手把手搭建微服务框架（三）：搭建服务消费者（使用Ribbon消费服务），并注册到注册中心(Eureka)，整合Hystrix

1.新建maven工程，在pom.xml导入相关依赖

<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>1.5.2.RELEASE</version>
		<relativePath /> <!-- lookup parent from repository -->
	</parent>
	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
		<java.version>1.8</java.version>
	</properties>

	<dependencies>
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-eureka</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-ribbon</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-hystrix</artifactId>
		</dependency>
	</dependencies>
	<dependencyManagement>
		<dependencies>
			<dependency>
				<groupId>org.springframework.cloud</groupId>
				<artifactId>spring-cloud-dependencies</artifactId>
				<version>Dalston.RC1</version>
				<type>pom</type>
				<scope>import</scope>
			</dependency>
		</dependencies>
	</dependencyManagement>
	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>
	<repositories>
		<repository>
			<id>spring-milestones</id>
			<name>Spring Milestones</name>
			<url>https://repo.spring.io/milestone</url>
			<snapshots>
				<enabled>false</enabled>
			</snapshots>
		</repository>
	</repositories>

2.在resources目录下新建application.properties

#端口
server.port=7777
#服务名称
spring.application.name=server-consume
#注册至注册中心,注册中心地址
eureka.client.serviceUrl.defaultZone=http://localhost:5555/eureka
#Eureka Client 向 Eureka Server 发送心跳的时间间隔
eureka.instance.lease-renewal-interval-in-seconds=10
#指定 Eureka Client 间隔多久需要向 Eureka Server 发送心跳来告知 Eureka Server 该实例还存活着。
eureka.instance.lease-expiration-duration-in-seconds=5

3.新建Uservice类

package com.consume.service;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;

@Service
public class UserService {
    
    
	@Autowired
	RestTemplate restTemplate;
	
	public ResponseEntity<String> UserName() {
    
    
		//参数：（远程调用服务名称，返回类型）
		return restTemplate.getForEntity("http://server-provision/username", String.class);
	}
}

·4.将Userservice注入到UserController

package com.consume.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import com.consume.service.UserService;

@RestController
public class UserController {
    
    
	@Autowired
	UserService service;
	
	@GetMapping("/consume")
	public String userName() {
    
    
		ResponseEntity<String> userName = service.UserName();
		System.out.println(userName);
		return userName.toString();
	}
}

5.编写启动类，注册到注册中心

package com.consume;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@SpringBootApplication
@EnableEurekaClient
public class ConsumeApp {
    
    
	public static void main(String[] args) {
    
    
		SpringApplication.run(ConsumeApp.class, args);
	}
	
	@Bean//将RestTemplate交给spring管理
	@LoadBalanced//实现客户端负载均衡
	RestTemplate restTemplate() {
    
    
		return new RestTemplate();
	}
}

6.访问server-consume服务消费server-provision服务

浏览器访问：http://localhost:7777/consume
输出以下内容证明消费成功

7.由于我们前面配置了ribbon负载均衡，这里我们修改服务提供者端口号，再次启动服务server-provision

8.查看注册中心会有两条名称相同，端口不同的服务

9.此时我们刷新服务消费者，端口会随之改变

10.整合断路器（Hystrix）

在远程调用方法上添加注解@HystrixCommand(fallbackMethod = “error”)
error为服务提供者异常时的跳转方法

package com.consume.service;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;

import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;

@Service
public class UserService {
    
    
	@Autowired
	RestTemplate restTemplate;
	
	@HystrixCommand(fallbackMethod = "error")
	public ResponseEntity<String> UserName() {
    
    
		//参数：（远程调用服务名称，返回类型）
		return restTemplate.getForEntity("http://server-provision/username", String.class);
	}
	
	public ResponseEntity<String> error() {
    
    
		//参数：（远程调用服务名称，返回类型）	
		return new ResponseEntity<>("网络异常!", HttpStatus.OK);
	}
	
}

11.关闭所有服务提供者，启动注册中心和服务消费者，访问

此时页面输出：网络异常