1、
引包
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>
2、主類 加Feign客戶端 @EnableFeignClients註解開啓Feign的功能
@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
public class ServiceFeignApplication {
public static void main(String[] args) {
SpringApplication.run(ServiceFeignApplication.class, args);
}
}
3、service 定義一個feign接口,通過@ FeignClient(“服務名”),來指定調用哪個服務。
@FeignClient(value = "service-helloworld")
public interface HelloWorldService {
@RequestMapping(value = "/",method = RequestMethod.GET)
String sayHello();
}
conller調用
public class WebController {
@Autowired
HelloWorldService helloworldservice;
@RequestMapping(value = "/",method = RequestMethod.GET)
public String sayHello(){
return helloworldservice.sayHello();
}
}
- Feign在默認情況下使用的是JDK原生的URLConnection發送HTTP請求,沒有連接池,但是對每個地址gwai會保持一個長連接,即利用HTTP的persistence
connection 。我們可以用Apache的HTTP Client替換Feign原始的http client,
從而獲取連接池、超時時間等與性能息息相關的控制能力。Spring
Cloud從Brixtion.SR5版本開始支持這種替換,首先在項目中聲明Apache HTTP
Client和feign-httpclient依賴:
<!-- 使用Apache HttpClient替換Feign原生httpclient -->
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
</dependency>
<dependency>
<groupId>com.netflix.feign</groupId>
<artifactId>feign-httpclient</artifactId>
<version>${feign-httpclient}</version>
</dependency>