001/*
002 * The contents of this file are subject to the terms of the Common Development and
003 * Distribution License (the License). You may not use this file except in compliance with the
004 * License.
005 *
006 * You can obtain a copy of the License at legal/CDDLv1.0.txt. See the License for the
007 * specific language governing permission and limitations under the License.
008 *
009 * When distributing Covered Software, include this CDDL Header Notice in each file and include
010 * the License file at legal/CDDLv1.0.txt. If applicable, add the following below the CDDL
011 * Header, with the fields enclosed by brackets [] replaced by your own identifying
012 * information: "Portions Copyright [year] [name of copyright owner]".
013 *
014 * Copyright 2008 Sun Microsystems, Inc.
015 * Portions Copyright 2015 ForgeRock AS.
016 */
017
018package org.opends.quicksetup.util;
019
020import java.io.OutputStream;
021import java.io.IOException;
022import java.io.PrintStream;
023
024/**
025 * Tool for suppressing and unsuppressing output to standard
026 * output streams.
027 */
028public class StandardOutputSuppressor {
029
030  private static Token token;
031
032  /** Object to return to this class for unsuppressing output. */
033  private static class Token {
034    PrintStream out;
035    PrintStream err;
036  }
037
038  /** Suppresses output to the standard output streams. */
039  public static synchronized void suppress() {
040    if (token == null) {
041      token = new Token();
042      token.out = System.out;
043      token.err = System.err;
044      System.out.flush();
045      System.err.flush();
046      System.setOut(new PrintStream(new NullOutputStream()));
047      System.setErr(new PrintStream(new NullOutputStream()));
048    } else {
049      throw new IllegalStateException("Standard streams currently suppressed");
050    }
051  }
052
053  /**
054   * Unsuppresses the standard output streams.  Following a call to this
055   * method System.out and System.err will point to the descriptor prior
056   * to calling <code>suppress()</code>.
057   */
058  public static synchronized void unsuppress() {
059    if (token != null) {
060      System.setOut(token.out);
061      System.setErr(token.err);
062      token = null;
063    } else {
064      throw new IllegalStateException(
065              "Standard streams not currently suppressed");
066    }
067  }
068
069  /**
070   * Checks whether or not this class has suppressed standard out streams.
071   * @return boolean where true indicates output is suppressed
072   */
073  public static boolean isSuppressed() {
074    return token != null;
075  }
076
077  /**
078   * PrintWriter for suppressing stream.
079   */
080  private static class NullOutputStream extends OutputStream {
081
082    /** {@inheritDoc} */
083    public void write(int b) throws IOException {
084      // do nothing;
085    }
086  }
087}