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. 014 015 package org.apache.tapestry.enhance; 016 017 import java.lang.reflect.Modifier; 018 019 import org.apache.hivemind.Location; 020 import org.apache.hivemind.service.BodyBuilder; 021 import org.apache.hivemind.service.ClassFabUtils; 022 import org.apache.hivemind.service.MethodSignature; 023 import org.apache.hivemind.util.Defense; 024 import org.apache.tapestry.engine.state.ApplicationStateManager; 025 import org.apache.tapestry.event.PageDetachListener; 026 import org.apache.tapestry.spec.InjectSpecification; 027 028 /** 029 * Worker for injecting application state objects as properties of the component. These properties 030 * are read/write and must be "live" (changes are propogated back into the 031 * {@link org.apache.tapestry.engine.state.ApplicationStateManager}). They should also cache in a 032 * local variable for efficiency, and clear out that variable at the end of the request. 033 * 034 * @author Howard M. Lewis Ship 035 * @since 4.0 036 */ 037 public class InjectStateWorker implements InjectEnhancementWorker 038 { 039 private ApplicationStateManager _applicationStateManager; 040 041 public void performEnhancement(EnhancementOperation op, InjectSpecification spec) 042 { 043 injectState(op, spec.getObject(), spec.getProperty(), spec.getLocation()); 044 } 045 046 void injectState(EnhancementOperation op, String objectName, String propertyName, 047 Location location) 048 { 049 Defense.notNull(op, "op"); 050 Defense.notNull(objectName, "objectName"); 051 Defense.notNull(propertyName, "propertyName"); 052 053 Class propertyType = EnhanceUtils.extractPropertyType(op, propertyName, null); 054 String fieldName = "_$" + propertyName; 055 056 // State properties are read/write 057 058 op.claimProperty(propertyName); 059 060 op.addField(fieldName, propertyType); 061 062 String managerField = op.addInjectedField( 063 "_$applicationStateManager", 064 ApplicationStateManager.class, 065 _applicationStateManager); 066 067 BodyBuilder builder = new BodyBuilder(); 068 069 // Accessor 070 071 builder.begin(); 072 builder.addln("if ({0} == null)", fieldName); 073 builder.addln(" {0} = ({1}) {2}.get(\"{3}\");", new Object[] 074 { fieldName, ClassFabUtils.getJavaClassName(propertyType), managerField, objectName }); 075 builder.addln("return {0};", fieldName); 076 builder.end(); 077 078 String methodName = op.getAccessorMethodName(propertyName); 079 080 MethodSignature sig = new MethodSignature(propertyType, methodName, null, null); 081 082 op.addMethod(Modifier.PUBLIC, sig, builder.toString(), location); 083 084 // Mutator 085 086 builder.clear(); 087 builder.begin(); 088 builder.addln("{0}.store(\"{1}\", $1);", managerField, objectName); 089 builder.addln("{0} = $1;", fieldName); 090 builder.end(); 091 092 sig = new MethodSignature(void.class, EnhanceUtils.createMutatorMethodName(propertyName), 093 new Class[] 094 { propertyType }, null); 095 096 op.addMethod(Modifier.PUBLIC, sig, builder.toString(), location); 097 098 // Extend pageDetached() to clean out the cached field value. 099 100 op.extendMethodImplementation( 101 PageDetachListener.class, 102 EnhanceUtils.PAGE_DETACHED_SIGNATURE, 103 fieldName + " = null;"); 104 } 105 106 public void setApplicationStateManager(ApplicationStateManager applicationStateManager) 107 { 108 _applicationStateManager = applicationStateManager; 109 } 110 }