简介

Spring Cloud Ribbon 是Spring Cloud Netflix 子项目的核心组件之一，主要给服务间调用及API网关转发提供负载均衡的功能，负载均衡可以增加系统的可用性和扩展性，当我们使用RestTemplate来调用其他服务时，Ribbon可以很方便的实现负载均衡功能。

项目搭建

项目源码

搭建服务提供模块

1、创建一个user-service，用于给Ribbon提供服务调用。
2、引入依赖

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

3、配置

server:
port: 8201
spring:
application:
name: user-service
eureka:
client:
register-with-eureka: true
fetch-registry: true
service-url:
defaultZone: http://localhost:8001/eureka/

4、创建服务提供接口

@RestController
@RequestMapping("/user")
public class UserController {

private Logger LOGGER = LoggerFactory.getLogger(this.getClass());

@Autowired
private UserService userService;

@PostMapping("/create")
public CommonResult create(@RequestBody User user) {
userService.create(user);
return new CommonResult("操作成功", 200);
}

@GetMapping("/{id}")
public CommonResult<User> getUser(@PathVariable Long id) {
User user = userService.getUser(id);
LOGGER.info("根据id获取用户信息，用户名称为：{}",user.getUsername());
return new CommonResult<>(user);
}

@GetMapping("/getUserByIds")
public CommonResult<List<User>> getUserByIds(@RequestParam List<Long> ids) {
List<User> userList= userService.getUserByIds(ids);
LOGGER.info("根据ids获取用户信息，用户列表为：{}",userList);
return new CommonResult<>(userList);
}

@GetMapping("/getByUsername")
public CommonResult<User> getByUsername(@RequestParam String username) {
User user = userService.getByUsername(username);
return new CommonResult<>(user);
}

@PostMapping("/update")
public CommonResult update(@RequestBody User user) {
userService.update(user);
return new CommonResult("操作成功", 200);
}

@PostMapping("/delete/{id}")
public CommonResult delete(@PathVariable Long id) {
userService.delete(id);
return new CommonResult("操作成功", 200);
}
}

搭建服务调用模块

同样的步骤
1、引入依赖

<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-ribbon</artifactId>
</dependency>

2、修改配置

server:
port: 8301
spring:
application:
name: ribbon-service
zipkin:
base-url: http://localhost:9411
sleuth:
sampler:
probability: 0.1 #设置Sleuth的抽样收集概率
eureka:
client:
register-with-eureka: true
fetch-registry: true
service-url:
defaultZone: http://localhost:8001/eureka/
service-url:
user-service: http://user-service

3、服务调用

@RestController
@RequestMapping("/user")
public class UserRibbonController {
@Autowired
private RestTemplate restTemplate;
@Value("${service-url.user-service}")
private String userServiceUrl;

@GetMapping("/{id}")
public CommonResult getUser(@PathVariable Long id) {
return restTemplate.getForObject(userServiceUrl + "/user/{1}", CommonResult.class, id);
}

@GetMapping("/getByUsername")
public CommonResult getByUsername(@RequestParam String username) {
return restTemplate.getForObject(userServiceUrl + "/user/getByUsername?username={1}", CommonResult.class, username);
}

@GetMapping("/getEntityByUsername")
public CommonResult getEntityByUsername(@RequestParam String username) {
ResponseEntity<CommonResult> entity = restTemplate.getForEntity(userServiceUrl + "/user/getByUsername?username={1}", CommonResult.class, username);
if (entity.getStatusCode().is2xxSuccessful()) {
return entity.getBody();
} else {
return new CommonResult("操作失败", 500);
}
}

@PostMapping("/create")
public CommonResult create(@RequestBody User user) {
return restTemplate.postForObject(userServiceUrl + "/user/create", user, CommonResult.class);
}

@PostMapping("/update")
public CommonResult update(@RequestBody User user) {
return restTemplate.postForObject(userServiceUrl + "/user/update", user, CommonResult.class);
}

@PostMapping("/delete/{id}")
public CommonResult delete(@PathVariable Long id) {
return restTemplate.postForObject(userServiceUrl + "/user/delete/{1}", null, CommonResult.class, id);
}
}

负载均衡功能演示

1、启动eureka-server于8001端口；
2、启动Ribbon-service于8301端口；
3、启动两个user-service，分别用8201和8202端口

4、调用接口进行测试：http://localhost:8301/user/1