跟我学---三、声明式RESTful客户端：Spring Cloud OpenFeign
OpenFeign 简介
OpenFeign是一个声明式RESTful网络请求客户端。OpenFeign会根据带有注释的函数信息构造出网络请求的模板，在发送网络请求之前，OpenFeign会将函数的参数值设置到这些请求模板中。
1.搭建Eureka 服务注册中心
在idea创建SpringBoot 项目，主要依赖如下：
1.8
Greenwich.RELEASE
org.springframework.cloud
spring-cloud-starter-netflix-eureka-server
org.springframework.boot
spring-boot-starter-test
test
org.springframework.cloud
spring-cloud-dependencies
${spring-cloud.version}
pom
import
在启动类中添加注释@EnableEurekaServer，代码如下所示：
//会为项目自动配置必须得配置类，标识该服务为注册中心
@EnableEurekaServer
@SpringBootApplication
public class EurakeServerApplication {
public static void main(String[] args) {
SpringApplication.run(EurakeServerApplication.class, args);
}
}
在application.yml 配置文件中添加一下配置，配置注册中心得端口和标识：
server:
port: 8761
eureka:
instance:
hostname: standalone
instance-id: ${spring.application.name}:${vcap.application.instance-id:${spring.application.instance-id:${random.value}}}
client:
register-with-eureka: false #表明该服务不会向Eureka Server注册自己得信息
fetch-registry: false #表明该服务不会向Eureka Server获取注册信息
service-url: #Eureka Server注册中心得地址，用于Client与Server交流
defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/
spring:
application:
name: eureka-service
2.搭建Euraka服务提供者
在idea创建SpringBoot 项目，主要依赖如下
1.8
Greenwich.RELEASE
org.springframework.boot
spring-boot-starter-web
org.springframework.cloud
spring-cloud-starter-netflix-eureka-client
org.springframework.boot
spring-boot-starter-test
test
org.springframework.cloud
spring-cloud-dependencies
${spring-cloud.version}
pom
import
启动类如下：
@SpringBootApplication
public class EurakeClient01Application {
public static void main(String[] args) {
SpringApplication.run(EurakeClient01Application.class, args);
}
}
application.yml 配置如下：
server:
port: 8762
eureka:
instance:
hostname: client
instance-id: ${spring.application.name}:${vcap.application.instance-id:${spring.application.instance-id:${random.value}}}
client:
service-url:
defaultZone: http://localhost:8761/eureka/ #服务注册中心访问地址
spring:
application:
name: feign-service
新建一个controller包，添加一个提供服务的接口，代码如下：
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;
/*
* @Author chencundeng
* @Description //TODO
* @Date 2019/2/23
**/
@RequestMapping("/feign-service")
@RestController
public class FeignServiceController {
@GetMapping("/say-hello/{name}")
public String sayHello(@PathVariable("name") String name){
return "hello ".concat(name).concat("!");
}
}
3.Feign服务消费者搭建
在idea创建SpringBoot 项目，主要依赖如下
org.springframework.boot
spring-boot-starter-web
org.springframework.cloud
spring-cloud-starter-netflix-eureka-client
org.springframework.cloud
spring-cloud-starter-openfeign
org.springframework.boot
spring-boot-starter-test
test
org.springframework.cloud
spring-cloud-dependencies
${spring-cloud.version}
pom
import
启动类如下：
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.openfeign.EnableFeignClients;
@SpringBootApplication
@EnableFeignClients
public class FeignClientApplication {
public static void main(String[] args) {
SpringApplication.run(FeignClientApplication.class, args);
}
}
application.yml 配置如下：
server:
port: 8763
eureka:
instance:
hostname: client
instance-id: ${spring.application.name}:${vcap.application.instance-id:${spring.application.instance-id:${random.value}}}
client:
service-url:
defaultZone: http://localhost:8761/eureka/ #服务注册中心地址
spring:
application:
name: feign-client
新建一个controller包，添加一个Feign客户端接口及提供服务类，代码如下：
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
@FeignClient("feign-service") //指定调用的远程服务名称
@RequestMapping("/feign-service")
public interface FeignServiceClient {
@GetMapping("/say-hello/{name}")
public String sayHello(@PathVariable("name") String name);
}
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.RestController;
/*
* @Author chencundeng
* @Description //TODO
* @Date 2019/2/22
**/
@RestController
public class FeignClientController {
@Autowired
private FeignServiceClient feignServiceClient;
@GetMapping("/say-hello/{name}")
public String sayHello(@PathVariable("name") String name){
return feignServiceClient.sayHello(name);
};
}
4.OpenFeign客户端调用
搭建好上述三个服务后，依次启动三个服务，输入地址http://127.0.0.1:8762/say-hello/feign就可以看到输出语句。
5.例子源码地址如下：
https://gitee.com/mingzhishuyuan/spring-cloud.git