org.formic.util.CommandExecutor.java Source code

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Here is the source code for org.formic.util.CommandExecutor.java

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/**
 * Formic installer framework.
 * Copyright (C) 2005 - 2010  Eric Van Dewoestine
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
package org.formic.util;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;

import java.util.Arrays;

import org.apache.commons.io.IOUtils;

import org.apache.commons.lang.StringUtils;

import org.apache.log4j.Logger;

/**
 * Thread to run the external command.
 */
public class CommandExecutor extends Thread {
    private static final Logger logger = Logger.getLogger(CommandExecutor.class);

    protected int returnCode = -1;
    protected String result;
    protected String error;
    protected String[] cmd;
    protected Process process;

    private boolean shutdown;
    private ShutdownHook shutdownHook;

    /**
     * Construct a new instance.
     */
    protected CommandExecutor() {
    }

    /**
     * Construct a new instance.
     */
    protected CommandExecutor(String[] cmd) {
        this.cmd = cmd;
    }

    /**
     * Execute the supplied command.
     *
     * @param cmd The command to execute.
     */
    public static CommandExecutor execute(String[] cmd) throws Exception {
        return execute(cmd, -1);
    }

    /**
     * Execute the supplied command.
     *
     * @param cmd The command to execute.
     * @param timeout Timeout in milliseconds.
     * @return The CommandExecutor instance containing the ending state of the
     * process.
     */
    public static CommandExecutor execute(String[] cmd, long timeout) throws Exception {
        CommandExecutor executor = new CommandExecutor(cmd);
        executor.start();

        if (timeout > 0) {
            executor.join(timeout);
        } else {
            executor.join();
        }

        return executor;
    }

    /**
     * Run the thread.
     */
    public void run() {
        logger.info(this.toString());
        Runtime runtime = Runtime.getRuntime();
        try {
            process = runtime.exec(cmd);

            shutdownHook = new ShutdownHook();
            try {
                runtime.addShutdownHook(shutdownHook);
            } catch (IllegalStateException ignore) {
                // happens if this is called during shutdown
            }

            ByteArrayOutputStream out = new ByteArrayOutputStream();
            Thread outThread = createOutThread(out);
            outThread.start();

            ByteArrayOutputStream err = new ByteArrayOutputStream();
            Thread errThread = createErrThread(err);
            errThread.start();

            returnCode = process.waitFor();
            outThread.join(1000);
            errThread.join(1000);

            if (result == null) {
                result = out.toString();
            }
            if (error == null) {
                error = err.toString();
            }
        } catch (Exception e) {
            returnCode = 12;
            error = e.getMessage();
            e.printStackTrace();
        } finally {
            if (shutdownHook != null) {
                try {
                    runtime.removeShutdownHook(shutdownHook);
                } catch (IllegalStateException ignore) {
                    // happens if this is called during shutdown
                }
            }
        }
    }

    /**
     * Create the thread that will handle the process's output stream.
     *
     * @param out An OutputStream which can be used to buffer up the entire
     * process output.
     * @return The Thread instance.
     */
    protected Thread createOutThread(final OutputStream out) {
        return new Thread() {
            public void run() {
                try {
                    IOUtils.copy(process.getInputStream(), out);
                } catch (IOException ioe) {
                    ioe.printStackTrace();
                }
            }
        };
    }

    /**
     * Create the thread that will handle the process's error stream.
     *
     * @param err An OutputStream which can be used to buffer up the entire
     * process error output.
     * @return The Thread instance.
     */
    protected Thread createErrThread(final OutputStream err) {
        return new Thread() {
            public void run() {
                try {
                    IOUtils.copy(process.getErrorStream(), err);
                } catch (IOException ioe) {
                    ioe.printStackTrace();
                }
            }
        };
    }

    /**
     * Destroy this process.
     */
    public void destroy() {
        if (process != null) {
            process.destroy();
        }
    }

    /**
     * Gets the output of the command.
     *
     * @return The command result.
     */
    public String getResult() {
        return result;
    }

    /**
     * Get the return code from the process.
     *
     * @return The return code.
     */
    public int getReturnCode() {
        return returnCode;
    }

    /**
     * Gets the error message from the command if there was one.
     *
     * @return The possibly empty error message.
     */
    public String getErrorMessage() {
        return error;
    }

    /**
     * Determines if the process was terminated during a shutdown.
     *
     * @return The true if shutdown, false otherwise.
     */
    public boolean isShutdown() {
        return this.shutdown;
    }

    public String toString() {
        return StringUtils.join(cmd, ' ');
    }

    private class ShutdownHook extends Thread {
        public void run() {
            logger.info("Terminating process for command: " + Arrays.toString(cmd));
            shutdown = true;
            process.destroy();
        }
    }
}