spring 不一样的整合fastjson

1、什么是fastjson

fastjson是阿里巴巴开发的一个高性能的Java JSON处理库，它支持将Java对象转换成JSON格式，同时也支持将JSON字符串解析成Java对象。

2、pom.xml 配置

<dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-web</artifactId>
   <exclusions>
       <exclusion>
           <groupId>org.springframework.boot</groupId>
           <artifactId>spring-boot-starter-json</artifactId>
       </exclusion>
   </exclusions>
</dependency>
<dependency>
   <groupId>com.alibaba</groupId>
   <artifactId>fastjson</artifactId>
   <version>1.2.79</version>
</dependency>

3、全局WebMvcConfig配置

package com.gis.fastjson.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);
    }
 
}

4、controller测试

package com.gis.fastjson.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("/test")
    public Map<String, Object> showHelloWorld(){
        Map<String, Object> map = new HashMap<>();
        map.put("msg", "Hello World!");
        return map;
    }
}

5、闭坑指南

BigDecimal精度丢失

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

        String createtime ="2024-07-22 09:03:26.968";
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS");
        Date date = format.parse(createtime);
        book.setCreateTime(date);

        List<BookDTO> list = new ArrayList<>();
        list.add(book);
        String json =J SON.toJSONString(list);
        System.out.println(json);
        // 解决方法
		// String json = JSON.toJSONString(list,  JSONWriter.Feature.WriteBigDecimalAsPlain);
    }
}

日期解析问题

@Test
public void parseArray()  {
    String json="[{\"create_time\":\"2024-07-22 10:03:26.968\",\"money\":-40090.0700}]";
    System.out.println(json);
    List<BookDTO> list1 = JSON.parseArray(json, BookDTO.class,JSONReader.Feature.SupportSmartMatch);
    System.out.println();
}

运行结果
java.time.format.DateTimeParseException: Text ‘2024-07-22 10:03:26.968’ could not be parsed, unparsed text found at index 10

解决方法
BookDTO上加上@JSONField(format= “yyyy-MM-dd HH:mm:ss”)