1 /** 2 * This file Copyright (c) 2010-2011 Magnolia International 3 * Ltd. (http://www.magnolia-cms.com). All rights reserved. 4 * 5 * 6 * This file is dual-licensed under both the Magnolia 7 * Network Agreement and the GNU General Public License. 8 * You may elect to use one or the other of these licenses. 9 * 10 * This file is distributed in the hope that it will be 11 * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the 12 * implied warranty of MERCHANTABILITY or FITNESS FOR A 13 * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT. 14 * Redistribution, except as permitted by whichever of the GPL 15 * or MNA you select, is prohibited. 16 * 17 * 1. For the GPL license (GPL), you can redistribute and/or 18 * modify this file under the terms of the GNU General 19 * Public License, Version 3, as published by the Free Software 20 * Foundation. You should have received a copy of the GNU 21 * General Public License, Version 3 along with this program; 22 * if not, write to the Free Software Foundation, Inc., 51 23 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 24 * 25 * 2. For the Magnolia Network Agreement (MNA), this file 26 * and the accompanying materials are made available under the 27 * terms of the MNA which accompanies this distribution, and 28 * is available at http://www.magnolia-cms.com/mna.html 29 * 30 * Any modifications to this file must keep this entire header 31 * intact. 32 * 33 */ 34 package info.magnolia.cms.util; 35 36 import javax.servlet.ServletResponse; 37 import java.io.IOException; 38 import java.io.PrintWriter; 39 import java.io.Writer; 40 41 /** 42 * Writer that only opens the underlying writer when there is something needed to be written. This allows us to pass 43 * around a Writer instance without actually having acquired it from the servlet response. 44 */ 45 public class LazyInitPrintWriter extends PrintWriter { 46 47 public LazyInitPrintWriter(final ServletResponse response) { 48 super(new Writer() { 49 50 private Writer writer; 51 52 @Override 53 public void write(char[] cbuf, int off, int len) throws IOException { 54 getTargetWriter().write(cbuf, off, len); 55 } 56 57 @Override 58 public void flush() throws IOException { 59 if (writer != null) { 60 writer.flush(); 61 } 62 } 63 64 @Override 65 public void close() throws IOException { 66 getTargetWriter().close(); 67 } 68 69 private Writer getTargetWriter() throws IOException { 70 if (writer != null) { 71 return writer; 72 } 73 writer = response.getWriter(); 74 return writer; 75 } 76 }); 77 } 78 }