Groovy example source code file (ProcessGroovyMethods.java)

This example Groovy source code file (ProcessGroovyMethods.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 - Groovy tags/keywords

appendable, groovyruntimeexception, inputstream, interruptedexception, io, ioexception, ioexception, outputstream, outputstream, process, process, processrunner, runnable, thread, thread

The Groovy ProcessGroovyMethods.java source code

/*
 * Copyright 2003-2010 the original author or authors.
 *
 * Licensed 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 org.codehaus.groovy.runtime;

import groovy.lang.Closure;
import groovy.lang.GroovyRuntimeException;

import java.io.*;

/**
 * This class defines new groovy methods which appear on normal JDK
 * classes related to process management.
 * <p/>
 * Static methods are used with the first parameter being the destination class,
 * i.e. <code>public static String reverse(String self)
 * provides a <code>reverse() method for String.
 * <p>
 * NOTE: While this class contains many 'public' static methods, it is
 * primarily regarded as an internal class (its internal package name
 * suggests this also). We value backwards compatibility of these
 * methods when used within Groovy but value less backwards compatibility
 * at the Java method call level. I.e. future versions of Groovy may
 * remove or move a method call in this file but would normally
 * aim to keep the method available from within Groovy.
 */
public class ProcessGroovyMethods extends DefaultGroovyMethodsSupport {

    /**
     * An alias method so that a process appears similar to System.out, System.in, System.err;
     * you can use process.in, process.out, process.err in a similar fashion.
     *
     * @param self a Process instance
     * @return the InputStream for the process
     * @since 1.0
     */
    public static InputStream getIn(Process self) {
        return self.getInputStream();
    }

    /**
     * Read the text of the output stream of the Process.
     *
     * @param self a Process instance
     * @return the text of the output
     * @throws java.io.IOException if an IOException occurs.
     * @since 1.0
     */
    public static String getText(Process self) throws IOException {
        return DefaultGroovyMethods.getText(new BufferedReader(new InputStreamReader(self.getInputStream())));
    }

    /**
     * An alias method so that a process appears similar to System.out, System.in, System.err;
     * you can use process.in, process.out, process.err in a similar fashion.
     *
     * @param self a Process instance
     * @return the error InputStream for the process
     * @since 1.0
     */
    public static InputStream getErr(Process self) {
        return self.getErrorStream();
    }

    /**
     * An alias method so that a process appears similar to System.out, System.in, System.err;
     * you can use process.in, process.out, process.err in a similar fashion.
     *
     * @param self a Process instance
     * @return the OutputStream for the process
     * @since 1.0
     */
    public static OutputStream getOut(Process self) {
        return self.getOutputStream();
    }

    /**
     * Overloads the left shift operator (<<) to provide an append mechanism
     * to pipe data to a Process.
     *
     * @param self  a Process instance
     * @param value a value to append
     * @return a Writer
     * @throws java.io.IOException if an IOException occurs.
     * @since 1.0
     */
    public static Writer leftShift(Process self, Object value) throws IOException {
        return DefaultGroovyMethods.leftShift(self.getOutputStream(), value);
    }

    /**
     * Overloads the left shift operator to provide an append mechanism
     * to pipe into a Process
     *
     * @param self  a Process instance
     * @param value data to append
     * @return an OutputStream
     * @throws java.io.IOException if an IOException occurs.
     * @since 1.0
     */
    public static OutputStream leftShift(Process self, byte[] value) throws IOException {
        return DefaultGroovyMethods.leftShift(self.getOutputStream(), value);
    }

    /**
     * Wait for the process to finish during a certain amount of time, otherwise stops the process.
     *
     * @param self           a Process
     * @param numberOfMillis the number of milliseconds to wait before stopping the process
     * @since 1.0
     */
    public static void waitForOrKill(Process self, long numberOfMillis) {
        ProcessRunner runnable = new ProcessRunner(self);
        Thread thread = new Thread(runnable);
        thread.start();
        runnable.waitForOrKill(numberOfMillis);
    }

    /**
     * Gets the output and error streams from a process and reads them
     * to keep the process from blocking due to a full output buffer.
     * The stream data is thrown away but blocking due to a full output buffer is avoided.
     * Use this method if you don't care about the standard or error output and just
     * want the process to run silently - use carefully however, because since the stream
     * data is thrown away, it might be difficult to track down when something goes wrong.
     * For this, two Threads are started, so this method will return immediately.
     *
     * @param self a Process
     * @since 1.0
     */
    public static void consumeProcessOutput(Process self) {
        consumeProcessOutput(self, (OutputStream)null, (OutputStream)null);
    }

    /**
     * Gets the output and error streams from a process and reads them
     * to keep the process from blocking due to a full output buffer.
     * The processed stream data is appended to the supplied Appendable.
     * For this, two Threads are started, so this method will return immediately.
     *
     * @param self a Process
     * @param output an Appendable to capture the process stdout
     * @param error an Appendable to capture the process stderr
     * @since 1.7.5
     */
    public static void consumeProcessOutput(Process self, Appendable output, Appendable error) {
        consumeProcessOutputStream(self, output);
        consumeProcessErrorStream(self, error);
    }

    /**
     * Gets the output and error streams from a process and reads them
     * to keep the process from blocking due to a full output buffer.
     * The processed stream data is appended to the supplied OutputStream.
     * For this, two Threads are started, so this method will return immediately.
     *
     * @param self a Process
     * @param output an OutputStream to capture the process stdout
     * @param error an OutputStream to capture the process stderr
     * @since 1.5.2
     */
    public static void consumeProcessOutput(Process self, OutputStream output, OutputStream error) {
        consumeProcessOutputStream(self, output);
        consumeProcessErrorStream(self, error);
    }

    /**
     * Gets the output and error streams from a process and reads them
     * to keep the process from blocking due to a full output buffer.
     * The stream data is thrown away but blocking due to a full output buffer is avoided.
     * Use this method if you don't care about the standard or error output and just
     * want the process to run silently - use carefully however, because since the stream
     * data is thrown away, it might be difficult to track down when something goes wrong.
     * For this, two Threads are started, but join()ed, so we wait.
     * As implied by the waitFor... name, we also wait until we finish
     * as well.
     *
     * @param self a Process
     * @since 1.6.5
     */
    public static void waitForProcessOutput(Process self) {
        waitForProcessOutput(self, (OutputStream)null, (OutputStream)null);
    }

    /**
     * Gets the output and error streams from a process and reads them
     * to keep the process from blocking due to a full output buffer.
     * The processed stream data is appended to the supplied Appendable.
     * For this, two Threads are started, but join()ed, so we wait.
     * As implied by the waitFor... name, we also wait until we finish
     * as well.
     *
     * @param self a Process
     * @param output an Appendable to capture the process stdout
     * @param error an Appendable to capture the process stderr
     * @since 1.7.5
     */
    public static void waitForProcessOutput(Process self, Appendable output, Appendable error) {
        Thread tout = consumeProcessOutputStream(self, output);
        Thread terr = consumeProcessErrorStream(self, error);
        try { tout.join(); } catch (InterruptedException ignore) {}
        try { terr.join(); } catch (InterruptedException ignore) {}
        try { self.waitFor(); } catch (InterruptedException ignore) {}
    }

    /**
     * Gets the output and error streams from a process and reads them
     * to keep the process from blocking due to a full output buffer.
     * The processed stream data is appended to the supplied OutputStream.
     * For this, two Threads are started, but join()ed, so we wait.
     * As implied by the waitFor... name, we also wait until we finish
     * as well.
     *
     * @param self a Process
     * @param output an OutputStream to capture the process stdout
     * @param error an OutputStream to capture the process stderr
     * @since 1.6.5
     */
    public static void waitForProcessOutput(Process self, OutputStream output, OutputStream error) {
        Thread tout = consumeProcessOutputStream(self, output);
        Thread terr = consumeProcessErrorStream(self, error);
        try { tout.join(); } catch (InterruptedException ignore) {}
        try { terr.join(); } catch (InterruptedException ignore) {}
        try { self.waitFor(); } catch (InterruptedException ignore) {}
    }

    /**
     * Gets the error stream from a process and reads it
     * to keep the process from blocking due to a full buffer.
     * The processed stream data is appended to the supplied OutputStream.
     * A new Thread is started, so this method will return immediately.
     *
     * @param self a Process
     * @param err an OutputStream to capture the process stderr
     * @return the Thread
     * @since 1.5.2
     */
    public static Thread consumeProcessErrorStream(Process self, OutputStream err) {
        Thread thread = new Thread(new ByteDumper(self.getErrorStream(), err));
        thread.start();
        return thread;
    }

    /**
     * Gets the error stream from a process and reads it
     * to keep the process from blocking due to a full buffer.
     * The processed stream data is appended to the supplied Appendable.
     * A new Thread is started, so this method will return immediately.
     *
     * @param self a Process
     * @param error an Appendable to capture the process stderr
     * @return the Thread
     * @since 1.7.5
     */
    public static Thread consumeProcessErrorStream(Process self, Appendable error) {
        Thread thread = new Thread(new TextDumper(self.getErrorStream(), error));
        thread.start();
        return thread;
    }

    /**
     * Gets the output stream from a process and reads it
     * to keep the process from blocking due to a full output buffer.
     * The processed stream data is appended to the supplied Appendable.
     * A new Thread is started, so this method will return immediately.
     *
     * @param self a Process
     * @param output an Appendable to capture the process stdout
     * @return the Thread
     * @since 1.7.5
     */
    public static Thread consumeProcessOutputStream(Process self, Appendable output) {
        Thread thread = new Thread(new TextDumper(self.getInputStream(), output));
        thread.start();
        return thread;
    }

    /**
     * Gets the output stream from a process and reads it
     * to keep the process from blocking due to a full output buffer.
     * The processed stream data is appended to the supplied OutputStream.
     * A new Thread is started, so this method will return immediately.
     *
     * @param self a Process
     * @param output an OutputStream to capture the process stdout
     * @return the Thread
     * @since 1.5.2
     */
    public static Thread consumeProcessOutputStream(Process self, OutputStream output) {
        Thread thread = new Thread(new ByteDumper(self.getInputStream(), output));
        thread.start();
        return thread;
    }

    /**
     * Creates a new BufferedWriter as stdin for this process,
     * passes it to the closure, and ensures the stream is flushed
     * and closed after the closure returns.
     * A new Thread is started, so this method will return immediately.
     *
     * @param self a Process
     * @param closure a closure
     * @since 1.5.2
     */
    public static void withWriter(final Process self, final Closure closure) {
        new Thread(new Runnable() {
            public void run() {
                try {
                    DefaultGroovyMethods.withWriter(new BufferedOutputStream(getOut(self)), closure);
                } catch (IOException e) {
                    throw new GroovyRuntimeException("exception while reading process stream", e);
                }
            }
        }).start();
    }

    /**
     * Creates a new buffered OutputStream as stdin for this process,
     * passes it to the closure, and ensures the stream is flushed
     * and closed after the closure returns.
     * A new Thread is started, so this method will return immediately.
     *
     * @param self a Process
     * @param closure a closure
     * @since 1.5.2
     */
    public static void withOutputStream(final Process self, final Closure closure) {
        new Thread(new Runnable() {
            public void run() {
                try {
                    DefaultGroovyMethods.withStream(new BufferedOutputStream(getOut(self)), closure);
                } catch (IOException e) {
                    throw new GroovyRuntimeException("exception while reading process stream", e);
                }
            }
        }).start();
    }

    /**
     * Allows one Process to asynchronously pipe data to another Process.
     *
     * @param left  a Process instance
     * @param right a Process to pipe output to
     * @return the second Process to allow chaining
     * @throws java.io.IOException if an IOException occurs.
     * @since 1.5.2
     */
    public static Process pipeTo(final Process left, final Process right) throws IOException {
        new Thread(new Runnable() {
            public void run() {
                InputStream in = new BufferedInputStream(getIn(left));
                OutputStream out = new BufferedOutputStream(getOut(right));
                byte[] buf = new byte[8192];
                int next;
                try {
                    while ((next = in.read(buf)) != -1) {
                        out.write(buf, 0, next);
                    }
                } catch (IOException e) {
                    throw new GroovyRuntimeException("exception while reading process stream", e);
                } finally {
                    closeWithWarning(out);
                }
            }
        }).start();
        return right;
    }

    /**
     * Overrides the or operator to allow one Process to asynchronously
     * pipe data to another Process.
     *
     * @param left  a Process instance
     * @param right a Process to pipe output to
     * @return the second Process to allow chaining
     * @throws java.io.IOException if an IOException occurs.
     * @since 1.5.1
     */
    public static Process or(final Process left, final Process right) throws IOException {
        return pipeTo(left, right);
    }

    /**
     * A Runnable which waits for a process to complete together with a notification scheme
     * allowing another thread to wait a maximum number of seconds for the process to complete
     * before killing it.
     *
     * @since 1.0
     */
    protected static class ProcessRunner implements Runnable {
        Process process;
        private boolean finished;

        public ProcessRunner(Process process) {
            this.process = process;
        }

        private void doProcessWait() {
            try {
                process.waitFor();
            } catch (InterruptedException e) {
                // Ignore
            }
        }

        public void run() {
            doProcessWait();
            synchronized (this) {
                notifyAll();
                finished = true;
            }
        }

        public synchronized void waitForOrKill(long millis) {
            if (!finished) {
                try {
                    wait(millis);
                } catch (InterruptedException e) {
                    // Ignore
                }
                if (!finished) {
                    process.destroy();
                    doProcessWait();
                }
            }
        }
    }

    private static class TextDumper implements Runnable {
        InputStream in;
        Appendable app;

        public TextDumper(InputStream in, Appendable app) {
            this.in = in;
            this.app = app;
        }

        public void run() {
            InputStreamReader isr = new InputStreamReader(in);
            BufferedReader br = new BufferedReader(isr);
            String next;
            try {
                while ((next = br.readLine()) != null) {
                    if (app != null) {
                        app.append(next);
                        app.append("\n");
                    }
                }
            } catch (IOException e) {
                throw new GroovyRuntimeException("exception while reading process stream", e);
            }
        }
    }

    private static class ByteDumper implements Runnable {
        InputStream in;
        OutputStream out;

        public ByteDumper(InputStream in, OutputStream out) {
            this.in = new BufferedInputStream(in);
            this.out = out;
        }

        public void run() {
            byte[] buf = new byte[8192];
            int next;
            try {
                while ((next = in.read(buf)) != -1) {
                    if (out != null) out.write(buf, 0, next);
                }
            } catch (IOException e) {
                throw new GroovyRuntimeException("exception while dumping process stream", e);
            }
        }
    }

}