容错保护就是当请求的服务报错或者超时时,可以优雅降级.介绍两种实现:
- RestTemplate 容错
- FeignClient 容错
1.RestTemplate 容错
pom.xml
<!-- hystrix 断路器 -->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
</dependency>
application.yml
spring:
application:
name: hystrix-client
server:
port: 8091
application.java
@EnableCircuitBreaker
@SpringBootApplication
public class HystrixClientApplication {
@Bean
@LoadBalanced
RestTemplate restTemplate(){
return new RestTemplate();
}
public static void main(String[] args) {
SpringApplication.run(HystrixClientApplication.class, args);
}
}
@EnableCircuitBreaker 开启断路器功能
HelloService.java
@Service
public class HelloService {
@Autowired
private RestTemplate template;
@HystrixCommand(fallbackMethod = "errorCallback")
public String hello(){
return template.getForObject("http://HELLO-SERVICE/hello",String.class);
}
public String errorCallback(){
return "error";
}
}
@HystrixCommand(fallbackMethod = "errorCallback")fallbackMethod 指定报错回调errorCallback错误回调方法
Controller.java
@RestController
@RequestMapping("hystrix")
public class HystrixHelloController {
@Autowired
private HelloService helloService;
@GetMapping("hi")
public String hi(){
return helloService.hello();
}
}
访问: http://localhost:8091/hystrix/hi
Hello World!
关闭服务在访问
访问: http://localhost:8091/hystrix/hi
error
2.FeignClient 容错
pom.xml
<!-- feign 声明式服务调用 -->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>
application.yml
spring:
application:
name: hystrix-client
server:
port: 8091
feign:
hystrix:
enabled: true
Application.java
@EnableFeignClients
@EnableCircuitBreaker
@SpringBootApplication
public class HystrixClientApplication {
@Bean
@LoadBalanced
RestTemplate restTemplate(){
return new RestTemplate();
}
public static void main(String[] args) {
SpringApplication.run(HystrixClientApplication.class, args);
}
}
必须同时开启断路器@EnableCircuitBreaker和feign客户端@EnableFeignClients
ServiceClient.java
@FeignClient(value = "hello-service", fallback = HystrixClientFallback.class)
public interface HelloServiceClient {
@RequestMapping(method = RequestMethod.GET, value = "/hello")
String hello();
}
fallback 指定回调的类
Fallback.java
@Component
public class HystrixClientFallback implements HelloServiceClient {
@Override
public String hello() {
return "error-feign";
}
}
访问: http://localhost:8091/hystrix/he
Hello World!
关闭服务再访问:
访问: http://localhost:8091/hystrix/he
error-feign