001 /*
002 * Copyright 2001-2010 Stephen Colebourne
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016 package org.joda.beans;
017
018 import java.beans.IntrospectionException;
019 import java.beans.PropertyDescriptor;
020 import java.lang.reflect.InvocationTargetException;
021 import java.lang.reflect.Method;
022
023 /**
024 * A meta-property implemented using a {@code PropertyDescriptor}.
025 * <p>
026 * The property descriptor class is part of the JDK JavaBean standard.
027 * It provides access to get and set a property on a bean.
028 *
029 * @param <B> the type of the bean
030 * @param <P> the type of the property content
031 * @author Stephen Colebourne
032 */
033 public final class StandardMetaProperty<B, P> implements MetaProperty<B, P> {
034
035 /** The name of the property. */
036 private final String name;
037 /** The type of the property. */
038 private final Class<P> propertyClass;
039 /** The type of the bean. */
040 private final Class<B> beanClass;
041 /** The read method. */
042 private final Method readMethod;
043 /** The write method. */
044 private final Method writeMethod;
045
046 /**
047 * Factory to create a meta-property avoiding duplicate generics.
048 *
049 * @param beanType the bean type
050 * @param propertyName the property name
051 */
052 public static <B, P> StandardMetaProperty<B, P> of(Class<B> beanType, String propertyName) {
053 return new StandardMetaProperty<B, P>(beanType, propertyName);
054 }
055
056 /**
057 * Constructor using {@code PropertyDescriptor} to find the get and set methods.
058 *
059 * @param beanType the bean type, not null
060 * @param propertyName the property name, not null
061 */
062 @SuppressWarnings("unchecked")
063 private StandardMetaProperty(Class<B> beanType, String propertyName) {
064 PropertyDescriptor descriptor;
065 try {
066 descriptor = new PropertyDescriptor(propertyName, beanType);
067 } catch (IntrospectionException ex) {
068 throw new NoSuchFieldError("Invalid property: " + propertyName + ": " + ex.getMessage());
069 }
070 Method readMethod = descriptor.getReadMethod();
071 Method writeMethod = descriptor.getWriteMethod();
072 if (readMethod == null && writeMethod == null) {
073 throw new NoSuchFieldError("Invalid property: " + propertyName + ": Both read and write methods are missing");
074 }
075 this.name = descriptor.getName();
076 this.propertyClass = (Class<P>) descriptor.getPropertyType();
077 this.readMethod = readMethod;
078 this.writeMethod = writeMethod;
079 this.beanClass = beanType;
080 }
081
082 //-----------------------------------------------------------------------
083 @Override
084 public Property<B, P> createProperty(B bean) {
085 return StandardProperty.of(bean, this);
086 }
087
088 @Override
089 public String name() {
090 return name;
091 }
092
093 @Override
094 public Class<P> propertyClass() {
095 return propertyClass;
096 }
097
098 @Override
099 public Class<B> beanClass() {
100 return beanClass;
101 }
102
103 @Override
104 public ReadWriteProperty readWrite() {
105 return (readMethod == null ? ReadWriteProperty.WRITE_ONLY :
106 (writeMethod == null ? ReadWriteProperty.READ_ONLY : ReadWriteProperty.READ_WRITE));
107 }
108
109 //-----------------------------------------------------------------------
110 /**
111 * Gets the value of the bound property for the provided bean.
112 * <p>
113 * This is the equivalent to calling <code>getFoo()</code> on the bean itself.
114 * However some implementations of this interface may not require an actual get method.
115 *
116 * @param bean the bean to query, not null
117 * @return the value of the property on the bound bean
118 * @throws UnsupportedOperationException if the property is write-only
119 */
120 @SuppressWarnings("unchecked")
121 public P get(B bean) {
122 if (readWrite().isReadable() == false) {
123 throw new UnsupportedOperationException("Property cannot be read: " + name);
124 }
125 try {
126 return (P) readMethod.invoke(bean, (Object[]) null);
127 } catch (IllegalArgumentException ex) {
128 throw new UnsupportedOperationException("Property cannot be read: " + name, ex);
129 } catch (IllegalAccessException ex) {
130 throw new UnsupportedOperationException("Property cannot be read: " + name, ex);
131 } catch (InvocationTargetException ex) {
132 if (ex.getCause() instanceof RuntimeException) {
133 throw (RuntimeException) ex.getCause();
134 }
135 throw new RuntimeException(ex);
136 }
137 }
138
139 /**
140 * Sets the value of the bound property on the provided bean.
141 * <p>
142 * This is the equivalent to calling <code>setFoo()</code> on the bean itself.
143 * However some implementations of this interface may not require an actual set method.
144 *
145 * @param bean the bean to update, not null
146 * @param value the value to set into the property on the bound bean
147 * @throws UnsupportedOperationException if the property is read-only
148 */
149 public void set(B bean, P value) {
150 if (readWrite().isWritable() == false) {
151 throw new UnsupportedOperationException("Property cannot be written: " + name);
152 }
153 try {
154 writeMethod.invoke(bean, value);
155 } catch (IllegalArgumentException ex) {
156 if (value == null && writeMethod.getParameterTypes()[0].isPrimitive()) {
157 throw new NullPointerException("Property cannot be written: " + name + ": Cannot store null in primitive");
158 }
159 throw new UnsupportedOperationException("Property cannot be written: " + name, ex);
160 } catch (IllegalAccessException ex) {
161 throw new UnsupportedOperationException("Property cannot be written: " + name, ex);
162 } catch (InvocationTargetException ex) {
163 if (ex.getCause() instanceof RuntimeException) {
164 throw (RuntimeException) ex.getCause();
165 }
166 throw new RuntimeException(ex);
167 }
168 }
169
170 //-----------------------------------------------------------------------
171 /**
172 * Returns a string that summarizes the property.
173 *
174 * @return a summary string, never null
175 */
176 @Override
177 public String toString() {
178 return "MetaProperty:" + name;
179 }
180
181 }