Ant example source code file (Exec.java)

This example Ant source code file (Exec.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

bufferedreader, buildexception, buildexception, exec, exec, interruptedexception, io, ioexception, myos, printwriter, property, streampumper, streampumper, string, string

The Exec.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.BufferedReader;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;

import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.MagicNames;
import org.apache.tools.ant.Project;
import org.apache.tools.ant.Task;

/**
 * Executes a given command if the os platform is appropriate.
 *
 * <p>As of Ant 1.2, this class is no longer the
 * implementation of Ant's <exec> task - it is considered to be
 * dead code by the Ant developers and is unmaintained.  Don't use
 * it.</strong>

 *
 * @deprecated since 1.2.
 *             delegate to {@link org.apache.tools.ant.taskdefs.Execute Execute}
 *             instead.
 */
public class Exec extends Task {
    private String os;
    private String out;
    private File dir;
    private String command;
    // CheckStyle:VisibilityModifier OFF - bc
    protected PrintWriter fos = null;
    // CheckStyle:VisibilityModifier ON
    private boolean failOnError = false;

    /**
     * Constructor for Exec.
     * Prints a warning message to std error.
     */
    public Exec() {
        System.err.println("As of Ant 1.2 released in October 2000, "
            + "the Exec class");
        System.err.println("is considered to be dead code by the Ant "
            + "developers and is unmaintained.");
        System.err.println("Don\'t use it!");
    }

    /**
     * Execute the task.
     * @throws BuildException on error
     */
    public void execute() throws BuildException {
        run(command);
    }

    /**
     * Execute the command.
     * @param command the command to exec
     * @return the exit value of the command
     * @throws BuildException on error
     */
    protected int run(String command) throws BuildException {

        int err = -1; // assume the worst

        // test if os match
        String myos = System.getProperty("os.name");
        log("Myos = " + myos, Project.MSG_VERBOSE);
        if ((os != null) && (os.indexOf(myos) < 0)) {
            // this command will be executed only on the specified OS
            log("Not found in " + os, Project.MSG_VERBOSE);
            return 0;
        }

        // default directory to the project's base directory
        if (dir == null) {
          dir = getProject().getBaseDir();
        }

        if (myos.toLowerCase().indexOf("windows") >= 0) {
            if (!dir.equals(getProject().resolveFile("."))) {
                if (myos.toLowerCase().indexOf("nt") >= 0) {
                    command = "cmd /c cd " + dir + " && " + command;
                } else {
                    String ant = getProject().getProperty(MagicNames.ANT_HOME);
                    if (ant == null) {
                        throw new BuildException("Property '" + MagicNames.ANT_HOME + "' not "
                            + "found", getLocation());
                    }

                    String antRun = getProject().resolveFile(ant + "/bin/antRun.bat").toString();
                    command = antRun + " " + dir + " " + command;
                }
            }
        } else {
            String ant = getProject().getProperty(MagicNames.ANT_HOME);
            if (ant == null) {
              throw new BuildException("Property '" + MagicNames.ANT_HOME + "' not found",
                                       getLocation());
            }
            String antRun = getProject().resolveFile(ant + "/bin/antRun").toString();

            command = antRun + " " + dir + " " + command;
        }

        try {
            // show the command
            log(command, Project.MSG_VERBOSE);

            // exec command on system runtime
            Process proc = Runtime.getRuntime().exec(command);

            if (out != null)  {
                fos = new PrintWriter(new FileWriter(out));
                log("Output redirected to " + out, Project.MSG_VERBOSE);
            }

            // copy input and error to the output stream
            StreamPumper inputPumper =
                new StreamPumper(proc.getInputStream(), Project.MSG_INFO);
            StreamPumper errorPumper =
                new StreamPumper(proc.getErrorStream(), Project.MSG_WARN);

            // starts pumping away the generated output/error
            inputPumper.start();
            errorPumper.start();

            // Wait for everything to finish
            proc.waitFor();
            inputPumper.join();
            errorPumper.join();
            proc.destroy();

            // close the output file if required
            logFlush();

            // check its exit value
            err = proc.exitValue();
            if (err != 0) {
                if (failOnError) {
                    throw new BuildException("Exec returned: " + err, getLocation());
                } else {
                    log("Result: " + err, Project.MSG_ERR);
                }
            }
        } catch (IOException ioe) {
            throw new BuildException("Error exec: " + command, ioe, getLocation());
        } catch (InterruptedException ex) {
            //ignore
        }

        return err;
    }

    /**
     * Set the directory.
     * @param d a <code>String value
     */
    public void setDir(String d) {
        this.dir = getProject().resolveFile(d);
    }

    /**
     * Set the Operating System that this exec is to run in.
     * @param os a <code>String value
     */
    public void setOs(String os) {
        this.os = os;
    }

    /**
     * Set the command to exec.
     * @param command a <code>String value
     */
    public void setCommand(String command) {
        this.command = command;
    }

    /**
     * Set the output filename.
     * @param out a <code>String value
     */
    public void setOutput(String out) {
        this.out = out;
    }

    /**
     * Set the failOnError attribute.
     * Default is false.
     * @param fail a <code>boolean value
     */
    public void setFailonerror(boolean fail) {
        failOnError = fail;
    }

    /**
     * Log an output message.
     * @param line the line to putput
     * @param messageLevel the level of logging - ignored
     *                     if output is going to a file
     */
    protected void outputLog(String line, int messageLevel) {
        if (fos == null) {
            log(line, messageLevel);
        } else {
            fos.println(line);
        }
    }

    /**
     * Close output.
     */
    protected void logFlush() {
        if (fos != null) {
          fos.close();
        }
    }

    // Inner class for continually pumping the input stream during
    // Process's runtime.
    class StreamPumper extends Thread {
        private BufferedReader din;
        private int messageLevel;
        private boolean endOfStream = false;
        private static final int SLEEP_TIME = 5;

        public StreamPumper(InputStream is, int messageLevel) {
            this.din = new BufferedReader(new InputStreamReader(is));
            this.messageLevel = messageLevel;
        }

        public void pumpStream() throws IOException {
            if (!endOfStream) {
                String line = din.readLine();

                if (line != null) {
                    outputLog(line, messageLevel);
                } else {
                    endOfStream = true;
                }
            }
        }

        public void run() {
            try {
                try {
                    while (!endOfStream) {
                        pumpStream();
                        sleep(SLEEP_TIME);
                    }
                } catch (InterruptedException ie) {
                    //ignore
                }
                din.close();
            } catch (IOException ioe) {
                // ignore
            }
        }
    }
}