目录

1、新建数据库

2、新建项目

2.1导入依赖

2.2创建子工程（新建模块）

2.3添加配置文件mybatis-config.xml

2.4添加数据源

2.5编写mybatis核心配置文件

2.6编写MybatisUtils工具类

3、编写代码

3.1实体类

3.2 Mapper(UserDao)接口

3.3 接口实现类（mapper.xml）

4、测试 

---

1、新建数据库

2、新建项目

2.1导入依赖

创建maven工程并导入坐标（创建一个普通maven项目，删除src文件夹，作为父工程）

此处特别注意<build>中代码

<!--引入依赖-->
    <dependencies>

        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.5</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>

        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.12</version>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.10</version>
        </dependency>

    </dependencies>

<!--在build中配置resources来防止资源导出失败的问题-->
    <build>
        <resources>
            <resource>
                <directory>src/main/resources</directory>
                <excludes>
                    <exclude>**/*.properties</exclude>
                    <exclude>**/*.xml</exclude>
                </excludes>
                <filtering>true</filtering>
            </resource>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>
        </resources>
    </build>

2.2创建子工程（新建模块）

2.3添加配置文件mybatis-config.xml

2.4添加数据源

2.5编写mybatis核心配置文件

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">

<!-- 核心配置文件-->
<configuration>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis?
useSSL=true&amp;useUnicode=true&amp;characterEncoding=utf8"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>
<!--每个Mapper.XML都需要在Mybatis核心配置文件中注册-->
    <mappers>
        <mapper resource="com/dymic/dao/UserMapper.xml"></mapper>
    </mappers>
</configuration>

</configuration>

2.6编写MybatisUtils工具类

public class MybatisUtils {
   
    private  static SqlSessionFactory sqlSessionFactory ;
    static{
       
        try {
            // 第一步获取 SqlSessionFactory对象
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    //SqlSession 包含了面向数据库执行SQL所需的方法
    public static SqlSession getSqlSession(){
        return sqlSessionFactory.openSession();
    }

}

3、编写代码

3.1实体类

public class User {
private int id;
private  String username;
private  String password;
 public User(){}
    public User(int id,String username,String password){
     this.id=id;
     this.username=username;
     this.password=password;
    }
    public int getId() {
        return id;
    }

    public String getUsername() {
        return username;
    }

    public String getPassword() {
        return password;
    }

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

    public void setUsername(String username) {
        this.username = username;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}

3.2 Mapper(UserDao)接口

public interface UserDao {
    List<User>getUserList();
}

3.3 接口实现类（mapper.xml）

（之前的接口实现类）

<?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">
<!--namespace绑定一个对应的Dao/Mapper的接口-->
<mapper namespace="com.dymic.dao.UserDao">
    
    <!-- id 是接口要实现的方法 ,resultType是实体类全类名-->
    <select id="getUserList" resultType="com.dymic.pojo.User" >
        select * from mybatis.user
    </select>
</mapper>

这里用一张图说下Dao层接口和Mpper.xml的关系 

4、测试 

public class UserDaoTest {
    @Test
    public void test() {
        //获得SqlSession
        SqlSession sqlSession = MybatisUtils.getSqlSession();

        UserDao userDao = sqlSession.getMapper(UserDao.class);
        List<User> userList = userDao.getUserList();

        for (User user : userList) {
            System.out.println(user);
        }
        //关闭SqlSessstion
        sqlSession.close();
    }

}