View Javadoc

1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  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  package org.apache.mina.integration.ognl;
18  
19  import java.util.LinkedHashSet;
20  import java.util.Set;
21  
22  import ognl.Ognl;
23  import ognl.OgnlContext;
24  import ognl.OgnlException;
25  import ognl.TypeConverter;
26  
27  import org.apache.mina.core.session.IoSession;
28  
29  /**
30   * Finds {@link IoSession}s that match a boolean OGNL expression.
31   * 
32   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
33   */
34  public class IoSessionFinder {
35      
36      private final String query;
37      private final TypeConverter typeConverter = new PropertyTypeConverter();
38      private final Object expression;
39      
40      /**
41       * Creates a new instance with the specified OGNL expression that returns
42       * a boolean value (e.g. <tt>"id == 0x12345678"</tt>).
43       */
44      public IoSessionFinder(String query) {
45          if (query == null) {
46              throw new NullPointerException("query");
47          }
48          
49          query = query.trim();
50          if (query.length() == 0) {
51              throw new IllegalArgumentException("query is empty.");
52          }
53          
54          this.query = query;
55          try {
56              expression = Ognl.parseExpression(query);
57          } catch (OgnlException e) {
58              throw new IllegalArgumentException("query: " + query);
59          }
60      }
61      
62      /**
63       * Finds a {@link Set} of {@link IoSession}s that matches the query
64       * from the specified sessions and returns the matches.
65       * @throws OgnlException if failed to evaluate the OGNL expression
66       */
67      public Set<IoSession> find(Iterable<IoSession> sessions) throws OgnlException {
68          if (sessions == null) {
69              throw new NullPointerException("sessions");
70          }
71          
72          Set<IoSession> answer = new LinkedHashSet<IoSession>();
73          for (IoSession s: sessions) {
74              OgnlContext context = (OgnlContext) Ognl.createDefaultContext(s);
75              context.setTypeConverter(typeConverter);
76              context.put(AbstractPropertyAccessor.READ_ONLY_MODE, true);
77              context.put(AbstractPropertyAccessor.QUERY, query);
78              Object result = Ognl.getValue(expression, context, s);
79              if (result instanceof Boolean) {
80                  if (((Boolean) result).booleanValue()) {
81                      answer.add(s);
82                  }
83              } else {
84                  throw new OgnlException(
85                          "Query didn't return a boolean value: " + query);
86              }
87          }
88          
89          return answer;
90      }
91  }