1 服务说明

准备两个maven项目，eureka-sales、eureka-user，通过访问eureka-sales服务调用eureka-user服务，三种访问方式下 eureka-user 代码不变，只是为了提供被访问接口。

1-1 eureka

pom依赖：

   <dependencies><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-eureka-server</artifactId></dependency></dependencies><dependencyManagement><dependencies><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-parent</artifactId><version>Camden.SR3</version><type>pom</type><scope>import</scope></dependency></dependencies></dependencyManagement>

application.yml

server:port: 8761spring:application:name: eurekaeureka: client:register-with-eureka: falsefetch-registry: falseserver:waitTimeInMsWhenSyncEmpty: 0serviceUrl:defaultZone: http://localhost:${server.port}/eureka/

启动类，加上 @EnableEurekaServer 注解：

@SpringBootApplication
@EnableEurekaServer
public class EurekaApplication {public static void main(String[] args) {SpringApplication.run(EurekaApplication.class, args);}
}

1-2 eureka-sales

pom依赖：

   <dependencies><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-eureka</artifactId></dependency><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-feign</artifactId></dependency></dependencies><dependencyManagement><dependencies><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-parent</artifactId><version>Camden.SR3</version><type>pom</type><scope>import</scope></dependency></dependencies></dependencyManagement>

定义接口：

@RequestMapping("/sales")
public interface SalesRest {@RequestMapping(value = "/queryGoodsList/{type}", method = RequestMethod.GET)Object queryGoodsList(Integer type);
}

接口实现类，根据传入的type，决定以何种方式访问 eureka-user 服务，1 表示 ribbon 方式，2 表示feign 方式，其他数字表示 http 方式：

@RestController
public class SalesRestImpl implements SalesRest {@Autowiredprivate SalesService salesService;@Overridepublic String queryGoodsList(@PathVariable Integer type) {System.out.println("start to queryGoodsList --->");if(type.intValue() == 1) {return salesService.queryGoodsListByRibbon();}else if(type.intValue() == 2) {return salesService.queryGoodsListByFeign();}else {return salesService.queryGoodsListByHttp();}}}

方法实现：

@Service
public class SalesService {@AutowiredRestTemplate restTemplate;@AutowiredUserFeignClient userFeignClient;private static final String RIBBON_URL = "http://user:8082/user/getUserInfo";private static final String HTTP_URL = "http://127.0.0.1:8082/user/getUserInfo";private static final String IP = IpUtil.getIp();public String queryGoodsListByRibbon() {String sales_result = "queryGoodsListByRibbon success : [sales_ip:" + IP + "] ";String result = restTemplate.getForObject(RIBBON_URL, String.class);return sales_result + result;}public String queryGoodsListByFeign() {String sales_result = "queryGoodsListByFeign success : [sales_ip:" + IP + "] ";String result = (String) userFeignClient.getUserInfo();return sales_result + result;}public String queryGoodsListByHttp() {String sales_result = "queryGoodsListByHttp success : [sales_ip:" + IP + "] ";String result = HttpClientUtil.doGet(HTTP_URL);return sales_result + result;}
}

client

@FeignClient(name = "USER")
public interface UserFeignClient {@RequestMapping(value = "/user/getUserInfo", method = RequestMethod.GET)String getUserInfo();
}

1-3 eureka-user

pom依赖：

   <dependencies><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-eureka</artifactId></dependency></dependencies><dependencyManagement><dependencies><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-parent</artifactId><version>Camden.SR3</version><type>pom</type><scope>import</scope></dependency></dependencies></dependencyManagement>

接口：

@RequestMapping("/user")
public interface UserRest {@RequestMapping(value = "/getUserInfo", method = RequestMethod.GET)String getUserInfo();
}

接口实现类：

@RestController
public class UserRestImpl implements UserRest{@Autowiredprivate UserService userService;@Overridepublic String getUserInfo() {System.out.println("start to getUserInfo --->");return userService.getUserInfo(); }}

方法实现，为了验证 ribbon 的负载均衡，这里返回服务的端口号：

@Service("userService")
public class UserService {@Value("${server.port}")private Integer port;public String getUserInfo() {// 当前项目所在IPString ip = IpUtil.getIp();return "getUserInfo success : [user_ip:" + ip + "user_port:" + port + "] ";}}

2 ribbon方式

Ribbon 是 Netflix 发布的负载均衡器，与 Eureka 配合使用时，Ribbon 可以自动从 Eureka Server 获取服务提供者地址列表，并基于负载均衡算法，请求其中某个服务提供者实例。Ribbon的依赖是：

       <dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-ribbon</artifactId></dependency>

但是 spring-cloud-starter-eureka 中已经包含了 ribbon 依赖，所以直接添加 eureka 即可。

2-1 eureka-sales

pom依赖，这里直接有 eureka 就行，eureka 已经包含了 ribbon 依赖：

 <dependencies><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-eureka</artifactId></dependency></dependencies><dependencyManagement><dependencies><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-parent</artifactId><version>Camden.SR3</version><type>pom</type><scope>import</scope></dependency></dependencies></dependencyManagement>

application.yml

server:port: 8081spring:application:name: saleseureka:client:serviceUrl: defaultZone: http://localhost:8761/eureka/instance:prefer-ip-address: true

启动类，这里把 RestTemplate 注册一下，并且加上 @LoadBalanced 开启负载均衡：

@SpringBootApplication
@EnableDiscoveryClient
public class SalesApplication {@Bean@LoadBalancedRestTemplate restTemplate() {return new RestTemplate();}public static void main(String[] args) {SpringApplication.run(SalesApplication.class,args);}}

调用 eureka-user 服务，其中 RIBBON_URL 中的 user 是eureka-user注册到eureka中心的名称，也就是 application.name ：

@Service
public class SalesService {@AutowiredRestTemplate restTemplate;private static final String RIBBON_URL = "http://user:8082/user/getUserInfo";private static final String IP = IpUtil.getIp();public String queryGoodsListByRibbon() {String sales_result = "queryGoodsListByRibbon success : [sales_ip:" + IP + "] ";String result = restTemplate.getForObject(RIBBON_URL, String.class);return sales_result + result;}
}

2-2 测试

1. 启动 eureka 2. 启动 eureka-sales 3.启动 eureka-user 4.修改 eureka-user 的 application.yml 文件，将端口改为8083，启动第二个 eureka-user 服务。

访问接口：http://127.0.0.1:8081/sales/queryGoodsList/1

此时以 ribbon 的方式访问10次，结果说明有进行负载均衡

3 feign方式

3-1 eureka-sales

pom依赖，添加 feign 依赖：

   <dependencies><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-eureka</artifactId></dependency><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-feign</artifactId></dependency></dependencies></build><dependencyManagement><dependencies><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-parent</artifactId><version>Camden.SR3</version><type>pom</type><scope>import</scope></dependency></dependencies></dependencyManagement>

application.yml

server:port: 8081spring:application:name: saleseureka:client:serviceUrl: defaultZone: http://localhost:8761/eureka/instance:prefer-ip-address: true

启动类，添加 @EnableFeignClients 注解：

@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
public class SalesApplication {@Bean@LoadBalancedRestTemplate restTemplate() {return new RestTemplate();}public static void main(String[] args) {SpringApplication.run(SalesApplication.class,args);}}

创建 feign client 接口，这里的 USER 是 eureka-user 在 eureka 中心的注册名称，里面的接口定义成跟 eureka-user（被调用服务）中的接口一样：

@FeignClient(name = "USER")
public interface UserFeignClient {@RequestMapping(value = "/user/getUserInfo", method = RequestMethod.GET)String getUserInfo();
}

调用 eureka-user 服务：

@Service
public class SalesService {@AutowiredUserFeignClient userFeignClient;private static final String IP = IpUtil.getIp();public String queryGoodsListByFeign() {String sales_result = "queryGoodsListByFeign success : [sales_ip:" + IP + "] ";String result = (String) userFeignClient.getUserInfo();return sales_result + result;}
}

3-2 测试

1. 启动 eureka 2. 启动 eureka-sales 3.启动 eureka-user 4.修改 eureka-user 的 application.yml 文件，将端口改为8083，启动第二个 eureka-user 服务。

访问接口：http://127.0.0.1:8081/sales/queryGoodsList/2

此时以 ribbon 的方式访问10次，结果说明有进行负载均衡

4 http方式

就是自己封装一个 httpclient 的 get 方法，然后访问：

http://127.0.0.1:8081/sales/queryGoodsList/3，然后观察结果，发现并没有自动进行负载均衡：

5 附录

eureka 项目：https://code.aliyun.com/995586041/eureka.git

eureka-sales 项目：https://code.aliyun.com/995586041/ribbon_feign_http_sales.git

eureka-user 项目：https://code.aliyun.com/995586041/ribbon_feign_http_user.git

core-simple 项目：https://code.aliyun.com/995586041/core-simple.git

上文中相关工具方法在 core-simple 中