001 /** 002 * 003 * Copyright 2003-2004 The Apache Software Foundation 004 * 005 * Licensed under the Apache License, Version 2.0 (the "License"); 006 * you may not use this file except in compliance with the License. 007 * You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017 018 // 019 // This source code implements specifications defined by the Java 020 // Community Process. In order to remain compliant with the specification 021 // DO NOT add / change / or delete method signatures! 022 // 023 024 package javax.servlet.jsp.el; 025 026 /** 027 * <p>This class is used to customize the way an ExpressionEvaluator resolves 028 * variable references at evaluation time. For example, instances of this class can 029 * implement their own variable lookup mechanisms, or introduce the 030 * notion of "implicit variables" which override any other variables. 031 * An instance of this class should be passed when evaluating 032 * an expression.</p> 033 * 034 * <p>An instance of this class includes the context against which resolution 035 * will happen</p> 036 * 037 * @since 2.0 038 */ 039 public interface VariableResolver 040 { 041 //------------------------------------- 042 /** 043 * Resolves the specified variable. 044 * Returns null if the variable is not found. 045 * 046 * @param pName the name of the variable to resolve 047 * @return the result of the variable resolution 048 * 049 * @throws ELException if a failure occurred while trying to resolve 050 * the given variable 051 **/ 052 public Object resolveVariable (String pName) 053 throws ELException; 054 055 //------------------------------------- 056 }