springcloud-hystrix circuit breaker practice

1. Brief introduction

Hystrix is ​​a latency and fault-tolerant library designed to isolate access points to remote systems, services and third-party libraries, stop cascading failures, and achieve resilience in complex distributed systems where failures are inevitable.

2. Springboot integrated hystrix fusing practice

1. Import dependencies

        <!-- hystrix -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-hystrix</artifactId>
            <version>1.4.6.RELEASE</version>
        </dependency>

2. Method of writing circuit breaker

First of all, this is the code located in the service provider. When the hello method throws an exception, it uses the annotation @HystrixCommand(fallbackMethod = "Hystrix") to call the Hystrix method

    @RequestMapping("/findById")
    @HystrixCommand(fallbackMethod = "Hystrix")
    public User hello(Long id){
    
    
        User user = userService.findById(id);
        if (user==null){
    
    
            throw new RuntimeException("id => " + id + ",不存在该用户，或者信息无法找到");
        }
        return user;
    }

    //备选方法
    public User Hystrix(Long id){
    
    
        return new User()
                .setId(id)
                .setName("id => " + id + ",不存在该用户，或者信息无法找到")
                .setDb("no db ");
    }

3. Start the project in the startup class to support the fuse

@EnableCircuitBreaker means adding support for circuit breaker

package com.hzxy.springcloud;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;

@MapperScan("com.hzxy.springcloud.mapper")
@EnableDiscoveryClient       //服务发现
@EnableEurekaClient      //在服务启动后自动注册到Eureka中
@SpringBootApplication
@EnableCircuitBreaker     //添加对熔断的支持
public class HystrixProvider_8001 {
    
    
    public static void main(String[] args) {
    
    
        SpringApplication.run(HystrixProvider_8001.class,args);
    }
}

3. Test

Access the data contained in the database, it finds the result

When accessing data that the database does not have, it will execute the alternate method, as follows: The

test is successful!