[Java知识库]SpringCloud04_OpenFeign的概述(远程调用)、基本使用、超时控制、日志打印功能

①. OpenFeign的概述

• ①. Feign是一个服务接口的绑定器,(接口+@FeignClient(value=“服务名称”)) 接口与接口之间的一个调用

• ②. Feign集成了Ribbon。利用Ribbon维护了Payment的服务列表信息,并且通过轮询实现了客户端的负载均衡。而与Ribbon不同的是,通过feign值需要定义服务绑定接口且以声明式的方法,优雅而简单的实现了服务调用
  

• ③. Feign和OpenFeign的区别
  

• ④. SpringMvc中能用的在Feign中都能使用
  

②. Feign的基本使用(消费端)

• ①.新建 cloud-consumer-feign-order80

• ②. pom

    <!--openfeign-->
    <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-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>com.atguigu.springcloud</groupId>
            <artifactId>cloud-api-commons</artifactId>
            <version>${project.version}</version>
        </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>
    </dependencies>

• ③.yml

server:
  port: 80
eureka:
  client:
    register-with-eureka: false
    service-url:
      defaultZone: http://eureka7001.com:7001/eureka, http://eureka7002.com:7002/eureka

• ④. 主启动类:@EnableFeignClients

@SpringBootApplication
@EnableFeignClients
public class OrderFeignMain80 {
    public static void main(String[] args) {
        SpringApplication.run(OrderFeignMain80.class,args);
    }
}
 

• ⑤. 业务类

@Component
@FeignClient(value = "CLOUD-PAYMENT-SERVICE")
public interface PaymentFeignService {

    @GetMapping("/payment/get/{id}")
    public CommonResult<Payment> getPaymentById(@PathVariable("id") Long id);

    @GetMapping("/payment/feign/timeout")
    public String paymentFeignTimeOut();
}

@RestController
@RequestMapping("/feignClient")
public class OrderFeignController {

    @Autowired
    private PaymentFeignService paymentFeignService;

    @GetMapping("/payment/getPaymentById/{id}")
    public CommonResult<Payment>getPaymentById(@PathVariable("id") Long id){
        return paymentFeignService.getPaymentById(id);
    }
}

• ⑥. 测试
  先启动2个eureka集群7001/7002
  再启动2个微服务8001/8002
  启动OpenFeign启动
  http://localhost/consumer/payment/get/31
  Feign自带负载均衡配置项
  
• ⑦. 小总结:
  

③. OpenFeign超时控制

• ①. 超时设置,故意设置超时演示出错情况。由于Feign的默认超时时间是1s,这里我们在8001、8002中写一个方法,在方法中停顿3s
  

• ②. OpenFeign默认等待一秒钟,超过后报错

YML文件里需要开启OpenFeign客户端超时控制
ribbon:
  #指的是建立连接所用时间,适用于网络状况正常情况下,两端连接所用时间
  ReadTimeout:  5000
  #指的是建立连接后从服务器读取可用资源所用时间
  ConnectTimeout: 5000

@Component
@FeignClient(value = "CLOUD-PAYMENT-SERVICE")
public interface PaymentFeignService {

    @GetMapping("/payment/getPaymentById/{id}")
    public CommonResult<Payment> getPaymentById(@PathVariable("id")Long id);

    @GetMapping("/payment/timeout")
    public String timeout();
}

• ③. 进行了上述②的配置后,再次访问:不会出现错误页面,会等待3s后出现结果

④. OpenFeign日志打印功能

• ①. Feign提供了日志打印功能,我们可以通过配置来调整日志级别,从而了解Feign中Http请求的细节。说白了就是对Feign接口的调用情况进行监控和输出

• ②. 日志级别

1. NONE:默认的,不显示任何日志
2. BASIC:仅记录请求方法、URL\响应状态码及执行时间
3. HEADERS:除了BASIC中定义的信息之外,还又请求和响应的头信息
4. FULL:除了HEADERS中定义的信息之外,还又请求和响应的正文及元数据

• ③. 配置日志bean

@Configuration
public class FeignConfig {
    @Bean
    Logger.Level feignLoggerLevel(){
        return Logger.Level.FULL;
    }
}

• ④. YML文件里需要开启日志的Feign客户端

logging:
  level:
    com.atguigu.springcloud.service.PaymentFeignService: debug

• ⑤. 后台日志查看