SpringBoot01-- 默认Jackson和fastJson的Json转化器对null处理对比

       前言：在实际项目中，我们难免会遇到一些 null 值的出现，我们转 JSON 时，不希望这些 null 出现，比如我们期望所有的 null 在转 JSON 时都变成 "" 这种空字符串 我们这里使用默认Jackson和fastJson的Json转化器对null处理做一个对比

1.默认Jackson的JSON转化器对null的处理

写一个JacksonConfig配置类

package com.itcodai.course01.configuration;

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializerProvider;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder;

import java.io.IOException;

/**
 * 使用Jackon作为JSON MessageConverter
 * 对null处理为""
 *
 * @author XuHao
 * Email [email protected]
 * create on 2018/7/29
 */

@Configuration
public class JacksonConfig {

    @Bean
    @Primary
    @ConditionalOnMissingBean(ObjectMapper.class)
    public ObjectMapper jacksonObjectMapper(Jackson2ObjectMapperBuilder builder) {
        ObjectMapper objectMapper = builder.createXmlMapper(false).build();
        objectMapper.getSerializerProvider().setNullValueSerializer(new JsonSerializer