SpringCloud : Feign 使用 FastJson 解析数据

Fastjson 版本1.2.60

Spring 版本 5.1.5.RELEASE

SpringBoot 版本 2.1.5.RELEASE

SpringCloud 版本 2.1.1.RELEASE

SpringCloud 中配置 FastJson 如下：

@Configuration
public class FastJsonConverterConfig extends WebMvcConfigurationSupport {

    /**
     * 使用fastjson代替jackson
     */
    @Override
    protected void extendMessageConverters(List<HttpMessageConverter<?>> converters) {
        //先把JackSon的消息转换器删除.
        //(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);
            }
        }

        //自定义fastjson配置
        FastJsonConfig config = new FastJsonConfig();
        config.setSerializerFeatures(
                // 是否输出值为null的字段,默认为false,我们将它打开
                SerializerFeature.WriteMapNullValue,
                // 将Collection类型字段的字段空值输出为[]
                SerializerFeature.WriteNullListAsEmpty,
                // 将字符串类型字段的空值输出为空字符串
                SerializerFeature.WriteNullStringAsEmpty,
                // 将数值类型字段的空值输出为0
                SerializerFeature.WriteNullNumberAsZero,
                SerializerFeature.WriteDateUseDateFormat,
                // 禁用循环引用
                SerializerFeature.DisableCircularReferenceDetect
        );

        // 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
        List<MediaType> fastMediaTypes = new ArrayList<>();
        fastMediaTypes.add(MediaType.APPLICATION_JSON);
        fastMediaTypes.add(MediaType.APPLICATION_JSON_UTF8);

        FastJsonHttpMessageConverter fastJsonHttpMessageConverter = new FastJsonHttpMessageConverter();
        fastJsonHttpMessageConverter.setFastJsonConfig(config);
        fastJsonHttpMessageConverter.setSupportedMediaTypes(fastMediaTypes);
        converters.add(fastJsonHttpMessageConverter);
        //支持XML格式的请求
        converters.add(new StringHttpMessageConverter());
    }
}

但是，在使用Feign的Spring Cloud微服务项目中，要特别注意需要为Feign单独配置。因为Feign并不共用Spring MVC的消息转换器链，默认使用的是Jackson Json解析库。

所以需要单独如下配置：

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.serializer.SerializerFeature;
import com.alibaba.fastjson.support.config.FastJsonConfig;
import com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter;
import com.alibaba.fastjson.support.springfox.SwaggerJsonSerializer;
import feign.Logger;
import feign.codec.Decoder;
import feign.codec.Encoder;
import org.springframework.beans.factory.ObjectFactory;
import org.springframework.boot.autoconfigure.http.HttpMessageConverters;
import org.springframework.cloud.openfeign.support.SpringDecoder;
import org.springframework.cloud.openfeign.support.SpringEncoder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.MediaType;

import java.util.ArrayList;
import java.util.List;

/**
 * Feign 客户端配置
 *
 * @author xushiling
 * @date 2018/8/13
 */
@Configuration
public class FeignConfig {

    @Bean
    Logger.Level feignLoggerLevel() {
        //这里记录所有，根据实际情况选择合适的日志level
        return Logger.Level.FULL;
    }

    @Bean
    public Encoder feignEncoder() {
        return new SpringEncoder(feignHttpMessageConverter());
    }

    @Bean
    public Decoder feignDecoder() {
        return new SpringDecoder(feignHttpMessageConverter());
    }

    /**
     * 设置解码器为fastjson
     *
     * @return
     */
    private ObjectFactory<HttpMessageConverters> feignHttpMessageConverter() {
        final HttpMessageConverters httpMessageConverters = new HttpMessageConverters(this.getFastJsonConverter());
        return () -> httpMessageConverters;
    }

    private FastJsonHttpMessageConverter getFastJsonConverter() {
        FastJsonHttpMessageConverter converter = new FastJsonHttpMessageConverter();

        List<MediaType> supportedMediaTypes = new ArrayList<>();
        MediaType mediaTypeJson = MediaType.valueOf(MediaType.APPLICATION_JSON_UTF8_VALUE);
        supportedMediaTypes.add(mediaTypeJson);
        converter.setSupportedMediaTypes(supportedMediaTypes);
        FastJsonConfig config = new FastJsonConfig();
        config.getSerializeConfig().put(JSON.class, new SwaggerJsonSerializer());
        config.setSerializerFeatures(SerializerFeature.DisableCircularReferenceDetect);
        converter.setFastJsonConfig(config);

        return converter;
    }
}

PS：

https://blog.csdn.net/lppl010_/article/details/94215233

https://www.jianshu.com/p/b3b93a32cb05