001 // Copyright 2006, 2007, 2008, 2010, 2011 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.tapestry5.internal.transform;
016
017 import org.apache.tapestry5.annotations.Environmental;
018 import org.apache.tapestry5.internal.services.ComponentClassCache;
019 import org.apache.tapestry5.model.MutableComponentModel;
020 import org.apache.tapestry5.plastic.*;
021 import org.apache.tapestry5.services.Environment;
022 import org.apache.tapestry5.services.transform.ComponentClassTransformWorker2;
023 import org.apache.tapestry5.services.transform.TransformationSupport;
024
025 /**
026 * Obtains a value from the {@link Environment} service based on the field type. This is triggered by the presence of
027 * the {@link Environmental} annotation.
028 */
029 @SuppressWarnings("rawtypes")
030 public class EnvironmentalWorker implements ComponentClassTransformWorker2
031 {
032 private final Environment environment;
033
034 private final ComponentClassCache classCache;
035
036
037 @SuppressWarnings("unchecked")
038 private final class EnvironmentalConduit implements FieldConduit
039 {
040 private final String componentClassName;
041
042 private final String fieldName;
043
044 private final Class environmentalType;
045
046 private final boolean required;
047
048 private EnvironmentalConduit(String componentClassName, String fieldName, final Class environmentalType,
049 boolean required)
050 {
051 this.componentClassName = componentClassName;
052 this.fieldName = fieldName;
053 this.environmentalType = environmentalType;
054 this.required = required;
055 }
056
057 public Object get(Object instance, InstanceContext context)
058 {
059 return required ? environment.peekRequired(environmentalType) : environment.peek(environmentalType);
060 }
061
062 public void set(Object instance, InstanceContext context, Object newValue)
063 {
064 throw new RuntimeException(String.format("Field %s.%s is read only.", componentClassName, fieldName));
065 }
066 }
067
068 public EnvironmentalWorker(Environment environment, ComponentClassCache classCache)
069 {
070 this.environment = environment;
071
072 this.classCache = classCache;
073 }
074
075 public void transform(PlasticClass plasticClass, TransformationSupport support, MutableComponentModel model)
076 {
077 for (PlasticField field : plasticClass.getFieldsWithAnnotation(Environmental.class))
078 {
079 transform(model.getComponentClassName(), field);
080 }
081 }
082
083 private void transform(final String componentClassName, PlasticField field)
084 {
085 Environmental annotation = field.getAnnotation(Environmental.class);
086
087 field.claim(annotation);
088
089 final String fieldName = field.getName();
090
091 final Class fieldType = classCache.forName(field.getTypeName());
092
093 final boolean required = annotation.value();
094
095 ComputedValue<FieldConduit<Object>> provider = new ComputedValue<FieldConduit<Object>>()
096 {
097 public FieldConduit<Object> get(InstanceContext context)
098 {
099 return new EnvironmentalConduit(componentClassName, fieldName, fieldType, required);
100 }
101
102 public void set(Object instance, InstanceContext context, Object newValue)
103 {
104 throw new RuntimeException(
105 String.format("Field %s of component %s is read only.", fieldName, componentClassName));
106 }
107 };
108
109 field.setComputedConduit(provider);
110 }
111
112 }