①. Feign的概述

1>. Feign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 掌握

②. Feign的基本使用

2>. Feign的基本使用(Feign在消费端使用)

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 ⑦. 小总结：

③. OpenFeign超时控制

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

NONE:默认的,不显示任何日志BASIC：仅记录请求方法、URL\响应状态码及执行时间HEADERS：除了BASIC中定义的信息之外,还又请求和响应的头信息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