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Groovy example source code file (RootLoaderRef.java)

This example Groovy source code file (RootLoaderRef.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Groovy tags/keywords

antclassloader, antclassloader, buildexception, loaderconfiguration, loaderconfiguration, matchingtask, path, path, project, rootloader, rootloaderref, string, string

The Groovy RootLoaderRef.java source code

/*
 * Copyright 2003-2007 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 
package org.codehaus.groovy.ant;

import org.apache.tools.ant.AntClassLoader;
import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.Project;
import org.apache.tools.ant.taskdefs.MatchingTask;
import org.apache.tools.ant.types.Path;
import org.apache.tools.ant.types.Reference;
import org.codehaus.groovy.tools.LoaderConfiguration;
import org.codehaus.groovy.tools.RootLoader;

 
/**
 * Sets the RootLoader as reference.
 * Reexecution of this task will set a new instance of RootLoader for
 * the reference. 
 *
 * arguments:
 * <ul>
 * <li>ref
 * <li>classpath
 * </ul>
 * 
 * all arguments are required.
 *
 * As ant requires an AntClassLoader as reference, this will create a RootLoader
 * and set an AntClassLoader as child and stored in the reference. The AntClassLoader
 * instance will not have a classpath nor will it have access to the classpath somehow,
 * all loading is done by the RootLoader parent. To avoid problems with loading classes 
 * multiple times and using them at the same time, this task will filter out the ant jars
 * and the commons-logging jars. This only works if the ant jars are starting with "ant-" and
 * the logging jar starts with "commons-logging-".
 * 
 * This was needed because if ant wants to access a task argument that uses for example a Path
 * it look for a matching method which includes a matching class. But two classes of the same name
 * with different classloaders are different, so ant would not be able to find the method.
 *
 * @see org.codehaus.groovy.tools.RootLoader
 * @author Jochen Theodorou
 * @version $Revision: 21223 $ 
 */
public class RootLoaderRef extends MatchingTask {
    private String name;
    private Path taskClasspath;
    
    /**
     * sets the name of the reference which should store the Loader
     */
    public void setRef(String n){
        name = n;
    }
    
    public void execute() throws BuildException {
        if (taskClasspath==null || taskClasspath.size()==0) {
            throw new BuildException("no classpath given");
        }
        Project project = getProject();
        AntClassLoader loader = new AntClassLoader(makeRoot(),true);
        project.addReference(name,loader);
    }
    
    private RootLoader makeRoot() {
        String[] list = taskClasspath.list();
        LoaderConfiguration lc = new LoaderConfiguration();
        for (int i=0; i<list.length; i++) {
            if (list[i].matches(".*ant-[^/]*jar$")) {
                continue;
            }
            if (list[i].matches(".*commons-logging-[^/]*jar$")) {
                continue;
            }
            if (list[i].matches(".*xerces-[^/]*jar$")) {
                continue;
            }
            lc.addFile(list[i]);
        }
        return new RootLoader(lc);
    }
    
    /**
     * Set the classpath to be used for this compilation.
     *
     * @param classpath an Ant Path object containing the compilation classpath.
     */
    public void setClasspath(Path classpath) {
        if (taskClasspath == null) {
            taskClasspath = classpath;
        }
        else {
            taskClasspath.append(classpath);
        }
    }
    
    /**
     * Adds a reference to a classpath defined elsewhere.
     * @param r a reference to a classpath
     */
    public void setClasspathRef(Reference r) {
        createClasspath().setRefid(r);
    }
    
    /**
     * Adds a path to the classpath.
     * @return a class path to be configured
     */
    public Path createClasspath() {
        if (taskClasspath == null) {
            taskClasspath = new Path(getProject());
        }
        return taskClasspath.createPath();
    }
}

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