（二）声明式REST客户端Feign

Feign：一个声明式的REST客户端，它能让REST调用更加简单。

Spring cloud集成Feign

1. 搭建Spring cloud的基本环境

参考：https://blog.csdn.net/admin_15082037343/article/details/106959438

1. 在demo-client中添加依赖

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

1. 启动类添加注解@EnableFeignClients

package com.demo.client;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.openfeign.EnableFeignClients;

@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
public class ClientApplication {

    public static void main(String[] args) {
        SpringApplication.run(ClientApplication.class, args);
    }

}
           

1. 新增接口UserClient

package com.demo.client.api;

import com.demo.client.entity.User;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.*;

@FeignClient(value = "demo-provider", path = "/user")
public interface UserClient {

    @GetMapping
    Object findUser(@RequestParam("pageNo") Integer pageNo, @RequestParam("size") Integer size);

    @PostMapping
    User save(@RequestBody User user);

    @GetMapping("/{id}")
    User findById(@PathVariable("id") String id);

    @DeleteMapping("/{id}")
    String deleteById(@PathVariable("id") String id);

}
           

findUser()方法返回Object在这里只是为了方便，可以自己封装实体类。

@FeignClient：value代表访问的应用，path：请求路径的统一前缀。

1. UserController更新如下

package com.demo.client.controller;

import com.demo.client.api.UserClient;
import com.demo.client.entity.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

@RestController
@RequestMapping("/user")
public class UserController {

    @Autowired
    private UserClient userClient;

    @GetMapping
    public Object findUser(@RequestParam(required = false, defaultValue = "1") Integer pageNo
            , @RequestParam(required = false, defaultValue = "10") Integer size) {
        return userClient.findUser(pageNo, size);
    }

    @RequestMapping(method = { RequestMethod.POST, RequestMethod.PUT })
    public User save(@RequestBody User user) {
        return userClient.save(user);
    }

    @GetMapping("/{id}")
    public User findById(@PathVariable String id) {
        return userClient.findById(id);
    }

    @DeleteMapping("/{id}")
    public String deleteById(@PathVariable String id) {
        userClient.deleteById(id);
        return id;
    }

}
           

在这里就不使用RestTemplate对象去调用接口了，而是使用UserClient替换，替换之后代码更简单了。

左边为使用RestTemplate调用接口，右边为Feign调用接口。

Feign日志配置

1. 新建类FeignConfiguration

package com.demo.client.conf;

import feign.Logger;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class FeignConfiguration {

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

}
           

1. UserClient 的 @FeignClient注解指定

1. application.yml配置

logging:
  level:
    com:
      demo:
        client:
          api:
            UserClient: debug
           

此时访问接口发现控制台打印日志如下

源码参考

https://github.com/phone[phone]/demo.git