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  ;
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   input) {
42          try {
43              Digester digester = createDigester();
44              result = (RuleChain) digester.parse(input);
45          } catch (Exception   e) {
46              throw new RuntimeException  (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   rules = "rules";
69          String   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
A to Z: JavaDoc & Examples Daily Java News & Articles Open Source Projects Open Source Codes Free Computer Books Remove Frame
Popular Tags