001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 * 
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 * 
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.mina.integration.ognl;
018
019import java.util.LinkedHashSet;
020import java.util.Set;
021
022import ognl.Ognl;
023import ognl.OgnlContext;
024import ognl.OgnlException;
025import ognl.TypeConverter;
026
027import org.apache.mina.core.session.IoSession;
028
029/**
030 * Finds {@link IoSession}s that match a boolean OGNL expression.
031 * 
032 * @author <a href="http://mina.apache.org">Apache MINA Project</a>
033 */
034public class IoSessionFinder {
035
036    private final String query;
037
038    private final TypeConverter typeConverter = new PropertyTypeConverter();
039
040    private final Object expression;
041
042    /**
043     * Creates a new instance with the specified OGNL expression that returns
044     * a boolean value (e.g. <tt>"id == 0x12345678"</tt>).
045     */
046    public IoSessionFinder(String query) {
047        if (query == null) {
048            throw new IllegalArgumentException("query");
049        }
050
051        query = query.trim();
052        if (query.length() == 0) {
053            throw new IllegalArgumentException("query is empty.");
054        }
055
056        this.query = query;
057        try {
058            expression = Ognl.parseExpression(query);
059        } catch (OgnlException e) {
060            throw new IllegalArgumentException("query: " + query);
061        }
062    }
063
064    /**
065     * Finds a {@link Set} of {@link IoSession}s that matches the query
066     * from the specified sessions and returns the matches.
067     * @throws OgnlException if failed to evaluate the OGNL expression
068     */
069    public Set<IoSession> find(Iterable<IoSession> sessions) throws OgnlException {
070        if (sessions == null) {
071            throw new IllegalArgumentException("sessions");
072        }
073
074        Set<IoSession> answer = new LinkedHashSet<IoSession>();
075        for (IoSession s : sessions) {
076            OgnlContext context = (OgnlContext) Ognl.createDefaultContext(s);
077            context.setTypeConverter(typeConverter);
078            context.put(AbstractPropertyAccessor.READ_ONLY_MODE, true);
079            context.put(AbstractPropertyAccessor.QUERY, query);
080            Object result = Ognl.getValue(expression, context, s);
081            if (result instanceof Boolean) {
082                if (((Boolean) result).booleanValue()) {
083                    answer.add(s);
084                }
085            } else {
086                throw new OgnlException("Query didn't return a boolean value: " + query);
087            }
088        }
089
090        return answer;
091    }
092}