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The MyBatis SQL mapper framework makes it easier to use a relational database with object-oriented applications. MyBatis couples objects with stored procedures or SQL statements using a XML descriptor or annotations. Simplicity is the biggest advantage of the MyBatis data mapper over object relational mapping tools.

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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.ibatis.ognl;

import java.beans.IntrospectionException;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Method;

/**
 * PropertyDescriptor subclass that describes an indexed set of read/write
 * methods to get a property. Unlike IndexedPropertyDescriptor this allows
 * the "key" to be an arbitrary object rather than just an int.  Consequently
 * it does not have a "readMethod" or "writeMethod" because it only expects
 * a pattern like:
 *  *    public void setProperty(KeyType, ValueType);
 *    public ValueType getProperty(KeyType);
 * 
 * and does not require the methods that access it as an array.  OGNL can
 * get away with this without losing functionality because if the object
 * does expose the properties they are most probably in a Map and that case
 * is handled by the normal OGNL property accessors.
 * 
 * For example, if an object were to have methods that accessed and "attributes"
 * property it would be natural to index them by String rather than by integer
 * and expose the attributes as a map with a different property name:
 * 
 *    public void setAttribute(String name, Object value);
 *    public Object getAttribute(String name);
 *    public Map getAttributes();
 * 
 * Note that the index get/set is called get/set Attribute
 * whereas the collection getter is called Attributes.  This
 * case is handled unambiguously by the OGNL property accessors because the
 * set/getAttribute methods are detected by this object and the
 * "attributes" case is handled by the MapPropertyAccessor.
 * Therefore OGNL expressions calling this code would be handled in the
 * following way:
 * 
 * 
 *  
 *  
 *      
 *  
 *  
 *      
 *      
 *  
 *  
 *      
 *      
 *  
 *  
 *      
 *      
 *  
 *  
 *      
 *      
 *  
 * OGNL ExpressionOGNL Expression Handling
attribute["name"] Handled by an index getter, like getAttribute(String).
attribute["name"] = value Handled by an index setter, like setAttribute(String, Object).
attributes["name"] Handled by MapPropertyAccessor via a Map.get().  This
 *          will not go through the index get accessor.
 *      
attributes["name"] = value Handled by MapPropertyAccessor via a Map.put().  This
 *          will not go through the index set accessor.
 *      
 */
public class ObjectIndexedPropertyDescriptor extends PropertyDescriptor {

    private final Method indexedReadMethod;
    private final Method indexedWriteMethod;
    private final Class propertyType;

    public ObjectIndexedPropertyDescriptor(String propertyName, Class propertyType, Method indexedReadMethod, Method indexedWriteMethod) throws IntrospectionException {
        super(propertyName, null, null);
        this.propertyType = propertyType;
        this.indexedReadMethod = indexedReadMethod;
        this.indexedWriteMethod = indexedWriteMethod;
    }

    public Method getIndexedReadMethod() {
        return indexedReadMethod;
    }

    public Method getIndexedWriteMethod() {
        return indexedWriteMethod;
    }

    public synchronized Class getPropertyType() {
        return propertyType;
    }
}

OGNL Expression	Handling
`attribute["name"]`	Handled by an index getter, like `getAttribute(String)`.
`attribute["name"] = value`	Handled by an index setter, like `setAttribute(String, Object)`.
`attributes["name"]`	Handled by `MapPropertyAccessor` via a `Map.get()`. This * will not go through the index get accessor. *
`attributes["name"] = value`	Handled by `MapPropertyAccessor` via a `Map.put()`. This * will not go through the index set accessor. *