001    /* Process.java - Represent spawned system process
002       Copyright (C) 1998, 1999, 2001, 2002, 2003, 2004, 2005
003       Free Software Foundation, Inc.
004    
005    This file is part of GNU Classpath.
006    
007    GNU Classpath is free software; you can redistribute it and/or modify
008    it under the terms of the GNU General Public License as published by
009    the Free Software Foundation; either version 2, or (at your option)
010    any later version.
011    
012    GNU Classpath is distributed in the hope that it will be useful, but
013    WITHOUT ANY WARRANTY; without even the implied warranty of
014    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
015    General Public License for more details.
016    
017    You should have received a copy of the GNU General Public License
018    along with GNU Classpath; see the file COPYING.  If not, write to the
019    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
020    02110-1301 USA.
021    
022    Linking this library statically or dynamically with other modules is
023    making a combined work based on this library.  Thus, the terms and
024    conditions of the GNU General Public License cover the whole
025    combination.
026    
027    As a special exception, the copyright holders of this library give you
028    permission to link this library with independent modules to produce an
029    executable, regardless of the license terms of these independent
030    modules, and to copy and distribute the resulting executable under
031    terms of your choice, provided that you also meet, for each linked
032    independent module, the terms and conditions of the license of that
033    module.  An independent module is a module which is not derived from
034    or based on this library.  If you modify this library, you may extend
035    this exception to your version of the library, but you are not
036    obligated to do so.  If you do not wish to do so, delete this
037    exception statement from your version. */
038    
039    
040    package java.lang;
041    
042    import java.io.File;
043    import java.io.InputStream;
044    import 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     */
070    public 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