Spring Cloud Alibaba学习03OpenFeign基本使用

OpenFeight是由Spring Cloud官方开发的组件，它是一种声明式，模板化的HTTP客户端。

在Spring Cloud中使用OpenFeign，可以做到使用HTTP请求远程服务时与调用本地方法一样的编程体验，开发者完全感知不到是在调用远程方法，更感知不到这是HTTP请求。同时OpenFeign通过集成Ribbon实现客户端的负载均衡。使用OpenFeign可以代替RestTemplate。

1、添加新模块，作为服务提供者，cloud-jifen

使用IDEA创建新模块，在pom文件中引用：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>cloud-demo01</artifactId>
        <groupId>org.yas</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>
    <artifactId>cloud-jifen</artifactId>
    <dependencies>
        <!-- web场景依赖 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!-- 端点监控场景依赖 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <!-- nacos场景依赖 -->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>
        <dependency>
            <groupId>org.yas</groupId>
            <artifactId>cloud-entity</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
    </dependencies>
    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>
</project>

添加配置文件，application.yml：

spring:
  application:
    name: cloud-jifen #服务名称，必须唯一
  cloud:
    nacos:
      discovery:
        server-addr: localhost:8848 #指定nacos服务地址
        username: nacos
        password: nacos
        # namespace: public
        # group: DEFAULT_GROUP
server:
  port: 9904

添加启动类：

package com.yas;

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

@SpringBootApplication
@EnableDiscoveryClient//开启服务注册与发现功能
public class JifenApp {
    public static void main(String[] args) {
        SpringApplication.run(JifenApp.class);
    }
}

编写服务提供者controller：

package com.yas.controller;

import com.yas.Customer;
import com.yas.Jifen;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.*;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

@RestController
@RequestMapping("/jifen")
public class JifenController {

    @RequestMapping("/save")
    public Map save(@RequestBody Jifen jifen){
        System.out.println("调用了积分保存接口");
        System.out.println(jifen);
        Map map = new HashMap();
        map.put("isSuccess",true);
        map.put("msg","save success");
        return map;
    }

    @RequestMapping("/update")
    public Map update(@RequestBody Jifen jifen){
        System.out.println(jifen);
        Map map = new HashMap();
        map.put("isSuccess",true);
        map.put("msg","update success");
        return map;
    }

    @RequestMapping("/delete")
    public Map deleById(Integer jifenId){
        System.out.println("删除id为"+jifenId+"的积分信息");
        Map map = new HashMap();
        map.put("isSuccess",true);
        map.put("msg","delete success");
        return map;
    }

    @RequestMapping("/find/{jifenId}")
    public Jifen findJifenById(@PathVariable Integer jifenId){
        System.out.println("一查询到"+jifenId+"积分数据");
        return new Jifen(jifenId,12,jifenId+"号积分");
    }

    @RequestMapping("/search")
    public Jifen search(@RequestParam Integer uid,@RequestParam String type){
        System.out.println("uid:"+uid+",type:"+type);
        return new Jifen(uid,12,type);
    }

    @RequestMapping("/searchByEntity")
    public List<Jifen> searchMap(@RequestBody Jifen jifen){
        System.out.println(jifen);
        List<Jifen> jifens = new ArrayList<>();
        jifens.add(new Jifen(110,12,"下单积分"));
        jifens.add(new Jifen(111,10,"支付积分"));
        return jifens;
    }
}

2、接口模块，cloud-api：

使用IDEA建立新模块，pom文件如下：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>cloud-demo01</artifactId>
        <groupId>org.yas</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>
    <artifactId>cloud-api</artifactId>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <dependency>
            <groupId>org.yas</groupId>
            <artifactId>cloud-entity</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
    </dependencies>
    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>
</project>

添加OpenFeign接口：

package com.api;

import com.yas.Jifen;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.PathVariable;
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;
import java.util.Map;

@FeignClient("cloud-jifen")
@RequestMapping("/jifen")
public interface JifenApi {
    @RequestMapping("/save")
    Map save(@RequestBody Jifen jifen);

    @RequestMapping("/update")
    Map update(@RequestBody Jifen jifen);

    @RequestMapping("/delete")
    Map deleById(@RequestParam Integer jifenId);

    @RequestMapping("/find/{jifenId}")
    Jifen findJifenById(@PathVariable Integer jifenId);

    @RequestMapping("/search")
    Jifen search(@RequestParam Integer uid,@RequestParam String type);

    @RequestMapping("/searchByEntity")
    List<Jifen> searchMap(@RequestBody Jifen jifen);
}

3、修改cloud-order模块：

pom文件增加新引用：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>cloud-demo01</artifactId>
        <groupId>org.yas</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>
    <artifactId>cloud-order</artifactId>
    <dependencies>
        <!-- web场景依赖 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!-- 端点监控场景依赖 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <!-- nacos场景依赖 -->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>
        <dependency>
            <groupId>org.yas</groupId>
            <artifactId>cloud-entity</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <dependency>
            <groupId>org.yas</groupId>
            <artifactId>cloud-api</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
    </dependencies>
    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>
</project>

启动类修改如下：

package com.yas;

import com.rule.MyRule;
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.netflix.ribbon.RibbonClient;
import org.springframework.cloud.openfeign.EnableFeignClients;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@SpringBootApplication
@EnableDiscoveryClient
@RibbonClient(name = "cloud-goods",configuration = {MyRule.class})
@EnableFeignClients(basePackages = {"com.api"})//开启OpenFeign
public class OrderApp {
    public static void main(String[] args) {
        SpringApplication.run(OrderApp.class);
    }

//    @Bean
//    @LoadBalanced//使用Ribon调用服务，将域名请求变为服务地址请求
//    public RestTemplate initRestTemplate() {
//        return new RestTemplate();
//    }
}

编写测试controller：

package com.yas.controller;

import com.api.JifenApi;
import com.yas.Jifen;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.Map;

@RestController
@RequestMapping("/feign")
public class FeignController {

    @Autowired
    JifenApi jifenApi;

    @RequestMapping("/save")
    public Map save(){
        Jifen jifen = new Jifen(1,10,"注册积分");
        return jifenApi.save(jifen);
    }

    @RequestMapping("/update")
    public Map update(){
        Jifen jifen = new Jifen(1,10,"注册积分");
        return jifenApi.update(jifen);
    }

    @RequestMapping("/delete")
    public Map delete(){
        return jifenApi.deleById(1);
    }

    @RequestMapping("/find")
    public Jifen find(){
        return jifenApi.findJifenById(1);
    }
}

4、测试：

使用postman请求：localhost:9900/feign/save

总结：使用OpenFeign后，可以不再显示的调用RestTemplate的API了，而是像调用本地资源一样的方式调用远程服务。