环境搭建

创建 maven 工程

创建实体类和dao接口

[User.java]

package com.gphper.domain;

import java.util.Date;

public class User {
    int id;
    String number;
    String name;
    String password;
    String gender;
    Date create_time;
    Date update_time;
    int sex;

    public int getId() {
        return id;
    }

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

    public String getNumber() {
        return number;
    }

    public void setNumber(String number) {
        this.number = number;
    }

    public String getName() {
        return name;
    }

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

    public String getPassword() {
        return password;
    }

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

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public Date getCreate_time() {
        return create_time;
    }

    public void setCreate_time(Date create_time) {
        this.create_time = create_time;
    }

    public Date getUpdate_time() {
        return update_time;
    }

    public void setUpdate_time(Date update_time) {
        this.update_time = update_time;
    }

    public int getSex() {
        return sex;
    }

    public void setSex(int sex) {
        this.sex = sex;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", number='" + number + '\'' +
                ", name='" + name + '\'' +
                ", password='" + password + '\'' +
                ", gender='" + gender + '\'' +
                ", create_time=" + create_time +
                ", update_time=" + update_time +
                ", sex=" + sex +
                '}';
    }
}

[IUserDao]

package com.gphper.dao;

import com.gphper.domain.User;

import java.util.List;

public interface IUserDAo {
    List<User> findAll();
}

创建Mybatis的主配置文件 SqlMapConfig.xml

<?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">
<configuration>

    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <!--配置数据源：创建Connection对象-->
            <dataSource type="POOLED">
                <!--driver：驱动内容-->
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <!--连接数据库的url-->
                <property name="url" value="jdbc:mysql://localhost:3306/book?useUnicode=true&amp;characterEncoding=utf-8"/>
                <!--用户名-->
                <property name="username" value="root"/>
                <!--密码-->
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>

    <mappers>
        <mapper resource="com/gphper/dao/IUserDao.xml"/>
    </mappers>
</configuration>

创建映射配置文件 IUserDao.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="com.gphper.dao.IUserDAo">
    <!--  配置查询所有  -->
    <select id="findAll" resultType="com.gphper.domain.User">
        select * from user
    </select>
</mapper>

入门代码【xml版】

       package com.gphper;

       import com.gphper.dao.IUserDAo;
       import com.gphper.domain.User;
       import org.apache.ibatis.io.Resources;
       import org.apache.ibatis.session.SqlSession;
       import org.apache.ibatis.session.SqlSessionFactory;
       import org.apache.ibatis.session.SqlSessionFactoryBuilder;

       import java.io.InputStream;
       import java.util.List;

       public class MybatisTest {
           public static void main(String[] args) throws Exception {
               //读取配置文件
               InputStream in = Resources.getResourceAsStream("MysqlMapConf.xml");
               // 创建SqlSessionFactory 工厂
               SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
               SqlSessionFactory build = sqlSessionFactoryBuilder.build(in);
               // 使用工厂创建SqlSession 对象
               SqlSession sqlSession = build.openSession();
               // 使用session对象创建Dao接口的代理对象
               IUserDAo userDao = sqlSession.getMapper(IUserDAo.class);
               // 使用代理对象执行方法
               List<User> users = userDao.findAll();
               for(User user:users){
                   System.out.println(user);
               }
               //释放资源
               sqlSession.close();
               in.close();
           }
       }
   ```    
* 注意事项
   > mybaits的映射配置文件位置必须和dao接口的的包结构相同
   > 配置文件的`mapper`标签`namespace`属性的取值必须是dao接口的全限定类名
   > 映射配置文件的操作配置id属性的值必须是dao接口的方法名

6. 注解版
   IUserDao.xml
   ``` xml
    <mappers>
       <mapper class="com.gphper.dao.IUserDAo" />
    </mappers>

[IUserDao]

package com.gphper.dao;

import com.gphper.domain.User;

import java.util.List;

public interface IUserDAo {

    @Select("select * from user")
    List<User> findAll();
}