Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * */ package com.example.gridtest; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import org.apache.commons.exec.ExecuteStreamHandler; import org.apache.commons.exec.InputStreamPumper; import org.apache.commons.exec.util.DebugUtils; /** * Copies standard output and error of subprocesses to standard output and error * of the parent process. If output or error stream are set to null, any feedback * from that stream will be lost. */ public class MyPumpStreamHandler implements ExecuteStreamHandler { private Thread outputThread; private Thread errorThread; private Thread inputThread; private final OutputStream out; private final OutputStream err; private final InputStream input; private InputStreamPumper inputStreamPumper; /** * Construct a new <CODE>PumpStreamHandler</CODE>. */ public MyPumpStreamHandler() { this(System.out, System.err); } /** * Construct a new <CODE>PumpStreamHandler</CODE>. * * @param outAndErr * the output/error <CODE>OutputStream</CODE>. */ public MyPumpStreamHandler(final OutputStream outAndErr) { this(outAndErr, outAndErr); } /** * Construct a new <CODE>PumpStreamHandler</CODE>. * * @param out * the output <CODE>OutputStream</CODE>. * @param err * the error <CODE>OutputStream</CODE>. */ public MyPumpStreamHandler(final OutputStream out, final OutputStream err) { this(out, err, null); } /** * Construct a new <CODE>PumpStreamHandler</CODE>. * * @param out * the output <CODE>OutputStream</CODE>. * @param err * the error <CODE>OutputStream</CODE>. * @param input * the input <CODE>InputStream</CODE>. */ public MyPumpStreamHandler(final OutputStream out, final OutputStream err, final InputStream input) { this.out = out; this.err = err; this.input = input; } /** * Set the <CODE>InputStream</CODE> from which to read the standard output * of the process. * * @param is * the <CODE>InputStream</CODE>. */ public void setProcessOutputStream(final InputStream is) { if (out != null) { createProcessOutputPump(is, out); } } /** * Set the <CODE>InputStream</CODE> from which to read the standard error * of the process. * * @param is * the <CODE>InputStream</CODE>. */ public void setProcessErrorStream(final InputStream is) { if (err != null) { createProcessErrorPump(is, err); } } /** * Set the <CODE>OutputStream</CODE> by means of which input can be sent * to the process. * * @param os * the <CODE>OutputStream</CODE>. */ public void setProcessInputStream(final OutputStream os) { if (input != null) { if (input == System.in) { inputThread = createSystemInPump(input, os); } else { inputThread = createPump(input, os, false); } } else { try { os.close(); } catch (IOException e) { String msg = "Got exception while closing output stream"; DebugUtils.handleException(msg, e); } } } /** * Start the <CODE>Thread</CODE>s. */ public void start() { if (outputThread != null) { outputThread.start(); } if (errorThread != null) { errorThread.start(); } if (inputThread != null) { inputThread.start(); } } /** * Stop pumping the streams. */ public void stop() { if (inputStreamPumper != null) { inputStreamPumper.stopProcessing(); } if (outputThread != null) { try { outputThread.join(); outputThread = null; } catch (InterruptedException e) { // ignore } } if (errorThread != null) { try { errorThread.join(); errorThread = null; } catch (InterruptedException e) { // ignore } } if (inputThread != null) { try { inputThread.join(); inputThread = null; } catch (InterruptedException e) { // ignore } } if (err != null && err != out) { try { err.flush(); } catch (IOException e) { String msg = "Got exception while flushing the error stream : " + e.getMessage(); DebugUtils.handleException(msg, e); } } if (out != null) { try { out.flush(); } catch (IOException e) { String msg = "Got exception while flushing the output stream"; DebugUtils.handleException(msg, e); } } } /** * Get the error stream. * * @return <CODE>OutputStream</CODE>. */ protected OutputStream getErr() { return err; } /** * Get the output stream. * * @return <CODE>OutputStream</CODE>. */ protected OutputStream getOut() { return out; } /** * Create the pump to handle process output. * * @param is * the <CODE>InputStream</CODE>. * @param os * the <CODE>OutputStream</CODE>. */ protected void createProcessOutputPump(final InputStream is, final OutputStream os) { outputThread = createPump(is, os); } /** * Create the pump to handle error output. * * @param is * the <CODE>InputStream</CODE>. * @param os * the <CODE>OutputStream</CODE>. */ protected void createProcessErrorPump(final InputStream is, final OutputStream os) { errorThread = createPump(is, os); } /** * Creates a stream pumper to copy the given input stream to the given * output stream. * * @param is the input stream to copy from * @param os the output stream to copy into * @return the stream pumper thread */ protected Thread createPump(final InputStream is, final OutputStream os) { return createPump(is, os, false); } /** * Creates a stream pumper to copy the given input stream to the given * output stream. * * @param is the input stream to copy from * @param os the output stream to copy into * @param closeWhenExhausted close the output stream when the input stream is exhausted * @return the stream pumper thread */ protected Thread createPump(final InputStream is, final OutputStream os, final boolean closeWhenExhausted) { final Thread result = new Thread(new MyStreamPumper(is, os, closeWhenExhausted)); result.setDaemon(true); return result; } /** * Creates a stream pumper to copy the given input stream to the given * output stream. * * @param is the System.in input stream to copy from * @param os the output stream to copy into * @return the stream pumper thread */ private Thread createSystemInPump(InputStream is, OutputStream os) { inputStreamPumper = new InputStreamPumper(is, os); final Thread result = new Thread(inputStreamPumper); result.setDaemon(true); return result; } }