5 SpringCloud中服务消费者Feign

首先server，client1和client2和Ribbon里面一模一样，主要是消费者Feign和Ribbon的区别。
工程目录还是和Ribbon一样，不过Ribbon改成了Feign

主要看feign的结构。
首先是依赖

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.5.9.RELEASE</version>
    <relativePath/> <!-- lookup parent from repository -->
</parent>

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    <java.version>1.8</java.version>
</properties>

<dependencies>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-eureka</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-feign</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-dependencies</artifactId>
            <version>Dalston.RC1</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

<repositories>
    <repository>
        <id>spring-milestones</id>
        <name>Spring Milestones</name>
        <url>https://repo.spring.io/milestone</url>
        <snapshots>
            <enabled>false</enabled>
        </snapshots>
    </repository>
</repositories>

然后配置文件和ribbon也一样

eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/
server:
  port: 8765
spring:
  application:
    name: service-feign

启动类上，这里多了个@EnableFeignClients注解开启Feign,而不需要加载ribbon里面的RestTemplate

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

@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
public class AppFeign {

    public static void main(String[] args) {
        SpringApplication.run(AppFeign.class, args);
    }
}

然后Controller，对外提供一个“/hi”的接口

import com.lijia.service.HelloService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HiController {

    @Autowired
    HelloService helloService;
    @RequestMapping(value = "/hi",method = RequestMethod.GET)
    public String sayHi(@RequestParam String name){
        return helloService.callClientOne(name);
    }
}

service层，通过@FeignClient(value = "服务名")来确定调用哪个服务，在@RequestMapping确定调用服务的哪个接口

import org.springframework.cloud.netflix.feign.FeignClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;

@FeignClient(value = "service-hi")
public interface HelloService {
    @RequestMapping(value = "/hi",method = RequestMethod.GET)
    String callClientOne(@RequestParam(value = "name") String name);
}

然后启动AppFeign，输入http://localhost:8765/hi?name=lijia
结果也实现了负载均衡的效果。

代码在 https://github.com/lijiaccy/springcloud-study/tree/master/eurefa-Feign

参考： http://blog.csdn.net/forezp/article/details/69808079