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.tagext; 027 028 029 030 /** 031 * The auxiliary interface of a Tag, IterationTag or BodyTag tag 032 * handler that wants additional hooks for managing resources. 033 * 034 * <p>This interface provides two new methods: doCatch(Throwable) 035 * and doFinally(). The prototypical invocation is as follows: 036 * 037 * <pre> 038 * h = get a Tag(); // get a tag handler, perhaps from pool 039 * 040 * h.setPageContext(pc); // initialize as desired 041 * h.setParent(null); 042 * h.setFoo("foo"); 043 * 044 * // tag invocation protocol; see Tag.java 045 * try { 046 * doStartTag()... 047 * .... 048 * doEndTag()... 049 * } catch (Throwable t) { 050 * // react to exceptional condition 051 * h.doCatch(t); 052 * } finally { 053 * // restore data invariants and release per-invocation resources 054 * h.doFinally(); 055 * } 056 * 057 * ... other invocations perhaps with some new setters 058 * ... 059 * h.release(); // release long-term resources 060 * </pre> 061 */ 062 063 public interface TryCatchFinally { 064 065 /** 066 * Invoked if a Throwable occurs while evaluating the BODY 067 * inside a tag or in any of the following methods: 068 * Tag.doStartTag(), Tag.doEndTag(), 069 * IterationTag.doAfterBody() and BodyTag.doInitBody(). 070 * 071 * <p>This method is not invoked if the Throwable occurs during 072 * one of the setter methods. 073 * 074 * <p>This method may throw an exception (the same or a new one) 075 * that will be propagated further up the nest chain. If an exception 076 * is thrown, doFinally() will be invoked. 077 * 078 * <p>This method is intended to be used to respond to an exceptional 079 * condition. 080 * 081 * @param t The throwable exception navigating through this tag. 082 * @throws Throwable if the exception is to be rethrown further up 083 * the nest chain. 084 */ 085 086 void doCatch(Throwable t) throws Throwable; 087 088 /** 089 * Invoked in all cases after doEndTag() for any class implementing 090 * Tag, IterationTag or BodyTag. This method is invoked even if 091 * an exception has occurred in the BODY of the tag, 092 * or in any of the following methods: 093 * Tag.doStartTag(), Tag.doEndTag(), 094 * IterationTag.doAfterBody() and BodyTag.doInitBody(). 095 * 096 * <p>This method is not invoked if the Throwable occurs during 097 * one of the setter methods. 098 * 099 * <p>This method should not throw an Exception. 100 * 101 * <p>This method is intended to maintain per-invocation data 102 * integrity and resource management actions. 103 */ 104 105 void doFinally(); 106 }