feign组件

• feign组件作用
• RestTemplate调用存在的问题
• 快速入门
• 自定义配置
• • 配置日志
  • • 方式一 配置文件
    • 方式二 java代码的方式
• feign性能优化
• feign企业实践

feign组件作用

feign组件替代了restTemplate实现远程调用

RestTemplate调用存在的问题

快速入门

1.引入依赖

<!--开启基于feign的远程调用-->
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>

2.开启配置

@SpringBootApplication
@EnableFeignClients
@EnableSwagger2
@EnableDiscoveryClient
@MapperScan(basePackages = {"com.zhw.orderservice.mapper"})
public class OrderApp {
    public static void main(String[] args) {
        SpringApplication.run(OrderApp.class, args);
    }
}

3.编写Fegin客户端

//服务提供者名字
@FeignClient("service-user")
public interface UserClient {
	//与服务提供者的方法一样
    @GetMapping("/orderservice/tb-user/{id}")
    public TbUser getUserById(@PathVariable("id") Integer id);

}

主要是基于SpringMVC的注解声明远程调用的信息，比如：
服务名称：service-user
请求方式：get
请求路径：orderservice/tb-user/{id}
请求参数：Integer id
返回值类型：TbUser

4.用feign代替RestTemplate

@GetMapping("getUserByEureka/{oid}")
private OrderWithUser getUserByEureka(@PathVariable Integer oid) {
        //1.获取订单信息
        TbOrders result = ordersService.getById(oid);
        //2.远程调用获取订单的用户信息,很优雅只是调用方法
        TbUser user = userClient.getUserById(result.getUid());
        //3.将用户信息和订单信息封装
        OrderWithUser orderWithUser = new OrderWithUser();
        BeanUtils.copyProperties(result,orderWithUser);
        orderWithUser.setUser(user);
        //4.返回订单和用户信息
        return orderWithUser;
}

自定义配置

配置日志

关于openfegin的日志可以参看这篇文章: https://www.cnblogs.com/maybesuch/p/12175002.html.
或者官方文档

方式一 配置文件

#开启servcie-user服务的日志级别，只针对service-user服务的配置
feign.client.config.service-user.logger-level=full
#针对全局的服务日志配置
feign.client.config.default.logger-level=full
#将接口所在的包的日志级别设置为debug级别
logging.level.com.zhw=debug

方式二 java代码的方式

1.定义配置类

package com.zhw.orderservice.config;

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

//注意该类不需要加@Configuration注解
public class OpenFeignConfig {
    @Bean
    Logger.Level feignLoggerLevel(){
        // 设置日志
        return Logger.Level.FULL;
    }
}

2.修改配置文件

#将接口所在的包的日志级别设置为debug级别
logging.level.com.zhw=debug

3.针对某一微服务的配置

package com.zhw.orderservice.client;

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.zhw.base.entity.TbUser;
import com.zhw.orderservice.config.OpenFeignConfig;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;

@FeignClient(value = "service-user",configuration = OpenFeignConfig.class)
public interface UserClient {

    @GetMapping("/orderservice/tb-user/{id}")
    public TbUser getUserById(@PathVariable("id") Integer id);

}

4.全局的feign日志配置

package com.zhw.orderservice;

import com.netflix.loadbalancer.IRule;
import com.netflix.loadbalancer.RandomRule;
import com.netflix.loadbalancer.RoundRobinRule;
import com.zhw.orderservice.config.OpenFeignConfig;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.cloud.openfeign.EnableFeignClients;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;
import springfox.documentation.swagger2.annotations.EnableSwagger2;


@SpringBootApplication
//定义 openfeign全局配置
@EnableFeignClients(defaultConfiguration = OpenFeignConfig.class)
@EnableSwagger2
@EnableDiscoveryClient
@MapperScan(basePackages = {"com.zhw.orderservice.mapper"})
public class OrderApp {
    public static void main(String[] args) {
        ConfigurableApplicationContext run = SpringApplication.run(OrderApp.class, args);
    }

feign性能优化

1.引入依赖

<!--        openfeign默认不支持连接池，引入httpclient支持连接池子-->
        <dependency>
            <groupId>io.github.openfeign</groupId>
            <artifactId>feign-httpclient</artifactId>
        </dependency>

2.修改配置文件

#启用httpclient
feign.httpclient.enabled=true
# 配置总共有多少个连接
feign.httpclient.max-connections=200
# 每一个服务最大由多少个连接
feign.httpclient.max-connections-per-route=50

feign企业实践