Ant example source code file (ExecuteJava.java)

This example Ant source code file (ExecuteJava.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, commandlinejava, could, executejava, interruptedexception, io, ioexception, ioexception, redirector, reflection, string, string, thread, throwable, throwable

The ExecuteJava.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 java.io.PrintStream;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import org.apache.tools.ant.AntClassLoader;
import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.Project;
import org.apache.tools.ant.ProjectComponent;
import org.apache.tools.ant.Task;
import org.apache.tools.ant.taskdefs.condition.Os;
import org.apache.tools.ant.types.Commandline;
import org.apache.tools.ant.types.CommandlineJava;
import org.apache.tools.ant.types.Path;
import org.apache.tools.ant.types.Permissions;
import org.apache.tools.ant.util.JavaEnvUtils;
import org.apache.tools.ant.util.TimeoutObserver;
import org.apache.tools.ant.util.Watchdog;

/**
 * Execute a Java class.
 * @since Ant 1.2
 */
public class ExecuteJava implements Runnable, TimeoutObserver {

    private Commandline javaCommand = null;
    private Path classpath = null;
    private CommandlineJava.SysProperties sysProperties = null;
    private Permissions  perm = null;
    private Method main = null;
    private Long timeout = null;
    private volatile Throwable caught = null;
    private volatile boolean timedOut = false;
    private Thread thread = null;

    /**
     * Set the Java "command" for this ExecuteJava.
     * @param javaCommand the classname and arguments in a Commandline.
     */
    public void setJavaCommand(Commandline javaCommand) {
        this.javaCommand = javaCommand;
    }

    /**
     * Set the classpath to be used when running the Java class.
     *
     * @param p an Ant Path object containing the classpath.
     */
    public void setClasspath(Path p) {
        classpath = p;
    }

    /**
     * Set the system properties to use when running the Java class.
     * @param s CommandlineJava system properties.
     */
    public void setSystemProperties(CommandlineJava.SysProperties s) {
        sysProperties = s;
    }

    /**
     * Set the permissions for the application run.
     * @param permissions the Permissions to use.
     * @since Ant 1.6
     */
    public void setPermissions(Permissions permissions) {
        perm = permissions;
    }

    /**
     * Set the stream to which all output (System.out as well as System.err)
     * will be written.
     * @param out the PrintStream where output should be sent.
     * @deprecated since 1.4.x.
     *             manage output at the task level.
     */
    public void setOutput(PrintStream out) {
    }

    /**
     * Set the timeout for this ExecuteJava.
     * @param timeout timeout as Long.
     * @since Ant 1.5
     */
    public void setTimeout(Long timeout) {
        this.timeout = timeout;
    }

    /**
     * Execute the Java class against the specified Ant Project.
     * @param project the Project to use.
     * @throws BuildException on error.
     */
    public void execute(Project project) throws BuildException {
        final String classname = javaCommand.getExecutable();

        AntClassLoader loader = null;
        try {
            if (sysProperties != null) {
                sysProperties.setSystem();
            }
            Class target = null;
            try {
                if (classpath == null) {
                    target = Class.forName(classname);
                } else {
                    loader = project.createClassLoader(classpath);
                    loader.setParent(project.getCoreLoader());
                    loader.setParentFirst(false);
                    loader.addJavaLibraries();
                    loader.setIsolated(true);
                    loader.setThreadContextLoader();
                    loader.forceLoadClass(classname);
                    target = Class.forName(classname, true, loader);
                }
            } catch (ClassNotFoundException e) {
                throw new BuildException("Could not find " + classname + "."
                                         + " Make sure you have it in your"
                                         + " classpath");
            }
            main = target.getMethod("main", new Class[] {String[].class});
            if (main == null) {
                throw new BuildException("Could not find main() method in "
                                         + classname);
            }
            if ((main.getModifiers() & Modifier.STATIC) == 0) {
                throw new BuildException("main() method in " + classname
                    + " is not declared static");
            }
            if (timeout == null) {
                run();
            } else {
                thread = new Thread(this, "ExecuteJava");
                Task currentThreadTask
                    = project.getThreadTask(Thread.currentThread());
                // XXX is the following really necessary? it is in the same thread group...
                project.registerThreadTask(thread, currentThreadTask);
                // if we run into a timeout, the run-away thread shall not
                // make the VM run forever - if no timeout occurs, Ant's
                // main thread will still be there to let the new thread
                // finish
                thread.setDaemon(true);
                Watchdog w = new Watchdog(timeout.longValue());
                w.addTimeoutObserver(this);
                synchronized (this) {
                    thread.start();
                    w.start();
                    try {
                        wait();
                    } catch (InterruptedException e) {
                        // ignore
                    }
                    if (timedOut) {
                        project.log("Timeout: sub-process interrupted",
                                    Project.MSG_WARN);
                    } else {
                        thread = null;
                        w.stop();
                    }
                }
            }
            if (caught != null) {
                throw caught;
            }
        } catch (BuildException e) {
            throw e;
        } catch (SecurityException e) {
            throw e;
        } catch (ThreadDeath e) {
            // XXX could perhaps also call thread.stop(); not sure if anyone cares
            throw e;
        } catch (Throwable e) {
            throw new BuildException(e);
        } finally {
            if (loader != null) {
                loader.resetThreadContextLoader();
                loader.cleanup();
                loader = null;
            }
            if (sysProperties != null) {
                sysProperties.restoreSystem();
            }
        }
    }

    /**
     * Run this ExecuteJava in a Thread.
     * @since Ant 1.5
     */
    public void run() {
        final Object[] argument = {javaCommand.getArguments()};
        try {
            if (perm != null) {
                perm.setSecurityManager();
            }
            main.invoke(null, argument);
        } catch (InvocationTargetException e) {
            Throwable t = e.getTargetException();
            if (!(t instanceof InterruptedException)) {
                caught = t;
            } /* else { swallow, probably due to timeout } */
        } catch (Throwable t) {
            caught = t;
        } finally {
            if (perm != null) {
                perm.restoreSecurityManager();
            }
            synchronized (this) {
                notifyAll();
            }
        }
    }

    /**
     * Mark timeout as having occurred.
     * @param w the responsible Watchdog.
     * @since Ant 1.5
     */
    public synchronized void timeoutOccured(Watchdog w) {
        if (thread != null) {
            timedOut = true;
            thread.interrupt();
        }
        notifyAll();
    }

    /**
     * Get whether the process was killed.
     * @return <code>true if the process was killed, false otherwise.
     * @since 1.19, Ant 1.5
     */
    public synchronized boolean killedProcess() {
        return timedOut;
    }

    /**
     * Run the Java command in a separate VM, this does not give you
     * the full flexibility of the Java task, but may be enough for
     * simple needs.
     * @param pc the ProjectComponent to use for logging, etc.
     * @return the exit status of the subprocess.
     * @throws BuildException on error.
     * @since Ant 1.6.3
     */
    public int fork(ProjectComponent pc) throws BuildException {
        CommandlineJava cmdl = new CommandlineJava();
        cmdl.setClassname(javaCommand.getExecutable());
        String[] args = javaCommand.getArguments();
        for (int i = 0; i < args.length; i++) {
            cmdl.createArgument().setValue(args[i]);
        }
        if (classpath != null) {
            cmdl.createClasspath(pc.getProject()).append(classpath);
        }
        if (sysProperties != null) {
            cmdl.addSysproperties(sysProperties);
        }
        Redirector redirector = new Redirector(pc);
        Execute exe
            = new Execute(redirector.createHandler(),
                          timeout == null
                          ? null
                          : new ExecuteWatchdog(timeout.longValue()));
        exe.setAntRun(pc.getProject());
        if (Os.isFamily("openvms")) {
            setupCommandLineForVMS(exe, cmdl.getCommandline());
        } else {
            exe.setCommandline(cmdl.getCommandline());
        }
        try {
            int rc = exe.execute();
            redirector.complete();
            return rc;
        } catch (IOException e) {
            throw new BuildException(e);
        } finally {
            timedOut = exe.killedProcess();
        }
    }

    /**
     * On VMS platform, we need to create a special java options file
     * containing the arguments and classpath for the java command.
     * The special file is supported by the "-V" switch on the VMS JVM.
     *
     * @param exe the Execute instance to alter.
     * @param command the command-line.
     */
    public static void setupCommandLineForVMS(Execute exe, String[] command) {
        //Use the VM launcher instead of shell launcher on VMS
        exe.setVMLauncher(true);
        File vmsJavaOptionFile = null;
        try {
            String [] args = new String[command.length - 1];
            System.arraycopy(command, 1, args, 0, command.length - 1);
            vmsJavaOptionFile = JavaEnvUtils.createVmsJavaOptionFile(args);
            //we mark the file to be deleted on exit.
            //the alternative would be to cache the filename and delete
            //after execution finished, which is much better for long-lived runtimes
            //though spawning complicates things...
            vmsJavaOptionFile.deleteOnExit();
            String [] vmsCmd = {command[0], "-V", vmsJavaOptionFile.getPath()};
            exe.setCommandline(vmsCmd);
        } catch (IOException e) {
            throw new BuildException("Failed to create a temporary file for \"-V\" switch");
        }
    }

}