Spring Cloud Ribbon:负载均衡的服务调用
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,本文将对其用法进行详细介绍
Ribbon简介
Ribbon 是 Netflix 公司开源的一个用于负载均衡的客户端组件,它是 Spring Cloud 生态系统中的一部分;Ribbon 的主要目标是提供一种简单且可定制的负载均衡解决方案,用于在微服务架构中实现服务之间的调用和负载均衡
RestTemplate
RestTemplate 是 Spring Framework 提供的一个用于进行 HTTP 请求的客户端工具类;简化了在 Java 应用程序中进行 HTTP 通信的过程,并提供了丰富的方法来处理请求和响应
RestTemplate 提供了各种方法来执行不同类型的 HTTP 请求,包括 GET、POST、PUT、DELETE 等;支持发送请求并接收响应的各种数据类型,如字符串、字节数组、JSON 对象等
GET请求方法
<T> T getForObject(String url, Class<T> responseType, Object... uriVariables);<T> T getForObject(String url, Class<T> responseType, Map<String, ?> uriVariables);<T> T getForObject(URI url, Class<T> responseType);<T> ResponseEntity<T> getForEntity(String url, Class<T> responseType, Object... uriVariables);<T> ResponseEntity<T> getForEntity(String url, Class<T> responseType, Map<String, ?> uriVariables);<T> ResponseEntity<T> getForEntity(URI var1, Class<T> responseType);
POST请求方法
<T> T postForObject(String url, @Nullable Object request, Class<T> responseType, Object... uriVariables);<T> T postForObject(String url, @Nullable Object request, Class<T> responseType, Map<String, ?> uriVariables);<T> T postForObject(URI url, @Nullable Object request, Class<T> responseType);<T> ResponseEntity<T> postForEntity(String url, @Nullable Object request, Class<T> responseType, Object... uriVariables);<T> ResponseEntity<T> postForEntity(String url, @Nullable Object request, Class<T> responseType, Map<String, ?> uriVariables);<T> ResponseEntity<T> postForEntity(URI url, @Nullable Object request, Class<T> responseType);
PUT请求方法
void put(String url, @Nullable Object request, Object... uriVariables);void put(String url, @Nullable Object request, Map<String, ?> uriVariables);void put(URI url, @Nullable Object request);
DELETE请求方法
void delete(String url, Object... uriVariables);void delete(String url, Map<String, ?> uriVariables);void delete(URI url);
创建user-service模块
创建user-service,用于给Ribbon提供服务调用
- 添加依赖
<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>
- 添加application.yml配置
server:port: 8201 spring:application:name: user-service eureka:client:register-with-eureka: truefetch-registry: trueservice-url:defaultZone: http://localhost:8001/eureka/
- 添加UserController用于提供调用接口
/*** Created by macro on 2019/8/29.*/ @RestController @RequestMapping("/user") public class UserController {private Logger LOGGER = LoggerFactory.getLogger(this.getClass());@Autowiredprivate 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);} }
创建ribbon-service模块
创建ribbon-service模块调用user-service模块演示负载均衡的服务调用
- 添加依赖
<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-ribbon</artifactId> </dependency>
- 配置application.yml
配置端口、注册中心地址及user-service的调用路径
server:port: 8301 spring:application:name: ribbon-service eureka:client:register-with-eureka: truefetch-registry: trueservice-url:defaultZone: http://localhost:8001/eureka/ service-url:user-service: http://user-service
负载均衡
- @LoadBalanced注解赋予RestTemplate负载均衡的能力
/*** Created by macro on 2019/8/29.*/ @Configuration public class RibbonConfig {@Bean@LoadBalancedpublic RestTemplate restTemplate(){return new RestTemplate();} }
- 添加UserRibbonController类
注入RestTemplate,使用其调用user-service中提供的相关接口
/*** Created by macro on 2019/8/29.*/ @RestController @RequestMapping("/user") public class UserRibbonController {@Autowiredprivate 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);} }