Feign负载均衡(客户端)

Feign是一个声明式的Web Service客户端,比Ribbon好用，默认也是轮巡。我们只需要使用Feign创建一个接口，并用注解就好了。

案例编写：

　 一：搭建Eureka服务器

　　目录结构：

　　　　　　　　

 

　　1.1导入依赖包

<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">
  <modelVersion>4.0.0</modelVersion>
  <groupId>org.springCloud</groupId>
  <artifactId>first-server</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <!-- 基于springboot -->
   <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.8.RELEASE</version> 
        <relativePath/>
    </parent>
  
  <!-- springcloud依赖 -->
  <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Dalston.SR3</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-config</artifactId>
        </dependency>
        <!-- eureka服务器依赖 -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka-server</artifactId>
        </dependency>
    </dependencies>
  
</project>

　　1.2编写配配置文件  在resource目录下创建application.yml文件

# 指定默认端口
server:
  port: 8761
  
# eureka默认把自己到服务器注册会报错，这里禁止掉

eureka:
  client: 
    register-with-eureka: false
    fetch-registry: false

　　1.3编写启动类

package org.wulei;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;

@SpringBootApplication//表示这是一个springboot应用
@EnableEurekaServer// 申明这是一个eureka服务器
public class ServerApp {

    public static void main(String[] args) {
    
        SpringApplication.run(ServerApp.class, args);
        //new SpringApplicationBuilder(ServerApp.class).web(true).run(args); 
    }
}

 　　这时，浏览器访问localhost:8761会进入eureka管控台，出现这个页面就表示启动成功了，但这个时候还没有服务注册上来，下面我们继续编写服务端与客户端。

　　二：编写服务提供者

 　　　目录结构：

　　　　　　　　

　　2.1 导入依赖包

<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">
  <modelVersion>4.0.0</modelVersion>
  <groupId>org.springCloud</groupId>
  <artifactId>spring_feign_police</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  
  <!-- 基于springboot -->
   <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.8.RELEASE</version> 
        <relativePath/>
    </parent>
  <!-- springcloud -->
  <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Dalston.SR3</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-config</artifactId>
        </dependency>
        <!-- eureka客户端 -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka</artifactId>
        </dependency>
    </dependencies>
</project>

 　　2.2 编写appliaction.yml配置文件

# 设置服务名称
spring:
  application:
    name: police

# 设置eureka服务器的注册地址
eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/

 　　2.3 编写实体类，供接口返回json字符串使用。

public class Police {

    private Integer id;
    private String name;
    //记录访问路径用
    private String message;
    
    
    public String getMessage() {
        return message;
    }
    public void setMessage(String message) {
        this.message = message;
    }
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
}

 　　2.4  Controller层

import javax.servlet.http.HttpServletRequest;

import org.springframework.http.MediaType;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class PoliceController {

    @RequestMapping(value = "/call/{id}", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
    public Police call(@PathVariable Integer id,HttpServletRequest req) {
        Police p = new Police();
        p.setId(id);
        p.setName("吴磊");
        p.setMessage(req.getRequestURL().toString());
        return p;
    }
    
    @RequestMapping("/hello/{name}")
    public String hello(@PathVariable String name){
        return "hello"+name;
    }
}

 　　2.5 编写启动类

import java.util.Scanner;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;

@SpringBootApplication
@EnableEurekaClient//开启eureka服务
public class PoliceServer {

    public static void main(String[] args) {
        //new SpringApplicationBuilder(PoliceServer.class).web(true).run(args);
        //1. 启动main方法后，在控制台输入端口号.
        Scanner scan = new Scanner(System.in);
        String port = scan.nextLine();
        //以输入的端口号启动
        new SpringApplicationBuilder(PoliceServer.class)
                .properties("server.port="+port).run(args);
        //2. 启动2次，分别以8080， 8081启动，浏览器访问测试一下。
    }
}

 　　分别访问8080和8081端口进行测试， 刷新eureka管控台，这里看到我们的服务已经注册上去了。

三：编写服务调用者

 　　目录结构：

　　　　　　　　

 

 

 

　　3.1 导入依赖包

<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">
    <modelVersion>4.0.0</modelVersion>
    <groupId>org.crazyit.cloud</groupId>
    <artifactId>spring_feign_person</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <!-- 基于springboot -->
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.8.RELEASE</version> 
        <relativePath/>
    </parent>
    <!-- springCloud -->
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Dalston.SR3</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-config</artifactId>
        </dependency>
        <!-- eureka客户端 -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka</artifactId>
        </dependency>
         <!-- feign客户端 -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-feign</artifactId>
        </dependency>
    </dependencies>
    
</project>

　　3.2 编写application.yml配置信息

# 指定端口
server:
  port: 9000
  
# 服务名称
spring:
  application:
    name: invoker
    
# eureka服务器注册地址
eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/

　　3.3 我们要调用服务提供者的 host：port/call/{ id } 接口返回实体类信息，所以把之前的实体复制过来，减少系统耦合度。

public class Police {

    private Integer id;
    private String name;
    private String message;
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getMessage() {
        return message;
    }
    public void setMessage(String message) {
        this.message = message;
    }
}

 　　3.4 用feign注解来远程调用

import org.springframework.cloud.netflix.feign.FeignClient;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
//指定服务提供者的服务名
@FeignClient("police")
public interface HelloClient {
    //翻译服务提供者的地址
    @RequestMapping(method = RequestMethod.GET, value="/hello/{name}")
    String hello(@PathVariable("name") String name);
    
    //翻译服务提供者的地址
    @RequestMapping(method = RequestMethod.GET, value="/call/{id}")
    Police getPolice(@PathVariable("id") Integer id);
}

　　3.5 编写controller

package org.wulei;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.MediaType;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class TestController {
    //把刚才的feign注解类依赖过来
    @Autowired
    private HelloClient helloClient;

    @RequestMapping(method = RequestMethod.GET, value="/router")
    public String router() {
        String result = helloClient.hello("angus");
        return result;
    }
    @RequestMapping(method = RequestMethod.GET, value="/police", 
            produces = MediaType.APPLICATION_JSON_VALUE)
    public Police getPolice() {
        Police p = helloClient.getPolice(1);
        return p;
    }
    
}

　　3.6 编写主函数入口

@SpringBootApplication
@EnableEurekaClient//开启eureka
@EnableFeignClients//开启feign
public class ServerMain {
    
    public static void main(String[] args) {
        new SpringApplicationBuilder(ServerMain.class).web(true).run(args);
    }

}

 　　3.7 测试 我们调用消费者的接口，实际是用feign远程调用的服务提供者。刷新eureka管控台，可以看到消费者注册成功了。