Ant example source code file (ManifestClassPath.java)

This example Ant source code file (ManifestClassPath.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 - Ant tags/keywords

buildexception, buildexception, file, file, fileutils, io, manifestclasspath, missing, no, path, string, string, stringbuffer, stringbuffer, task

The ManifestClassPath.java source code

/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You 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.apache.tools.ant.taskdefs;

import java.io.File;
import java.io.UnsupportedEncodingException;

import org.apache.tools.ant.Task;
import org.apache.tools.ant.types.Path;
import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.launch.Locator;
import org.apache.tools.ant.util.FileUtils;

/**
 * Converts a Path into a property suitable as a Manifest classpath.
 *
 * @since Ant 1.7
 *
 * @ant.task category="property"
 */
public class ManifestClassPath extends Task {

    /** The property name to hold the classpath value. */
    private String name;

    /** The directory the classpath will be relative from. */
    private File dir;

    /** The maximum parent directory level to traverse. */
    private int maxParentLevels = 2;

    /** The classpath to convert. */
    private Path path;

    /**
     * Sets a property, which must not already exist, with a space
     * separated list of files and directories relative to the jar
     * file's parent directory.
     */
    public void execute() {
        if (name == null) {
          throw new BuildException("Missing 'property' attribute!");
        }
        if (dir == null) {
          throw new BuildException("Missing 'jarfile' attribute!");
        }
        if (getProject().getProperty(name) != null) {
          throw new BuildException("Property '" + name + "' already set!");
        }
        if (path == null) {
            throw new BuildException("Missing nested <classpath>!");
        }

        // Normalize the reference directory (containing the jar)
        final FileUtils fileUtils = FileUtils.getFileUtils();
        dir = fileUtils.normalize(dir.getAbsolutePath());

        // Create as many directory prefixes as parent levels to traverse,
        // in addition to the reference directory itself
        File currDir = dir;
        String[] dirs = new String[maxParentLevels + 1];
        for (int i = 0; i < maxParentLevels + 1; ++i) {
            dirs[i] = currDir.getAbsolutePath() + File.separatorChar;
            currDir = currDir.getParentFile();
            if (currDir == null) {
                maxParentLevels = i + 1;
                break;
            }
        }

        String[] elements = path.list();
        StringBuffer buffer = new StringBuffer();
        StringBuffer element = new StringBuffer();
        for (int i = 0; i < elements.length; ++i) {
            // Normalize the current file
            File pathEntry = new File(elements[i]);
            pathEntry = fileUtils.normalize(pathEntry.getAbsolutePath());
            String fullPath = pathEntry.getAbsolutePath();

            // Find the longest prefix shared by the current file
            // and the reference directory.
            String relPath = null;
            for (int j = 0; j <= maxParentLevels; ++j) {
                String dir = dirs[j];
                if (!fullPath.startsWith(dir)) {
                    continue;
                }

                // We have a match! Add as many ../ as parent
                // directory traversed to get the relative path
                element.setLength(0);
                for (int k = 0; k < j; ++k) {
                    element.append("..");
                    element.append(File.separatorChar);
                }
                element.append(fullPath.substring(dir.length()));
                relPath = element.toString();
                break;
            }

            // No match, so bail out!
            if (relPath == null) {
                throw new BuildException(
                    "No suitable relative path from "
                    + dir + " to " + fullPath);
            }

            // Manifest's ClassPath: attribute always uses forward
            // slashes '/', and is space-separated. Ant will properly
            // format it on 72 columns with proper line continuation
            if (File.separatorChar != '/') {
                relPath = relPath.replace(File.separatorChar, '/');
            }
            if (pathEntry.isDirectory()) {
                relPath = relPath + '/';
            }
            try {
                relPath = Locator.encodeURI(relPath);
            } catch (UnsupportedEncodingException exc) {
                throw new BuildException(exc);
            }
            buffer.append(relPath);
            buffer.append(' ');
        }

        // Finally assign the property with the manifest classpath
        getProject().setNewProperty(name, buffer.toString().trim());
    }

    /**
     * Sets the property name to hold the classpath value.
     *
     * @param  name the property name
     */
    public void setProperty(String name) {
        this.name = name;
    }

    /**
     * The JAR file to contain the classpath attribute in its manifest.
     *
     * @param  jarfile the JAR file. Need not exist yet, but its parent
     *         directory must exist on the other hand.
     */
    public void setJarFile(File jarfile) {
        File parent = jarfile.getParentFile();
        if (!parent.isDirectory()) {
            throw new BuildException("Jar's directory not found: " + parent);
        }
        this.dir = parent;
    }

    /**
     * Sets the maximum parent directory levels allowed when computing
     * a relative path.
     *
     * @param  levels the max level. Defaults to 2.
     */
    public void setMaxParentLevels(int levels) {
        this.maxParentLevels = levels;
    }

    /**
     * Adds the classpath to convert.
     *
     * @param  path the classpath to convert.
     */
    public void addClassPath(Path path) {
        this.path = path;
    }

}