001 /* 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, 013 * software distributed under the License is distributed on an 014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 015 * KIND, either express or implied. See the License for the 016 * specific language governing permissions and limitations 017 * under the License. 018 */ 019 020 // 021 // This source code implements specifications defined by the Java 022 // Community Process. In order to remain compliant with the specification 023 // DO NOT add / change / or delete method signatures! 024 // 025 026 package javax.servlet.jsp.el; 027 028 /** 029 * <p>This class is used to customize the way an ExpressionEvaluator resolves 030 * variable references at evaluation time. For example, instances of this class can 031 * implement their own variable lookup mechanisms, or introduce the 032 * notion of "implicit variables" which override any other variables. 033 * An instance of this class should be passed when evaluating 034 * an expression.</p> 035 * 036 * <p>An instance of this class includes the context against which resolution 037 * will happen</p> 038 * 039 * @since 2.0 040 */ 041 public interface VariableResolver 042 { 043 //------------------------------------- 044 /** 045 * Resolves the specified variable. 046 * Returns null if the variable is not found. 047 * 048 * @param pName the name of the variable to resolve 049 * @return the result of the variable resolution 050 * 051 * @throws ELException if a failure occurred while trying to resolve 052 * the given variable 053 **/ 054 public Object resolveVariable (String pName) 055 throws ELException; 056 057 //------------------------------------- 058 }