RuntimeStreamer.java

package net.ftb.util.winreg;

/**
 * Java Finder by petrucio@stackoverflow(828681) is licensed under a Creative Commons Attribution 3.0 Unported License.
 * Needs WinRegistry.java. Get it at: http://stackoverflow.com/questions/62289/read-write-to-windows-registry-using-java
 *
 * JavaFinder - Windows-specific classes to search for all installed versions of java on this system
 * Author: petrucio@stackoverflow (828681)
 *****************************************************************************/

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

/**
 * Helper class to fetch the stdout and stderr outputs from started Runtime execs
 * Modified from http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html?page=4
 *****************************************************************************/
public class RuntimeStreamer extends Thread
{
	InputStream is;
	String lines;

	RuntimeStreamer (InputStream is)
	{
		this.is = is;
		this.lines = "";
	}

	public String contents ()
	{
		return this.lines;
	}

	public void run ()
	{
		try
		{
			InputStreamReader isr = new InputStreamReader(is);
			BufferedReader br = new BufferedReader(isr);
			String line;
			while ((line = br.readLine()) != null)
			{
				this.lines += line + "\n";
			}
		}
		catch (IOException ioe)
		{
			ioe.printStackTrace();
		}
	}

	/**
	 * Execute a command and wait for it to finish
	 * @return The resulting stdout and stderr outputs concatenated
	 ****************************************************************************/
	public static String execute (String[] cmdArray)
	{
		try
		{
			Runtime runtime = Runtime.getRuntime();
			Process proc = runtime.exec(cmdArray);
			RuntimeStreamer outputStreamer = new RuntimeStreamer(proc.getInputStream());
			RuntimeStreamer errorStreamer = new RuntimeStreamer(proc.getErrorStream());
			outputStreamer.start();
			errorStreamer.start();
			// close process' stdin
			proc.getOutputStream().close();
			proc.waitFor();
			return outputStreamer.contents() + errorStreamer.contents();
		}
		catch (Throwable t)
		{
			t.printStackTrace();
		}
		return null;
	}

	public static String execute (String cmd)
	{
		String[] cmdArray =
			{cmd};
		return RuntimeStreamer.execute(cmdArray);
	}
}