SpringCloud教程 - 微服务熔断机制，断路器hystrix的使用
一，概念
二，hystrix的实际使用
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>cn.jorian.framework</groupId>
<artifactId>j-cloud-consumer-feign-hystrix</artifactId>
<version>1.0.0</version>
<name>j-cloud-consumer-feign-hystrix</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.4.RELEASE</version>
<relativePath /> <!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
<cloud.version>Dalston.SR1</cloud.version>
</properties>
<dependencies>
<!-- hystrix断路器 -->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-hystrix</artifactId>
</dependency>
<!-- hystrix断路器仪表盘 -->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-hystrix-dashboard</artifactId>
</dependency>
<!-- eureka 服务注册中心 -->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka</artifactId>
</dependency>
<!-- fegin -->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-feign</artifactId>
</dependency>
<!-- boot-web -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-test</artifactId>
<version>2.2.4.RELEASE</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.11</version>
<scope>test</scope>
</dependency>
<!--LOMBOK-->
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.16.20</version>
<scope>provided</scope>
</dependency>
</dependencies>
<!-- dependency management -->
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${cloud.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
</project>
4、控制器HelloController代码如下：
package cn.jorian.framework.controller;
import cn.jorian.framework.client.UserClient;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
/**
*
* @author jorian
*
*/
@RestController
public class HelloController {
@Autowired
public UserClient feignClient;
/**
* 此处的mapping是一级controller，
* 调用方法里边绑定了二级的conroller，相当于用http完成一次转发
* @return
*/
@GetMapping("/hello")
@HystrixCommand(fallbackMethod = "helloFallback")//失败时调用默认返回,
public String hello(){
return feignClient.hello();
}
@GetMapping("/hi")
@HystrixCommand(fallbackMethod = "hiFailBack") //失败时调用默认返回,demo中现在我们的客户端调用的接口实际是不存在，所以这个接口会返回下方的默认值
public String hi(){
return feignClient.sayHi();
}
@GetMapping("/haha")
@HystrixCommand(fallbackMethod = "hahaFailBack")//失败时调用默认返回,demo中现在我们的客户端调用的接口实际是不存在，所以这个接口会返回下方的默认值
public String haha(){
return feignClient.sayHaha();
}
/**
*
* 对应上面的方法，参数必须一致，当访问失败时，hystrix直接回调用此方法
* @return 失败调用时，返回默认值:
*/
public String helloFallback(){
return "您请求的数据没拿到，我是hystrix返回的默认数据--helloxxxx";
}
public String hiFailBack(){
return "您请求的数据没拿到，我是hystrix返回的默认数据--hixxxx";
}
public String hahaFailBack(){
return "您请求的数据没拿到，我是hystrix返回的默认数据--hahaxxxx";
}
}
5、feign客户端FeignClient代码如下：
package cn.jorian.framework.client;
import org.springframework.cloud.netflix.feign.FeignClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
/**
* @author: jorian
* @date: 2020/2/27 10:51
* @description: this is description for the class
*/
@FeignClient("provider-user")
public interface UserClient {
/**
* @FeignClient(value="provider-user") 应用名称
* Feign中没有原生的@GetMapping/@PostMapping/@DeleteMapping/@PutMapping，要指定需要用method进行
*
* 定义方法，方法上部使用 @RequestMapping(value="/sayHello",method= RequestMethod.GET)
* 映射转发请求
*/
@RequestMapping(value="/user/sayHello",method= RequestMethod.GET)
String hello();
@RequestMapping(value="/sayHi",method=RequestMethod.GET)
String sayHi();
@RequestMapping(value="/sayHaha",method=RequestMethod.GET)
String sayHaha();
}
6、应用启动器代码：
package cn.jorian.framework;
import org.springframework.boot.SpringApplication;
import org.springframework.cloud.client.SpringCloudApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.netflix.feign.EnableFeignClients;
import org.springframework.cloud.netflix.hystrix.dashboard.EnableHystrixDashboard;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.core.env.Environment;
import java.net.InetAddress;
import java.net.UnknownHostException;
import lombok.extern.slf4j.Slf4j;
@Slf4j
@SpringCloudApplication
@EnableEurekaClient
@EnableFeignClients
@EnableHystrixDashboard //开启仪表盘
public class JCloudConsumerFeignHystrixApplication {
public static void main(String[] args) throws UnknownHostException {
ConfigurableApplicationContext application = SpringApplication.run(JCloudConsumerFeignHystrixApplication.class, args);
Environment env = application.getEnvironment();
String ip = InetAddress.getLocalHost().getHostAddress();
String port = env.getProperty("server.port");
String path = env.getProperty("server.servlet.context-path");
log.info("\n----------------------------------------------------------\n\t" +
"Application is running! Access URLs:\n\t" +
"Local: \t\thttp://localhost:" + port + path + "/\n\t" +
"External: \thttp://" + ip + ":" + port + path + "/\n\t" +
"swagger-ui: \t\thttp://" + ip + ":" + port + path + "/doc.html\n" +
"HystrixDashboard: \t\thttp://" + ip + ":" + port + path + "/hystrix\n" +
"----------------------------------------------------------");
}
}
7、application.yml配置如下：
server:
port: 8003
servlet:
context-path:
spring:
application:
name: j-cloud-consumer-feign-hystrix
# eureka 配置
eureka:
client:
serviceUrl:
defaultZone: http://jorian:123456@localhost:8761/eureka
logging:
level:
root: INFO
8、依次启动j-cloud-server,j-cloud-provider1,j-cloud-provider2,j-cloud-consumer-feign-hystrix
9、在注册中心查看各个服务是否上线
10、测试
①先访问j-cloud-consumer-feign-hystrix中相应接口：http://localhost:8003/hello 可以看到正确的返回响应结果
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