Java spring cloud gateway GlobalFilter通过feign调用其他服务

需求说明：在gateway服务里面需要调用其他服务的接口

问题分析：1.在GlobalFilter过滤类中获取feign服务类时，用@Autowired注解获取会报错，这和servlet, filter的加载顺序有关，所以使用AutowiredBean类，原理是从spring上下文中获取feign的自定义Bean，然后在正常调用接口

2.在过滤类中正常调用feign服务接口时，会抛出一个java.lang.IllegalStateException: block()/blockFirst()/blockLast() are blocking, which is not supported in thread reactor-http-nio-2，意思是线程堵塞，使用CompletableFuture.supplyAsync异步调用解决

3.FeignConfig类解决异步调用 feign 的错误，不加这个类会抛一个异常java.util.concurrent.ExecutionException: feign.codec.DecodeException: No qualifying bean of type 'org.springframework.boot.autoconfigure.http.HttpMessageConverters' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

 

1.GlobalFilter过滤类

@Component
public class InnerFilter implements GlobalFilter, Ordered {

    @SneakyThrows
    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        SysLog sysLog = new SysLog();
        sysLog.setLoginName("lsz");

        //获取的关键看这里，在用的时候在获取bean  
        SysLogClient sysLogClient = AutowiredBean.getBean(SysLogClient.class);
　　　　　//异步调用feign服务接口 　　
        CompletableFuture<HttpResult> f = CompletableFuture.supplyAsync(()->{
            return sysLogClient.getSysLogListWithPage(0, 10, "ad");
        });

        HttpResult result = f.get();
        // TODO 这里未来还可以限制一些格式
        return chain.filter(exchange.mutate().request(exchange.getRequest()).build());
    }
    
    /**
     * 优先级默认设置为最高
     *
     * @return
     */
    @Override
    public int getOrder() {
        return -800;
    }
}

2.获取feign服务类AutowiredBean

 2 
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;

public class AutowiredBean{

    private static ApplicationContext applicationContext;

    public static void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        if (AutowiredBean.applicationContext == null) {
            AutowiredBean.applicationContext = applicationContext;
        }
    }

    public static ApplicationContext getApplicationContext() {
        return applicationContext;
    }

    public static Object getBean(String name) {
        return getApplicationContext().getBean(name);
    }

    public static <T> T getBean(Class<T> clazz) {
        return getApplicationContext().getBean(clazz);
    }

    public static <T> T getBean(String name, Class<T> clazz) {
        return getApplicationContext().getBean(name, clazz);
    }

}

3. Feign配置类，解决异步调用 feign 的错误

package com.hnlt.cloud.gateway.config;

import feign.Logger;
import feign.codec.Decoder;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.ObjectFactory;
import org.springframework.boot.autoconfigure.http.HttpMessageConverters;
import org.springframework.cloud.openfeign.support.ResponseEntityDecoder;
import org.springframework.cloud.openfeign.support.SpringDecoder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.MediaType;
import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
import java.util.ArrayList;
import java.util.List;

/**
 * Feign 配置
 * @author: lsz
 * @time: 2021/10/15
 */
@Configuration
public class FeignConfig {

    @Bean
    Logger.Level feignLevel() {
        //这里记录所有
        return Logger.Level.FULL;
    }

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

    public ObjectFactory<HttpMessageConverters> feignHttpMessageConverter() {
        final HttpMessageConverters httpMessageConverters = new HttpMessageConverters(new PhpMappingJackson2HttpMessageConverter());
        return new ObjectFactory<HttpMessageConverters>() {
            @Override
            public HttpMessageConverters getObject() throws BeansException {
                return httpMessageConverters;
            }
        };
    }

    public class PhpMappingJackson2HttpMessageConverter extends MappingJackson2HttpMessageConverter {
        PhpMappingJackson2HttpMessageConverter(){
            List<MediaType> mediaTypes = new ArrayList<>();
            mediaTypes.add(MediaType.valueOf(MediaType.TEXT_HTML_VALUE + ";charset=UTF-8"));
            setSupportedMediaTypes(mediaTypes);
        }
    }
}