Spring Boot(三)：SpringBoot多模块（module）项目搭建
一、前言
记录在IDEA中怎么搭建SpringBoot多模块（module）的过程，以一个交党费的项目为例，多模块的目录结构如下：
dajia-dangfei-api：存放实体类和一些service层接口
dajia-dangfei-provider：存放dao层接口及其实现类和service的实现类
dajia-dangfei-consumer：存放controller层
dajia-dangfei-web：存放前端页面等资源
二、搭建步骤
1、创建父工程
① IDEA 工具栏选择菜单 File -> New -> Project...
② 选择Spring Initializr，Initializr默认选择Default，点击Next
③ 填写输入框，点击Next
④ 这步不需要选择直接点Next
⑤ 点击Finish创建项目
⑥ 最终得到的项目目录结构如下
⑦ 删除无用的.mvn目录、src目录、mvnw及mvnw.cmd文件，最终只留.gitignore和pom.xml
2、创建子模块
① 选择项目根目录dajia-dangfei右键呼出菜单，选择New -> Module
② 选择Maven，点击Next
③ 填写ArifactId，点击Next
④ 修改Module name增加横杠提升可读性，点击Finish
⑤ 同理添加dajia-dangfei-provider、dajia-dangfei-consumer子模块，项目目录结构如下图
⑥添加dajia-dangfei-web的directory
⑦最终的目录结构如下
3、运行项目
① 在dajia-dangfei-consumer中创建com.dajia.income包，添加入口类ConsumerApplicationMain.java，并在income包下创建controller包放BillOrderController.java，目录结构如下
ConsumerApplicationMain.java：
@SpringBootApplication public class ConsumerApplicationMain { public static void main(String[] args) { SpringApplication.run(ConsumerApplicationMain.class,args); } }
因为要通过前端访问BillOrderController中的方法，所以引入spring-boot-starter-web的jar包，在父工程的pom文件中定义，子模块自然可以用到
父工程dajia-dangfei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 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <packaging>pom</packaging> <modules> <module>dajia-dangfei-api</module> <module>dajia-dangfei-provider</module> <module>dajia-dangfei-consumer</module> </modules> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.1.4.RELEASE</version> <relativePath/> <!-- lookup parent from repository --> </parent> <groupId>com.dajia</groupId> <artifactId>dajia-dangfei</artifactId> <version>0.0.1-SNAPSHOT</version> <name>dajia-dangfei</name> <description>Demo project for Spring Boot</description> <properties> <java.version>1.8</java.version> </properties> <dependencies> <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> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project>
引入springboot starter web的jar包
<dependencies> <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>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> </dependencies>
②BillOrderController中添加测试方法
@RestController @RequestMapping("/billOrder") public class BillOrderController { @RequestMapping("/test") public String test(){ return "hello World!!!"; } }
③ 运行ConsumerApplicationMain类中的main方法启动项目，默认端口为8080，访问http://localhost:8080/billOrder/test得到如下效果
以上的项目虽然能启动，但是模块间的依赖关系还没添加，下面继续完善
4、配置模块间的依赖关系
各个子模块的依赖关系：dajia-dangfei-consumer依赖dajia-dangfei-provider，dajia-dangfei-provider依赖dajia-dangfei-api
①在dajia-dangfei-provider中的pom文件中添加dajia-dangfei-api依赖
<dependencies> <dependency> <artifactId>dajia-dangfei-api</artifactId> <groupId>com.dajia</groupId> <version>0.0.1-SNAPSHOT</version> </dependency> </dependencies>
②在dajia-dangfei-consumer中的pom文件中添加dajia-dangfei-provider依赖
<dependencies> <dependency> <artifactId>dajia-dangfei-provider</artifactId> <groupId>com.dajia</groupId> <version>0.0.1-SNAPSHOT</version> </dependency> </dependencies>
5、各模块见得相互调用，从前端到数据库
①dajia-dangfei-api中定义BillOrder实体类、BillOrderService接口
BillOrder.java
public class BillOrder implements Serializable{ private static final long serialVersionUID = -1764514095260116666L; /* * 交费单ID * */ private String billOrderID; /* * 交费单姓名 * */ private String personName; /* * 交费单证件号 * */ private String idNumber; /* * 应交金额 * */ private BigDecimal payAmt; /* * 交费单创建时间 * */ private Date createTime; }
BillOrderService.java
public interface BillOrderService { /** * 根据交费单ID查找对应的交费单 * @param billOrderID * @return */ BillOrder getBillOrderByID(String billOrderID); }
dajia-dangfei-api中的目录结构如下
②dajia-dangfei-provider中定义billOrderServiceImpl实现类，dao层接口，数据库连接
数据库连接
父工程引入mybatis-spring-boot-starter和mysql-connector-java的jar包
<dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.34</version> </dependency> <dependency> <groupId>org.mybatis.spring.boot</groupId> <artifactId>mybatis-spring-boot-starter</artifactId> <version>1.1.1</version> </dependency>
resources下配置application.properties文件，主要配置两部分。一个是数据库的连接，一个是mybatis的mapper文件路径
spring.datasource.url=jdbc:mysql://localhost:3306/databasezfy?useUnicode=true&characterEncoding=UTF-8&useSSL=false spring.datasource.driverClassName=com.mysql.jdbc.Driver spring.datasource.username=root spring.datasource.password=123456 mybatis.config-locations=mybatis/mybatis-config.xml mybatis.mapper-locations=mybatis/mapper/*.xml
填写billOrder-mapper.xml中对应的SQL语句
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> <mapper namespace="com.dajia.income.dao.BillOrderMapper"> <sql id="base_column"> billOrderID,personName,idNumber,payAmt,createTime </sql> <select id="getBillOrderByID" resultType="com.dajia.income.entity.BillOrder" parameterType="string"> SELECT <include refid="base_column"/> FROM billOrder WHERE billOrderID = #{billOrderID} </select> </mapper>
dao层接口，@Repository注解是为了在serviceImpl中可以同过@Autowired的方式注入BillOrderMapper
@Repository public interface BillOrderMapper { /** * 根据交费单ID查找对应的交费单 * @param billOrderID * @return */ BillOrder getBillOrderByBillOrderID(String billOrderID); }
billOrderServiceImpl实现类，@Service注解是为了在controller中可以同过@Autowired的方式注入BillOrderService
@Service public class BillOrderServiceImpl implements BillOrderService{ @Autowired private BillOrderMapper billOrderMapper; @Override public BillOrder getBillOrderByID(String billOrderID) { return billOrderMapper.getBillOrderByBillOrderID(billOrderID); } }
③dajia-dangfei-consumer中通过调用service中的方法实现查询
@RestController @RequestMapping("/billOrder") public class BillOrderController { @Autowired private BillOrderService billOrderService; @RequestMapping("/getBillOrderByID") public BillOrder getBillOrderByID(){ return billOrderService.getBillOrderByID("1"); } }
运行ConsumerApplicationMain类中的main方法启动项目，会发现报错
Description:
Field billOrderMapper in com.dajia.income.service.impl.BillOrderServiceImpl required a bean of type 'com.dajia.income.dao.BillOrderMapper' that could not be found.
The injection point has the following annotations:
- @org.springframework.beans.factory.annotation.Autowired(required=true)
Action:
Consider defining a bean of type 'com.dajia.income.dao.BillOrderMapper' in your configuration.
原因：@Repository注解是Spring的，Spring在扫描注解时，取消了扫描抽象类和接口，所以无法找到你用@reponsitory注解的dao接口。两种方法解决：
一是用@Mapper注解替代@Repository注解，二是在启动项目时指定要扫描的包，我们这里使用第二种
@SpringBootApplication @MapperScan("com.dajia.income.dao") public class ConsumerApplicationMain { public static void main(String[] args) { SpringApplication.run(ConsumerApplicationMain.class,args); } }
重新启动，访问http://localhost:8080/billOrder/getBillOrderByID得到如下效果
至此，一个简单的SpringBoot+Mybatis多模块项目已经搭建完毕，我们也通过启动项目调用接口验证其正确性。
