spring cloud服务间调用feign

参考文章：Spring Cloud Feign设计原理

1.feign是spring cloud服务间相互调用的组件，声明式、模板化的HTTP客户端。类似的HttpURLConnection、Apache HttpComponnets、OkHttp3 、Netty都实现相同功能。

目录结构

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.5.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.test</groupId>
    <artifactId>feigtest</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>feigtest</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Greenwich.SR1</spring-cloud.version>
        <fastjson.version>1.2.32</fastjson.version>

    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!--feign -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <!--引入这个包才能使用fegin-->

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
        </dependency>
       
        <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>fastjson</artifactId>
        <version>${fastjson.version}</version>
        </dependency>
    </dependencies>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>



</project>

application.yml

spring:
  application:
    name: service-feigntest
server:
  port: 8702
eureka:
  client:
    serviceUrl:
      #指向注册中心
      defaultZone: http://192.168.111.133:8888/eureka/
  instance:
    # 每间隔1s，向服务端发送一次心跳，证明自己依然”存活“
    lease-renewal-interval-in-seconds: 1
    # 告诉服务端，如果我2s之内没有给你发心跳，就代表我“死”了，将我踢出掉。
    lease-expiration-duration-in-seconds: 2

IHiService.java

package com.feigtest;


import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.PostMapping;

@FeignClient("service-hi")
public interface IHiService {
    @PostMapping("/hi")
    public String say();
}

FeigTestController.java

package com.feigtest;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;


@RestController
public class FeigTestController {
    @Autowired
    IHiService hiService;

    @RequestMapping("/hifeign")
    public String getFeignService(){
        return hiService.say();
    }
}

FeigtestApplication

package com.feigtest;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.openfeign.EnableFeignClients;

@EnableEurekaClient
@SpringBootApplication
@EnableFeignClients
public class FeigtestApplication {

    public static void main(String[] args) {
        SpringApplication.run(FeigtestApplication.class, args);
    }

}

 2.feign带token,服务调用时保持token不丢失。

package com.Interceptor;

import feign.RequestInterceptor;
import feign.RequestTemplate;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;

import javax.servlet.http.HttpServletRequest;

/**
 * Feign配置
 * 使用FeignClient进行服务间调用，传递headers信息
 */
@Configuration
public class FeignConfig implements RequestInterceptor {
    @Override
    public void apply(RequestTemplate requestTemplate) {
        ServletRequestAttributes attributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
        HttpServletRequest request = attributes.getRequest();
        //添加token
        requestTemplate.header("token", request.getHeader("token"));
    }
}