SpringCloud-聲明式Rest調用Feign（四）

時間 2020-06-03

標籤 springcloud 聲明 rest 調用 feign 简体版

原文原文鏈接

前言：通常狀況下咱們一般使用RestTemplate來實現聲明式遠程調用，可是當參數過多，那麼效率就會變得很低，而且難以維護，因此在微服務當中也有聲明式Rest調用的組件Feignhtml

1、Feign簡介

　　Feign是Netflix開發的聲明式、模板化的http客戶端，Feign能夠幫咱們更加便捷、優雅地調用HTTP API。在SpringCloud中使用Feign很是簡單，建立一個接口，並在接口上加上註解，就完成了聲明式調用；java

2、Feign與SpringCloud的整合簡單使用

　　注：本次學習記錄是基於以前的Eureka介紹和Ribbon介紹之上實踐，這裏只展現關鍵代碼，其他代碼可在代碼示例中查看；git

　　一、建立基於Eureka和Ribbon的服務端和兩個客戶端生產者、消費者：web

　　Server：spring

<?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">
  <modelVersion>4.0.0</modelVersion>

  <groupId>com.cn</groupId>
  <artifactId>eureka-ribbon-server</artifactId>
  <version>1.0-SNAPSHOT</version>

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

  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.5.13.RELEASE</version>
  </parent>

  <dependencies>
    <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-eureka-server</artifactId>
    </dependency>
  </dependencies>
  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-dependencies</artifactId>
        <version>Edgware.SR3</version>
        <type>pom</type>
        <scope>import</scope>
      </dependency>
    </dependencies>
  </dependencyManagement>
  <!-- 添加spring-boot的maven插件 -->
  <build>
    <plugins>
      <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
      </plugin>
    </plugins>
  </build>
</project>

pom.xml

server.port=8761 #注意：這兩個配置eureka默認爲true，要改爲false，不然會報錯，connot connect server #表示是否將本身註冊在EurekaServer上 eureka.client.register-with-eureka=false #表示是否從EurekaServer獲取註冊信息 eureka.client.fetch-registry=false eureka.client.service-url.defaultZone=http://localhost:8761/eureka/

application.properties

package com.cn; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer; /** * @program: springcloud-example * @description: 啓動類 * @author: * @create: 2018-06-15 15:43 **/ @SpringBootApplication @EnableEurekaServer public class ServerApplication { public static void main(String[] args) { SpringApplication.run(ServerApplication.class,args); } }

ServerApplication.java

　　Client生產者：apache

<?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">
  <modelVersion>4.0.0</modelVersion>

  <groupId>com.cn</groupId>
  <artifactId>eureka-ribbon-client2</artifactId>
  <version>1.0-SNAPSHOT</version>

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

  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.5.13.RELEASE</version>
  </parent>

  <dependencies>
    <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-ribbon</artifactId>
    </dependency>
    <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-eureka</artifactId>
    </dependency>
  </dependencies>
  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-dependencies</artifactId>
        <version>Edgware.SR3</version>
        <type>pom</type>
        <scope>import</scope>
      </dependency>
    </dependencies>
  </dependencyManagement>
  <!-- 添加spring-boot的maven插件 -->
  <build>
    <plugins>
      <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
      </plugin>
    </plugins>
  </build>
</project>

pom.xml

server.port=8763 spring.application.name=client-87 eureka.client.service-url.defaultZone=http://localhost:8761/eureka

application.properties

package com.cn; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.cloud.client.discovery.EnableDiscoveryClient; /** * @program: springcloud-example * @description: * @author: * @create: 2018-06-15 16:05 **/ @SpringBootApplication @EnableDiscoveryClient public class ClientApplication { public static void main(String[] args) { SpringApplication.run(ClientApplication.class, args); } }

ClientApplication.java

package com.cn.contorller; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.ResponseBody; /** * @program: springcloud-example * @description: * @author: * @create: 2018-06-15 16:12 **/ @Controller public class ClientController { @GetMapping("/getUser") @ResponseBody public String getUser() { System.out.println("獲取用戶成功"); return "{\"username\":\"張三\",\"age\":\"10\"}"; } }

ClientController.java

　　二、在消費者module中的maven依賴中添加相關依賴庫，建立Feign訪問接口，並註解，經過識別Eureka提供的應用名稱，來找對應的請求路徑：架構

　　pom.xml：app

<?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">
  <modelVersion>4.0.0</modelVersion>

  <groupId>com.cn</groupId>
  <artifactId>eureka-feign-client</artifactId>
  <version>1.0-SNAPSHOT</version>

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

  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.5.13.RELEASE</version>
  </parent>

  <dependencies>
    <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-ribbon</artifactId>
    </dependency>
    <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>

  </dependencies>
  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-dependencies</artifactId>
        <version>Edgware.SR3</version>
        <type>pom</type>
        <scope>import</scope>
      </dependency>
    </dependencies>
  </dependencyManagement>
  <!-- 添加spring-boot的maven插件 -->
  <build>
    <plugins>
      <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
      </plugin>
    </plugins>
  </build>
</project>

　　application.properties:maven

server.port=8762 spring.application.name=client-8762 eureka.client.service-url.defaultZone=http://localhost:8761/eureka/

　　Feign接口：ide

import org.springframework.cloud.netflix.feign.FeignClient; import org.springframework.web.bind.annotation.RequestMapping; @FeignClient(name = "CLIENT-87") public interface UserFeign { @RequestMapping("/getUser") public String getUser(); }

FeignController：

package com.cn.controller;

import com.cn.feign.UserFeign;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.loadbalancer.LoadBalancerClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

/**
 * @program: springcloud-example
 * @description:
 * @author:
 * @create: 2018-06-15 15:55
 **/
@RestController
public class FeignController {
    @Autowired
    private LoadBalancerClient loadBalancerClient;

    @Autowired
    private RestTemplate restTemplate;

    @Autowired
 private UserFeign userFeign;

 @RequestMapping("/getUser")
 public String getUser() {
 return userFeign.getUser();
 }

    @GetMapping("/loadInstance")
    public String loadInstance() {
        ServiceInstance choose = this.loadBalancerClient.choose("client-87");
        System.out.println(choose.getServiceId()+":"+choose.getHost()+":"+choose.getPort());
        return choose.getServiceId() + ":" + choose.getHost() + ":" + choose.getPort();
    }

}

　　在ClientApplication.java啓動類中加入@EnableFeignClients註解：

package com.cn; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.cloud.client.discovery.EnableDiscoveryClient; import org.springframework.cloud.client.loadbalancer.LoadBalanced; import org.springframework.cloud.netflix.feign.EnableFeignClients; import org.springframework.context.annotation.Bean; import org.springframework.web.client.RestTemplate; /** * @program: springcloud-example * @description: * @author: * @create: 2018-06-15 15:51 **/ @SpringBootApplication @EnableDiscoveryClient @EnableFeignClients public class ClientApplication { public static void main(String[] args) { SpringApplication.run(ClientApplication.class, args); } /** * @Description: * @Param: * @return: * @Author: * @Date: 2018/6/15 */ @Bean @LoadBalanced public RestTemplate getRestTemplate() { return new RestTemplate(); } }