PropertyResolver.java

/*
 * Copyright 2004,2006 The Apache Software Foundation.
 * 
 * Licensed 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 javax.faces.el;

/**
 * Provides methods to read, write and inspect properties of javabeans, Maps,
 * Arrays and Lists. This class is used by such things as the ValueBinding
 * implementation and the ManagedBeanBuilder to access JSF beans.
 *
 * See the javadoc of the <a href="http://java.sun.com/j2ee/javaserverfaces/1.1_01/docs/api/index.html">JSF Specification</a>
 * for more details.
 *
 * @author Thomas Spiegl (latest modification by $Author$)
 * @version $Revision$ $Date$
 */
public abstract class PropertyResolver
{

    public PropertyResolver()
    {
    }
    
    /**
     * Returns the datatype of the specified element within a list or array.
     * <p>
     * Param base must be of type Array or List.
     */
    public abstract Class getType(Object base, int index)
        throws EvaluationException, PropertyNotFoundException;

    /**
     * Returns the datatype of the specified javabean property on the
     * specified object.
     * <p>
     * Param base may be a map, in which case param property is used
     * as a key into the map, and the type of the object with that key
     * is returned. If there is no such key in the map, then Object.class
     * is returned.
     * <p>
     * Otherwise java.beans.Introspector is used to determine the actual
     * property type. If the base bean has no such property then a
     * PropertyNotFoundException is thrown.
     * 
     * @param base must not be null.
     * @param property must be of type String, must not be null and
     *  must not be an empty string.
     */
    public abstract Class getType(Object base, java.lang.Object property)
        throws EvaluationException, PropertyNotFoundException;

    /**
     * Return the specified element from a list or array.
     * <p>
     * Param base must be of type Array or List. When the array is of a
     * primitive type, the appropriate wrapper is returned.
     * <p>
     * Null is returned when param index is "out of bounds" for the provided
     * base object.
     *  
     * @throws ReferenceSyntaxException if the base object is not an Array
     * or List.
     */
    public abstract Object getValue(Object base, int index)
        throws EvaluationException, PropertyNotFoundException;

    /**
     * Return the current value of the specified property on the base
     * object.
     * <p>
     * If base is a Map, then Map.get(property) is returned. Null is
     * returned if there is no entry with that key.
     * <p>
     * Otherwise, java.beans.Introspector is applied to the base object
     * to find the associated PropertyDescriptor and the specified
     * read method is invoked.
     * 
     * @throws PropertyNotFoundException if the provided object does
     * not have the specified property.
     */
    public abstract Object getValue(Object base, java.lang.Object property)
        throws EvaluationException, PropertyNotFoundException;

    public abstract boolean isReadOnly(Object base, int index)
        throws EvaluationException, PropertyNotFoundException;

    public abstract boolean isReadOnly(Object base, java.lang.Object property)
        throws EvaluationException, PropertyNotFoundException;

    /**
     * Replace the object at the specified index within the base collection
     * with the provided value.
     * <p>
     * Param base is expected to be an Array or List object.
     * 
     * @throws EvaluationException if the base object is not an Array or List.
     * @throws PropertyNotFoundException if the index is "out of bounds".
     */
    public abstract void setValue(Object base, int index, java.lang.Object value)
        throws EvaluationException, PropertyNotFoundException;

    /**
     * Set the named property on the base object to the provided value.
     */
    public abstract void setValue(Object base, Object property, java.lang.Object value)
        throws EvaluationException, PropertyNotFoundException;
}