TarTool example source code file (Exec.java)

This example TarTool 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 - TarTool tags/keywords

bufferedreader, bufferedreader, exec, execexception, interruptedexception, io, ioexception, ioexception, printwriter, string, string, stringbuffer, stringbuffer, stringwriter, thread, util

The TarTool Exec.java source code

/*
** Copyright (c) 1998 by Timothy Gerard Endres
** <mailto:time@ice.com>  
** 
** This program is free software.
** 
** You may redistribute it and/or modify it under the terms of the GNU
** General Public License as published by the Free Software Foundation.
** Version 2 of the license should be included with this distribution in
** the file LICENSE, as well as License.html. If the license is not
** included	with this distribution, you may find a copy at the FSF web
** site at 'www.gnu.org' or 'www.fsf.org', or you may write to the
** Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139 USA.
**
** THIS SOFTWARE IS PROVIDED AS-IS WITHOUT WARRANTY OF ANY KIND,
** NOT EVEN THE IMPLIED WARRANTY OF MERCHANTABILITY. THE AUTHOR
** OF THIS SOFTWARE, ASSUMES _NO_ RESPONSIBILITY FOR ANY
** CONSEQUENCE RESULTING FROM THE USE, MODIFICATION, OR
** REDISTRIBUTION OF THIS SOFTWARE. 
** 
*/

package com.ice.util;

import java.io.*;
import java.util.*;


/**
 * Implements a consistent exec() interface.
 *
 * @author Tim Endres,
 *  <a href="mailto:time@gjt.org">time@gjt.org
 */

public
class		Exec
extends		Thread
	{
	private String[]		argv;
	private String[]		envp;
	private StringBuffer	results;

	private BufferedReader	errRdr;
	private BufferedReader	outRdr;
	private Process			proc;
	private String			lnSep;

	public
	Exec( StringBuffer resultBuf, String[] argv, String[] envp )
		{
		this.argv = argv;
		this.envp = envp;
		this.results = resultBuf;
		this.lnSep =
			System.getProperty( "line.separator", "\n" );
		}

	public void
	exec()
		throws ExecException
		{
		try {
			this.proc =
				Runtime.getRuntime().exec( this.argv, this.envp );

			this.start();

			try { this.join(); }
			catch ( InterruptedException ex )
				{
				this.appendEx( ex, "joining exec stdout thread" );
				}

			try { proc.waitFor(); }
			catch ( InterruptedException ex )
				{
				this.appendEx( ex, "waiting for exec process" );
				}

			int exitVal = proc.exitValue();

			if ( this.results != null )
				{
				this.append
					( "& Exit status = '" + exitVal + "'." );
				}

			if ( exitVal != 0 )
				{
				throw new ExecException
					( "non-zero exist status", exitVal );
				}

			}
		catch ( IOException ex )
			{
			throw new ExecException
				( "IO exception exec-ing '" + argv[0] + "', "
					+ ex.getMessage(), -1 );
			}
		}

	// UNDONE
	// Should I not be using the File.separator for the "\n"'s below?

	public void
	run()
		{
		try {
			this.proc.getOutputStream().close();

			// STDERR
			this.errRdr =
				new BufferedReader
					( new InputStreamReader
						( this.proc.getErrorStream() ) );

			Thread t = new Thread(
				new Runnable()
					{
					public void
					run()
						{
						try {
							for ( ; ; )
								{
								String ln = errRdr.readLine();
								if ( ln == null )
									break;
								append( ". " + ln );
								}

							errRdr.close();
							}
						catch ( IOException ex )
							{
							appendEx( ex, "reading exec stderr stream" );
							}
						}
					}
				);

			t.start();

			// STDOUT
			this.outRdr =
				new BufferedReader
					( new InputStreamReader
						( this.proc.getInputStream() ) );

			for ( ; this.results != null ; )
				{
				String ln = this.outRdr.readLine();
				if ( ln == null )
					break;				
				this.append( "o " + ln );
				}

			this.outRdr.close();

			try { t.join(); }
			catch ( InterruptedException ex )
				{
				this.appendEx( ex, "joining exec stderr thread" );
				}
			}
		catch ( IOException ex )
			{
			this.appendEx( ex, "reading exec stdout stream" );
			}
		}

	private void
	append( String str )
		{
		if ( this.results != null )
			this.results.append( str + this.lnSep );
		}

	private void
	appendEx( Exception ex, String msg )
		{
		if ( this.results != null )
			{
			StringWriter sW = new StringWriter();
			PrintWriter pW = new PrintWriter( sW );
			ex.printStackTrace( pW );
			this.results.append( "* " + msg + this.lnSep );
			this.results.append( sW.toString() );
			}
		}

	public void
	dump()
		{
		System.err.println( "EXEC PARAMETERS:" );

		for ( int i = 0 ; i < this.argv.length ; ++i )
			System.err.println
				( "   ARGS["+i+"] '" + this.argv[i] + "'" );

		for ( int i = 0 ; i < this.envp.length ; ++i )
			System.err.println
				( "   ENVP["+i+"] '" + this.envp[i] + "'" );
		}

	public void
	debugExec( StringBuffer buf )
		{
		buf.append( "EXEC PARAMETERS: ----------------------" + this.lnSep );
		for ( int i = 0 ; i < this.argv.length ; ++i )
			buf.append( "   ARGS["+i+"] '"+this.argv[i]+"'" + this.lnSep );
		for ( int i = 0 ; i < this.envp.length ; ++i )
			buf.append( "   ENVP["+i+"] '"+this.envp[i]+"'" + this.lnSep );
		}

	}