1 package org.apache.commons.ognl;
2
3 /*
4 * Licensed to the Apache Software Foundation (ASF) under one
5 * or more contributor license agreements. See the NOTICE file
6 * distributed with this work for additional information
7 * regarding copyright ownership. The ASF licenses this file
8 * to you under the Apache License, Version 2.0 (the
9 * "License"); you may not use this file except in compliance
10 * with the License. You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing,
15 * software distributed under the License is distributed on an
16 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17 * KIND, either express or implied. See the License for the
18 * specific language governing permissions and limitations
19 * under the License.
20 */
21
22 import java.util.Map;
23
24 /**
25 * This interface defines methods for setting and getting a property from a target object. A "property" in this case is
26 * a named data value that takes the generic form of an Object---the same definition as is used by beans. But the
27 * operational semantics of the term will vary by implementation of this interface: a bean-style implementation will get
28 * and set properties as beans do, by reflection on the target object's class, but other implementations are possible,
29 * such as one that uses the property name as a key into a map.
30 * <p>
31 * An implementation of this interface will often require that its target objects all be of some particular type. For
32 * example, the MapPropertyAccessor class requires that its targets all implement the java.util.Map interface.
33 * <p>
34 * Note that the "name" of a property is represented by a generic Object. Some implementations may require properties'
35 * names to be Strings, while others may allow them to be other types---for example, ArrayPropertyAccessor treats Number
36 * names as indexes into the target object, which must be an array.
37 *
38 * @author Luke Blanshard (blanshlu@netscape.net)
39 * @author Drew Davidson (drew@ognl.org)
40 */
41 public interface PropertyAccessor
42 {
43
44 /**
45 * Extracts and returns the property of the given name from the given target object.
46 *
47 * @param context The current execution context.
48 * @param target the object to get the property from
49 * @param name the name of the property to get.
50 * @return the current value of the given property in the given object
51 * @exception OgnlException if there is an error locating the property in the given object
52 */
53 Object getProperty( Map<String, Object> context, Object target, Object name )
54 throws OgnlException;
55
56 /**
57 * Sets the value of the property of the given name in the given target object.
58 *
59 * @param context The current execution context.
60 * @param target the object to set the property in
61 * @param name the name of the property to set
62 * @param value the new value for the property.
63 * @exception OgnlException if there is an error setting the property in the given object
64 */
65 void setProperty( Map<String, Object> context, Object target, Object name, Object value )
66 throws OgnlException;
67
68 /**
69 * Returns a java string representing the textual method that should be called to access a particular element. (ie
70 * "get")
71 *
72 * @param context The current execution context.
73 * @param target The current object target on the expression tree being evaluated.
74 * @param index The index object that will be placed inside the string to access the value.
75 * @return The source accessor method to call.
76 */
77 String getSourceAccessor( OgnlContext context, Object target, Object index );
78
79 /**
80 * Returns a java string representing the textual method that should be called to set a particular element. (ie
81 * "set")
82 *
83 * @param context The current execution context.
84 * @param target The current object target on the expression tree being evaluated.
85 * @param index The index object that will be placed inside the string to set the value.
86 * @return The source setter method to call.
87 */
88 String getSourceSetter( OgnlContext context, Object target, Object index );
89 }