1 /**
2 *
3 * Copyright 2003-2004 The Apache Software Foundation
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 //
19 // This source code implements specifications defined by the Java
20 // Community Process. In order to remain compliant with the specification
21 // DO NOT add / change / or delete method signatures!
22 //
23
24 package javax.servlet.jsp.tagext;
25
26
27
28 /**
29 * The auxiliary interface of a Tag, IterationTag or BodyTag tag
30 * handler that wants additional hooks for managing resources.
31 *
32 * <p>This interface provides two new methods: doCatch(Throwable)
33 * and doFinally(). The prototypical invocation is as follows:
34 *
35 * <pre>
36 * h = get a Tag(); // get a tag handler, perhaps from pool
37 *
38 * h.setPageContext(pc); // initialize as desired
39 * h.setParent(null);
40 * h.setFoo("foo");
41 *
42 * // tag invocation protocol; see Tag.java
43 * try {
44 * doStartTag()...
45 * ....
46 * doEndTag()...
47 * } catch (Throwable t) {
48 * // react to exceptional condition
49 * h.doCatch(t);
50 * } finally {
51 * // restore data invariants and release per-invocation resources
52 * h.doFinally();
53 * }
54 *
55 * ... other invocations perhaps with some new setters
56 * ...
57 * h.release(); // release long-term resources
58 * </pre>
59 */
60
61 public interface TryCatchFinally {
62
63 /**
64 * Invoked if a Throwable occurs while evaluating the BODY
65 * inside a tag or in any of the following methods:
66 * Tag.doStartTag(), Tag.doEndTag(),
67 * IterationTag.doAfterBody() and BodyTag.doInitBody().
68 *
69 * <p>This method is not invoked if the Throwable occurs during
70 * one of the setter methods.
71 *
72 * <p>This method may throw an exception (the same or a new one)
73 * that will be propagated further up the nest chain. If an exception
74 * is thrown, doFinally() will be invoked.
75 *
76 * <p>This method is intended to be used to respond to an exceptional
77 * condition.
78 *
79 * @param t The throwable exception navigating through this tag.
80 * @throws Throwable if the exception is to be rethrown further up
81 * the nest chain.
82 */
83
84 void doCatch(Throwable t) throws Throwable;
85
86 /**
87 * Invoked in all cases after doEndTag() for any class implementing
88 * Tag, IterationTag or BodyTag. This method is invoked even if
89 * an exception has occurred in the BODY of the tag,
90 * or in any of the following methods:
91 * Tag.doStartTag(), Tag.doEndTag(),
92 * IterationTag.doAfterBody() and BodyTag.doInitBody().
93 *
94 * <p>This method is not invoked if the Throwable occurs during
95 * one of the setter methods.
96 *
97 * <p>This method should not throw an Exception.
98 *
99 * <p>This method is intended to maintain per-invocation data
100 * integrity and resource management actions.
101 */
102
103 void doFinally();
104 }