springboot 多模块 -- 将 dao(mybatis) 拆分出去

前言:

　　以前我们在建项目的时候, 要么将所有的package建在一个项目里面, 在处理引用的时候, 真的很方便. 不用担心, 有些东西配置不到或者读取不到. 

　　或者, 将package独立出去, 到一个项目中或者子项目中. 这时候, 项目中的引用处理, 还是有些麻烦的. 不过好处更多, 不再表述.

　　在 idea 里面, 推荐使用 多模块 建项目, 而不再是 eclipse 里面的那种方式. 那这里, 就试着将一个springboot 的项目拆分到子模块中去, 看看效果如何.

项目拆分:

1. 目录变化

　　

2. 父项目

父pom.xml理论上来说, 应该是对子项目中的引用进行一个约束, 主要是版本约束.

所以父 pom.xm 中, 应该使用  dependencyManagement 来约束 子项目中 jar 包版本.

然后对于一些子项目都用得着的引用, 可以提到 父项目中去. 

<?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>cn.elvinle</groupId>
    <artifactId>parent</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>pom</packaging>

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

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.9.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <modules>
        <module>pojo</module>
        <module>web</module>
        <module>dao</module>
        <module>service</module>
        <module>simpl</module>
    </modules>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
        <druid.version>1.1.3</druid.version>
        <mybatis.boot.starter.version>1.3.1</mybatis.boot.starter.version>
        <mysql.connector.java.version>5.1.44</mysql.connector.java.version>
    </properties>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>com.alibaba</groupId>
                <artifactId>druid</artifactId>
                <version>${druid.version}</version>
            </dependency>

            <dependency>
                <groupId>org.mybatis.spring.boot</groupId>
                <artifactId>mybatis-spring-boot-starter</artifactId>
                <version>${mybatis.boot.starter.version}</version>
            </dependency>

            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <version>${mysql.connector.java.version}</version>
            </dependency>

        </dependencies>
    </dependencyManagement>

    <!--申明依赖关系-->
    <dependencies>
        <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>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

3. 子项目 - pojo

3.1 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>

    <parent>
        <groupId>cn.elvinle</groupId>
        <artifactId>parent</artifactId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>

    <groupId>cn.elvinle</groupId>
    <artifactId>pojo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

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

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

3.2 db实体 

package cn.elvinle.pojo;

/**
 * @author: elvin
 */
public class User {
    private int id;

    private String name;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

对于pojo和dao中的内容, 可以使用mybatis逆向工程生成, 可以省去很多麻烦.

4. 子项目 - dao

 

4.1 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>

    <parent>
        <groupId>cn.elvinle</groupId>
        <artifactId>parent</artifactId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>

    <groupId>cn.elvinle</groupId>
    <artifactId>dao</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

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

    <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>
        <!-- 内部引用 -->
        <dependency>
            <groupId>cn.elvinle</groupId>
            <artifactId>pojo</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </dependency>

        <!-- 外部引用 -->
        <!-- https://mvnrepository.com/artifact/com.alibaba/druid -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>

        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

4.2 mapper

UserMapper.java:

public interface UserMapper {
    public List<User> getAll();
}

UserMapper.xml:

<?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="cn.elvinle.dao.mapper.UserMapper" >

    <select id="getAll" resultType="cn.elvinle.pojo.User">
        select * from user
    </select>

</mapper>

5. 子项目 - service

5.1 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>

    <parent>
        <groupId>cn.elvinle</groupId>
        <artifactId>parent</artifactId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>

    <groupId>cn.elvinle</groupId>
    <artifactId>service</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

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

    <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>cn.elvinle</groupId>
            <artifactId>pojo</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

5.2 UserService.java

public interface UserService {
    public List<User> getAll();
}

6. 子项目 - simpl

6.1 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>

    <parent>
        <groupId>cn.elvinle</groupId>
        <artifactId>parent</artifactId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>

    <groupId>cn.elvinle</groupId>
    <artifactId>simpl</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

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

    <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>cn.elvinle</groupId>
            <artifactId>pojo</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </dependency>
        <dependency>
            <groupId>cn.elvinle</groupId>
            <artifactId>service</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </dependency>
        <dependency>
            <groupId>cn.elvinle</groupId>
            <artifactId>dao</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

6.2 UserSImpl

@Service
public class UserSImpl implements UserService {

    @Autowired
    private UserMapper userMapper;

    @Override
    public List<User> getAll() {
        System.out.println("UserSImpl getAll");

        return userMapper.getAll();
    }
}

7. 子项目 - web

关键的地方来了.

7.1 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>

    <parent>
        <groupId>cn.elvinle</groupId>
        <artifactId>parent</artifactId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>

    <groupId>cn.elvinle</groupId>
    <artifactId>web</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

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

    <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>cn.elvinle</groupId>
            <artifactId>simpl</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

7.2 application.yml

server:
  context-path: /parent
  port: 8080

mybatis:
  config-location: /mapper/*.xml

spring:
  datasource:
    username: root
    password: root
    url: jdbc:mysql://localhost:3306/shop?useUnicode=true&characterEncoding=utf-8
    driver-class-name: com.mysql.jdbc.Driver

7.3 控制器

@RestController
@RequestMapping("api")
public class ApiController {

    @Autowired
    private UserService userService;

    @RequestMapping("index")
    public List<User> index(){

        List<User> all = userService.getAll();

        return all;
    }
}

到目前为止, 没什么特别的, 都是正常修改, 接下来, 会出现与不分模块不同的地方.

7.4 入口处修改

@ComponentScan({"cn.elvinle"})
@SpringBootApplication
public class WebApplication {

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

这时候, 如果直接运行起程序, 是不会成功访问的. 原因在于, mybatis的自动化配置和自动化创建, 没有支持到多模块中.

这时候, 需要我们手动进行配置和创建.

7.5 Mybatis java 配置

<!-- mybatis 的工厂 -->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <property name="configLocation" value="classpath:mybatis/SqlMapConfig.xml"/>
        <!-- 自动扫描mapping.xml文件 -->
        <!--<property name="mapperLocations" value="classpath:mapper/*.xml" />-->
    </bean>

    <!-- DAO接口所在包名，Spring会自动查找其下的类 -->
    <bean id="mapperScannerConfigurer" class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <property name="basePackage" value="cn.elvinle.bookshop.mapper" />
        <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/>
    </bean>

可以对照着上面的配置文件, 进行java配置

MybatisConfig:

@Configuration
public class MybatisConfig {

    @Value("${mybatis.config-location}")
    private String mapperLocationPattern;

    @Bean
    @ConfigurationProperties(prefix = "spring.datasource")
    public DataSource dataSource(){return new com.alibaba.druid.pool.DruidDataSource();
    }

    @Bean(name="sqlSessionFactory")
    public SqlSessionFactory sqlSessionFactory() throws  Exception{
        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
        sqlSessionFactoryBean.setDataSource(dataSource());
        PathMatchingResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
        sqlSessionFactoryBean.setMapperLocations(resolver.getResources(mapperLocationPattern));
        return sqlSessionFactoryBean.getObject();
    }
}

MybatisMapperScannerConfig:

@Configuration
@AutoConfigureAfter(MybatisConfig.class)
@MapperScan("cn.elvinle.dao.mapper")
public class MybatisMapperScannerConfig {
    public MapperScannerConfigurer mapperScannerConfigurer(){
        MapperScannerConfigurer mapperScannerConfigurer = new MapperScannerConfigurer();
        mapperScannerConfigurer.setSqlSessionFactoryBeanName("sqlSessionFactory");
        mapperScannerConfigurer.setBasePackage("cn.elvinle.dao.mapper");
        return mapperScannerConfigurer;
    }
}

OK, 到这里, 就可以把程序跑起来了, 看一下结果: