Ant example source code file (Patch.java)

This example Ant source code file (Patch.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, commandline, commandline, execute, execute, file, file, io, ioexception, logstreamhandler, patch, r, task

The Patch.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.IOException;
import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.Project;
import org.apache.tools.ant.Task;
import org.apache.tools.ant.types.Commandline;

/**
 * Patches a file by applying a 'diff' file to it; requires "patch" to be
 * on the execution path.
 *
 * @since Ant 1.1
 *
 * @ant.task category="utility"
 */
public class Patch extends Task {

    private File originalFile;
    private File directory;
    private boolean havePatchfile = false;
    private Commandline cmd = new Commandline();

    /**
     * The file to patch; optional if it can be inferred from
     * the diff file
     * @param file the file to patch
     */
    public void setOriginalfile(File file) {
        originalFile = file;
    }

    /**
     * The name of a file to send the output to, instead of patching
     * the file(s) in place; optional.
     * @param file the file to send the output to
     * @since Ant 1.6
     */
    public void setDestfile(File file) {
        if (file != null) {
            cmd.createArgument().setValue("-o");
            cmd.createArgument().setFile(file);
        }
    }

    /**
     * The file containing the diff output; required.
     * @param file the file containing the diff output
     */
    public void setPatchfile(File file) {
        if (!file.exists()) {
            throw new BuildException("patchfile " + file + " doesn\'t exist",
                                     getLocation());
        }
        cmd.createArgument().setValue("-i");
        cmd.createArgument().setFile(file);
        havePatchfile = true;
    }

    /**
     * flag to create backups; optional, default=false
     * @param backups if true create backups
     */
    public void setBackups(boolean backups) {
        if (backups) {
            cmd.createArgument().setValue("-b");
        }
    }

    /**
     * flag to ignore whitespace differences; default=false
     * @param ignore if true ignore whitespace differences
     */
    public void setIgnorewhitespace(boolean ignore) {
        if (ignore) {
            cmd.createArgument().setValue("-l");
        }
    }

    /**
     * Strip the smallest prefix containing <i>num leading slashes
     * from filenames.
     *
     * <p>patch's -p option.
     * @param num number of lines to strip
     * @exception BuildException if num is < 0, or other errors
     */
    public void setStrip(int num) throws BuildException {
        if (num < 0) {
            throw new BuildException("strip has to be >= 0", getLocation());
        }
        cmd.createArgument().setValue("-p" + num);
    }

    /**
     * Work silently unless an error occurs; optional, default=false
     * @param q if true suppress set the -s option on the patch command
     */
    public void setQuiet(boolean q) {
        if (q) {
            cmd.createArgument().setValue("-s");
        }
    }

    /**
     * Assume patch was created with old and new files swapped; optional,
     * default=false
     * @param r if true set the -R option on the patch command
     */
    public void setReverse(boolean r) {
        if (r) {
            cmd.createArgument().setValue("-R");
        }
    }

    /**
     * The directory to run the patch command in, defaults to the
     * project's base directory.
     * @param directory the directory to run the patch command in
     * @since Ant 1.5
     */
    public void setDir(File directory) {
        this.directory = directory;
    }

    /**
     * execute patch
     * @throws BuildException when it all goes a bit pear shaped
     */
    public void execute() throws BuildException {
        if (!havePatchfile) {
            throw new BuildException("patchfile argument is required",
                                     getLocation());
        }
        Commandline toExecute = (Commandline) cmd.clone();
        toExecute.setExecutable("patch");

        if (originalFile != null) {
            toExecute.createArgument().setFile(originalFile);
        }

        Execute exe = new Execute(new LogStreamHandler(this, Project.MSG_INFO,
                                                       Project.MSG_WARN),
                                  null);
        exe.setCommandline(toExecute.getCommandline());

        if (directory != null) {
            if (directory.exists() && directory.isDirectory()) {
                exe.setWorkingDirectory(directory);
            } else if (!directory.isDirectory()) {
                throw new BuildException(directory + " is not a directory.",
                                         getLocation());
            } else {
                throw new BuildException("directory " + directory
                                         + " doesn\'t exist", getLocation());
            }
        } else {
            exe.setWorkingDirectory(getProject().getBaseDir());
        }

        log(toExecute.describeCommand(), Project.MSG_VERBOSE);
        try {
            exe.execute();
        } catch (IOException e) {
            throw new BuildException(e, getLocation());
        }
    }
}