SpringCloud 实战十四：Hystrix服务降级

cloud-provider-hystrix-payment8001服务模块

1、引入依赖

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>cloud2020</artifactId>
        <groupId>com.laoxu.springcloud</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>cloud-provider-hystrix-payment8001</artifactId>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
        </dependency>
        <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>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>com.laoxu.springcloud</groupId>
            <artifactId>cloud-api-common</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
    </dependencies>

</project>

2、配置端口

server:
  port: 8001
spring:
  application:
    name: cloud-provier-hystrix-payment

eureka:
  client:
    fetch-registry: true
    register-with-eureka: true
    service-url:
      defualtZone: http://eureka7001.com:7001/eureka

3、创建启动类

package com.laoxu.springcloud;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;

@SpringBootApplication
@EnableEurekaClient
public class PaymentHystrixMain8001 {
    public static void main(String[] args) {
        SpringApplication.run(PaymentHystrixMain8001.class, args);
    }
}

4、业务层

package com.laoxu.springcloud.service;

import org.springframework.stereotype.Service;

import java.util.concurrent.TimeUnit;

@Service
public class PaymentService {

    //正常访问返回ok的方法
    public String paymentInfo_OK(Integer id){
        return "线程池：" + Thread.currentThread().getName() + "paymentInfo_OK, id:" + id + "\t" + "哈哈";
    }

    public String paymentInfo_Timeout(Integer id){
        long second = 3;
        try {
            TimeUnit.SECONDS.sleep(second);
        }catch (InterruptedException e){
            e.printStackTrace();
        }
        return "线程池：" + Thread.currentThread().getName() + "paymentInfo_Timeout, id:" + id + "\t" + "哈哈" + "耗时" +second+"秒钟";
    }

}

package com.laoxu.springcloud.controller;

import com.laoxu.springcloud.service.PaymentService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

@RestController
@Slf4j
public class PaymentController {

    @Autowired
    private PaymentService paymentService;

    @Value("${server.port}")
    private String serverPort;

    @GetMapping("/payment/hystrix/ok/{id}")
    public String paymentInfo_OK(@PathVariable("id") Integer id){
        String result = paymentService.paymentInfo_OK(id);
        log.info("******result: " + result);
        return result;
    }


    @GetMapping("/payment/hystrix/timeout/{id}")
    public String paymentInfo_Timeout(@PathVariable("id") Integer id){
        String result = paymentService.paymentInfo_Timeout(id);
        log.info("******result: " + result);
        return result;
    }

}

5、启动服务

6、测试

访问 http://localhost:8001/payment/hystrix/ok/31

访问 http://localhost:8001/payment/hystrix/timeout/31

cloud-consumer-feign-hystrix-order80服务模块

1、引入依赖

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>cloud2020</artifactId>
        <groupId>com.laoxu.springcloud</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>cloud-consumer-feign-hystrix-order80</artifactId>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
        </dependency>
        <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>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>com.laoxu.springcloud</groupId>
            <artifactId>cloud-api-common</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
    </dependencies>

</project>

2、配置端口

server:
  port: 80
spring:
  application:
    name: cloud-consumer-feign-hystrix-order

eureka:
  client:
    # 将自己注册进eureka中心
    register-with-eureka: false
    service-url:
      defaultZone: http://eureka7001.com:7001/eureka, http://eureka7002.com:7002/eureka

3、创建启动类

package com.laoxu.springcloud;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.openfeign.EnableFeignClients;

@SpringBootApplication
@EnableFeignClients
public class OrderHystrixMain80 {
    public static void main(String[] args) {
        SpringApplication.run(OrderHystrixMain80.class, args);
    }
}

4、创建控制器

package com.laoxu.springcloud.service;

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.stereotype.Component;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;

@Component
@FeignClient(value = "CLOUD-PROVIDER-HYSTRIX-PAYMENT")
public interface PaymentHystrixService {

    @GetMapping("/payment/hystrix/ok/{id}")
    public String paymentInfo_OK(@PathVariable("id") Integer id);

    @GetMapping("/payment/hystrix/timeout/{id}")
    public String paymentInfo_Timeout(@PathVariable("id") Integer id);
}

package com.laoxu.springcloud.controller;

import com.laoxu.springcloud.service.PaymentHystrixService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

@RestController
@Slf4j
public class OrderHystrixController {

    @Autowired
    private PaymentHystrixService paymentHystrixService;

    @GetMapping("/consumer/payment/hystrix/ok/{id}")
    public String paymentInfo_OK(@PathVariable("id") Integer id){
        String result = paymentHystrixService.paymentInfo_OK(id);
        return result;

    }


    @GetMapping("/consumer/payment/hystrix/timeout/{id}")
    public String paymentInfo_Timeout(@PathVariable("id") Integer id){
        String result = paymentHystrixService.paymentInfo_Timeout(id);
        return result;
    }

}

5、测试

访问：http://localhost/consumer/payment/hystrix/ok/31 成功

访问：http://localhost/consumer/payment/hystrix/timeout/31 超时

解决方案：服务降级

相当于：try{  当前服务  }catch{  降级服务  }

• 修改服务提供者模块：cloud-provider-hystrix-payment

原服务层：

package com.laoxu.springcloud.service;

import org.springframework.stereotype.Service;

import java.util.concurrent.TimeUnit;

@Service
public class PaymentService {

    //正常访问返回ok的方法
    public String paymentInfo_OK(Integer id){
        return "线程池：" + Thread.currentThread().getName() + "paymentInfo_OK, id:" + id + "\t" + "哈哈";
    }

    public String paymentInfo_Timeout(Integer id){
        long second = 3;
        try {
            TimeUnit.SECONDS.sleep(second);
        }catch (InterruptedException e){
            e.printStackTrace();
        }
        return "线程池：" + Thread.currentThread().getName() + "paymentInfo_Timeout, id:" + id + "\t" + "哈哈" + "耗时" +second+"秒钟";
    }

}

添加降级服务：

package com.laoxu.springcloud.service;

import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixProperty;
import org.springframework.stereotype.Service;

import java.util.concurrent.TimeUnit;

@Service
public class PaymentService {

    //正常访问返回ok的方法
    public String paymentInfo_OK(Integer id){
        return "线程池：" + Thread.currentThread().getName() + "paymentInfo_OK, id:" + id + "\t" + "哈哈";
    }

    @HystrixCommand(fallbackMethod = "paymentInfo_TimeoutHandler", commandProperties = {
            @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "2000")
    })
    public String paymentInfo_Timeout(Integer id){
        long second = 3;
        try {
            TimeUnit.SECONDS.sleep(second);
        }catch (InterruptedException e){
            e.printStackTrace();
        }
        return "线程池：" + Thread.currentThread().getName() + "paymentInfo_Timeout, id:" + id + "\t" + "哈哈" + "耗时" +second+"秒钟";
    }

    public String paymentInfo_TimeoutHandler(Integer id){
        return "线程池：" + Thread.currentThread().getName() + "paymentInfo_Timeout, id:" + id + "\t" + "系统繁忙！请稍后再试！！";
    }


}

@HystrixCommand 指定降级服务

@HystrixProperty 指定超时时间，这里表示等待2秒后则会直接调用降级服务(paymentInfo_TimeoutHandler)并返回

• 在启动类添加注解开启服务降级

package com.laoxu.springcloud;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;

@SpringBootApplication
@EnableEurekaClient
@EnableCircuitBreaker
public class PaymentHystrixMain8001 {
    public static void main(String[] args) {
        SpringApplication.run(PaymentHystrixMain8001.class, args);
    }
}

• 重启服务：cloud-provider-hystrix-payment

• 测试超时异常
• 访问：http://localhost:8001/payment/hystrix/timeout/31

调用降级服务：

• 测试运行异常

• 修改代码，故意制造运行异常

package com.laoxu.springcloud.service;

import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixProperty;
import org.springframework.stereotype.Service;

import java.util.concurrent.TimeUnit;

@Service
public class PaymentService {

    //正常访问返回ok的方法
    public String paymentInfo_OK(Integer id){
        return "线程池：" + Thread.currentThread().getName() + "paymentInfo_OK, id:" + id + "\t" + "哈哈";
    }

    @HystrixCommand(fallbackMethod = "paymentInfo_TimeoutHandler", commandProperties = {
            @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "2000")
    })
    public String paymentInfo_Timeout(Integer id){
//        long second = 3;
//        try {
//            TimeUnit.SECONDS.sleep(second);
//        }catch (InterruptedException e){
//            e.printStackTrace();
//        }
        int age = 10/0;
        return "线程池：" + Thread.currentThread().getName() + "paymentInfo_Timeout, id:" + id + "\t" + "哈哈";
    }

    public String paymentInfo_TimeoutHandler(Integer id){
        return "线程池：" + Thread.currentThread().getName() + "paymentInfo_Timeout, id:" + id + "\t" + "系统繁忙！请稍后再试！！";
    }


}

• 访问：http://localhost:8001/payment/hystrix/timeout/31

调用降级服务：

一般服务降级放在消费者，这里服务降级是放在服务提供者。

-----------------------------------------------------------------

全局服务降级方法

1. 添加全局fallback方法：payment_Globle_FallbackMethod
2. 添加全局注解指定默认降级方法@DefaultProperties(defaultFallback = "payment_Globle_FallbackMethod")
3. 在需要服务降级的接口上方添加注解@HystrixCommand即可启动服务降级
4. paymentInfo_Timeout方法已经指定了特定的服务降级，那么只会调用特定的服务降级方法，不会调用默认的服务降级方法
5. 全局服务降级避免了代码膨胀，合理的减少了代码量

修改服务层：

package com.laoxu.springcloud.service;

import com.netflix.hystrix.contrib.javanica.annotation.DefaultProperties;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixProperty;
import org.springframework.stereotype.Service;

import java.util.concurrent.TimeUnit;

@Service
@DefaultProperties(defaultFallback = "payment_Globle_FallbackMethod")
public class PaymentService {

    //正常访问返回ok的方法
    @HystrixCommand
    public String paymentInfo_OK(Integer id){
        int age = 10/0;
        return "线程池：" + Thread.currentThread().getName() + "paymentInfo_OK, id:" + id + "\t" + "哈哈";
    }

    @HystrixCommand(fallbackMethod = "paymentInfo_TimeoutHandler", commandProperties = {
            @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "2000")
    })
    public String paymentInfo_Timeout(Integer id){
        long second = 3;
        try {
            TimeUnit.SECONDS.sleep(second);
        }catch (InterruptedException e){
            e.printStackTrace();
        }
        return "线程池：" + Thread.currentThread().getName() + "paymentInfo_Timeout, id:" + id + "\t" + "哈哈" + "耗时" +second+"秒钟";
    }

    public String paymentInfo_TimeoutHandler(Integer id){
        return "线程池：" + Thread.currentThread().getName() + "paymentInfo_Timeout, id:" + id + "\t" + "系统繁忙！请稍后再试！！";
    }

    //全局fallback方法
    public String payment_Globle_FallbackMethod(){
        return "系统繁忙！请稍后再试！！";
    }
}

访问：http://localhost:8001/payment/hystrix/ok/31