比起传统复杂的单体工程，使用Maven的多模块配置，可以帮助项目划分模块，鼓励重用，防止POM变得过于庞大，方便某个模块的构建，而不用每次都构建整个项目，并且使得针对某个模块的特殊控制更为方便。接下来，本文将重点阐述SpringBoot在Maven环境的多模块构建过程
一、创建聚合父工程
1.首先使用 Spring Initializr 来快速创建好一个Maven工程。然后删除无关的文件，只需保留pom.xml 文件。
图片.png
然后在 pom.xml 里面声明该父工程包含的子模块。（其它信息就不逐一讲述了，诸如继承SpringBoot官方父工程以及统一依赖管理 请查看下面的注释说明
<?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">
<!-- 基本信息 -->
<description>SpringBoot 多模块构建示例</description>
<modelVersion>4.0.0</modelVersion>
<name>spring-boot-integration</name>
<packaging>pom</packaging>
<!-- 项目说明：这里作为聚合工程的父工程 -->
<groupId>com.hehe</groupId>
<artifactId>springboot-integration</artifactId>
<version>1.0.0.RELEASE</version>
<!-- 继承说明：这里继承SpringBoot提供的父工程 -->
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.7.RELEASE</version>
<relativePath/>
</parent>
<!-- 模块说明：这里声明多个子模块 -->
<modules>
<module>mm-web</module>
<module>mm-service</module>
<module>mm-repo</module>
<module>mm-entity</module>
</modules>
<!-- 版本说明：这里统一管理依赖的版本号 -->
<dependencyManagement>
<dependencies>
<dependency>
<groupId>com.hehe</groupId>
<artifactId>mm-web</artifactId>
<version>0.0.1-SNAPSHOT</version>
</dependency>
<dependency>
<groupId>com.hehe</groupId>
<artifactId>mm-service</artifactId>
<version>0.0.1-SNAPSHOT</version>
</dependency>
<dependency>
<groupId>com.hehe</groupId>
<artifactId>mm-repo</artifactId>
<version>0.0.1-SNAPSHOT</version>
</dependency>
<dependency>
<groupId>com.hehe</groupId>
<artifactId>mm-entity</artifactId>
<version>0.0.1-SNAPSHOT</version>
</dependency>
</dependencies>
</dependencyManagement>
</project>
二、创建子模块（module）
注：这里是使用IDEA来创建子模块，使用Eclipse的小伙伴可通过 Spring Initializr 构建，然后复制去进去父工程根目录即可。
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1.对着父工程右键 - New - Module - > 输入 mm-web
-
2.对着父工程右键 - New - Module - > 输入 mm-service
-
3.对着父工程右键 - New - Module - > 输入 mm-repo
-
4.对着父工程右键 - New - Module - > 输入 mm-entity
-
1~4 步骤完成后，分别调整它们的pom.xml 以继承上面的父工程。
例如mm-web模块的pom.xml 需要改造成这样：
<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>
<!-- 基本信息 -->
<groupId>com.hehe</groupId>
<artifactId>mm-web</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>mm-web</name>
<!-- 继承本项目的父工程 -->
<parent>
<groupId>com.hehe</groupId>
<artifactId>springboot-integration</artifactId>
<version>1.0.0.RELEASE</version>
</parent>
<!-- Web模块相关依赖 -->
<dependencies>
<dependency>
<groupId>com.hehe</groupId>
<artifactId>mm-service</artifactId>
</dependency>
<!--<dependency>
<groupId>com.hehe</groupId>
<artifactId>mm-entity</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>
<build>
<plugins>
<plugin>
<!--该插件主要用途：构建可执行的JAR -->
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
三、编写子模块代码
1. 控制层（mm-web）
图片.png
启动类 ：SpringbootIntegrationApplication.java （mm-web）
package com.hehe.springbootintegration;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class SpringbootIntegrationApplication {
public static void main(String[] args) {
SpringApplication.run(SpringbootIntegrationApplication.class, args);
}
}
控制器：UserController.java （mm-web ）
package com.hehe.springbootintegration;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RequestMapping("city")
@RestController
public class CityController {
@Autowired
CityService service;
@GetMapping("list")
public R list() {
try {
return R.isOk().data(service.list());
} catch (Exception e) {
return R.isFail(e);
}
}
@GetMapping("cityList/{id}")
public R city(@PathVariable("id")Long id){
try
{
return R.isOk().data(service.findCity(id));
}catch (Exception e){
return R.isFail();
}
}
}
配置文件：application.yml （mm-web）
spring:
datasource:
url: jdbc:mysql://localhost:3306/springboot2?useSSL=false
username: root
password: 514730
driver-class-name: com.mysql.jdbc.Driver
2. 业务层（mm-service）
实现类：UserServiceImpl.java （mm-service）
package com.hehe.springbootintegration;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.List;
@Service
public class CityServiceImpl implements CityService {
@Autowired
CityRepo repo;
public List<City> list() {
return repo.findAll();
}
public City findCity(Long id){
return repo.findOne(id);
}
}
3. 数据层（mm-repo）
图片.png
数据层代码：CityRepo.java（mm-repo）
package com.hehe.springbootintegration;
import org.springframework.data.jpa.repository.JpaRepository;
public interface CityRepo extends JpaRepository<City,Long>{
}
4. mm-entity (实体模型层)
图片.png
R.java 作为统一返回的Bean对象
package com.hehe.springbootintegration;
import java.io.Serializable;
public class R<T> implements Serializable {
private static final long serialVersionUID = -4577255781088498763L;
private static final int OK = 0;
private static final int FAIL = 1;
private static final int UNAUTHORIZED = 2;
private T data; //服务端数据
private int status = OK; //状态码
private String msg = ""; //描述信息
//APIS
public static R isOk() {
return new R();
}
public static R isFail() {
return new R().status(FAIL);
}
public static R isFail(Throwable e) {
return isFail().msg(e);
}
public R msg(Throwable e) {
this.setMsg(e.toString());
return this;
}
public R data(T data) {
this.setData(data);
return this;
}
public R status(int status) {
this.setStatus(status);
return this;
}
//Constructors
public R() {
}
//Getter&Setters
public T getData() {
return data;
}
public void setData(T data) {
this.data = data;
}
public int getStatus() {
return status;
}
public void setStatus(int status) {
this.status = status;
}
public String getMsg() {
return msg;
}
public void setMsg(String msg) {
this.msg = msg;
}
}
package com.hehe.springbootintegration;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;
@Entity
@Table
public class City {
@Id
@Column(name = "id")
private long id;
@Column(name = "province_id")
private String provinceId;
@Column(name = "city_name")
private String cityName;
@Column(name = "description")
private String description;
public City(long id, String provinceId, String cityName, String description) {
this.id = id;
this.provinceId = provinceId;
this.cityName = cityName;
this.description = description;
}
public City() {
}
public long getId() {
return id;
}
@Override
public String toString() {
return "City{" +
"id=" + id +
", provinceId='" + provinceId + '\'' +
", cityName='" + cityName + '\'' +
", description='" + description + '\'' +
'}';
}
public void setId(long id) {
this.id = id;
}
public String getProvinceId() {
return provinceId;
}
public void setProvinceId(String provinceId) {
this.provinceId = provinceId;
}
public String getCityName() {
return cityName;
}
public void setCityName(String cityName) {
this.cityName = cityName;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
}
三、运行项目
图片.png
CREATE TABLE city
(
id INT AUTO_INCREMENT
PRIMARY KEY,
province_id INT NULL,
city_name VARCHAR(255) NULL,
description VARCHAR(255) NULL
)
ENGINE = InnoDB;
配置好整个项目之后，这里只需要运行mm-web模块下的Application的启动类就可以了，如正常启动后，访问http://localhost:8080 可查询到用户列表信息。如下图：
http://localhost:8080/city/list
http://localhost:8080/city/cityList/1
参考：
https://segmentfault.com/a/1190000011367492
https://github.com/yizhiwazi/springboot-socks/tree/master/springboot-integration
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