src/main/java/org/apache/ode/jacob/soup/jackson/ChannelProxyDeserializer.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.ode.jacob.soup.jackson;

import java.io.IOException;

import org.apache.ode.jacob.Channel;
import org.apache.ode.jacob.soup.CommChannel;
import org.apache.ode.jacob.vpu.ChannelFactory;

import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.core.JsonToken;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.deser.std.StdDeserializer;

/**
 * Jackson deserializer for Channels.
 * Creates ChannelProxy instances based on channel id and channel type.
 * 
 * @author Tammo van Lessen
 *
 */
public class ChannelProxyDeserializer extends StdDeserializer<Channel> {

    private static final long serialVersionUID = 1L;

    public ChannelProxyDeserializer() {
        super(Channel.class);
    }

    @Override
    public Channel deserialize(JsonParser jp, DeserializationContext ctxt)
            throws IOException, JsonProcessingException {

        String type = null;
        int id = -1;
        while (jp.nextToken() != JsonToken.END_OBJECT) {
            String fieldname = jp.getCurrentName();
            if (jp.getCurrentToken() == JsonToken.FIELD_NAME) {
                // if we're not already on the field, advance by one.
                jp.nextToken();
            }
            if ("channelType".equals(fieldname)) {
                type = jp.getText();
            } else if ("channelId".equals(fieldname)) {
                id = jp.getIntValue();
            } 
        }
        
        if (type == null) {
            throw ctxt.mappingException(Channel.class);
        }
        
        if (id < 0) {
            throw ctxt.mappingException(Channel.class);
        }

        
        try {
            CommChannel cchannel = new CommChannel(ctxt.findClass(type));
            cchannel.setId(id);
            return (Channel)ChannelFactory.createChannel(cchannel, cchannel.getType());

        } catch (ClassNotFoundException e) {
            throw ctxt.instantiationException(Channel.class, e);
        }
    }

}