FastJson2中FastJsonHttpMessageConverter找不到类问题

问题描述

如果你最近也在升级FastJson到FastJson2版本，而跟我一样也遇到了FastJsonHttpMessageConverter找不到类问题以及FastJsonConfig找不到问题，那么恭喜你，看完本文，安装完fastjson2、fastjson2-extension、fastjson2-extension-spring6这三个类库，你就可以成功使用新版FastJson2了。

旧代码

    @Overridepublic void configureMessageConverters(List<HttpMessageConverter<?>> converters) {converters.clear();//FastJsonHttpMessageConverterFastJsonHttpMessageConverter fastConverter = new FastJsonHttpMessageConverter();List<MediaType> fastMediaTypes = new ArrayList<>();fastMediaTypes.add(MediaType.APPLICATION_JSON_UTF8);fastConverter.setSupportedMediaTypes(fastMediaTypes);FastJsonConfig fastJsonConfig = new FastJsonConfig();fastJsonConfig.setCharset(StandardCharsets.UTF_8);fastConverter.setFastJsonConfig(fastJsonConfig);//StringHttpMessageConverterStringHttpMessageConverter stringConverter = new StringHttpMessageConverter();stringConverter.setDefaultCharset(StandardCharsets.UTF_8);stringConverter.setSupportedMediaTypes(fastMediaTypes);converters.add(stringConverter);converters.add(fastConverter);}

maven build error

RCA调查

通过官方一个issue中我们发现，他们把fastjson1中的一些类库拆分了FastJsonHttpMessageConverter在2.0.X中不存在的问题 · Issue #168 · alibaba/fastjson2 (github.com)

FastJSON1包

中我们用的是

import com.alibaba.fastjson.support.config.FastJsonConfig;
import com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter;

FastJSON2包

升级到FastJSON2，我们则需要升级为

import com.alibaba.fastjson2.support.config.FastJsonConfig;import com.alibaba.fastjson2.support.spring6.http.converter.FastJsonHttpMessageConverter;

解决方法

pom/xml引入完整类库

所以你单单引入还不够，我们还需要引入拆分的 fastjson2-extension、fastjson2-extension-spring6 库

<!--  FastJson2中FastJsonHttpMessageConverter找不到类问题 by https://zhengkai.blog.csdn.net/-->
<!-- https://mvnrepository.com/artifact/com.alibaba.fastjson2/fastjson2 -->
<dependency><groupId>com.alibaba.fastjson2</groupId><artifactId>fastjson2</artifactId><version>2.0.49</version>
</dependency>
<dependency><groupId>com.alibaba.fastjson2</groupId><artifactId>fastjson2-extension</artifactId><version>2.0.49</version>
</dependency>
<!-- https://mvnrepository.com/artifact/com.alibaba.fastjson2/fastjson2-extension-spring6 -->
<dependency><groupId>com.alibaba.fastjson2</groupId><artifactId>fastjson2-extension-spring6</artifactId><version>2.0.49</version>
</dependency>

WebMvcConfig和configureMessageConverters配置

其中，记得把其他相关的也要升级一下JSON/JSONArray/JSONObject

import com.alibaba.fastjson2.JSON;
import com.alibaba.fastjson2.JSONArray;
import com.alibaba.fastjson2.JSONObject;

（完整版供参考）

package com.softdev.system.generator.config;// import com.alibaba.fastjson.support.config.FastJsonConfig;
// import com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter;
import jakarta.servlet.DispatcherType;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.MediaType;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.StringHttpMessageConverter;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;import com.alibaba.fastjson2.JSONReader;
import com.alibaba.fastjson2.JSONWriter;
import com.alibaba.fastjson2.support.config.FastJsonConfig;
import com.alibaba.fastjson2.support.spring6.http.converter.FastJsonHttpMessageConverter;import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
/**
*  2019-2-11 liutf WebMvcConfig 整合 cors 和 SpringMvc MessageConverter
*/
@Configuration
public class WebMvcConfig implements WebMvcConfigurer {@Overridepublic void addResourceHandlers(ResourceHandlerRegistry registry) {registry.addResourceHandler("/statics/**").addResourceLocations("classpath:/statics/");}@Beanpublic FilterRegistrationBean xssFilterRegistration() {FilterRegistrationBean registration = new FilterRegistrationBean();registration.setDispatcherTypes(DispatcherType.REQUEST);registration.setFilter(new XssFilter());registration.addUrlPatterns("/*");registration.setName("xssFilter");registration.setOrder(Integer.MAX_VALUE);return registration;}// @Override// public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {//     converters.clear();//     //FastJsonHttpMessageConverter//     FastJsonHttpMessageConverter fastConverter = new FastJsonHttpMessageConverter();//     List<MediaType> fastMediaTypes = new ArrayList<>();//     fastMediaTypes.add(MediaType.APPLICATION_JSON_UTF8);//     fastConverter.setSupportedMediaTypes(fastMediaTypes);//     FastJsonConfig fastJsonConfig = new FastJsonConfig();//     fastJsonConfig.setCharset(StandardCharsets.UTF_8);//     fastConverter.setFastJsonConfig(fastJsonConfig);//     //StringHttpMessageConverter//     StringHttpMessageConverter stringConverter = new StringHttpMessageConverter();//     stringConverter.setDefaultCharset(StandardCharsets.UTF_8);//     stringConverter.setSupportedMediaTypes(fastMediaTypes);//     converters.add(stringConverter);//     converters.add(fastConverter);// }/*** FASTJSON2升级 by https://zhengkai.blog.csdn.net/* https://blog.csdn.net/moshowgame/article/details/138013669*/@Overridepublic void configureMessageConverters(List<HttpMessageConverter<?>> converters) {FastJsonHttpMessageConverter converter = new FastJsonHttpMessageConverter();//自定义配置...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);}}