1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.betwixt.expression;
18
19 import java.lang.reflect.Array;
20 import java.util.Collection;
21
22 import org.apache.commons.logging.Log;
23 import org.apache.commons.logging.LogFactory;
24
25 /**
26 * Abstracts common features for strongly typed <code>Updater</code>'s.
27 * Strongly type <code>Updater</code>'s perform conversions based on this
28 * the expected type before the bean update is invoked.
29 * @since 0.7
30 * @author <a href='http://commons.apache.org'>Apache Commons Team</a>, <a href='http://www.apache.org'>Apache Software Foundation</a>
31 */
32 public abstract class TypedUpdater implements Updater {
33
34 /** Logger */
35 private static final Log log = LogFactory.getLog( TypedUpdater.class );
36
37
38 /** The type of the first parameter of the method */
39 private Class valueType;
40
41 /**
42 * Updates the current bean context with the given String value
43 * @param context the Context to be updated
44 * @param newValue the update to this new value
45 */
46 public void update(Context context, Object newValue) {
47 Object bean = context.getBean();
48 if ( bean != null ) {
49 if ( newValue instanceof String ) {
50 // try to convert into primitive types
51 if ( log.isTraceEnabled() ) {
52 log.trace("Converting primitive to " + valueType);
53 }
54 newValue = context.getObjectStringConverter()
55 .stringToObject( (String) newValue, valueType, context );
56 }
57 if ( newValue != null ) {
58 // check that it is of the correct type
59 /*
60 if ( ! valueType.isAssignableFrom( newValue.getClass() ) ) {
61 log.warn(
62 "Cannot call setter method: " + method.getName() + " on bean: " + bean
63 + " with type: " + bean.getClass().getName()
64 + " as parameter should be of type: " + valueType.getName()
65 + " but is: " + newValue.getClass().getName()
66 );
67 return;
68 }
69 */
70 }
71 // special case for collection objects into arrays
72 if (newValue instanceof Collection && valueType.isArray()) {
73 Collection valuesAsCollection = (Collection) newValue;
74 Class componentType = valueType.getComponentType();
75 if (componentType != null) {
76 Object[] valuesAsArray =
77 (Object[]) Array.newInstance(componentType, valuesAsCollection.size());
78 newValue = valuesAsCollection.toArray(valuesAsArray);
79 }
80 }
81
82 ;
83 try {
84 executeUpdate( context, bean, newValue );
85
86 } catch (Exception e) {
87 String valueTypeName = (newValue != null) ? newValue.getClass().getName() : "null";
88 log.warn(
89 "Cannot evaluate: " + this.toString() + " on bean: " + bean
90 + " of type: " + bean.getClass().getName() + " with value: " + newValue
91 + " of type: " + valueTypeName
92 );
93 handleException(context, e);
94 }
95 }
96 }
97
98
99
100 /**
101 * Gets the type expected.
102 * The value passed into {@link #update}
103 * will be converted on the basis of this type
104 * before being passed to {@link #executeUpdate}.
105 * @return <code>Class</code> giving expected type, not null
106 */
107 public Class getValueType() {
108 return valueType;
109 }
110
111 /**
112 * Sets the type expected.
113 * The value passed into {@link #update}
114 * will be converted on the basis of this type
115 * before being passed to {@link #executeUpdate}.
116 * @param valueType <code>Class</code> giving expected type, not null
117 */
118 public void setValueType(Class valueType) {
119 this.valueType = valueType;
120 }
121
122 /**
123 * Updates the bean with the given value.
124 * @param bean
125 * @param value value after type conversion
126 */
127 protected abstract void executeUpdate(Context context, Object bean, Object value) throws Exception;
128
129 /**
130 * Strategy method to allow derivations to handle exceptions differently.
131 * @param context the Context being updated when this exception occured
132 * @param e the Exception that occured during the update
133 */
134 protected void handleException(Context context, Exception e) {
135 log.info( "Caught exception: " + e, e );
136 }
137
138 }