001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.wicket.markup.head.internal; 018 019import java.util.HashSet; 020import java.util.Set; 021 022import org.apache.wicket.markup.head.HeaderItem; 023import org.apache.wicket.markup.head.IHeaderResponse; 024import org.apache.wicket.request.Response; 025import org.apache.wicket.response.NullResponse; 026 027 028/** 029 * Default implementation of the {@link org.apache.wicket.markup.head.IHeaderResponse} interface. 030 * 031 * @author Matej Knopp 032 * @author Igor Vaynberg (ivaynberg) 033 */ 034public abstract class HeaderResponse implements IHeaderResponse 035{ 036 private final Set<Object> rendered = new HashSet<Object>(); 037 038 private boolean closed; 039 040 /** 041 * @see org.apache.wicket.markup.head.IHeaderResponse#markRendered(java.lang.Object) 042 */ 043 @Override 044 public void markRendered(Object object) 045 { 046 rendered.add(object); 047 } 048 049 @Override 050 public void render(HeaderItem item) 051 { 052 if (!closed && !wasItemRendered(item)) 053 { 054 item.render(getResponse()); 055 markItemRendered(item); 056 } 057 } 058 059 protected boolean wasItemRendered(HeaderItem item) 060 { 061 for (Object curToken : item.getRenderTokens()) 062 { 063 if (wasRendered(curToken)) 064 return true; 065 } 066 return false; 067 } 068 069 protected void markItemRendered(HeaderItem item) 070 { 071 for (Object curToken : item.getRenderTokens()) 072 { 073 markRendered(curToken); 074 } 075 } 076 077 /** 078 * @see org.apache.wicket.markup.head.IHeaderResponse#wasRendered(java.lang.Object) 079 */ 080 @Override 081 public boolean wasRendered(Object object) 082 { 083 return rendered.contains(object); 084 } 085 086 /** 087 * @see org.apache.wicket.markup.head.IHeaderResponse#close() 088 */ 089 @Override 090 public void close() 091 { 092 closed = true; 093 } 094 095 /** 096 * @see org.apache.wicket.markup.head.IHeaderResponse#getResponse() 097 */ 098 @Override 099 public final Response getResponse() 100 { 101 return closed ? NullResponse.getInstance() : getRealResponse(); 102 } 103 104 /** 105 * @see org.apache.wicket.markup.head.IHeaderResponse#isClosed() 106 */ 107 @Override 108 public boolean isClosed() 109 { 110 return closed; 111 } 112 113 /** 114 * Once the HeaderResponse is closed, no output may be written to it anymore. To enforce that, 115 * the {@link #getResponse()} is defined final in this class and will return a NullResponse 116 * instance once closed or otherwise the Response provided by this method. 117 * 118 * @return Response 119 */ 120 protected abstract Response getRealResponse(); 121}