Spring Cloud 整合 Nacos、Sentinel、OpenFigen 实战【微服务熔断降级实战】

在Spring Cloud整合Nacos、Sentinel和OpenFeign的实践中，我们可以通过以下步骤实现微服务的熔断降级：

1. 引入相关依赖：

<!-- Nacos Discovery -->
<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
</dependency>
<!-- Sentinel -->
<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
</dependency>
<!-- OpenFeign -->
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>

2. 配置application.yml文件，加入Nacos和Sentinel配置：

spring:
  cloud:
    nacos:
      discovery:
        server-addr: 127.0.0.1:8848
    sentinel:
      transport:
        dashboard: 127.0.0.1:8080
        port: 8719

3. 在启动类上添加@EnableFeignClients和@EnableCircuitBreaker注解：

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

4. 创建Feign客户端接口，并使用@FeignClient注解指定服务名称，并用@GetMapping等注解指定请求的URL和方法：

@FeignClient(value = "service-provider")
public interface ProviderClient {
    @GetMapping("/greeting")
    String greeting(@RequestParam(value = "name") String name);
}

5. 在业务代码中使用@SentinelResource注解指定资源，并配置熔断降级策略：

@RestController
public class ConsumerController {
 
    @Autowired
    private ProviderClient providerClient;
 
    @GetMapping("/doGreeting")
    @SentinelResource(value = "doGreeting", blockHandler = "handleFallback")
    public String doGreeting(@RequestParam String name) {
        return providerClient.greeting(name);
    }
 
    public String handleFallback(String name, BlockException ex) {
        return "Error: " + ex.getMessage();
    }
}

以上步骤展示了如何在Spring Cloud应用中整合Nacos作为服务注册与发