SpringCloud学习笔记（六、视图微服务-FEIGN）

原创

三分恶在51CTO 2022-04-18 16:16:57 博主文章分类：SpringCloud ©著作权

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是什么？

Feign 是什么呢？ Feign 是对 Ribbon的封装，使用注解的方式，调用起来更简单，是现在的主流方式。

比较一下二者调用的代码块----

Ribbon:

public List<Product> listProdcuts() {
    return restTemplate.getForObject("http://PRODUCT-DATA-SERVICE/products",List.class);
}

Feign:

@FeignClient(value = "PRODUCT-DATA-SERVICE")
public interface ProductClientFeign {
 
    @GetMapping("/products")
    public List<Product> listProdcuts();
}

创建子项目

创建名为product-view-service-feign的子项目。

pom.xml

多了个支持feign方式的依赖包：

<?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>springcloud</artifactId>
        <groupId>edu.hpu.springcloud</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>product-view-service-feign</artifactId>


    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>  <!--对feign方式的支持-->
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>

    </dependencies>


</project>

Feign 客户端

和Ribbon相比，大体上差不多，用起来简洁一点。

package edu.hpu.springcloud.client;

import edu.hpu.springcloud.pojo.Product;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;

import java.util.List;

@FeignClient(value = "PRODUCT-DATA-SERVICE")
public interface ProductClientFeign {
    @GetMapping("/products")
    public List<Product> listProducts();
}

实体类、控制类、服务类、视图

毫无疑问都是和Ribbon方式都是一样的

配置

无非改个application的名字，

eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/
spring:
  application:
    name: product-view-service-feign
  thymeleaf:
    cache: false
    prefix: classpath:/templates/
    suffix: .html
    encoding: UTF-8
    content-type: text/html
    mode: HTML5

启动类

ProductViewServiceFeignApplication,加了个@@EnableFeignClients，表示用Feign方式启动。

package edu.hpu.springcloud;

import cn.hutool.core.convert.Convert;
import cn.hutool.core.thread.ThreadUtil;
import cn.hutool.core.util.NetUtil;
import cn.hutool.core.util.NumberUtil;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.openfeign.EnableFeignClients;

import java.util.Scanner;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

@SpringBootApplication
@EnableEurekaClient
@EnableDiscoveryClient
@EnableFeignClients
public class ProductViewServiceFeignApplication {
    public static void main(String[] args) {
        int port = 0;
        int defaultPort = 8012;
        Future<Integer> future = ThreadUtil.execAsync(() ->{
            int p = 0;
            System.out.println("请于5秒钟内输入端口号, 推荐  8012 、 8013  或者  8014，超过5秒将默认使用"+defaultPort);
            Scanner scanner = new Scanner(System.in);
            while(true) {
                String strPort = scanner.nextLine();
                if(!NumberUtil.isInteger(strPort)) {
                    System.err.println("只能是数字");
                    continue;
                }
                else {
                    p = Convert.toInt(strPort);
                    scanner.close();
                    break;
                }
            }
            return p;
        });
        try{
            port=future.get(5, TimeUnit.SECONDS);
        }
        catch (InterruptedException | ExecutionException | TimeoutException e){
            port = defaultPort;
        }
        if(!NetUtil.isUsableLocalPort(port)) {
            System.err.printf("端口%d被占用了，无法启动%n", port );
            System.exit(1);
        }
        new SpringApplicationBuilder(ProductViewServiceFeignApplication.class).properties("server.port=" + port).run(args);

    }
}