A utility class for copying the output of a process to a Logger.

git-svn-id: https://samskivert.googlecode.com/svn/trunk@2281 6335cc39-0255-0410-8fd6-9bcaacd3b74c

src/java/com/samskivert/util/ProcessLogger.java

@@ -0,0 +1,79 @@
+//
+// $Id$
+//
+// samskivert library - useful routines for java programs
+// Copyright (C) 2001-2007 Michael Bayne
+// 
+// This library is free software; you can redistribute it and/or modify it
+// under the terms of the GNU Lesser General Public License as published
+// by the Free Software Foundation; either version 2.1 of the License, or
+// (at your option) any later version.
+//
+// This library 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 General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+package com.samskivert.util;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.util.logging.Logger;
+
+import com.samskivert.io.StreamUtil;
+
+/**
+ * Reads the output from a process and copies any output to a supplied Logger.
+ */
+public class ProcessLogger
+{
+    /**
+     * Starts threads that copy the output of the supplied process's stdout and stderr streams to
+     * the supplied target logger. When the streams reach EOF, the threads will exit. The threads
+     * will be set to daemon so that they do not prevent the VM from exiting.
+     *
+     * @param target the logger to which to copy the output.
+     * @param name prepended to all output lines as either <code>name stderr:</code> or <code>name
+     * stdout:</code>.
+     * @param process the process whose output should be copied.
+     */
+    public static void copyOutput (Logger target, String name, Process process)
+    {
+        new StreamReader(target, name + " stdout", process.getInputStream()).start();
+        new StreamReader(target, name + " stderr", process.getErrorStream()).start();
+    }
+
+    protected static class StreamReader extends Thread
+    {
+        public StreamReader (Logger target, String name, InputStream input)
+        {
+            setDaemon(true);
+            _name = name;
+            _reader = new BufferedReader(new InputStreamReader(input));
+        }
+
+        public void run ()
+        {
+            String line;
+            try {
+                while ((line = _reader.readLine()) != null) {
+                    _target.warning(_name + ": " + line);
+                }
+            } catch (Exception e) {
+                _target.warning(_name + " failure: " + e);
+            } finally {
+                StreamUtil.close(_reader);
+            }
+        }
+
+        protected Logger _target;
+        protected String _name;
+        protected BufferedReader _reader;
+    }
+}