CSDN话题挑战赛第2期
参赛话题:学习笔记
个人名片:
博主:酒徒ᝰ.
个人简介:沉醉在酒中,借着一股酒劲,去拼搏一个未来。
本篇励志:三人行,必有我师焉。
本项目基于B站黑马程序员Java《SpringCloud微服务技术栈》,SpringCloud+RabbitMQ+Docker+Redis+搜索+分布式
【SpringCloud+RabbitMQ+Docker+Redis+搜索+分布式,系统详解springcloud微服务技术栈课程|黑马程序员Java微服务】 点击观看
一、Feign替代RestTemplate
下面是我们之前的访问方式,需要输入url地址值,这种方式在之后地址值很长的时候就不在好用,可读性差,维护难。
String url = "http://userservice/user/" + userId;
User user = restTemplate.getForObject(url, User.class);
由于之前的方式难以维护,于是我们使用Feign来代替。
使用方式:
1.引入依赖
在orderservice中引入feign依赖
<!--feign客户端依赖-->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>
2.开启Feign
在order-service中添加@EnableFeignClients注解
package cn.itcast.order;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.openfeign.EnableFeignClients;
import org.springframework.context.annotation.Bean;
@MapperScan("cn.itcast.order.mapper")
@SpringBootApplication
@EnableFeignClients
public class OrderApplication {
public static void main(String[] args) {
SpringApplication.run(OrderApplication.class, args);
}
}
3.编写Feign客户端
创建clients模块,在其中创建UserClient类。
package cn.itcast.order.clients;
import cn.itcast.feign.pojo.User;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
@FeignClient(value = "userservice")
public interface UserClient {
@GetMapping("/user/{id}")
User findById(@PathVariable("id") Long id);
}
分析:(基于SpringMVC)
- 服务名称:userservice
- 请求方式:GET
- 请求路径:/user/{id}
- 请求参数:id
- 返回值类型:User
4.编写业务(service)
package cn.itcast.order.service;
import cn.itcast.feign.clients.UserClient;
import cn.itcast.feign.pojo.Order;
import cn.itcast.feign.pojo.User;
import cn.itcast.order.mapper.OrderMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
@Service
public class OrderService {
@Autowired
private OrderMapper orderMapper;
@Autowired
private UserClient userClient;
public Order queryOrderByUserId(Long orderId) {
//1.根据id查询订单
Order order = orderMapper.findById(orderId);
//2.查询user
User user = userClient.findById(order.getUserId());
//4.封装查询结果
order.setUser(user);
return order;
}
}
5.查询(controller)
package cn.itcast.order.web;
import cn.itcast.feign.pojo.Order;
import cn.itcast.order.service.OrderService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
@RequestMapping("order")
public class OrderController {
@Autowired
private OrderService orderService;
@GetMapping("/{orderId}")
public Order queryOrderById(@PathVariable("orderId") Long orderId) {
// 1.查询订单
return orderService.queryOrderByUserId(orderId);
}
}