07 Feign拼接请求地址

Feign主要作用：自动根据参数拼接http请求地址。
将原先 controller 中写死的调用服务地址 ，拆分单独写client客户端，调用时直接注入。

服务发现（consumer-demo）

添加spring-cloud-starter-openfeign坐标

导入坐标（openfeign）

• 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">
    <parent>
        <artifactId>springcloud_parent</artifactId>
        <groupId>li.chen.com</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>consumer_demo</artifactId>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
    </dependencies>
</project>

配置文件

• application.yml

spring:
  application:
    name: consumer_demo

eureka:
  client:
    service-url:
      defaultZone: http://127.0.0.1:10086/eureka

    # 获取服务地址列表间隔时间，默认30秒
    registry-fetch-interval-seconds: 10

hystrix:
  command:
    default:
      execution:
        isolation:
          thread:
            timeoutInMilliseconds: 2000   # 延迟？
      circuitBreaker:
        errorThresholdPercentage: 50 # 触发熔断错误比例阈值，默认值50%
        sleepWindowInMilliseconds: 10000 # 熔断后休眠时长，默认值5秒
        requestVolumeThreshold: 10 # 熔断触发最小请求次数，默认值是20

springboot启动类

• ConsumerApplication

package li.chen.com.consumer;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.cloud.openfeign.EnableFeignClients;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@EnableDiscoveryClient   //开启Eureka客户端发现功能
@SpringBootApplication
@EnableFeignClients  //开启Feign功能
public class ConsumerApplication {
    public static void main(String[] args) {
        SpringApplication.run(ConsumerApplication.class,args);
    }

    @Bean
    @LoadBalanced
    public RestTemplate restTemplate(){
        return new RestTemplate();
    }

}

各层文件

pojo层

• User

package li.chen.com.consumer.pojo;

import lombok.Data;

import java.util.Date;

/**
 * @ClassName: User
 * @Description 接收数据，不进行数据库交互，故不需要加user_service里的那些注解
 **/
@Data
public class User {

    private Integer id;

    private String userName;

    private String passWord;

    private Date birthday;
}

client层

package li.chen.com.consumer.client;

import li.chen.com.consumer.pojo.User;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;

//声明当前类是一个Feign客户端，指定服务名为UserService
@FeignClient("UserService")
public interface UserClient {

    // http://UserService/1   拼接的路径--》是UserService服务提供的路径
    @GetMapping("/UserController/{id}")
    User queryById(@PathVariable Long id);

}

controller层

• ConsumerFeignController

package li.chen.com.consumer.controller;

import li.chen.com.consumer.client.UserClient;
import li.chen.com.consumer.pojo.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("ConsumerFeignController")
public class ConsumerFeignController {

    @Autowired
    private UserClient userClient;

    @GetMapping("/{id}")
    public User queryById(@PathVariable Long id){
        return userClient.queryById(id);
    }

}

测试

启动UserApplication9090
启动 EurekaServerApplication
启动 ConsumerApplication
访问 http://localhost:8080/ConsumerFeignController/2