package com.devdaily.system;
import java.io.*;
import java.util.List;
/**
* This class can be used to execute a system command from a Java application.
* See the documentation for the public methods of this class for more
* information.
*
* Documentation for this class is available at this URL:
*
* http://devdaily.com/java/java-processbuilder-process-system-exec
*
*
* Copyright 2010 alvin j. alexander, devdaily.com.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
* This program 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 Public License for more details.
* You should have received a copy of the GNU Lesser Public License
* along with this program. If not, see .
*
* Please ee the following page for the LGPL license:
* http://www.gnu.org/licenses/lgpl.txt
*
*/
public class SystemCommandExecutor
{
private List commandInformation;
private String adminPassword;
private ThreadedStreamHandler inputStreamHandler;
private ThreadedStreamHandler errorStreamHandler;
/**
* Pass in the system command you want to run as a List of Strings, as shown here:
*
* List commands = new ArrayList();
* commands.add("/sbin/ping");
* commands.add("-c");
* commands.add("5");
* commands.add("www.google.com");
* SystemCommandExecutor commandExecutor = new SystemCommandExecutor(commands);
* commandExecutor.executeCommand();
*
* Note: I've removed the other constructor that was here to support executing
* the sudo command. I'll add that back in when I get the sudo command
* working to the point where it won't hang when the given password is
* wrong.
*
* @param commandInformation The command you want to run.
*/
public SystemCommandExecutor(final List commandInformation)
{
if (commandInformation==null) throw new NullPointerException("The commandInformation is required.");
this.commandInformation = commandInformation;
this.adminPassword = null;
}
public int executeCommand()
throws IOException, InterruptedException
{
int exitValue = -99;
try
{
ProcessBuilder pb = new ProcessBuilder(commandInformation);
Process process = pb.start();
// you need this if you're going to write something to the command's input stream
// (such as when invoking the 'sudo' command, and it prompts you for a password).
OutputStream stdOutput = process.getOutputStream();
// i'm currently doing these on a separate line here in case i need to set them to null
// to get the threads to stop.
// see http://java.sun.com/j2se/1.5.0/docs/guide/misc/threadPrimitiveDeprecation.html
InputStream inputStream = process.getInputStream();
InputStream errorStream = process.getErrorStream();
// these need to run as java threads to get the standard output and error from the command.
// the inputstream handler gets a reference to our stdOutput in case we need to write
// something to it, such as with the sudo command
inputStreamHandler = new ThreadedStreamHandler(inputStream, stdOutput, adminPassword);
errorStreamHandler = new ThreadedStreamHandler(errorStream);
// TODO the inputStreamHandler has a nasty side-effect of hanging if the given password is wrong; fix it
inputStreamHandler.start();
errorStreamHandler.start();
// TODO a better way to do this?
exitValue = process.waitFor();
// TODO a better way to do this?
inputStreamHandler.interrupt();
errorStreamHandler.interrupt();
inputStreamHandler.join();
errorStreamHandler.join();
}
catch (IOException e)
{
// TODO deal with this here, or just throw it?
throw e;
}
catch (InterruptedException e)
{
// generated by process.waitFor() call
// TODO deal with this here, or just throw it?
throw e;
}
finally
{
return exitValue;
}
}
/**
* Get the standard output (stdout) from the command you just exec'd.
*/
public StringBuilder getStandardOutputFromCommand()
{
return inputStreamHandler.getOutputBuffer();
}
/**
* Get the standard error (stderr) from the command you just exec'd.
*/
public StringBuilder getStandardErrorFromCommand()
{
return errorStreamHandler.getOutputBuffer();
}
}