SpringCloud Feign 以及一个标准的微服务的制作

一个标准的微服务制作

以一个咖啡小程序项目的订单模块为例，这个模块必将包括：

各种实体类（pojo,dto,vo....）

控制器 controller 服务类service

......

其中控制器中有的接口需要提供给其他微服务，订单模块也需要其他微服务提供接口。

那么在项目开发和维护的过程中，如果一个模块里面的内容发生变动，相关的模块的业务也要修改，有种“牵一发而动全身”的感觉。（如订单模块修改了一个订单pojo里面的一个字段，那么用户模块用到这个订单pojo的所有业务也要同时修改，十分麻烦）

于是乎，我们需要将一个完整的微服务模块拆成三个部分

baoder_orders是项目的订单模块，它被拆成了三个部分

其中：

baoder_orders_model ：包含了订单模块要用的所有的实体类

baoder_orders_service ：包含了订单模块的所有的业务，它会调用baoder_orders_model

baoder_orders_api ：包含了订单模块向其他微服务暴露的接口（基于Feign的声明式的http客户端）其他微服务可以通过引入 baoder_orders_api 来调用baoder_orders_service的服务

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那么这三个部分是怎么相互协作的呢？且看下文细细道来

*********************************************************

我们先分别分析三个部分的结构，最后再通过最上面的这个图来加深理解

baoder_orders_model

目录结构如下，baoder_orders_model模块用于保存订单模块需要的所有实体类，包括统一封装结果，自定义异常等，异常拦截器仍然放在baoder_orders_service里面。

打开它的pom文件，可以看到它确确实实只是作为存储实体类的模块，甚至连bulid标签都没有

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.gmgx</groupId><artifactId>baoder_orders_model</artifactId><version>0.0.1-SNAPSHOT</version><name>baoder_orders_model</name><description>baoder_orders_model</description>
<!--    baoder_parent用于管理项目需要的所有的依赖的版本--><parent><groupId>com.gmgx</groupId><artifactId>baoder_parent</artifactId><version>0.0.1-SNAPSHOT</version></parent><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter</artifactId></dependency><dependency><groupId>com.mysql</groupId><artifactId>mysql-connector-j</artifactId><scope>runtime</scope></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><optional>true</optional></dependency><dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-spring-boot3-starter</artifactId></dependency><dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-generator</artifactId></dependency><!--模板引擎--><dependency><groupId>org.apache.velocity</groupId><artifactId>velocity-engine-core</artifactId></dependency><dependency><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-databind</artifactId></dependency></dependencies></project>

我们需要做的事情就是让他被service和api引用，那么就需要把它安装到我们本地的maven仓库里面，需要的时候作为依赖在pom文件中引用即可。

执行完这三步后，去我们本地的maven仓库所在的文件夹里面，可以看到打包好的baoder_orders_model依赖

baoder_orders_service

目录结构如下，baoder_orders_service包含了订单模块的所有业务，这个模块是要被打包发布到docker上的，所以会有有关docker的两个文件

打开application.properties文件，可以看到关于数据库，nacos，redis的相关配置。

其中数据库和redis是业务需要的

同时利用nacos将这个微服务注册到nacos注册中心上，服务名为baoder-orders-service


# 应用服务 WEB 访问端口
server.port=8090# 数据库配置
spring.datasource.url=jdbc:mysql://192.168.2.222:3306/baoder-orders?useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&connectTimeout=10000&socketTimeout=30000&allowPublicKeyRetrieval=true&useSSL=false&serverTimezone=UTC&rewriteBatchedStatements=true
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver# Nacos帮助文档: https://nacos.io/zh-cn/docs/concepts.html
spring.application.name=baoder-orders-service
# Nacos认证信息
spring.cloud.nacos.discovery.username=nacos
spring.cloud.nacos.discovery.password=nacos
# Nacos 服务发现与注册配置，其中子属性 server-addr 指定 Nacos 服务器主机和端口
spring.cloud.nacos.discovery.server-addr=192.168.2.222:8848
# 注册到 nacos 的指定 namespace，默认为 public
spring.cloud.nacos.discovery.namespace=public# redis配置
spring.data.redis.host=192.168.2.222
spring.data.redis.database=0

（重头戏）打开pom文件

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.gmgx</groupId><artifactId>baoder_orders_service</artifactId><version>0.0.1-SNAPSHOT</version><name>baoder_orders_service</name><description>baoder_orders_service</description><parent><groupId>com.gmgx</groupId><artifactId>baoder_parent</artifactId><version>0.0.1-SNAPSHOT</version></parent><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId></dependency><dependency><groupId>com.mysql</groupId><artifactId>mysql-connector-j</artifactId><scope>runtime</scope></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><optional>true</optional></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-boot-starter</artifactId></dependency><dependency><groupId>com.github.xiaoymin</groupId><artifactId>knife4j-openapi3-jakarta-spring-boot-starter</artifactId></dependency><!--        redis--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-redis</artifactId></dependency><dependency><groupId>org.apache.commons</groupId><artifactId>commons-pool2</artifactId></dependency><dependency><groupId>com.gmgx</groupId><artifactId>baoder_orders_model</artifactId><version>0.0.1-SNAPSHOT</version></dependency></dependencies><build><plugins><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-compiler-plugin</artifactId><version>3.8.1</version><configuration><source>17</source><target>17</target><encoding>UTF-8</encoding></configuration></plugin><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId><version>${spring-boot.version}</version><configuration><mainClass>com.gmgx.BaoderOrdersServiceApplication</mainClass><skip>false</skip></configuration><executions><execution><id>repackage</id><goals><goal>repackage</goal></goals></execution></executions></plugin><!--            跳过测试--><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-surefire-plugin</artifactId><version>2.4.2</version><configuration><skipTests>true</skipTests></configuration></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>

可以看到我们刚才install到本地仓库的baoder_orders_model

我们随便打开一个服务，能看到baoder_orders_model里面的实体类已经被引进来了

这样一来，负责其他模块的同事们只需要拿到最新的baoder_orders_model，就可以愉快地做自己的模块了，只需要我把最新的 baoder_orders_model给他们，让他们在他们的本地仓库install就可以了。

baoder_orders_api（被调用方）

目录结构如下。baoder_orders_api 负责向其他调用者（其他微服务）提供baoder_service_api暴露出来的接口，我们需要详细说明这个模块是怎么做的，这就是SpringCloud中Feign组件的应用。

1.引入依赖

我们需要引入如下依赖（这两个依赖是feign要用的）

        <dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-openfeign</artifactId></dependency><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-loadbalancer</artifactId></dependency>

最终的pom文件是这样的，声明http请求需要实体类，因此引入了baoder_orders_model

其实只需要三个依赖（2+1）就行了，boot的依赖调用者肯定会有

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.gmgx</groupId><artifactId>baoder_orders_api</artifactId><version>0.0.1-SNAPSHOT</version><name>baoder_orders_api</name><description>baoder_orders_api</description><parent><groupId>com.gmgx</groupId><artifactId>baoder_parent</artifactId><version>0.0.1-SNAPSHOT</version></parent><dependencies><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-openfeign</artifactId></dependency><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-loadbalancer</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><dependency><groupId>com.gmgx</groupId><artifactId>baoder_orders_model</artifactId><version>0.0.1-SNAPSHOT</version></dependency></dependencies><dependencyManagement><dependencies><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-dependencies</artifactId><version>${spring-cloud.version}</version><type>pom</type><scope>import</scope></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-dependencies</artifactId><version>${spring-boot.version}</version><type>pom</type><scope>import</scope></dependency></dependencies></dependencyManagement><build><plugins><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-compiler-plugin</artifactId><version>3.8.1</version><configuration><source>17</source><target>17</target><encoding>UTF-8</encoding></configuration></plugin><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId><version>${spring-boot.version}</version><configuration><mainClass>com.gmgx.BaoderOrdersApiApplication</mainClass><skip>true</skip></configuration><executions><execution><id>repackage</id><goals><goal>repackage</goal></goals></execution></executions></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>

2.写客户端接口

java">package com.gmgx.api;import com.gmgx.common.Result;import com.gmgx.dto.OrderSearchDto;
import com.gmgx.dto.SubmitDto;
import com.gmgx.entity.Orders;import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.stereotype.Component;
import org.springframework.web.bind.annotation.*;@FeignClient(name = "baoder-orders-service",contextId = "baoder-orders-service"
)
@Component
public interface OrdersClient {static final String prefix = "order";@PutMapping(prefix + "/cancel")public Result<Object> cancel(@RequestBody Orders order);@PutMapping(prefix + "rejection")public Result<Object> rejection(@RequestBody Orders order);@PutMapping(prefix + "confirm")public Result<Object> confirm(@RequestBody Orders order);@PutMapping(prefix + "delivery/{id}")public Result<String> delivery(@PathVariable(value = "id") String id);@PutMapping(prefix + "complete/{id}")public Result<Object> complete(@PathVariable(value = "id") String id);@PostMapping(prefix + "conditionSearch")public Result<Object> conditionSearch(@RequestBody OrderSearchDto dto);@GetMapping(prefix + "details/{oId}")public Result<Object> getDetails(@PathVariable(value = "id") String oId);@PutMapping(prefix + "cancel/{id}/{cancelReason}")public Result<Object> cancelByMember(@PathVariable("id") String id, @PathVariable(value = "cancelReason") String cancelReason);@GetMapping(prefix + "historyOrders/{memberId}")public Result<Object> getHistoryOrders(@PathVariable(value = "memberId") String memberId);@PostMapping(prefix + "submit")public Result<String> submit(@RequestBody SubmitDto submitDto);@PutMapping(prefix + "payment/{oId}/{type}")public Result<Object> payment(@PathVariable(value = "oId") String oId, @PathVariable(value = "type") String type);@PostMapping(prefix + "repetition/{oId}")public Result<Object> repetition(@PathVariable(value = "oid") String oId);
}

*************************************************************************************************************

@FeignClient用于声明要调用哪个service，这个从service的配置文件里面找，即nacos注册的服务名（所有的微服务都要注册到nacos）

要把这个接口注册成一个组件，这样调用方就可以通过@Resource 自动装配使用Feign客户端了

feign客户端的接口路径，访问方法，请求参数，返回值等要和service那边的控制器一样

最后，baoder_orders_api也要被install到本地仓库，我们只需要把这个模块给需要调用我们接口的同事就可以了

调用api

现在用一个demo-useOrders项目来模拟baoder_orders_service的调用方

创建好项目后，打开它的pom文件

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.gmgx</groupId><artifactId>demo-useOrders</artifactId><version>0.0.1-SNAPSHOT</version><name>demo-useOrders</name><description>demo-useOrders</description><properties><java.version>17</java.version><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding><spring-boot.version>3.0.2</spring-boot.version><spring-cloud-alibaba.version>2022.0.0.0-RC2</spring-cloud-alibaba.version><spring-cloud.version>2022.0.0-RC2</spring-cloud.version></properties><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId></dependency><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-openfeign</artifactId></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><optional>true</optional></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><dependency><groupId>com.github.xiaoymin</groupId><artifactId>knife4j-openapi3-jakarta-spring-boot-starter</artifactId><version>4.5.0</version></dependency><dependency><groupId>com.gmgx</groupId><artifactId>baoder_orders_api</artifactId><version>0.0.1-SNAPSHOT</version></dependency><dependency><groupId>com.gmgx</groupId><artifactId>baoder_orders_model</artifactId><version>0.0.1-SNAPSHOT</version></dependency></dependencies><dependencyManagement><dependencies><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-dependencies</artifactId><version>${spring-cloud.version}</version><type>pom</type><scope>import</scope></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-dependencies</artifactId><version>${spring-boot.version}</version><type>pom</type><scope>import</scope></dependency><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-alibaba-dependencies</artifactId><version>${spring-cloud-alibaba.version}</version><type>pom</type><scope>import</scope></dependency></dependencies></dependencyManagement><build><plugins><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-compiler-plugin</artifactId><version>3.8.1</version><configuration><source>17</source><target>17</target><encoding>UTF-8</encoding></configuration></plugin><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId><version>${spring-boot.version}</version><configuration><mainClass>com.gmgx.DemoUseOrdersApplication</mainClass><skip>false</skip></configuration><executions><execution><id>repackage</id><goals><goal>repackage</goal></goals></execution></executions></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>

导入的依赖如下（注意导入了api和model）

控制器中直接注入就可以使用feign客户端了

applicaton.properties如下

# 应用服务 WEB 访问端口
server.port=8088
# Nacos帮助文档: https://nacos.io/zh-cn/docs/concepts.html
spring.application.name=useOrders-service
# Nacos认证信息
spring.cloud.nacos.discovery.username=nacos
spring.cloud.nacos.discovery.password=nacos
# Nacos 服务发现与注册配置，其中子属性 server-addr 指定 Nacos 服务器主机和端口
spring.cloud.nacos.discovery.server-addr=192.168.2.222:8848
# 注册到 nacos 的指定 namespace，默认为 public
spring.cloud.nacos.discovery.namespace=public# 数据库配置
spring.datasource.url=jdbc:mysql://192.168.2.222:3306/baoder-orders?useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&connectTimeout=10000&socketTimeout=30000&allowPublicKeyRetrieval=true&useSSL=false&serverTimezone=UTC&rewriteBatchedStatements=true
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

现在把service和demo-useOrders都跑起来（我服务器已经部署了baoder_orders_service容器和demo-useOrders，但是本地连服务器访问会超时，干脆直接启动本地的service模块，效果是一样的）