org.safs.jvmagent

Class AgentClassLoader

java.lang.Object

java.lang.ClassLoader

org.safs.jvmagent.AgentClassLoader

public class AgentClassLoader
extends java.lang.ClassLoader

Provide a class loader that loads from a custom path. The original intention is to provide a ClassLoader for an Assistive Technologies Java Extension. The new Bootstrap mechanism for Java JVMs does not have access to the system CLASSPATH while extensions are being loaded.

This classloader doesn't do the security checks normally done by the default ClassLoaders. If path given is null, uses java.class.path.

Author:

Carl Nagle 2005.01.06 Original Release, Carl Nagle 2005.01.20 Converted static functions to instance functions., Lei Wang 2013.02.07 Use IndependantLog instead of Log to log message.

See Also:

Java Accessibility, Bootstrap, AgentImpl, org.safs.abbot.jvmagent.JVMAgent

Field Summary

Fields

Modifier and Type	Field and Description
static java.lang.String	DEFAULT_PATH_SEP Default path separators for tokenizers: ":;"
protected static java.lang.String	PSEP convenient File.pathSeparator

Constructor Summary

Constructors

Constructor and Description
AgentClassLoader(java.lang.String path) Create a class loader that loads classes from the given search paths.
AgentClassLoader(java.lang.String path, java.lang.ClassLoader parent) Preferred constructor creates a class loader that loads classes from the given search paths.

Method Summary

Modifier and Type	Method and Description
java.lang.String[]	convertPathToFilenames(java.lang.String path) calls convertPathToFilenames(path, DEFAULT_PATH_SEP);
java.lang.String[]	convertPathToFilenames(java.lang.String path, java.lang.String seps) Convert the given CLASSPATH type string into an array of unique filename paths.
java.io.File[]	convertPathToFiles(java.lang.String path, java.lang.String seps) Convert the given CLASSPATH type string into an array of Files.
protected java.lang.Class	findClass(java.lang.String name) Overrides the superclass implementation.
static java.net.URL	findCustomizedJARResource(java.net.URL url, java.lang.String resource) Assuming the URL represents a resource found in a JAR file, this routine will attempt to return a URL pointing to a user customized resource file of the given name located in the same directory containing the JAR file.
protected java.net.URL	findResource(java.lang.String name) Overrides the superclass implementation.
static java.io.File	findResourceDirectory(java.net.URL url) Attempts to locate the system directory where a file or resource was successfully located.
protected java.lang.Class	loadClass(java.lang.String name, boolean resolve) Cycle through the chain of parent ClassLoaders before resorting to ours.
static java.net.URL	locateResource(java.lang.String resource) Searches the following chain for a resource: Thread.currentThread().getContextClassLoader().getResource(resource); AgentClassLoader.class.getResource(resource); ClassLoader.getSystemResource(resource);
java.lang.String	toString()

Methods inherited from class java.lang.ClassLoader

clearAssertionStatus, defineClass, defineClass, defineClass, defineClass, definePackage, findLibrary, findLoadedClass, findResources, findSystemClass, getClassLoadingLock, getPackage, getPackages, getParent, getResource, getResourceAsStream, getResources, 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

Field Detail

DEFAULT_PATH_SEP

public static final java.lang.String DEFAULT_PATH_SEP

Default path separators for tokenizers: ":;"

See Also:

Constant Field Values

PSEP

protected static final java.lang.String PSEP

convenient File.pathSeparator

Constructor Detail

AgentClassLoader

public AgentClassLoader(java.lang.String path)

Create a class loader that loads classes from the given search paths. The search paths are in typical CLASSPATH format. Though Windows file separators '\' may need to be reversed to prevent character escaping: C:/MyApp.JAR;C:/ChildDir/Another.JAR Unix paths should not have this problem. Using this constructor is the same as using the preferred constructor: AgentClassLoader( path, null);

AgentClassLoader

public AgentClassLoader(java.lang.String path,
                        java.lang.ClassLoader parent)

Preferred constructor creates a class loader that loads classes from the given search paths. Will also refer to any parent ClassLoader as necessary. The search paths are in typical CLASSPATH format. Though Windows file separators '\' may need to be reversed to prevent character escaping: C:/MyApp.JAR;C:/ChildDir/Another.JAR Unix paths should not have this problem.

Method Detail

loadClass

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

Cycle through the chain of parent ClassLoaders before resorting to ours. Overrides the superclass implementation.

Overrides:

loadClass in class java.lang.ClassLoader

Throws:

java.lang.ClassNotFoundException

findClass

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

Overrides the superclass implementation. Invokes findIt and defineIt to return the desired Class.

Overrides:

findClass in class java.lang.ClassLoader

Throws:

java.lang.ClassNotFoundException

findResource

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

Overrides the superclass implementation. Invokes findURL to return the URL.

Overrides:

findResource in class java.lang.ClassLoader

convertPathToFilenames

public java.lang.String[] convertPathToFilenames(java.lang.String path)

calls convertPathToFilenames(path, DEFAULT_PATH_SEP);

convertPathToFiles

public java.io.File[] convertPathToFiles(java.lang.String path,
                                         java.lang.String seps)

Convert the given CLASSPATH type string into an array of Files. Only valid paths are copied into the array. File.exists() must be true to make it into the array.

convertPathToFilenames

public java.lang.String[] convertPathToFilenames(java.lang.String path,
                                                 java.lang.String seps)

Convert the given CLASSPATH type string into an array of unique filename paths. The validity of these filename paths is not verified or checked.

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

findResourceDirectory

public static java.io.File findResourceDirectory(java.net.URL url)

Attempts to locate the system directory where a file or resource was successfully located. The URL is assumed to be a successfully found resource resulting from a call to getResource or getSystemResource. Since these can be found in the file system or in JAR files we attempt to identify the directory where the file or JAR was located. We use the URL from the calling class because this Method may end up using different ClassLoaders and locate resources in different locations than the one needed by the caller. If the URL does NOT ultimately point to a local system directory then this routine returns null.

Parameters:

resource - URL to parse for directory information.

Returns:

File pointing to containing directory, or null.

findCustomizedJARResource

public static java.net.URL findCustomizedJARResource(java.net.URL url,
                                                     java.lang.String resource)

Assuming the URL represents a resource found in a JAR file, this routine will attempt to return a URL pointing to a user customized resource file of the given name located in the same directory containing the JAR file.

Parameters:

url - of existing (JAR'd) resource.

Returns:

URL to a standalone resource on the local file system, or null.

locateResource

public static java.net.URL locateResource(java.lang.String resource)
                                   throws java.util.MissingResourceException

Searches the following chain for a resource:

1. Thread.currentThread().getContextClassLoader().getResource(resource);
2. AgentClassLoader.class.getResource(resource);
3. ClassLoader.getSystemResource(resource);

Parameters:

resource - Name of resource to locate (Ex: "JavaObjectsMap.dat")

Returns:

URL to resource

Throws:

java.util.MissingResourceException - if resource (URL) cannot be found.