File pathComponent)
          Add a file to the path
 void addSystemPackageRoot(java.lang.String packageRoot)
          Adds a package root to the list of packages which must be loaded on the parent loader.
 void buildFinished(BuildEvent event)
          Cleans up any resources held by this classloader at the end of a build.
 void buildStarted(BuildEvent event)
          Empty implementation to satisfy the BuildListener interface.
 void cleanup()
          Cleans up any resources held by this classloader.
protected  java.lang.Class defineClassFromData(java.io.File container, byte[] classData, java.lang.String classname)
          Define a class given its bytes
 java.lang.Class findClass(java.lang.String name)
          Searches for and load a class on the classpath of this class loader.
protected  java.util.Enumeration findResources(java.lang.String name)
          Returns an enumeration of URLs representing all the resources with the given name by searching the class loader's classpath.
 java.lang.Class forceLoadClass(java.lang.String classname)
          Loads a class through this class loader even if that class is available on the parent classpath.
 java.lang.Class forceLoadSystemClass(java.lang.String classname)
          Loads a class through this class loader but defer to the parent class loader.
 java.lang.String getClasspath()
          Returns the classpath this classloader will consult.
 java.net.URL getResource(java.lang.String name)
          Finds the resource with the given name.
 java.io.InputStream getResourceAsStream(java.lang.String name)
          Returns a stream to read the requested resource name.
protected  java.net.URL getResourceURL(java.io.File file, java.lang.String resourceName)
          Returns the URL of a given resource in the given file which may either be a directory or a zip file.
static void initializeClass(java.lang.Class theClass)
          Deprecated. use Class.forName with initialize=true instead.
protected  boolean isInPath(java.io.File component)
          Indicate if the given file is in this loader's path
protected  java.lang.Class loadClass(java.lang.String classname, boolean resolve)
          Loads a class with this class loader.
protected  void log(java.lang.String message, int priority)
          Logs a message through the project object if one has been provided.
 void messageLogged(BuildEvent event)
          Empty implementation to satisfy the BuildListener interface.
 void resetThreadContextLoader()
          Resets the current thread's context loader to its original value.
 void setClassPath(Path classpath)
          Set the classpath to search for classes to load.
 void setIsolated(boolean isolated)
          Sets whether this classloader should run in isolated mode.
 void setParent(java.lang.ClassLoader parent)
          Set the parent for this class loader.
 void setParentFirst(boolean parentFirst)
          Control whether class lookup is delegated to the parent loader first or after this loader.
 void setProject(Project project)
          Set the project associated with this class loader
 void setThreadContextLoader()
          Sets the current thread's context loader to this classloader, storing the current loader value for later resetting.
 void subBuildFinished(BuildEvent event)
          Cleans up any resources held by this classloader at the end of a subbuild if it has been created for the subbuild's project instance.
 void subBuildStarted(BuildEvent event)
          Empty implementation to satisfy the BuildListener interface.
 void targetFinished(BuildEvent event)
          Empty implementation to satisfy the BuildListener interface.
 void targetStarted(BuildEvent event)
          Empty implementation to satisfy the BuildListener interface.
 void taskFinished(BuildEvent event)
          Empty implementation to satisfy the BuildListener interface.
 void taskStarted(BuildEvent event)
          Empty implementation to satisfy the BuildListener interface.
 
Methods inherited from class java.lang.ClassLoader
clearAssertionStatus, defineClass, defineClass, defineClass, definePackage, findLibrary, findLoadedClass, findResource, 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, toString, wait, wait, wait
 

Constructor Detail

AntClassLoader

public AntClassLoader()
Create an Ant Class Loader


AntClassLoader

public AntClassLoader(Project project,
                      Path classpath)
Creates a classloader for the given project using the classpath given.

Parameters:
project - The project to which this classloader is to belong. Must not be null.
classpath - The classpath to use to load the classes. This is combined with the system classpath in a manner determined by the value of ${build.sysclasspath}. May be null, in which case no path elements are set up to start with.

AntClassLoader

public AntClassLoader(java.lang.ClassLoader parent,
                      Project project,
                      Path classpath,
                      boolean parentFirst)
Creates a classloader for the given project using the classpath given.

Parameters:
parent - The parent classloader to which unsatisfied loading attempts are delegated. May be null, in which case the classloader which loaded this class is used as the parent.
project - The project to which this classloader is to belong. Must not be null.
classpath - the classpath to use to load the classes. May be null, in which case no path elements are set up to start with.
parentFirst - If true, indicates that the parent classloader should be consulted before trying to load the a class through this loader.

AntClassLoader

public AntClassLoader(Project project,
                      Path classpath,
                      boolean parentFirst)
Creates a classloader for the given project using the classpath given.

Parameters:
project - The project to which this classloader is to belong. Must not be null.
classpath - The classpath to use to load the classes. May be null, in which case no path elements are set up to start with.
parentFirst - If true, indicates that the parent classloader should be consulted before trying to load the a class through this loader.

AntClassLoader

public AntClassLoader(java.lang.ClassLoader parent,
                      boolean parentFirst)
Creates an empty class loader. The classloader should be configured with path elements to specify where the loader is to look for classes.

Parameters:
parent - The parent classloader to which unsatisfied loading attempts are delegated. May be null, in which case the classloader which loaded this class is used as the parent.
parentFirst - If true, indicates that the parent classloader should be consulted before trying to load the a class through this loader.
Method Detail

setProject

public void setProject(Project project)
Set the project associated with this class loader

Parameters:
project - the project instance

setClassPath

public void setClassPath(Path classpath)
Set the classpath to search for classes to load. This should not be changed once the classloader starts to server classes

Parameters:
classpath - the search classpath consisting of directories and jar/zip files.

setParent

public void setParent(java.lang.ClassLoader parent)
Set the parent for this class loader. This is the class loader to which this class loader will delegate to load classes

Parameters:
parent - the parent class loader.

setParentFirst

public void setParentFirst(boolean parentFirst)
Control whether class lookup is delegated to the parent loader first or after this loader. Use with extreme caution. Setting this to false violates the class loader hierarchy and can lead to Linkage errors

Parameters:
parentFirst - if true, delegate initial class search to the parent classloader.

log

protected void log(java.lang.String message,
                   int priority)
Logs a message through the project object if one has been provided.

Parameters:
message - The message to log. Should not be null.
priority - The logging priority of the message.

setThreadContextLoader

public void setThreadContextLoader()
Sets the current thread's context loader to this classloader, storing the current loader value for later resetting.


resetThreadContextLoader

public void resetThreadContextLoader()
Resets the current thread's context loader to its original value.


addPathElement

public void addPathElement(java.lang.String pathElement)
                    throws BuildException
Adds an element to the classpath to be searched.

Parameters:
pathElement - The path element to add. Must not be null.
Throws:
BuildException - if the given path element cannot be resolved against the project.

addPathFile

protected void addPathFile(java.io.File pathComponent)
                    throws java.io.IOException
Add a file to the path

Parameters:
pathComponent - the file which is to be added to the path for this class loader
Throws:
java.io.IOException - if data needed from the file cannot be read.

getClasspath

public java.lang.String getClasspath()
Returns the classpath this classloader will consult.

Returns:
the classpath used for this classloader, with elements separated by the path separator for the system.

setIsolated

public void setIsolated(boolean isolated)
Sets whether this classloader should run in isolated mode. In isolated mode, classes not found on the given classpath will not be referred to the parent class loader but will cause a ClassNotFoundException.

Parameters:
isolated - Whether or not this classloader should run in isolated mode.

initializeClass

public static void initializeClass(java.lang.Class theClass)
Deprecated. use Class.forName with initialize=true instead.

Forces initialization of a class in a JDK 1.1 compatible, albeit hacky way.

Parameters:
theClass - The class to initialize. Must not be null.

addSystemPackageRoot

public void addSystemPackageRoot(java.lang.String packageRoot)
Adds a package root to the list of packages which must be loaded on the parent loader. All subpackages are also included.

Parameters:
packageRoot - The root of all packages to be included. Should not be null.

addLoaderPackageRoot

public void addLoaderPackageRoot(java.lang.String packageRoot)
Adds a package root to the list of packages which must be loaded using this loader. All subpackages are also included.

Parameters:
packageRoot - The root of all packages to be included. Should not be null.

forceLoadClass

public java.lang.Class forceLoadClass(java.lang.String classname)
                               throws java.lang.ClassNotFoundException
Loads a class through this class loader even if that class is available on the parent classpath. This ensures that any classes which are loaded by the returned class will use this classloader.

Parameters:
classname - The name of the class to be loaded. Must not be null.
Returns:
the required Class object
Throws:
java.lang.ClassNotFoundException - if the requested class does not exist on this loader's classpath.

forceLoadSystemClass

public java.lang.Class forceLoadSystemClass(java.lang.String classname)
                                     throws java.lang.ClassNotFoundException
Loads a class through this class loader but defer to the parent class loader. This ensures that instances of the returned class will be compatible with instances which have already been loaded on the parent loader.

Parameters:
classname - The name of the class to be loaded. Must not be null.
Returns:
the required Class object
Throws:
java.lang.ClassNotFoundException - if the requested class does not exist on this loader's classpath.

getResourceAsStream

public java.io.InputStream getResourceAsStream(java.lang.String name)
Returns a stream to read the requested resource name.

Overrides:
getResourceAsStream in class java.lang.ClassLoader
Parameters:
name - The name of the resource for which a stream is required. Must not be null.
Returns:
a stream to the required resource or null if the resource cannot be found on the loader's classpath.

getResource

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

Overrides:
getResource in class java.lang.ClassLoader
Parameters:
name - The name of the resource for which a stream is required. Must not be null.
Returns:
a URL for reading the resource, or null if the resource could not be found or the caller doesn't have adequate privileges to get the resource.

findResources

protected java.util.Enumeration findResources(java.lang.String name)
                                       throws java.io.IOException
Returns an enumeration of URLs representing all the resources with the given name by searching the class loader's classpath.

Overrides:
findResources in class java.lang.ClassLoader
Parameters:
name - The resource name to search for. Must not be null.
Returns:
an enumeration of URLs for the resources
Throws:
java.io.IOException - if I/O errors occurs (can't happen)

getResourceURL

protected java.net.URL getResourceURL(java.io.File file,
                                      java.lang.String resourceName)
Returns the URL of a given resource in the given file which may either be a directory or a zip file.

Parameters:
file - The file (directory or jar) in which to search for the resource. Must not be null.
resourceName - The name of the resource for which a stream is required. Must not be null.
Returns:
a stream to the required resource or null if the resource cannot be found in the given file object.

loadClass

protected java.lang.Class loadClass(java.lang.String classname,
                                    boolean resolve)
                             throws java.lang.ClassNotFoundException
Loads a class with this class loader. This class attempts to load the class in an order determined by whether or not the class matches the system/loader package lists, with the loader package list taking priority. If the classloader is in isolated mode, failure to load the class in this loader will result in a ClassNotFoundException.

Overrides:
loadClass in class java.lang.ClassLoader
Parameters:
classname - The name of the class to be loaded. Must not be null.
resolve - true if all classes upon which this class depends are to be loaded.
Returns:
the required Class object
Throws:
java.lang.ClassNotFoundException - if the requested class does not exist on the system classpath (when not in isolated mode) or this loader's classpath.

defineClassFromData

protected java.lang.Class defineClassFromData(java.io.File container,
                                              byte[] classData,
                                              java.lang.String classname)
                                       throws java.io.IOException
Define a class given its bytes

Parameters:
container - the container from which the class data has been read may be a directory or a jar/zip file.
classData - the bytecode data for the class
classname - the name of the class
Returns:
the Class instance created from the given data
Throws:
java.io.IOException - if the class data cannot be read.

findClass

public java.lang.Class findClass(java.lang.String name)
                          throws java.lang.ClassNotFoundException
Searches for and load a class on the classpath of this class loader.

Overrides:
findClass in class java.lang.ClassLoader
Parameters:
name - The name of the class to be loaded. Must not be null.
Returns:
the required Class object
Throws:
java.lang.ClassNotFoundException - if the requested class does not exist on this loader's classpath.

isInPath

protected boolean isInPath(java.io.File component)
Indicate if the given file is in this loader's path

Parameters:
component - the file which is to be checked
Returns:
true if the file is in the class path

cleanup

public void cleanup()
Cleans up any resources held by this classloader. Any open archive files are closed.


buildStarted

public void buildStarted(BuildEvent event)
Empty implementation to satisfy the BuildListener interface.

Specified by:
buildStarted in interface BuildListener
Parameters:
event - the buildStarted event

buildFinished

public void buildFinished(BuildEvent event)
Cleans up any resources held by this classloader at the end of a build.

Specified by:
buildFinished in interface BuildListener
Parameters:
event - the buildFinished event
See Also:
BuildEvent.getException()

subBuildFinished

public void subBuildFinished(BuildEvent event)
Cleans up any resources held by this classloader at the end of a subbuild if it has been created for the subbuild's project instance.

Specified by:
subBuildFinished in interface SubBuildListener
Parameters:
event - the buildFinished event
Since:
Ant 1.6.2
See Also:
BuildEvent.getException()

subBuildStarted

public void subBuildStarted(BuildEvent event)
Empty implementation to satisfy the BuildListener interface.

Specified by:
subBuildStarted in interface SubBuildListener
Parameters:
event - the buildStarted event
Since:
Ant 1.6.2

targetStarted

public void targetStarted(BuildEvent event)
Empty implementation to satisfy the BuildListener interface.

Specified by:
targetStarted in interface BuildListener
Parameters:
event - the targetStarted event
See Also:
BuildEvent.getTarget()

targetFinished

public void targetFinished(BuildEvent event)
Empty implementation to satisfy the BuildListener interface.

Specified by:
targetFinished in interface BuildListener
Parameters:
event - the targetFinished event
See Also:
BuildEvent.getException()

taskStarted

public void taskStarted(BuildEvent event)
Empty implementation to satisfy the BuildListener interface.

Specified by:
taskStarted in interface BuildListener
Parameters:
event - the taskStarted event
See Also:
BuildEvent.getTask()

taskFinished

public void taskFinished(BuildEvent event)
Empty implementation to satisfy the BuildListener interface.

Specified by:
taskFinished in interface BuildListener
Parameters:
event - the taskFinished event
See Also:
BuildEvent.getException()

messageLogged

public void messageLogged(BuildEvent event)
Empty implementation to satisfy the BuildListener interface.

Specified by:
messageLogged in interface BuildListener
Parameters:
event - the messageLogged event
See Also:
BuildEvent.getMessage(), BuildEvent.getPriority()

addJavaLibraries

public void addJavaLibraries()
add any libraries that come with different java versions here



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