SpringMVC之自定義json轉換器

package com.zns.converter;

import java.io.IOException;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializerProvider;
import com.fasterxml.jackson.databind.module.SimpleModule;
import com.fasterxml.jackson.databind.ser.std.ToStringSerializer;

/**
 * 自定義轉換器
 */
public class CustomJsonConverter extends ObjectMapper {
    public CustomJsonConverter(){
        SimpleModule simpleModule = new SimpleModule();
        // 解決Long類型序列化，響應至前端JavaScript接收時的精度缺失問題
        // 解決方法：序列化的同時將Long類型轉換為String
        simpleModule.addSerializer(Long.class, ToStringSerializer.instance);
        simpleModule.addSerializer(Long.TYPE, ToStringSerializer.instance);
        
        // 空值處理為空串  
        this.getSerializerProvider().setNullValueSerializer(new JsonSerializer<Object>() {  
            @Override  
            public void serialize(Object value, JsonGenerator jg, SerializerProvider sp) throws IOException, JsonProcessingException {  
                jg.writeString("");  
            }  
        });         
        super.registerModule(simpleModule);
    } 
}

<mvc:annotation-driven>
        <mvc:message-converters>
            <!-- UTF-8字符格式化 -->
            <bean class="org.springframework.http.converter.StringHttpMessageConverter">
                <property name="supportedMediaTypes">
                    <list>
                        <value>application/json;charset=UTF-8</value>
                        <value>text/html;charset=UTF-8</value>
                    </list>
                </property>
            </bean>
            <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
                <property name="objectMapper">
                    <bean class="com.zns.converter.CustomJsonConverter">
                        <property name="dateFormat">
                            <bean class="java.text.SimpleDateFormat">
                                <constructor-arg type="java.lang.String" value="yyyy-MM-dd HH:mm:ss" />
                            </bean>
                        </property>
                    </bean>
                </property>
            </bean>
        </mvc:message-converters>
</mvc:annotation-driven>