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    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
    38      private final TypeConverter typeConverter = new PropertyTypeConverter();
    39
    40      private final Object expression;
    41
    42      /**
    43       * Creates a new instance with the specified OGNL expression that returns
    44       * a boolean value (e.g. <tt>"id == 0x12345678"</tt>).
    45       */
    46      public IoSessionFinder(String query) {
    47          if (query == null) {
    48              throw new IllegalArgumentException("query");
    49          }
    50
    51          query = query.trim();
    52          if (query.length() == 0) {
    53              throw new IllegalArgumentException("query is empty.");
    54          }
    55
    56          this.query = query;
    57          try {
    58              expression = Ognl.parseExpression(query);
    59          } catch (OgnlException e) {
    60              throw new IllegalArgumentException("query: " + query);
    61          }
    62      }
    63
    64      /**
    65       * Finds a {@link Set} of {@link IoSession}s that matches the query
    66       * from the specified sessions and returns the matches.
    67       * @throws OgnlException if failed to evaluate the OGNL expression
    68       */
    69      public Set<IoSession> find(Iterable<IoSession> sessions) throws OgnlException {
    70          if (sessions == null) {
    71              throw new IllegalArgumentException("sessions");
    72          }
    73
    74          Set<IoSession> answer = new LinkedHashSet<IoSession>();
    75          for (IoSession s : sessions) {
    76              OgnlContext context = (OgnlContext) Ognl.createDefaultContext(s);
    77              context.setTypeConverter(typeConverter);
    78              context.put(AbstractPropertyAccessor.READ_ONLY_MODE, true);
    79              context.put(AbstractPropertyAccessor.QUERY, query);
    80              Object result = Ognl.getValue(expression, context, s);
    81              if (result instanceof Boolean) {
    82                  if (((Boolean) result).booleanValue()) {
    83                      answer.add(s);
    84                  }
    85              } else {
    86                  throw new OgnlException("Query didn't return a boolean value: " + query);
    87              }
    88          }
    89
    90          return answer;
    91      }
    92  }