001 package org.apache.commons.ognl;
002
003 /*
004 * Licensed to the Apache Software Foundation (ASF) under one
005 * or more contributor license agreements. See the NOTICE file
006 * distributed with this work for additional information
007 * regarding copyright ownership. The ASF licenses this file
008 * to you under the Apache License, Version 2.0 (the
009 * "License"); you may not use this file except in compliance
010 * with the License. You may obtain a copy of the License at
011 *
012 * http://www.apache.org/licenses/LICENSE-2.0
013 *
014 * Unless required by applicable law or agreed to in writing,
015 * software distributed under the License is distributed on an
016 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
017 * KIND, either express or implied. See the License for the
018 * specific language governing permissions and limitations
019 * under the License.
020 */
021
022 import java.util.Map;
023
024 /**
025 * This interface defines methods for setting and getting a property from a target object. A "property" in this case is
026 * a named data value that takes the generic form of an Object---the same definition as is used by beans. But the
027 * operational semantics of the term will vary by implementation of this interface: a bean-style implementation will get
028 * and set properties as beans do, by reflection on the target object's class, but other implementations are possible,
029 * such as one that uses the property name as a key into a map.
030 * <p>
031 * An implementation of this interface will often require that its target objects all be of some particular type. For
032 * example, the MapPropertyAccessor class requires that its targets all implement the java.util.Map interface.
033 * <p>
034 * Note that the "name" of a property is represented by a generic Object. Some implementations may require properties'
035 * names to be Strings, while others may allow them to be other types---for example, ArrayPropertyAccessor treats Number
036 * names as indexes into the target object, which must be an array.
037 *
038 * @author Luke Blanshard (blanshlu@netscape.net)
039 * @author Drew Davidson (drew@ognl.org)
040 */
041 public interface PropertyAccessor
042 {
043
044 /**
045 * Extracts and returns the property of the given name from the given target object.
046 *
047 * @param context The current execution context.
048 * @param target the object to get the property from
049 * @param name the name of the property to get.
050 * @return the current value of the given property in the given object
051 * @exception OgnlException if there is an error locating the property in the given object
052 */
053 Object getProperty( Map<String, Object> context, Object target, Object name )
054 throws OgnlException;
055
056 /**
057 * Sets the value of the property of the given name in the given target object.
058 *
059 * @param context The current execution context.
060 * @param target the object to set the property in
061 * @param name the name of the property to set
062 * @param value the new value for the property.
063 * @exception OgnlException if there is an error setting the property in the given object
064 */
065 void setProperty( Map<String, Object> context, Object target, Object name, Object value )
066 throws OgnlException;
067
068 /**
069 * Returns a java string representing the textual method that should be called to access a particular element. (ie
070 * "get")
071 *
072 * @param context The current execution context.
073 * @param target The current object target on the expression tree being evaluated.
074 * @param index The index object that will be placed inside the string to access the value.
075 * @return The source accessor method to call.
076 */
077 String getSourceAccessor( OgnlContext context, Object target, Object index );
078
079 /**
080 * Returns a java string representing the textual method that should be called to set a particular element. (ie
081 * "set")
082 *
083 * @param context The current execution context.
084 * @param target The current object target on the expression tree being evaluated.
085 * @param index The index object that will be placed inside the string to set the value.
086 * @return The source setter method to call.
087 */
088 String getSourceSetter( OgnlContext context, Object target, Object index );
089 }