Use of hystrix

Hystrix Project use

To configure pom.xml rely on

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

To configure RestTemplate object

@Configuration
public class RestTemplateConfiguration {
    
	@Bean
	public RestTemplate create() {
    
		return new RestTemplate();
	}
}

Add test class

@RestController
public class HystrixController {
    
	@Autowired
	private RestTemplate restTemplate;
	
	@HystrixCommand(fallbackMethod = "failCallHello")
	@GetMapping("/hello")
	public String callHello() {
    
	    String result = restTemplate.getForObject("http://192.168.1.55:8081/hello", String.class);
	    return result;
	}
	
	public String failCallHello() {
    
		return "Fail";
	}
	
	@HystrixCommand(fallbackMethod = "failCallHello", commandProperties = {
    
			@HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "5000") })
	@GetMapping("/hello2")
	public String callHello2() {
    
		String result = "Ok";
		try {
    
			TimeUnit.SECONDS.sleep(2);
		} catch (InterruptedException e) {
    
			e.printStackTrace();
		}
		return result;
	}
}

• /hello The test program is abnormal
• /hello2 Test timeout exception

Activate Hystrix, Start the class to add comments @EnableHystrix

@EnableHystrix
@SpringBootApplication
public class Application {
    

	public static void main(String[] args) {
    
		SpringApplication.run(Application.class, args);
	}
}

Get ready

start-up Eureka service , And register two applications as test cluster machines , As shown in the figure ; Test interface /hello

Feign Project use

Then add the configuration pom.xml rely on

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

encapsulation Feign Interface ,eureka-provider-app To register to Eureka Service name in

@FeignClient(value = "eureka-provider-app", fallback = TestClientFailBack.class)
public interface TestClient {
    
	@GetMapping("/hello")
	String hello();
}

TestClientFailBack Failure handling strategy

@Component
public class TestClientFailBack implements TestClient{
    
	@Override
	public String hello() {
    
		return "FAIL_fail";
	}
}

Add test class

@RestController
public class TestController {
    
	@Autowired
	private TestClient client;

	@GetMapping("/test")
	public String test() {
    
		String result = client.hello();
		return result;
	}
}

Activate Feign To configure

@EnableFeignClients(basePackageClasses = {
    TestClient.class})
@EnableHystrix
@SpringBootApplication
public class Application {
    

	public static void main(String[] args) {
    
		SpringApplication.run(Application.class, args);
	}

}

The configuration file application.properties add to Eureka Registration configuration , start-up feign And hystrix Integrate

eureka.client.serviceUrl.defaultZone=http://192.168.1.55:8761/eureka/
feign.hystrix.enabled=true```

 Add test class 

```java
@RestController
public class TestController {
    
	@Autowired
	private TestClient client;

	@GetMapping("/test")
	public String test() {
    
		String result = client.hello();
		return result;
	}
}

test , Successful test

Stop the app , test