Spring Cloud Feign高级应用

1.使用feign进行服务间的调用

spring boot2X整合nacos一使用Feign实现服务调用

2.开启gzip压缩

Feign支持对请求与响应的压缩，以提高通信效率，需要在服务消费者配置文件开启压缩支持和压缩文件的类型

添加配置

feign.compression.request.enabled=true
feign.compression.response.enabled=true
feign.compression.request.mime-types=text/xml,application/xml,application/json
feign.compression.request.min-request-size=2048

3.开启日志

配置

logging.level.com.xyz.comsumer.feign.RemoteHelloService=debug

添加FeignLogConfig类

package com.xyz.comsumer.configure;

import feign.Logger;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class FeignLogConfig {
    @Bean
    Logger.Level feignLogger(){
        return Logger.Level.FULL;
    }
}

输出

2019-12-07 23:23:03.630 DEBUG 2668 --- [vice-provider-1] c.xyz.comsumer.feign.RemoteHelloService : [RemoteHelloService#hello] <--- HTTP/1.1 200 (671ms)
2019-12-07 23:23:03.631 DEBUG 2668 --- [vice-provider-1] c.xyz.comsumer.feign.RemoteHelloService : [RemoteHelloService#hello] content-length: 14
2019-12-07 23:23:03.631 DEBUG 2668 --- [vice-provider-1] c.xyz.comsumer.feign.RemoteHelloService : [RemoteHelloService#hello] content-type: text/plain;charset=UTF-8
2019-12-07 23:23:03.631 DEBUG 2668 --- [vice-provider-1] c.xyz.comsumer.feign.RemoteHelloService : [RemoteHelloService#hello] date: Sat, 07 Dec 2019 15:23:03 GMT
2019-12-07 23:23:03.631 DEBUG 2668 --- [vice-provider-1] c.xyz.comsumer.feign.RemoteHelloService : [RemoteHelloService#hello] vary: Origin
2019-12-07 23:23:03.631 DEBUG 2668 --- [vice-provider-1] c.xyz.comsumer.feign.RemoteHelloService : [RemoteHelloService#hello] vary: Access-Control-Request-Method
2019-12-07 23:23:03.631 DEBUG 2668 --- [vice-provider-1] c.xyz.comsumer.feign.RemoteHelloService : [RemoteHelloService#hello] vary: Access-Control-Request-Headers
2019-12-07 23:23:03.631 DEBUG 2668 --- [vice-provider-1] c.xyz.comsumer.feign.RemoteHelloService : [RemoteHelloService#hello]
2019-12-07 23:23:03.632 DEBUG 2668 --- [vice-provider-1] c.xyz.comsumer.feign.RemoteHelloService : [RemoteHelloService#hello] hello,provider
2019-12-07 23:23:03.632 DEBUG 2668 --- [vice-provider-1] c.xyz.comsumer.feign.RemoteHelloService : [RemoteHelloService#hello] <--- END HTTP (14-byte body)

说明：

　　Feign日志记录只能响应DEBUG日志级别

对每一个Feign客户端，可以配置一个Logger.Level对象，通过该对象控制日志输出内容。

Logger.Level有如下几种选择：

NONE, 不记录日志 (默认)。

BASIC, 只记录请求方法和URL以及响应状态代码和执行时间。

HEADERS, 记录请求和应答的头的基本信息。

FULL, 记录请求和响应的头信息，正文和元数据。

4.替换JDK默认的URLConnection为okhttp

在默认情况下 spring cloud feign在进行各个子服务之间的调用时，http组件使用的是jdk的HttpURLConnection

服务之间调用使用的HttpURLConnection，效率非常低

为了提高效率，可以通过连接池提高效率

使用okhttp，能提高qps，因为okhttp有连接池和超时时间进行调优

添加依赖

<dependency>
    <groupId>io.github.openfeign</groupId>
    <artifactId>feign-okhttp</artifactId>
</dependency>

修改配置

禁用默认的http，启用okhttp

feign.okhttp.enabled=true
feign.httpclient.enabled=false

添加FeignOkHttpConfig类

package com.xyz.comsumer.configure;

import feign.Feign;
import okhttp3.ConnectionPool;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.AutoConfigureBefore;
import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
import org.springframework.cloud.openfeign.FeignAutoConfiguration;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import java.util.concurrent.TimeUnit;

@Configuration
@ConditionalOnClass(Feign.class)
@AutoConfigureBefore(FeignAutoConfiguration.class)
public class FeignOkHttpConfig {

    @Bean
    public okhttp3.OkHttpClient okHttpClient(){
        return new okhttp3.OkHttpClient.Builder()
                .readTimeout(10, TimeUnit.SECONDS)
                .connectTimeout(10, TimeUnit.SECONDS)
                .writeTimeout(20, TimeUnit.SECONDS)
                .retryOnConnectionFailure(true)
                .connectionPool(new ConnectionPool())
                .build();
    }
}

5.超时设置

Feign调用服务的默认时长是1秒钟

hystrix的超时时间

hystrix.command.default.execution.timeout.enabled=true
hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds=10000

说明：

　　hystrix.command.default.execution.timeout.enabled 执行是否启用超时，默认启用true

　　hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds 命令执行超时时间，默认1000ms

　　常用的配置还有

　　　　hystrix.command.default.execution.isolation.strategy 隔离策略，默认是Thread, 可选THREAD｜SEMAPHORE，建议选择SEMAPHORE

Feign 的负载均衡底层用的就是 Ribbon

ribbon的超时时间

ribbon.ReadTimeout=10000
ribbon.ConnectTimeout=10000

6.使用hystrix进行熔断、降级处理

feign启用hystrix，才能熔断、降级

feign.hystrix.enabled=true

hystrix服务降级处理 

RemoteHelloServiceFallbackImpl

package com.xyz.comsumer.feign.fallback;

import com.xyz.comsumer.feign.RemoteHelloService;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;

@Component
public class RemoteHelloServiceFallbackImpl implements RemoteHelloService {
    private final Logger logger = LoggerFactory.getLogger(RemoteHelloServiceFallbackImpl.class);

    @Override
    public String hello() {
        logger.error("feign 查询信息失败:{}");
        return null;
    }

}