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Java > Open Source Codes > org > directwebremoting > AjaxFilter


1 /*
2  * Copyright 2005 Joe Walker
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 package org.directwebremoting;
17
18 import java.io.IOException JavaDoc;
19 import java.lang.reflect.Method JavaDoc;
20
21 /**
22  * A filter is a way to insert procesing tasks at various points during the
23  * processing of an Ajax call.
24  * <p>Example filters:</p>
25  * <ul>
26  * <li>Authentication</li>
27  * <li>Latency simulators</li>
28  * <li>Data cleansing - remove private data</li>
29  * <li>Logging filters - when you need specific logging action</li>
30  * </ul>
31  * @since DWR 2.0
32  * @author Joe Walker [joe at getahead dot ltd dot uk]
33  */
34 public interface AjaxFilter
35 {
36     /**
37      * The <code>doFilter</code> method of the AjaxFilter is called by DWR each
38      * time an Ajax request is made on a method that this filter is configured
39      * against. The <code>AjaxFilterChain<code> passed in to this method allows
40      * the filter to pass on method details to next entity in the chain.
41      * <p>Typically the method would do the following:</p>
42      * <ol>
43      * <li>Examine the request</li>
44      * <li>Optionally alter the method, object or parameters</li>
45      * <li>Either invoke the next entity in the chain using the AjaxFilterChain
46      * or decide to take some other action instead.</li>
47      * <li>Optionally modify the value returned to the user</li>
48      * <li>Take some other action (e.g. logging)</li>
49      * </ol>
50      * @param obj The object to execute the method on (i.e. 'this')
51      * @param method The method to execute
52      * @param params The parameters to the method call
53      * @param chain Allow the request to be passed on
54      * @return The results of the method execution
55      * @throws IOException When some I/O error occurs
56      * @throws Exception When some processing goes wrong
57      */
58     public Object JavaDoc doFilter(Object JavaDoc obj, Method JavaDoc method, Object JavaDoc[] params, AjaxFilterChain chain) throws Exception JavaDoc;
59 }
60
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