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Java > Open Source Codes > org > apache > webapp > balancer > RulesParser


1 /*
2  * Copyright 2000,2004 The Apache Software Foundation.
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.apache.webapp.balancer;
17
18 import org.apache.tomcat.util.digester.Digester;
19
20 import java.io.InputStream JavaDoc;
21
22
23 /**
24  * The rules parser uses Digester
25  * to parse the rules definition
26  * file and return a RuleChain object.
27  *
28  * @author Yoav Shapira
29  */

30 public class RulesParser {
31     /**
32      * The resulting rule chain.
33      */

34     private RuleChain result;
35
36     /**
37      * Constructor.
38      *
39      * @param input To read the configuration
40      */

41     public RulesParser(InputStream JavaDoc input) {
42         try {
43             Digester digester = createDigester();
44             result = (RuleChain) digester.parse(input);
45         } catch (Exception JavaDoc e) {
46             throw new RuntimeException JavaDoc(e);
47         }
48     }
49
50     /**
51      * Returns the parsed rule chain.
52      *
53      * @return The resulting RuleChain
54      */

55     public RuleChain getResult() {
56         return result;
57     }
58
59     /**
60      * Creates the digester instance.
61      *
62      * @return Digester
63      */

64     protected Digester createDigester() {
65         Digester digester = new Digester();
66         digester.setUseContextClassLoader(true);
67
68         String JavaDoc rules = "rules";
69         String JavaDoc rule = "/rule";
70
71         // Construct rule chain
72
digester.addObjectCreate(rules, RuleChain.class);
73
74         // Construct rule
75
digester.addObjectCreate(rules + rule, null, "className");
76
77         // Set rule properties
78
digester.addSetProperties(rules + rule);
79
80         // Add rule to chain
81
digester.addSetNext(rules + rule, "addRule", "org.apache.webapp.balancer.Rule");
82
83         return digester;
84     }
85 }
86
87
88 // End of class: RulesParser.java
89
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