001/* Process.java - Represent spawned system process
002   Copyright (C) 1998, 1999, 2001, 2002, 2003, 2004, 2005
003   Free Software Foundation, Inc.
004
005This file is part of GNU Classpath.
006
007GNU Classpath is free software; you can redistribute it and/or modify
008it under the terms of the GNU General Public License as published by
009the Free Software Foundation; either version 2, or (at your option)
010any later version.
011
012GNU Classpath is distributed in the hope that it will be useful, but
013WITHOUT ANY WARRANTY; without even the implied warranty of
014MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
015General Public License for more details.
016
017You should have received a copy of the GNU General Public License
018along with GNU Classpath; see the file COPYING.  If not, write to the
019Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02002110-1301 USA.
021
022Linking this library statically or dynamically with other modules is
023making a combined work based on this library.  Thus, the terms and
024conditions of the GNU General Public License cover the whole
025combination.
026
027As a special exception, the copyright holders of this library give you
028permission to link this library with independent modules to produce an
029executable, regardless of the license terms of these independent
030modules, and to copy and distribute the resulting executable under
031terms of your choice, provided that you also meet, for each linked
032independent module, the terms and conditions of the license of that
033module.  An independent module is a module which is not derived from
034or based on this library.  If you modify this library, you may extend
035this exception to your version of the library, but you are not
036obligated to do so.  If you do not wish to do so, delete this
037exception statement from your version. */
038
039
040package java.lang;
041
042import java.io.File;
043import java.io.InputStream;
044import java.io.OutputStream;
045
046/**
047 * An instance of a subclass of <code>Process</code> is created by the
048 * <code>Runtime.exec</code> methods.  Methods in <code>Process</code>
049 * provide a means to send input to a process, obtain the output from a
050 * subprocess, destroy a subprocess, obtain the exit value from a
051 * subprocess, and wait for a subprocess to complete.
052 *
053 * <p>This is dependent on the platform, and some processes (like native
054 * windowing processes, 16-bit processes in Windows, or shell scripts) may
055 * be limited in functionality. Because some platforms have limited buffers
056 * between processes, you may need to provide input and read output to prevent
057 * the process from blocking, or even deadlocking.
058 *
059 * <p>Even if all references to this object disapper, the process continues
060 * to execute to completion. There are no guarantees that the
061 * subprocess execute asynchronously or concurrently with the process which
062 * owns this object.
063 *
064 * @author Brian Jones
065 * @author Tom Tromey (tromey@cygnus.com)
066 * @see Runtime#exec(String[], String[], File)
067 * @since 1.0
068 * @status updated to 1.4
069 */
070public abstract class Process
071{
072  /**
073   * Empty constructor does nothing.
074   */
075  public Process()
076  {
077  }
078
079  /**
080   * Obtain the output stream that sends data to the subprocess. This is
081   * the STDIN of the subprocess. When implementing, you should probably
082   * use a buffered stream.
083   *
084   * @return the output stream that pipes to the process input
085   */
086  public abstract OutputStream getOutputStream();
087
088  /**
089   * Obtain the input stream that receives data from the subprocess. This is
090   * the STDOUT of the subprocess. When implementing, you should probably
091   * use a buffered stream.
092   *
093   * @return the input stream that pipes data from the process output
094   */
095  public abstract InputStream getInputStream();
096
097  /**
098   * Obtain the input stream that receives data from the subprocess. This is
099   * the STDERR of the subprocess. When implementing, you should probably
100   * use a buffered stream.
101   *
102   * @return the input stream that pipes data from the process error output
103   */
104  public abstract InputStream getErrorStream();
105
106  /**
107   * The thread calling <code>waitFor</code> will block until the subprocess
108   * has terminated. If the process has already terminated then the method
109   * immediately returns with the exit value of the subprocess.
110   *
111   * @return the subprocess exit value; 0 conventionally denotes success
112   * @throws InterruptedException if another thread interrupts the blocked one
113   */
114  public abstract int waitFor() throws InterruptedException;
115
116  /**
117   * When a process terminates there is associated with that termination
118   * an exit value for the process to indicate why it terminated. A return
119   * of <code>0</code> denotes normal process termination by convention.
120   *
121   * @return the exit value of the subprocess
122   * @throws IllegalThreadStateException if the subprocess has not terminated
123   */
124  public abstract int exitValue();
125
126  /**
127   * Kills the subprocess and all of its children forcibly.
128   */
129  public abstract void destroy();
130} // class Process