springcloud之OpenFeign

openFeign是用来进行服务调用的，功能和restTemplate相似。
相比restTemplate，openFeign更加方便。
Feign是一个声明式的web服务客户端，让编写web服务客户端变得非常容易，只需创建一个接口并在接口上添加注解即可。

新建模块Consumer-feign-80
pom

<?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-2020</artifactId>
        <groupId>com.mql</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>Consumer-feign-80</artifactId>

    <!--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.mql</groupId>
            <artifactId>cloud-api-commons</artifactId>
            <version>1.0-SNAPSHOT</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>
</project>

yml

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

启动类

@SpringBootApplication
@EnableFeignClients
public class ConsumerFeign80 {
    public static void main(String[] args) {
        SpringApplication.run(ConsumerFeign80.class,args);
    }
}

服务调用接口

@Component
@FeignClient(value = "CLOUD-PROVIDER-SERVICE")//服务名
public interface PaymentFeignService {

    @GetMapping(value = "/payment/get/{id}")
    CommonResult getPaymentById(@PathVariable("id") Long id);
   
}

@RestController
@Slf4j
public class FeignController {
    @Resource
    private PaymentFeignService paymentFeignService;

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

启动7001 7002注册中心8001 8002提供者
测试

OpenFeign默认等待—秒钟，超过后报错
改造8001Controller
添加方法

    @GetMapping(value = "/payment/feign/timeout")
    public String paymentFeignTimeout(){
        try { TimeUnit.SECONDS.sleep(3); }catch (Exception e) {e.printStackTrace();}
        System.out.println(serverPort);
        return serverPort;
    }

改造消费者服务调用接口和控制器，添加方法

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

    @GetMapping(value = "/payment/get/{id}")
    CommonResult getPaymentById(@PathVariable("id") Long id);

    @GetMapping(value = "/payment/feign/timeout")
    public String paymentFeignTimeout();

}

@RestController
@Slf4j
public class FeignController {
    @Resource
    private PaymentFeignService paymentFeignService;

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

    @GetMapping(value = "/consumer/payment/feign/timeout")
    public String paymentFeignTimeout(){
        return paymentFeignService.paymentFeignTimeout();
    }

}

测试

默认一秒。yml文件中配置

ribbon:
  ReadTimeout:  5000
  ConnectTimeout: 5000

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中说白了就是对Feign接口的调用情况进行监控和输出。

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，还有请求和响应的头信息
FULL:除了HEADERS中定义的信息之外，还有请求和响应的正文及元数据

配置对象

@Configuration
public class FeignConfig {

    @Bean
    Logger.Level feignLoggerLevel(){
        return Logger.Level.FULL;
    }
}

yml文件开启日志客户端

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

测试