proposal/mutant/src/main/org/apache/ant/core/config/ComponentManager.java

/*
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
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 * 4. The names "The Jakarta Project", "Ant", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
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 * 5. Products derived from this software may not be called "Apache"
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 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */
package org.apache.ant.core.config;

import java.io.*;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.*;
import org.apache.ant.core.execution.*;
import org.apache.ant.core.support.*;
import org.apache.ant.core.xml.AntLibParser;
import org.xml.sax.SAXParseException;

/**
 * Manager for Ant components
 *
 * The component manager is responsible for locating and loading the 
 * components contained in Ant's lib/task directory.
 * 
 * @author <a href="mailto:conor@apache.org">Conor MacNeill</a>
 */ 
public class ComponentManager {
    /**
     * When Ant is run remotely, we need to look up the list of component
     * libraries from the server.
     */
    static public String COMPONENT_INDEX = "taskindex";
    
    /**
     * Create the component manager. When the component manager is created
     * it will read the component definitions from the  files in
     * Ant's lib/task directory
     */ 
    static public AntLibrary[] getComponents() throws LocationException, ConfigException {
        try {
            URL componentsLocation = new URL(AntLocator.getLibraryURL(), "task/");
            URL[] componentFiles = null;
            if (componentsLocation.getProtocol().equals("file")) {
                // component directory is local - we determine the 
                // component files by scanning the local directory
                HashSet componentFilesTypes = new HashSet();
                componentFilesTypes.add(".tsk");
                componentFilesTypes.add(".jar");
                componentFilesTypes.add(".zip");
                File componentsDirectory = new File(componentsLocation.getFile());
                componentFiles = AntLocator.getDirectoryURLs(componentsDirectory, componentFilesTypes);
            }
            else {
                // The component directory is remote - we determine the
                // list of component files by reading a "known"  list file.
                URL componentListURL = new URL(componentsLocation, COMPONENT_INDEX);
                BufferedReader reader = null;
                List componentList = new ArrayList();
                try {
                    reader = new BufferedReader(new InputStreamReader(componentListURL.openStream()));
                    String line = null;
                    while ((line = reader.readLine()) != null) {
                        componentList.add(new URL(componentsLocation, line.trim()));
                    }
                }
                finally {
                    if (reader != null) {
                        reader.close();
                    }
                }
                componentFiles = (URL[])componentList.toArray(new URL[0]);
            }
                        
            AntLibParser libdefParser = new AntLibParser();
            
            List libraries = new ArrayList();
            
            for (int i = 0; i < componentFiles.length; ++i) {
                // We create a classloader for the component library
                URL[] componentURLs = new URL[]{componentFiles[i]};
                AntClassLoader componentClassLoader 
                    = new AntClassLoader(componentURLs, 
                                         ComponentManager.class.getClassLoader(),
                                         componentFiles[i].toString());
                URL libDefinition = componentClassLoader.getResource("ANT-INF/antlib.xml");
                if (libDefinition != null) {
                    AntLibrary library 
                        = libdefParser.parseAntLibrary(libDefinition, componentClassLoader);
                    libraries.add(library);                            
                }
            }
            
            return (AntLibrary[])libraries.toArray(new AntLibrary[0]);
        }
        catch (IOException e) {
            throw new ConfigException(e);
        }
    }
}