企業(yè)級java springboot b2bc商城系統(tǒng)開源源碼二次開發(fā)（三）服務(wù)消費者（Feign）

昵稱61506847 2019-01-28

展開全文

一、Feign簡介

Feign是一個聲明式的偽Http客戶端，它使得寫Http客戶端變得更簡單。使用Feign，只需要創(chuàng)建一個接口并注解。它具有可插拔的注解特性，可使用Feign 注解和JAX-RS注解。Feign支持可插拔的編碼器和解碼器。Feign默認(rèn)集成了Ribbon，并和Eureka結(jié)合，默認(rèn)實現(xiàn)了負載均衡的效果。

簡而言之：

Feign 采用的是基于接口的注解
Feign 整合了ribbon

二、準(zhǔn)備工作

繼續(xù)用上一節(jié)的工程，啟動eureka-server，端口為8761; 啟動service-hi 兩次，端口分別為8762 、8773.

三、創(chuàng)建一個feign的服務(wù)

新建一個spring-boot工程，取名為serice-feign，在它的pom文件引入Feign的起步依賴spring-cloud-starter-feign、Eureka的起步依賴spring-cloud-starter-eureka、Web的起步依賴spring-boot-starter-web，代碼如下：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven./POM/4.0.0" xmlns:xsi="http://www./2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven./POM/4.0.0 http://maven./xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
 
    <groupId>com.forezp</groupId>
    <artifactId>service-feign</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>
 
    <name>service-feign</name>
    <description>Demo project for Spring Boot</description>
 
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.2.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>
</project>

在工程的配置文件application.yml文件，指定程序名為service-feign，端口號為8765，服務(wù)注冊地址為http://localhost:8761/eureka/ ，代碼如下：

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

在程序的啟動類ServiceFeignApplication ，加上@EnableFeignClients注解開啟Feign的功能：

@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
public class ServiceFeignApplication {
 
    public static void main(String[] args) {
        SpringApplication.run(ServiceFeignApplication.class, args);
    }
}

定義一個feign接口，通過@ FeignClient（“服務(wù)名”），來指定調(diào)用哪個服務(wù)。比如在代碼中調(diào)用了service-hi服務(wù)的“/hi”接口，代碼如下：

/**
 * Created by fangzhipeng on 2017/4/6.
 */
@FeignClient(value = "service-hi")
public interface SchedualServiceHi {
    @RequestMapping(value = "/hi",method = RequestMethod.GET)
    String sayHiFromClientOne(@RequestParam(value = "name") String name);
}

在Web層的controller層，對外暴露一個”/hi”的API接口，通過上面定義的Feign客戶端SchedualServiceHi 來消費服務(wù)。代碼如下：

@RestController
public class HiController {
 
    @Autowired
    SchedualServiceHi schedualServiceHi;
    @RequestMapping(value = "/hi",method = RequestMethod.GET)
    public String sayHi(@RequestParam String name){
        return schedualServiceHi.sayHiFromClientOne(name);
    }
}

架構(gòu)代碼如下: