一、概述
SpringBoot在构建restfult风格的web服务时,默认使用的是Jackson作为JSON解析器,个人使用比较习惯的 json 框架是 fastjson,所以SpringBoot默认的 json 使用起来就很陌生了，如何使用 fastjson 进行 json 解析呢？
引入依赖
注意，1.2.61以下有严重高危漏洞，1.2.61修复，必须升级到1.2.61，目前最新版本为1.2.62
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.62</version>
</dependency>
二、SpringBoot1.x版本
第一种方法：通过extends WebMvcConfigurerAdapter并重写configureMessageConverters方法来实现。
import java.util.List;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.http.HttpMessageConverters;
import org.springframework.context.annotation.Bean;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
import com.alibaba.fastjson.serializer.SerializerFeature;
import com.alibaba.fastjson.support.config.FastJsonConfig;
import com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter;
@MapperScan("com.example.demo.mapper")
@SpringBootApplication(scanBasePackages= {"com.example.demo.controller","com.example.demo.service"})
public class HelloSpringBootApplication extends WebMvcConfigurerAdapter{
@Override
public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
//创建FastJson的消息转换器
FastJsonHttpMessageConverter convert = new FastJsonHttpMessageConverter();
//创建FastJson的配置对象
FastJsonConfig config = new FastJsonConfig();
//对Json数据进行格式化
config.setSerializerFeatures(SerializerFeature.PrettyFormat);
convert.setFastJsonConfig(config);
converters.add(convert);
}
public static void main(String[] args) {
SpringApplication.run(HelloSpringBootApplication.class, args);
}
}
第二种方法：在项目启动类中通过@Bean注解处理
import java.util.List;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.http.HttpMessageConverters;
import org.springframework.context.annotation.Bean;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
import com.alibaba.fastjson.serializer.SerializerFeature;
import com.alibaba.fastjson.support.config.FastJsonConfig;
import com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter;
@MapperScan("com.example.demo.mapper")
@SpringBootApplication(scanBasePackages= {"com.example.demo.controller","com.example.demo.service"})
public class HelloSpringBootApplication
{
@Bean
public HttpMessageConverters fastJsonMessageConverter() {
//创建FastJson的消息转换器
FastJsonHttpMessageConverter convert = new FastJsonHttpMessageConverter();
//创建FastJson的配置对象
FastJsonConfig config = new FastJsonConfig();
//对Json数据进行格式化
config.setSerializerFeatures(SerializerFeature.PrettyFormat);
convert.setFastJsonConfig(config);
HttpMessageConverter<?> con =convert;
return new HttpMessageConverters(con);
}
public static void main(String[] args) {
SpringApplication.run(HelloSpringBootApplication.class, args);
}
}
三、SpringBoot2.0版本
自定义配置类implements WebMvcConfigurer 类
import com.alibaba.fastjson.serializer.SerializerFeature;
import com.alibaba.fastjson.support.config.FastJsonConfig;
import com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.MediaType;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
import java.util.ArrayList;
import java.util.List;
@Configuration
public class JsonConfig implements WebMvcConfigurer {
/**
* 使用fastjson代替jackson
*/
@Override
public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
/*
先把JackSon的消息转换器删除.
备注: (1)源码分析可知，返回json的过程为:
Controller调用结束后返回一个数据对象，for循环遍历conventers，找到支持application/json的HttpMessageConverter，然后将返回的数据序列化成json。
具体参考org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor的writeWithMessageConverters方法
(2)由于是list结构，我们添加的fastjson在最后。因此必须要将jackson的转换器删除，不然会先匹配上jackson，导致没使用fastjson
*/
for (int i = converters.size() - 1; i >= 0; i--) {
if (converters.get(i) instanceof MappingJackson2HttpMessageConverter) {
converters.remove(i);
}
}
FastJsonHttpMessageConverter fastJsonHttpMessageConverter = new FastJsonHttpMessageConverter();
//自定义fastjson配置
FastJsonConfig config = new FastJsonConfig();
config.setSerializerFeatures(
SerializerFeature.WriteMapNullValue, // 是否输出值为null的字段,默认为false,我们将它打开
SerializerFeature.WriteNullListAsEmpty, // 将Collection类型字段的字段空值输出为[]
SerializerFeature.WriteNullStringAsEmpty, // 将字符串类型字段的空值输出为空字符串
SerializerFeature.WriteNullNumberAsZero, // 将数值类型字段的空值输出为0
SerializerFeature.WriteDateUseDateFormat,
SerializerFeature.DisableCircularReferenceDetect // 禁用循环引用
);
fastJsonHttpMessageConverter.setFastJsonConfig(config);
// 添加支持的MediaTypes;不添加时默认为*/*,也就是默认支持全部
// 但是MappingJackson2HttpMessageConverter里面支持的MediaTypes为application/json
// 参考它的做法, fastjson也只添加application/json的MediaType
List<MediaType> fastMediaTypes = new ArrayList<>();
fastMediaTypes.add(MediaType.APPLICATION_JSON_UTF8);
fastJsonHttpMessageConverter.setSupportedMediaTypes(fastMediaTypes);
converters.add(fastJsonHttpMessageConverter);
}
@Override
public void extendMessageConverters(List<HttpMessageConverter<?>> converters) {
for (HttpMessageConverter<?> messageConverter : converters) {
System.out.println("=====================" + messageConverter);
}
}
}
测试
@RestController
public class TestController {
@RequestMapping("/test")
public Object test() {
User user = new User();
user.date = new Date();
user.name = "张三";
return user;
}
}
public class User {
@JSONField(format = "yyyy-MM-dd HH:mm:ss")
public Date date;
public String name;
}