是什么

把需要暴露的api使用接口来暴露，客户端需要调用的时候，直接查看这个接口中有没有就可以了

通用步骤

架构说明

common模块

common 引入 openfeign

新建服务接口类

@FeignClient(value = "cloud-payment-service") // 服务名
public interface PayFeignApi {

    @PostMapping("/pay/add")
    public Result<Integer> addPay(@RequestBody PayDTO payDTO);

    @GetMapping("/pay/get/{id}")
    public Result<PayDTO> getById(@PathVariable("id") Integer id); // 必须指明 PathVariable 的 value

    @GetMapping("/pay/getInfo")
    public Result<String> getInfo();
}

客户端

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>

主启动类 @EnableFeignClients

使用

@RestController
public class OrderController {

    @Resource
    private PayFeignApi payFeignApi;

    @GetMapping("/consumer/pay/add")
    public Result addOrder(PayDTO payDTO) {
        return payFeignApi.addPay(payDTO);
    }

    @GetMapping("/consumer/pay/get/{id}")
    public Result<PayDTO> getPayByOrderNo(@PathVariable("id") Integer id) {
        return payFeignApi.getById(id);
    }

    @GetMapping("/consumer/pay/getInfo")
    public Result<String> getInfoByConsul() {
        return payFeignApi.getInfo();
    }
}

最后一个案例可以看到，openfeign 天生支持负载均衡

OpenFeign高级特性

日志打印

// 日志记录级别
    @Bean
    public Logger.Level feignLoggerLevel() {
        return Logger.Level.FULL;
    }

超时控制

测试超时时间异常

@GetMapping("/consumer/pay/getInfo")
    public Result<String> getInfoByConsul() {
        Result<String> result = null;
        try {
            System.out.println("调用开始: " + DateUtil.now());
            result = payFeignApi.getInfo();
        } catch (Exception e) {
            e.printStackTrace();
            System.out.println("调用结束: " + DateUtil.now());
            Result.fail(ReturnCodeEnum.RC500.getCode(), e.getMessage());
        }
        return result;
    }

read-timeout 默认 60s

如何调整

全局配置

调整后测试，发现3s后就异常返回

手动配置(服务级别)

同时存在，细粒度的覆盖粗粒度的

重试机制

性能优化HttpClient5替换

<dependency>
    <groupId>io.github.openfeign</groupId>
    <artifactId>feign-hc5</artifactId>
    <version>13.1</version>
</dependency>
<dependency>
    <groupId>org.apache.httpcomponents.client5</groupId>
    <artifactId>httpclient5</artifactId>
    <version>5.3.1</version>
</dependency>

spring:
  cloud:
    openfeign:
      httpclient:
        hc5:
          enabled: true

HttpClient5 开启

替换以后

请求回应压缩

spring:
  cloud:
    openfeign:
      compression:
        request:
          enabled: true
          mime-types: text/xml,application/xml,application/json
          min-request-size: 2048
        response:
          enabled: true