Spring Boot集成fastjson2快速入门Demo

1.什么是fastjson2？

• 支持JSON/JSONB两种协议，JSONPath 是一等公民。
• 支持全量解析和部分解析。
• 支持Java服务端、客户端Android、大数据场景。
• 支持Kotlin
• 支持JSON Schema https://alibaba.github.io/fastjson2/json_schema_cn
• 支持Android
• 支持Graal Native-Image

2.代码工程

实验目标

在 Spring Web MVC 中集成 Fastjson2

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>springboot-demo</artifactId>
        <groupId>com.et</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>fastjson2</artifactId>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-autoconfigure</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>com.alibaba.fastjson2</groupId>
            <artifactId>fastjson2</artifactId>
            <version>2.0.40</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba.fastjson2</groupId>
            <artifactId>fastjson2-extension-spring5</artifactId>
            <version>2.0.40</version>
        </dependency>
    </dependencies>
</project>

config

package com.et.fastjson2.config;
 

import com.alibaba.fastjson2.JSONReader;
import com.alibaba.fastjson2.JSONWriter;
import com.alibaba.fastjson2.support.config.FastJsonConfig;
import com.alibaba.fastjson2.support.spring.http.converter.FastJsonHttpMessageConverter;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.MediaType;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

import java.nio.charset.StandardCharsets;
import java.util.Collections;
import java.util.List;

@Configuration
public class WebMvcConfig implements WebMvcConfigurer {

    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        FastJsonHttpMessageConverter converter = new FastJsonHttpMessageConverter();
        //custom configuration
        FastJsonConfig config = new FastJsonConfig();
        config.setDateFormat("yyyy-MM-dd HH:mm:ss");
        config.setReaderFeatures(JSONReader.Feature.FieldBased, JSONReader.Feature.SupportArrayToBean);
        config.setWriterFeatures(JSONWriter.Feature.WriteMapNullValue, JSONWriter.Feature.PrettyFormat);
        converter.setFastJsonConfig(config);
        converter.setDefaultCharset(StandardCharsets.UTF_8);
        converter.setSupportedMediaTypes(Collections.singletonList(MediaType.APPLICATION_JSON));
        converters.add(0, converter);
    }
 
}

package com.et.fastjson2.controller;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.HashMap;
import java.util.Map;

@RestController
public class HelloWorldController {
    @RequestMapping("/hello")
    public Map<String, Object> showHelloWorld(){
        Map<String, Object> map = new HashMap<>();
        map.put("msg", "HelloWorld");
        return map;
    }
}

以上只是一些关键代码，所有代码请参见下面代码仓库

代码仓库

• https://github.com/Harries/springboot-demo

3.测试

• 启动spring boot工程，
• 访问http://127.0.0.1:8088/hello
• 返回美化的Json格式，说明生效了

4.fastjosn避坑

1.BigDecimal精度丢失问题

  @Test
    public void toJSONString() throws ParseException {
        UserDTO  user =  new UserDTO();
        BigDecimal money =new BigDecimal(-40090.07d);
        money = money.setScale(4, RoundingMode.HALF_UP);
        user.setMoney(money);

        String createtime ="2024-07-03 09:03:26.968";
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS");
        Date date = format.parse(createtime);
        user.setCreateTime(date);

        List<UserDTO> list = new ArrayList<>();
        list.add(user);
        String json=JSON.toJSONString(list);
        System.out.println(json);
    }

}

执行结果

[{"createTime":"2024-07-03","money":-40090.700}]

解决方法

String json=JSON.toJSONString(list,  JSONWriter.Feature.WriteBigDecimalAsPlain);

2.日期解析问题

@Test
public void parseArray()  {
    String json="[{\"create_time\":\"2024-07-03 09:03:26.968\",\"money\":-40090.0700}]";
    System.out.println(json);
    List<UserDTO> list1 = JSON.parseArray(json, UserDTO.class,JSONReader.Feature.SupportSmartMatch);
    System.out.println();
}

运行结果

java.time.format.DateTimeParseException: Text '2024-07-03 09:03:26.968' could not be parsed, unparsed text found at index 10

解决方法

UserDTO上加上@JSONField(format= "yyyy-MM-dd HH:mm:ss")

5.引用

• JSONB格式文档： https://alibaba.github.io/fastjson2/jsonb_format_cn
• FASTJSON v2性能有了很大提升，具体性能数据看这里： https://alibaba.github.io/fastjson2/benchmark_cn