IDEA项目搭建七——使用Feign简化消费者端操作

一、简介

我们可以看到上一篇文章的消费者这边调用Service时比较麻烦，所以我们可以使用Feign来简化这部分操作，它底层也是使用Ribbon实现的只是Ribbon支持HTTP和TCP两种通信协议，而Feign只支持HTTP一种，同样支持负载均衡，所以能满足90%以上的需求了。

二、搭建生产者模块

其实这部分是通用的，对于消费者这边使用什么Client并没有影响，Eureka还是使用之前搭建好的，生产者模块也用搭建好的，我们新建一个controller用于承接service，这边就算完成了

import javademo.tyh.model.hotel.BaseInfoModel;
import javademo.tyh.model.hotel.ResponseModel;
import javademo.tyh.model.hotel.SearchModel;
import javademo.tyh.service.hotel.service.HotelService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;
import javax.servlet.http.HttpServletRequest;

import java.util.List;
@Controller

@RequestMapping("/api/hotel")

public class HotelController {
</span><span style="color: #008000;">//</span><span style="color: #008000;">自动注入请求对象，查看header信息</span>

    @Autowired

HttpServletRequest request;
@Autowired
HotelService service;

@ResponseBody
@RequestMapping(</span>"/test"<span style="color: #000000;">)
</span><span style="color: #0000ff;">public</span> <span style="color: #0000ff;">void</span><span style="color: #000000;"> test() {
    </span><span style="color: #008000;">//</span><span style="color: #008000;">do something...</span>

    }
@ResponseBody
@RequestMapping(</span>"/get"<span style="color: #000000;">)
</span><span style="color: #0000ff;">public</span> BaseInfoModel get(@RequestParam(defaultValue = "0") <span style="color: #0000ff;">int</span><span style="color: #000000;"> id) {
    String tyh </span>= request.getHeader("taiyonghai"<span style="color: #000000;">);<span style="color: #008000;">//获取Header头信息</span>
    System.out.println(</span>"参数为：" +<span style="color: #000000;"> id);
    </span><span style="color: #0000ff;">return</span><span style="color: #000000;"> service.get(id);
}
</span><span style="color: #008000;">//</span><span style="color: #008000;">设置参数为@RequestBody可以自动序列化为对象</span>

    @ResponseBody

@RequestMapping("/list")

public ResponseModel<List<BaseInfoModel>> list(@RequestBody SearchModel search) {

System.out.println("参数为：" + search.getName());

List<BaseInfoModel> list = service.list();

ResponseModel<List<BaseInfoModel>> respModel = new ResponseModel<>();

respModel.setCode("000000");

respModel.setMsg("操作成功");

respModel.setData(list);

return respModel;

}

}

添加通用Model实体，同样不生成get/set方法，自己生成吧

import com.baomidou.mybatisplus.annotations.TableName;
import java.time.LocalDateTime;
@TableName("base_info")

public class BaseInfoModel {

private int id;

private String nickname;

private LocalDateTime updateTime;

}

public class SearchModel {
    private int id;
    private String name;
}

public class ResponseModel<T> {
    private String code;
    private String msg;
    private T data;
}

  

 三、搭建消费者模块——Feign

还是创建一个Maven模块，看一下我的项目结构

  

1、修改pom.xml文件，增加对spring boot、spring cloud、feign的引用 

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>2.0.3.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Finchley.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
    <dependencies>
        <!-- import spring boot -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!-- import openfeign -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
    </dependencies>
<span style="color: #0000ff;">&lt;</span><span style="color: #800000;">build</span><span style="color: #0000ff;">&gt;</span>
    <span style="color: #0000ff;">&lt;</span><span style="color: #800000;">plugins</span><span style="color: #0000ff;">&gt;</span>
        <span style="color: #0000ff;">&lt;</span><span style="color: #800000;">plugin</span><span style="color: #0000ff;">&gt;</span>
            <span style="color: #0000ff;">&lt;</span><span style="color: #800000;">groupId</span><span style="color: #0000ff;">&gt;</span>org.springframework.boot<span style="color: #0000ff;">&lt;/</span><span style="color: #800000;">groupId</span><span style="color: #0000ff;">&gt;</span>
            <span style="color: #0000ff;">&lt;</span><span style="color: #800000;">artifactId</span><span style="color: #0000ff;">&gt;</span>spring-boot-maven-plugin<span style="color: #0000ff;">&lt;/</span><span style="color: #800000;">artifactId</span><span style="color: #0000ff;">&gt;</span>
        <span style="color: #0000ff;">&lt;/</span><span style="color: #800000;">plugin</span><span style="color: #0000ff;">&gt;</span>
    <span style="color: #0000ff;">&lt;/</span><span style="color: #800000;">plugins</span><span style="color: #0000ff;">&gt;</span>
<span style="color: #0000ff;">&lt;/</span><span style="color: #800000;">build</span><span style="color: #0000ff;">&gt;</span></pre>

  2、新建resources文件夹，新建application.yml配置文件，并修改内容如下

#设置自己的程序名称
spring:
  application:
    name: javademo-tyh-web-hotel
  #thymeleaf 配置
  thymeleaf:
    encoding: UTF-8
    prefix: classpath:/templates
    cache: false
#服务注册中心地址（刚刚搭建的Eureka Server的地址）
eureka:
  client:
    #是否向服务中心注册自己
    register-with-eureka: false
    #设置eureka服务中心的地址
    service-url:
      defaultZone: http://localhost:11000/eureka
#设置自己启动的端口
server:
  port: 13000

 3、修改main()方法的类，增加Feign的注解

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.openfeign.EnableFeignClients;
//引入Feign注解

@EnableFeignClients

@SpringBootApplication

public class AppWebHotel {

public static void main(String[] args) {

SpringApplication.run(AppWebHotel.class, args);

}

}

 4、新建service文件夹，新建HotelService的Interface用来执行Feign向后端服务生产者的调用，指明服务生产者名称，接口方法指明具体的服务路由，这种方式比Ribbon简单很多，而且更直观更像调用后台方法

import javademo.tyh.model.hotel.BaseInfoModel;
import javademo.tyh.model.hotel.ResponseModel;
import javademo.tyh.model.hotel.SearchModel;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.stereotype.Service;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import java.util.List;
@Service

@FeignClient("javademo-tyh-service-hotel")//指明服务生产者名称

@RequestMapping("/api/hotel")//此位置的mapping与controller上的mapping是共享全局唯一的，如果这里的名字和controller的路由相同会报错ambiguous mapping

public interface HotelService {

//    //无参数无返回值

//    @RequestMapping("/test")

//    void test();

//基础类型参数

@RequestMapping("/get")

BaseInfoModel get(@RequestParam("id") int id);
</span><span style="color: #008000;">//</span><span style="color: #008000;">自定义类型参数以及泛型返回值</span>
@RequestMapping("/list"<span style="color: #000000;">)
ResponseModel</span>&lt;List&lt;BaseInfoModel&gt;&gt;<span style="color: #000000;"> list(@RequestBody SearchModel search);

}

  5、新建controller文件夹，新建HotelController的class用来接收页面调用

import javademo.tyh.model.hotel.BaseInfoModel;
import javademo.tyh.model.hotel.ResponseModel;
import javademo.tyh.model.hotel.SearchModel;
import javademo.tyh.web.hotel.service.HotelService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import java.util.List;
@Controller

@RequestMapping("/hotel")

public class HotelController {
</span><span style="color: #008000;">//</span><span style="color: #008000;">自动注入Feign接口对象</span>

    @Autowired

HotelService service;
@RequestMapping(</span>"/get"<span style="color: #000000;">)
</span><span style="color: #0000ff;">public</span><span style="color: #000000;"> String get(Model model) {
    </span><span style="color: #008000;">//</span><span style="color: #008000;">像调用方法一样调用即可实现服务生产者端的调用</span>
    model.addAttribute("model",service.get(1<span style="color: #000000;">));
    </span><span style="color: #0000ff;">return</span> "/hotel/get"<span style="color: #000000;">;
}

</span><span style="color: #008000;">//</span><span style="color: #008000;">直接返回json不写页面了</span>

    @ResponseBody

@RequestMapping("/list")

public List<BaseInfoModel> list() {

SearchModel search = new SearchModel();

search.setId(1);

search.setName("taiyonghai");

ResponseModel<List<BaseInfoModel>> result = service.list(search);

return result.getData();

}

}

 6、在resources文件夹下建立templates及hotel文件夹，新建get.html页面，用来渲染数据

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<h1>this is /hotel/get</h1>
<label th:text="${model.Id}">id</label>

<label th:text="${model.Nickname}">Nickname</label>

<label th:text="${model.UpdateTime}">UpdateTime</label>
</body>

</html>

 OK，现在启动Eureka注册中心、启动服务生产者、启动服务消费者访问http://localhost:13000/hotel/get就可以看到从service取到的结果了

本应该在这里就完成了，但有时候我们需要在Header头信息中增加些公共内容，在Feign中就可以使用如下方式实现

在消费者这边的service文件夹下新建FeignInterceptor实现RequestInterceptor接口

import feign.RequestInterceptor;
import feign.RequestTemplate;
import org.springframework.stereotype.Component;
//使用拦截器添加Header头信息

@Component

public class FeignInterceptor implements RequestInterceptor {

@Override

public void apply(RequestTemplate requestTemplate) {

System.out.println("调用了FeignInterceptor");

requestTemplate.header("taiyonghai", "1111111111111");

}

}

 Feign的简单使用就OK了

原文地址:https://www.cnblogs.com/taiyonghai/p/9306244.html