acromusashi.stream.example.spout.JsonExtractor.java Source code

Introduction

Here is the source code for acromusashi.stream.example.spout.JsonExtractor.java

Source

/**
* Copyright (c) Acroquest Technology Co, Ltd. All Rights Reserved.
* Please read the associated COPYRIGHTS file for more details.
*
* THE SOFTWARE IS PROVIDED BY Acroquest Technolog Co., Ltd.,
* WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
* BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDER BE LIABLE FOR ANY
* CLAIM, DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING
* OR DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
*/
package acromusashi.stream.example.spout;

import java.io.IOException;

import acromusashi.stream.component.rabbitmq.RabbitmqCommunicateException;
import acromusashi.stream.component.rabbitmq.spout.MessageKeyExtractor;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;

/**
 * JSON???<br>
 * JSON?"header"????JSON?"messageKey"?????
 * 
 * @author acromusashi
 */
public class JsonExtractor implements MessageKeyExtractor {
    /** serialVersionUID */
    private static final long serialVersionUID = -1L;

    /**  */
    private static final String PARENT_KEY = "header";

    /** ? */
    private static final String CHILD_KEY = "messageKey";

    /** Json?? */
    protected transient ObjectMapper mapper;

    /**
     * ?????
     */
    public JsonExtractor() {
        // Do nothing.
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public String extractMessageKey(Object target) throws RabbitmqCommunicateException {
        // ObjectMapper???????????????
        if (this.mapper == null) {
            this.mapper = new ObjectMapper();
        }

        JsonNode rootJson;
        try {
            // JsonNode???JsonNode_A
            rootJson = this.mapper.readTree(target.toString());
        } catch (IOException ex) {
            throw new RabbitmqCommunicateException(ex);
        }

        // JsonNode_A?????JsonNode_B
        JsonNode parentJson = rootJson.get(PARENT_KEY);
        if (parentJson == null) {
            String message = "Parent Value is not exist.";
            throw new RabbitmqCommunicateException(message);
        }

        // JsonNode_B??????
        JsonNode childJson = parentJson.get(CHILD_KEY);
        if (childJson == null) {
            String message = "Child Value is not exist.";
            throw new RabbitmqCommunicateException(message);
        }

        return childJson.textValue();
    }
}