001// Copyright 2005 The Apache Software Foundation 002// 003// Licensed under the Apache License, Version 2.0 (the "License"); 004// you may not use this file except in compliance with the License. 005// You may obtain a copy of the License at 006// 007// http://www.apache.org/licenses/LICENSE-2.0 008// 009// Unless required by applicable law or agreed to in writing, software 010// distributed under the License is distributed on an "AS IS" BASIS, 011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 012// See the License for the specific language governing permissions and 013// limitations under the License. 014 015package org.apache.tapestry.record; 016 017import java.util.ArrayList; 018import java.util.HashMap; 019import java.util.Iterator; 020import java.util.List; 021import java.util.Map; 022 023import org.apache.hivemind.util.Defense; 024 025/** 026 * Stores persistent property changes concerning a single page. The data may be stored as an encoded 027 * string and the PPD can turn between encoded and object form. 028 * 029 * @author Howard M. Lewis Ship 030 * @since 4.0 031 */ 032public class PersistentPropertyData 033{ 034 /** 035 * Keyed on {@link org.apache.tapestry.record.ChangeKey}, values are new objects. 036 */ 037 038 private Map _changes; 039 040 private String _encoded; 041 042 private final PersistentPropertyDataEncoder _encoder; 043 044 /** 045 * Creates a new data using the specified encoder. The set of page changes is initially empty. 046 */ 047 048 public PersistentPropertyData(PersistentPropertyDataEncoder encoder) 049 { 050 Defense.notNull(encoder, "encoder"); 051 052 _encoder = encoder; 053 _changes = new HashMap(); 054 } 055 056 public String getEncoded() 057 { 058 if (_encoded == null) 059 _encoded = encode(); 060 061 return _encoded; 062 } 063 064 public List getPageChanges() 065 { 066 if (_changes == null) 067 { 068 List pageChanges = _encoder.decodePageChanges(_encoded); 069 070 _changes = decode(pageChanges); 071 072 return pageChanges; 073 } 074 075 return createPageChangeList(); 076 } 077 078 public void store(String componentPath, String propertyName, Object newValue) 079 { 080 Defense.notNull(propertyName, "propertyName"); 081 082 if (_changes == null) 083 _changes = decode(_encoder.decodePageChanges(_encoded)); 084 085 ChangeKey key = new ChangeKey(componentPath, propertyName); 086 087 _changes.put(key, newValue); 088 089 // With the new (or changed) value, the encoded string is no 090 // longer valid. 091 092 _encoded = null; 093 } 094 095 public void storeEncoded(String encoded) 096 { 097 Defense.notNull(encoded, "encoded"); 098 099 _encoded = encoded; 100 101 // The decoded data is no longer valid now. 102 103 _changes = null; 104 } 105 106 private List createPageChangeList() 107 { 108 List result = new ArrayList(); 109 110 Iterator i = _changes.entrySet().iterator(); 111 112 while (i.hasNext()) 113 { 114 Map.Entry me = (Map.Entry) i.next(); 115 116 ChangeKey changeKey = (ChangeKey) me.getKey(); 117 Object value = me.getValue(); 118 119 PropertyChange change = new PropertyChangeImpl(changeKey.getComponentPath(), changeKey 120 .getPropertyName(), value); 121 122 result.add(change); 123 } 124 125 return result; 126 } 127 128 private String encode() 129 { 130 List changes = createPageChangeList(); 131 132 return _encoder.encodePageChanges(changes); 133 } 134 135 private Map decode(List pageChanges) 136 { 137 Map result = new HashMap(); 138 139 Iterator i = pageChanges.iterator(); 140 while (i.hasNext()) 141 { 142 PropertyChange pc = (PropertyChange) i.next(); 143 144 String propertyName = pc.getPropertyName(); 145 String componentPath = pc.getComponentPath(); 146 147 ChangeKey key = new ChangeKey(componentPath, propertyName); 148 149 result.put(key, pc.getNewValue()); 150 } 151 152 return result; 153 } 154}