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org.apache.tools.ant

Class AntClassLoader

  • java.lang.Object
    • java.lang.ClassLoader
      • org.apache.tools.ant.AntClassLoader
  • All Implemented Interfaces:
    java.io.Closeable, java.lang.AutoCloseable, java.util.EventListener, BuildListener, SubBuildListener
    Direct Known Subclasses:
    AntClassLoader2, AntClassLoader5, SplitClassLoader

    public class AntClassLoader
extends java.lang.ClassLoader
implements SubBuildListener, java.io.Closeable
    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.

    Note that this classloader has a feature to allow loading in reverse order and for "isolation". Due to the fact that a number of methods in java.lang.ClassLoader are final (at least in java 1.4 getResources) this means that the class has to fake the given parent.

    • Constructor Summary

      Constructors 
      Constructor and Description
      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)
      Create an Ant ClassLoader for a given project, with a parent classloader and an initial classpath.
      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

      All Methods Static Methods Instance Methods Concrete Methods Deprecated Methods 
      Modifier and Type Method and Description
      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 addPathComponent(java.io.File file)
      Add a path component.
      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.
      void close()
      protected java.lang.Class<?> defineClassFromData(java.io.File container, byte[] classData, java.lang.String classname)
      Define a class given its bytes
      protected void definePackage(java.io.File container, java.lang.String className)
      Define the package information associated with a class.
      protected void definePackage(java.io.File container, java.lang.String packageName, java.util.jar.Manifest manifest)
      Define the package information when the class comes from a jar with a manifest
      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<java.net.URL> 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.
      protected java.util.Enumeration<java.net.URL> findResources(java.lang.String name, boolean parentHasBeenSearched)
      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.lang.ClassLoader getConfiguredParent()
      Gets the parent as has been specified in the constructor or via setParent.
      java.util.Enumeration<java.net.URL> getNamedResources(java.lang.String name)
      Finds all the resources with the given name.
      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.
      java.util.Enumeration<java.net.URL> getResources(java.lang.String 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. 
      since 1.6.x. 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.
      static AntClassLoader newAntClassLoader(java.lang.ClassLoader parent, Project project, Path path, boolean parentFirst)
      Factory method
      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.
      java.lang.String toString()
      Returns a String representing this loader.

      • Methods inherited from class java.lang.ClassLoader

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

      • Methods inherited from class java.lang.Object

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

    • Constructor Detail

      • AntClassLoader

        public AntClassLoader(java.lang.ClassLoader parent,
                      Project project,
                      Path classpath)
        Create an Ant ClassLoader for a given project, with a parent classloader and an initial classpath.
        Parameters:
        parent - the parent for this classloader.
        project - The project to which this classloader is to belong.
        classpath - The classpath to use to load classes.
        Since:
        Ant 1.7.

      • 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.

      • addPathComponent

        public void addPathComponent(java.io.File file)
        Add a path component. This simply adds the file, unlike addPathElement it does not open jar files and load files from their CLASSPATH entry in the manifest file.
        Parameters:
        file - the jar file or directory to add.

      • addPathFile

        protected void addPathFile(java.io.File pathComponent)
                    throws java.io.IOException
        Add a file to the path. Reads the manifest, if available, and adds any additional class path jars specified in the manifest.
        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

        @Deprecated
public static void initializeClass(java.lang.Class<?> theClass)
        Deprecated. since 1.6.x. 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.

      • getNamedResources

        public java.util.Enumeration<java.net.URL> getNamedResources(java.lang.String name)
                                                      throws java.io.IOException
        Finds all the resources 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.

        Would override getResources if that wasn't final in Java 1.4.

        Parameters:
        name - name of the resource
        Returns:
        possible URLs as enumeration
        Throws:
        java.io.IOException - if something goes wrong
        Since:
        Ant 1.8.0
        See Also:
        findResources(String, boolean)

      • findResources

        protected java.util.Enumeration<java.net.URL> 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)

      • findResources

        protected java.util.Enumeration<java.net.URL> findResources(java.lang.String name,
                                                            boolean parentHasBeenSearched)
                                                     throws java.io.IOException
        Returns an enumeration of URLs representing all the resources with the given name by searching the class loader's classpath.
        Parameters:
        name - The resource name to search for. Must not be null.
        parentHasBeenSearched - whether ClassLoader.this.parent has been searched - will be true if the method is (indirectly) called from ClassLoader.getResources
        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.

      • definePackage

        protected void definePackage(java.io.File container,
                             java.lang.String className)
                      throws java.io.IOException
        Define the package information associated with a class.
        Parameters:
        container - the file containing the class definition.
        className - the class name of for which the package information is to be determined.
        Throws:
        java.io.IOException - if the package information cannot be read from the container.

      • definePackage

        protected void definePackage(java.io.File container,
                             java.lang.String packageName,
                             java.util.jar.Manifest manifest)
        Define the package information when the class comes from a jar with a manifest
        Parameters:
        container - the jar file containing the manifest
        packageName - the name of the package being defined.
        manifest - the jar's manifest

      • 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.

      • getConfiguredParent

        public java.lang.ClassLoader getConfiguredParent()
        Gets the parent as has been specified in the constructor or via setParent.
        Returns:
        classloader
        Since:
        Ant 1.8.0

      • buildStarted

        public void buildStarted(BuildEvent event)
        Empty implementation to satisfy the BuildListener interface.
        Specified by:
        buildStarted in interface BuildListener
        Parameters:
        event - the buildStarted event

      • 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

      • addJavaLibraries

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

      • toString

        public java.lang.String toString()
        Returns a String representing this loader.
        Overrides:
        toString in class java.lang.Object
        Returns:
        the path that this classloader has.

      • getResources

        public java.util.Enumeration<java.net.URL> getResources(java.lang.String name)
                                                 throws java.io.IOException
        Overrides:
        getResources in class java.lang.ClassLoader
        Throws:
        java.io.IOException

      • close

        public void close()
        Specified by:
        close in interface java.io.Closeable
        Specified by:
        close in interface java.lang.AutoCloseable

      • newAntClassLoader

        public static AntClassLoader newAntClassLoader(java.lang.ClassLoader parent,
                                               Project project,
                                               Path path,
                                               boolean parentFirst)
        Factory method
        Parameters:
        parent - ClassLoader
        project - Project
        path - Path
        parentFirst - boolean
        Returns:
        AntClassLoader
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