SpringCloud（19）：Sentinel：Rest实现服务降级

淡淡的烟草味﹌ 2022-10-25 01:20 151阅读 0赞

### 一、准备工作 ###

需要启动Nacos和Sentinel。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMjk4MzUx_size_16_color_FFFFFF_t_70][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMjk4MzUx_size_16_color_FFFFFF_t_70 1][]

### 二、服务提供者 ###

（1）导入依赖

<?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>springcloud</artifactId>
            <groupId>com.buba</groupId>
            <version>1.0-SNAPSHOT</version>
        </parent>
        <modelVersion>4.0.0</modelVersion>
    
        <artifactId>provider-8101</artifactId>
    
        <dependencies>
            
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
            
            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
            </dependency>
            
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-actuator</artifactId>
            </dependency>
        </dependencies>
    </project>

（2）application.yml配置文件

server:
      port: 8101
    spring:
      application:
        name: provider
      cloud:
        # nocos注册中心
        nacos:
          discovery:
            server-addr: localhost:8848
    management:
      endpoints:
        web:
          exposure:
            include: "*"

（3）业务逻辑代码

package com.buba.springcloud.controller;
    
    
    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
    public class HelloController {
        @Value("${server.port}")
        private String serverPort;
    
        @GetMapping(value = "/provider/get/{id}")
        public String getPayment(@PathVariable("id") Integer id) {
            return "Nacos的注册中心的端口是：: " + serverPort + ",id是：" + id;
        }
    
    }

（4）启动类

package com.buba.springcloud;
    
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
    
    
    @SpringBootApplication
    @EnableDiscoveryClient
    public class Provider_8101 {
        public static void main(String[] args) {
            SpringApplication.run(Provider_8101.class, args);
        }
    }

### 三、服务消费者 ###

（1）导入依赖

<?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>springcloud</artifactId>
            <groupId>com.buba</groupId>
            <version>1.0-SNAPSHOT</version>
        </parent>
        <modelVersion>4.0.0</modelVersion>
    
        <artifactId>consumer-80</artifactId>
    
        <dependencies>
            
            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
            </dependency>
            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-starter-alibaba-sentinel</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>
        </dependencies>
    </project>

（2）application.yml配置文件

server:
      port: 80
    spring:
      application:
        name: consumer
      cloud:
        # nocos注册中心
        nacos:
          discovery:
            server-addr: localhost:8848
        sentinel:
          transport:
            # 配置Sentinel Dashboard地址
            dashboard: 127.0.0.1:8080
            # 默认8719端口，假设被占用会自动从8719开始依次加1扫描，直到找到没有被占用的端口
            port: 8719
          # 取消懒加载
          eager: true
    
    management:
      endpoints:
        web:
          exposure:
            include: '*'

（3）业务逻辑代码

package com.buba.springcloud.util;
    
    import com.alibaba.csp.sentinel.slots.block.BlockException;
    
    public class ExceptionUtils {
        public static String handleBlock(Integer id, BlockException ex) {
            return "熔断降级";
        }
    
        public static String handleFallback(Integer id, Throwable tx) {
            return "异常降级";
        }
    }

package com.buba.springcloud.config;
    
    import org.springframework.cloud.client.loadbalancer.LoadBalanced;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.web.client.RestTemplate;
    
    @Configuration
    public class SpringConfig {
    
        @LoadBalanced
        @Bean
        public RestTemplate restTemplate() {
            return new RestTemplate();
        }
    
    }

package com.buba.springcloud.controller;
    
    import com.alibaba.csp.sentinel.annotation.SentinelResource;
    import com.buba.springcloud.util.ExceptionUtils;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.cloud.client.loadbalancer.LoadBalanced;
    import org.springframework.context.annotation.Bean;
    import org.springframework.web.bind.annotation.GetMapping;
    import org.springframework.web.bind.annotation.PathVariable;
    import org.springframework.web.bind.annotation.RestController;
    import org.springframework.web.client.RestTemplate;
    
    @RestController
    public class HelloController {
    
        private RestTemplate restTemplate;
    
        @GetMapping(value = "/order/{id}")
        @SentinelResource(blockHandlerClass = ExceptionUtils.class, blockHandler = "handleBlock", fallbackClass = ExceptionUtils.class, fallback = "handleFallback")
        public String order(@PathVariable(value = "id") Integer id) {
            if (4 == id) {
                throw new IllegalArgumentException("非法参数异常");
            }
            return this.restTemplate.getForObject("http://provider" + "/provider/get/" + id, String.class);
        }
    
        @Autowired
        public void setRestTemplate(RestTemplate restTemplate) {
            this.restTemplate = restTemplate;
        }
    }

（4）启动类

package com.buba.springcloud;
    
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
    
    @SpringBootApplication
    @EnableDiscoveryClient
    public class Consumer_80 {
        public static void main(String[] args) {
            SpringApplication.run(Consumer_80.class, args);
        }
    }

（5）启动测试

访问地址[http://localhost/order/1][http_localhost_order_1]

![20210130150145784.png][]

访问地址[http://localhost/order/4][http_localhost_order_4]

![20210130150212556.png][]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMjk4MzUx_size_16_color_FFFFFF_t_70]: /images/20221024/229b33e23d29427c9d0b0ea4a0402ce2.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMjk4MzUx_size_16_color_FFFFFF_t_70 1]: /images/20221024/8785bdcbcf74421d98d02553087d41c4.png
[http_localhost_order_1]: http://localhost/order/1
[20210130150145784.png]: /images/20221024/da8222cf18e34c0aa4b4579d0461acea.png
[http_localhost_order_4]: http://localhost/order/4
[20210130150212556.png]: /images/20221024/06acdde865dc4134a30da9864192f79f.png