ObjectStringConverter


1   /*
2    * Copyright 2001-2004 The Apache Software Foundation.
3    * 
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    * 
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    * 
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */ 
16  package org.apache.commons.betwixt.strategy;
17  
18  import java.io.Serializable  ;
19  
20  import org.apache.commons.betwixt.expression.Context;
21  
22  /** 
23   * <p>Strategy class for string &lt;-&gt; object conversions.
24   * Implementations of this interface are used by Betwixt to perform
25   * string &lt;-&gt; object conversions.
26   * This performs only the most basic conversions.
27   * Most applications will use a subclass.
28   * </p>
29   * <p>It is strongly recommended that (in order to support round tripping)
30   * that <code>objectToString</code> and <code>stringToObject</code>
31   * are inverse functions.
32   * In other words, given the same flavour, context and type the applying 
33   * objectToString to the result of stringToObject should be equal to the 
34   * original input.
35   * </p>
36   * @author Robert Burrell Donkin 
37   * @since 0.5
38   */
39  public class ObjectStringConverter implements Serializable   {
40      
41      /**
42        * Converts an object to a string representation.
43        * This basic implementation returns object.toString() 
44        * or an empty string if the given object is null.
45        *
46        * @param object the object to be converted, possibly null
47        * @param type the property class of the object, not null
48        * @param flavour a string allow symantic differences in formatting to be communicated
49        * @param context the context, not null
50        * @return a String representation, not null
51        */
52      public String   objectToString(Object   object, Class   type, String   flavour, Context context) {
53          if ( object != null ) {
54              return object.toString();
55          } 
56          return "";
57      }
58      
59      /**
60        * Converts a string representation to an object.
61        * It is acceptable for an implementation to return the string if it cannot convert 
62        * the string to the given class type.
63        * This basic implementation just returns a string.
64        * 
65        * @param value the String to be converted
66        * @param type the property class to be returned (if possible), not null
67        * @param flavour a string allow symantic differences in formatting to be communicated
68        * @param context the context, not null
69        * @return an Object converted from the String, not null
70        */
71      public Object   stringToObject(String   value, Class   type, String   flavour, Context context) {
72          return value;
73      }
74  }
75
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