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 2015-2016 ForgeRock AS. 016 */ 017 018package org.opends.quicksetup.util; 019 020import java.io.OutputStream; 021import java.io.IOException; 022import java.io.PrintStream; 023 024/** Tool for suppressing and unsuppressing output to standard output streams. */ 025public class StandardOutputSuppressor { 026 027 private static Token token; 028 029 /** Object to return to this class for unsuppressing output. */ 030 private static class Token { 031 PrintStream out; 032 PrintStream err; 033 } 034 035 /** Suppresses output to the standard output streams. */ 036 public static synchronized void suppress() { 037 if (token == null) { 038 token = new Token(); 039 token.out = System.out; 040 token.err = System.err; 041 System.out.flush(); 042 System.err.flush(); 043 System.setOut(new PrintStream(new NullOutputStream())); 044 System.setErr(new PrintStream(new NullOutputStream())); 045 } else { 046 throw new IllegalStateException("Standard streams currently suppressed"); 047 } 048 } 049 050 /** 051 * Unsuppresses the standard output streams. Following a call to this 052 * method System.out and System.err will point to the descriptor prior 053 * to calling <code>suppress()</code>. 054 */ 055 public static synchronized void unsuppress() { 056 if (token != null) { 057 System.setOut(token.out); 058 System.setErr(token.err); 059 token = null; 060 } else { 061 throw new IllegalStateException( 062 "Standard streams not currently suppressed"); 063 } 064 } 065 066 /** 067 * Checks whether this class has suppressed standard out streams. 068 * @return boolean where true indicates output is suppressed 069 */ 070 public static boolean isSuppressed() { 071 return token != null; 072 } 073 074 /** PrintWriter for suppressing stream. */ 075 private static class NullOutputStream extends OutputStream { 076 077 @Override 078 public void write(int b) throws IOException { 079 // do nothing; 080 } 081 } 082}