本文将阐述mybatis中原始dao方式的实现。

1、环境约束

• win10 64位操作系统
• idea2018.1.5
• jdk-8u162-windows-x64
• mybatis3.2.8
• mysql 6.5

2、前提约束

• 完成idea中创建mybatis项目 https://www.jianshu.com/p/86db0901156f
  请读者注意自己数据库账号密码驱动和url的适配。

3、操作步骤

• 创建一个t_user

create table t_user(id int,name varchar(20));
insert into t_user(id,name) values(1,'ali');
insert into t_user(id,name) values(2,'xiaoli');
insert into t_user(id,name) values(3,'zhangli');

• 在src/main/java中创建net.wanho.User.java：

public class User{
  private int id;
  private String name;
  ...
}

• 在src/main/java中创建net.wanho.UserDao.java:

import net.wanho.User;
import org.apache.ibatis.annotations.Select;

import java.util.List;

public interface UserDao {
    @Select("select * from t_user")
    List<User> query();
}

• 在src/main/java中创建net.wanho.UserDaoImpl.java:

import net.wanho.User;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;

import java.util.List;

public class UserDaoImpl implements UserDao {

    private SqlSessionFactory sqlsessionFactory;

    public UserDaoImpl(SqlSessionFactory sqlsessionFactory) {
        this.sqlsessionFactory = sqlsessionFactory;
    }

    @Override
    public List<User> query() {
        SqlSession sqlSession = sqlsessionFactory.openSession();
        List<User> list = sqlSession.selectList("query");
        sqlSession.close();
        return list;
    }
}

• 在src/java/resources下创建mybatis-config.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="environment">
        <environment id="environment">
            <transactionManager type="JDBC"></transactionManager>
            <dataSource type="POOLED">
                <property name="url" value="jdbc:mysql://localhost:3306/test"></property>
                <property name="driver" value="com.mysql.jdbc.Driver"></property>
                <property name="username" value="root"></property>
                <property name="password" value="123456"></property>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper class="net.wanho.UserDao"></mapper>
    </mappers>
</configuration>

• 在src/main/java文件夹下创建Test.java

import net.wanho.entity.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

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

public class Test {
    public static void main(String[] args) throws Exception{
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder()
                .build(inputStream);
        UserDao userDao = new UserDaoImpl(sqlSessionFactory);
        List<User> list = userDao.query();
        System.out.println(list);
    }
}

以上就是mybatis中原始dao的实现方式，用的较少，了解即可。