org.codehaus.mojo.jaxb2.shared.environment.classloading

Class ThreadContextClassLoaderBuilder

java.lang.Object

org.codehaus.mojo.jaxb2.shared.environment.classloading.ThreadContextClassLoaderBuilder

public class ThreadContextClassLoaderBuilder
extends Object

Utility class which assists in synthesizing a URLClassLoader for use as a ThreadLocal ClassLoader. Typical use:

     
         // Create and set the ThreadContext ClassLoader
         ThreadContextClassLoaderHolder holder = null;

         try {

          holder = ThreadContextClassLoaderBuilder.createFor(getClass())
              .addPath("some/path")
              .addURL(someURL)
              .addPaths(aPathList)
              .buildAndSet();

          // ... perform operations using the newly set ThreadContext ClassLoader...

         } finally {
          // Restore the original ClassLoader
          holder.restoreClassLoaderAndReleaseThread();
         }
     
 

Since:

2.0

Author:

Lennart Jörelid, jGuru Europe AB

Method Summary

Methods

Modifier and Type	Method and Description
ThreadContextClassLoaderBuilder	addPath(String path) Converts the supplied path to an URL and adds it to this ThreadContextClassLoaderBuilder.
ThreadContextClassLoaderBuilder	addPaths(List<String> paths) Converts the supplied path to an URL and adds it to this ThreadContextClassLoaderBuilder.
ThreadContextClassLoaderBuilder	addURL(URL anURL) Adds the supplied anURL to the list of internal URLs which should be used to build an URLClassLoader.
ThreadContextClassLoaderHolder	buildAndSet() This method performs 2 things in order:
static ThreadContextClassLoaderBuilder	createFor(Class<?> aClass, org.apache.maven.plugin.logging.Log log) Creates a new ThreadContextClassLoaderBuilder using the original ClassLoader from the supplied Class, as well as the given Maven Log.
static ThreadContextClassLoaderBuilder	createFor(ClassLoader classLoader, org.apache.maven.plugin.logging.Log log) Creates a new ThreadContextClassLoaderBuilder using the supplied original classLoader, as well as the supplied Maven Log.
static String	getClassPathElement(URL anURL) Converts the supplied URL to a class path element.
static List<URL>	getRootResources(ClassLoader classLoader) Acquires all URLs corresponding to the resource path "" within the supplied ClassLoader.

Methods inherited from class java.lang.Object

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

Method Detail

addURL

public ThreadContextClassLoaderBuilder addURL(URL anURL)

Adds the supplied anURL to the list of internal URLs which should be used to build an URLClassLoader. Will only add an URL once, and warns about trying to re-add an URL.

Parameters:

anURL - The URL to add.

Returns:

This ThreadContextClassLoaderBuilder, for builder pattern chaining.

addPath

public ThreadContextClassLoaderBuilder addPath(String path)

Converts the supplied path to an URL and adds it to this ThreadContextClassLoaderBuilder.

Parameters:

path - A path to convert to an URL and add.

Returns:

This ThreadContextClassLoaderBuilder, for builder pattern chaining.

See Also:

addURL(java.net.URL)

addPaths

public ThreadContextClassLoaderBuilder addPaths(List<String> paths)

Converts the supplied path to an URL and adds it to this ThreadContextClassLoaderBuilder.

Parameters:

paths - A List of path to convert to URLs and add.

Returns:

This ThreadContextClassLoaderBuilder, for builder pattern chaining.

See Also:

addPath(String)

buildAndSet

public ThreadContextClassLoaderHolder buildAndSet()

This method performs 2 things in order:

1. Builds a ThreadContext ClassLoader from the URLs supplied to this Builder, and assigns the newly built ClassLoader to the current Thread.
2. Stores the ThreadContextClassLoaderHolder for later restoration.

References to the original ThreadContextClassLoader and the currentThread are stored within the returned ThreadContextClassLoaderHolder, and can be restored by a call to ThreadContextClassLoaderHolder.restoreClassLoaderAndReleaseThread().

Returns:

A fully set up ThreadContextClassLoaderHolder which is used to set the

createFor

public static ThreadContextClassLoaderBuilder createFor(ClassLoader classLoader,
                                        org.apache.maven.plugin.logging.Log log)

Creates a new ThreadContextClassLoaderBuilder using the supplied original classLoader, as well as the supplied Maven Log.

Parameters:

classLoader - The original ClassLoader which should be used as the parent for the ThreadContext ClassLoader produced by the ThreadContextClassLoaderBuilder generated by this builder method. Cannot be null.

log - The active Maven Log. Cannot be null.

Returns:

A ThreadContextClassLoaderBuilder wrapping the supplied members.

getRootResources

public static List<URL> getRootResources(ClassLoader classLoader)
                                  throws IllegalStateException

Acquires all URLs corresponding to the resource path "" within the supplied ClassLoader.

Parameters:

classLoader - A non-null ClassLoader.

Returns:

all URLs corresponding to the resource path "" within the supplied ClassLoader. This corresponds to the classPath of the supplied ClassLoader.

Throws:

IllegalStateException - if the classLoader.getResources("") call fails.

createFor

public static ThreadContextClassLoaderBuilder createFor(Class<?> aClass,
                                        org.apache.maven.plugin.logging.Log log)

Creates a new ThreadContextClassLoaderBuilder using the original ClassLoader from the supplied Class, as well as the given Maven Log.

Parameters:

aClass - A non-null class from which to extract the original ClassLoader.

log - The active Maven Log. Cannot be null.

Returns:

A ThreadContextClassLoaderBuilder wrapping the supplied members.

getClassPathElement

public static String getClassPathElement(URL anURL)
                                  throws IllegalArgumentException

Converts the supplied URL to a class path element.

Parameters:

anURL - The non-null URL for which to acquire a classPath element.

Returns:

The full (i.e. non-chopped) classpath element corresponding to the supplied URL.

Throws:

IllegalArgumentException - if the supplied URL had an unknown protocol.