src/main/org/apache/tools/ant/taskdefs/Definer.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.
 *
 * 4. The names "The Jakarta Project", "Ant", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written 
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache"
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 *    permission of the Apache Group.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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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.tools.ant.taskdefs;

import org.apache.tools.ant.Task;
import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.Project;
import org.apache.tools.ant.AntClassLoader;
import org.apache.tools.ant.types.Path;
import org.apache.tools.ant.types.Reference;

import java.util.Properties;
import java.util.Enumeration;
import java.io.File;
import java.io.InputStream;
import java.io.FileInputStream;
import java.io.IOException;

/**
 * Base class for Taskdef and Typedef - does all the classpath
 * handling and and class loading.
 *
 * @author Costin Manolache
 * @author <a href="stefan.bodewig@epost.de">Stefan Bodewig</a>
 */
public abstract class Definer extends Task {
    private String name;
    private String value;
    private Path classpath;
    private File file;
    private String resource;
    private boolean reverseLoader = false;

    public void setReverseLoader(boolean reverseLoader) {
        this.reverseLoader = reverseLoader;
        log("The reverseloader attribute is DEPRECATED. It will be removed", Project.MSG_WARN);
    }
    
    public void setClasspath(Path classpath) {
        if (this.classpath == null) {
            this.classpath = classpath;
        } else {
            this.classpath.append(classpath);
        }
    }

    public Path createClasspath() {
        if (this.classpath == null) {
            this.classpath = new Path(project);
        }
        return this.classpath.createPath();
    }

    public void setClasspathRef(Reference r) {
        createClasspath().setRefid(r);
    }

    public void execute() throws BuildException {
        AntClassLoader al=createLoader();

        if (file==null && resource==null ) {

            // simple case - one definition
            if ( name==null || value==null  ) {
                String msg = "name or classname attributes of "
                    + getTaskName() + " element "
                    + "are undefined";
                throw new BuildException(msg);
            }
            addDefinition( al, name, value );

        } else {

            try {
                if (name != null || value != null) {
                    String msg = "You must not specify name or value "
                        + "together with file or resource.";
                    throw new BuildException(msg, location);
                }
            
                if (file != null && resource != null) {
                    String msg = "You must not specify both, file and resource.";
                    throw new BuildException(msg, location);
                }
            

                Properties props=new Properties();
                InputStream is=null;
                if( file != null ) {
                    log("Loading definitions from file " + file, 
                        Project.MSG_VERBOSE);
                    is=new FileInputStream( file );
                    if (is == null) {
                        log("Could not load definitions from file " + file
                            + ". It doesn\'t exist.", Project.MSG_WARN);
                    }
                }    
                if( resource!=null ) {
                    log("Loading definitions from resource " + resource, 
                        Project.MSG_VERBOSE);
                    is=al.getResourceAsStream( resource );
                    if (is == null) {
                        log("Could not load definitions from resource " 
                            + resource + ". It could not be found.", 
                            Project.MSG_WARN);
                    }
                }

                if( is!=null ) {
                    props.load( is );
                    Enumeration keys=props.keys();
                    while( keys.hasMoreElements() ) {
                        String n=(String)keys.nextElement();
                        String v=props.getProperty( n );
                        addDefinition( al, n, v );
                    }
                }
            } catch( IOException ex ) {
                throw new BuildException(ex, location);
            }
        }
    }
    
    private void addDefinition( ClassLoader al, String name, String value )
        throws BuildException {
        try {
            Class c = al.loadClass(value);
            AntClassLoader.initializeClass(c);
            addDefinition(name, c);
        } catch (ClassNotFoundException cnfe) {
            String msg = getTaskName()+" class " + value +
                " cannot be found";
            throw new BuildException(msg, cnfe, location);
        } catch (NoClassDefFoundError ncdfe) {
            String msg = getTaskName()+" class " + value +
                " cannot be found";
            throw new BuildException(msg, ncdfe, location);
        }
    }


    private AntClassLoader createLoader() {
        AntClassLoader al = null;
        if (classpath != null) {
            al = new AntClassLoader(project, classpath, !reverseLoader);
        } else {
            al = new AntClassLoader(project, Path.systemClasspath, !reverseLoader);
        }
        // need to load Task via system classloader or the new
        // task we want to define will never be a Task but always
        // be wrapped into a TaskAdapter.
        al.addSystemPackageRoot("org.apache.tools.ant");
        return al;
    }

    public void setFile( File file ) {
        this.file=file;
    }

    public void setResource( String res ) {
        this.resource=res;
    }

    public void setName( String name) {
        this.name = name;
    }

    public String getClassname() {
        return value;
    }

    public void setClassname(String v) {
        value = v;
    }

    protected abstract void addDefinition(String name, Class c);
}