org.springframework.kafka.support.converter.StringJsonMessageConverter.java Source code

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Here is the source code for org.springframework.kafka.support.converter.StringJsonMessageConverter.java

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/*
 * Copyright 2016 the original author or authors.
 *
 * Licensed 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.springframework.kafka.support.converter;

import java.io.IOException;
import java.lang.reflect.Type;

import org.apache.kafka.clients.consumer.ConsumerRecord;

import org.springframework.messaging.Message;
import org.springframework.util.Assert;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.MapperFeature;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.type.TypeFactory;

/**
 * JSON Message converter - String on output, String or byte[] on input.
 *
 * @author Gary Russell
 * @author Artem Bilan
 *
 */
public class StringJsonMessageConverter extends MessagingMessageConverter {

    private final ObjectMapper objectMapper;

    public StringJsonMessageConverter() {
        this(new ObjectMapper());
        this.objectMapper.configure(MapperFeature.DEFAULT_VIEW_INCLUSION, false);
        this.objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
    }

    public StringJsonMessageConverter(ObjectMapper objectMapper) {
        Assert.notNull(objectMapper, "'objectMapper' must not be null.");
        this.objectMapper = objectMapper;
    }

    @Override
    protected Object convertPayload(Message<?> message) {
        try {
            return this.objectMapper.writeValueAsString(message.getPayload());
        } catch (JsonProcessingException e) {
            throw new ConversionException("Failed to convert to JSON", e);
        }
    }

    @Override
    protected Object extractAndConvertValue(ConsumerRecord<?, ?> record, Type type) {
        JavaType javaType = TypeFactory.defaultInstance().constructType(type);
        Object value = record.value();
        if (value instanceof String) {
            try {
                return this.objectMapper.readValue((String) value, javaType);
            } catch (IOException e) {
                throw new ConversionException("Failed to convert from JSON", e);
            }
        } else if (value instanceof byte[]) {
            try {
                return this.objectMapper.readValue((byte[]) value, javaType);
            } catch (IOException e) {
                throw new ConversionException("Failed to convert from JSON", e);
            }
        } else {
            throw new IllegalStateException("Only String or byte[] supported");
        }
    }

}