前言

相信用过Spring Cloud对于Spring Feign并不陌生，但是实际使用过Feign的同学恐怕都会发现多客户端的代码重复问题确实十分恶心，特别是当需要调整接口时，往往牵一发而动全身，本文就这个问题进行讨论，并通过整套实例代码来说明如何解决多个客户端的feign client代码重复问题。
调用本地的FeignClient的实例这里就不赘述了，网上资料丰富。

多客户端的基本结构

首先先看一下服务端，客户端的结构。
这里写图片描述

代码实例

服务端

目录结构

这里写图片描述

DemoApplication

package com.zw.se2.research.feginutil.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.netflix.feign.EnableFeignClients;

@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients(basePackages = {"com.zw.se2.research.fegin.utils.client"})
public class DemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }
}

Controller

package com.zw.se2.research.feginutil.demo.ctrl;

import com.zw.se2.research.fegin.utils.client.HelloFeignUtil;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class Controller {
    @Autowired
    HelloFeignUtil helloFeignUtil;
    @GetMapping("hello")
    public String sayHello(){

        return helloFeignUtil.hello();
    }
}

pom.xml

<?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.zw.se2.research.feginUtil</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>demo</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.10.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>
        <spring-cloud.version>Edgware.SR2</spring-cloud.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</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>
        <dependency>
            <groupId>com.zw.se2.research.fegin.utils</groupId>
            <artifactId>feginUtilDemo</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </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>${spring-cloud.version}</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>


</project>

application.properties

server.port=8189
spring.application.name=demo-server
eureka.instance.prefer-ip-address=true

bootstrap.yaml

eureka:
  client:
    service-url:
        defaultZone: http://localhost:8797/eureka

客户端

目录结构

这里写图片描述

Controller

package com.zw.se2.research.fegin.client.demo.ctrl;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class Controller {
    @GetMapping("/hello")
    public String sayHello(){
        return "hello from client6667";
    }
}

DemoApplication

package com.zw.se2.research.fegin.client.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

@EnableDiscoveryClient
@SpringBootApplication
public class DemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }
}

application.properties

server.port=0
spring.application.name=demo-client
eureka.instance.prefer-ip-address=true

bootstrap.yaml

eureka:
  client:
    service-url:
        defaultZone: http://localhost:8797/eureka

pom.xml

<?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.zw.se2.research.fegin.client</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>demo</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.10.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>
        <spring-cloud.version>Edgware.SR2</spring-cloud.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka</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>${spring-cloud.version}</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>


</project>

抽取的工具类

目录结构

这里写图片描述

HelloFeignUtil

package com.zw.se2.research.fegin.utils.client;

import org.springframework.cloud.netflix.feign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;

/**
 * Created by ZEW on 2017/7/19.
 */
@FeignClient("demo-client")
public interface HelloFeignUtil {
    @GetMapping("/hello")
    String hello();

}

pom.xml

<?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.zw.se2.research.fegin.utils</groupId>
    <artifactId>feginUtilDemo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>feignUtilDemo</name>
    <description>Demo project for Spring Boot</description>


    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-netflix-core</artifactId>
            <version>1.4.3.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
            <version>4.3.14.RELEASE</version>
        </dependency>


    </dependencies>



</project>

注册中心

目录结构

这里写图片描述

RegisterAndDiscoveryApplication

package com.zw.se2.hy.uav;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;

@EnableEurekaServer
@SpringBootApplication
public class RegisterAndDiscoveryApplication {

    public static void main(String[] args) {
        SpringApplication.run(RegisterAndDiscoveryApplication.class, args);
    }
}

application.properties

server.port=8797
spring.application.name=reborn-register-server
eureka.client.fetch-registry=false

bootstrap.yaml

eureka:
  client:
    service-url:
        defaultZone: http://localhost:8797/eureka

pom.xml

<?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.zw.se2.hy.uav</groupId>
    <artifactId>register-and-discovery-server</artifactId>
    <version>1.0-SNAPSHOT</version>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.4.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-server</artifactId>
            <version>1.3.1.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <version>1.5.4.RELEASE</version>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                    <encoding>UTF-8</encoding>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.jacoco</groupId>
                <artifactId>jacoco-maven-plugin</artifactId>
                <version>0.7.5.201505241946</version>
                <executions>
                    <execution>
                        <id>default-prepare-agent</id>
                        <goals>
                            <goal>prepare-agent</goal>
                        </goals>
                    </execution>
                    <execution>
                        <id>default-prepare-agent-integration</id>
                        <goals>
                            <goal>prepare-agent-integration</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
            <!-- tag::plugin[] -->
            <plugin>
                <groupId>com.spotify</groupId>
                <artifactId>docker-maven-plugin</artifactId>
                <version>0.4.3</version>
                <configuration>
                    <imageName>zw/docker_gz_register</imageName>
                    <dockerDirectory>src/main/docker</dockerDirectory>
                    <resources>
                        <resource>
                            <targetPath>/</targetPath>
                            <directory>${project.build.directory}</directory>
                            <include>${project.build.finalName}.jar</include>
                        </resource>
                    </resources>
                </configuration>
            </plugin>
        </plugins>
    </build>


</project>

总结

关键就是下面这句话

@EnableFeignClients(basePackages = {"com.zw.se2.research.fegin.utils.client"})

服务端要指定feign客户端的扫描路径，仔细读说明文档是关键啊。

ps：支持数组的形式。

@EnableFeignClients(basePackages = {"com.zw.se2.research.fegin.utils.client1，com.zw.se2.research.fegin.utils.client2，com.zw.se2.research.fegin.utils.client3"})

解决SpringCloud中多客户端的Feign client代码重复问题的思路

前言

多客户端的基本结构

代码实例

服务端

目录结构

DemoApplication

Controller

pom.xml

application.properties

bootstrap.yaml

客户端

目录结构

Controller

DemoApplication

application.properties

bootstrap.yaml

pom.xml

抽取的工具类

目录结构

HelloFeignUtil

pom.xml

注册中心

目录结构

RegisterAndDiscoveryApplication

application.properties

bootstrap.yaml

pom.xml

总结