第一个基于MyBatis框架实现的DAO

一.配置环境

1.首先我们要导入相应的包：

下载地址：
https://github.com/mybatis/mybatis-3/releases

2.然后我们开始要配置数据库连接环境
在src文件下创建一个xml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">
 
 <configuration>
   <typeAliases>
    <typeAlias alias="role" type="mybaits.pojo.Role"/>//关联pojo对象
   </typeAliases>
 
   <environments default="development">
     <environment id="development">
       <transactionManager type="JDBC">
         <property name="autoCommit" value="false"/>
       </transactionManager>
       
       <dataSource type="POOLED">
        <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://localhost:3306/jdbc?&amp;useSSL=false&amp;serverTimezone=UTC"/>
        <property name="username" value="root"/>
        <property name="password" value="root"/>
       </dataSource>
     
     </environment>
   </environments>
   
   <mappers>
    <mapper resource="mybaits\mapper\RoleMapper.xml"/>//关联映射文件
   </mappers>
   
 </configuration>

获取连接的类：

package mybaits.util;

import java.io.IOException;
import java.io.InputStream;
import java.util.logging.Level;

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 org.apache.log4j.Logger;

public class SqlSessionFactoryUtil {
	
	private static SqlSessionFactory sqlSessionFactory=null;
	
	private static final Class CLASS_LOCK=SqlSessionFactoryUtil.class;
	
	private SqlSessionFactoryUtil() {}
	
	public static SqlSessionFactory initSqlSessionFactory() {
		String resource="mybaits-config.xml";
		InputStream inputStream=null;
		try {
			inputStream = Resources.getResourceAsStream(resource);
		}catch(IOException ex) {
			Logger.getLogger(SqlSessionFactoryUtil.class.getName()).log(null,ex);
		}
		
		synchronized(CLASS_LOCK) {
			if(sqlSessionFactory==null) {
				sqlSessionFactory=new SqlSessionFactoryBuilder().build(inputStream);
			}
		}
		return sqlSessionFactory;
	}
	
	public static SqlSession openSqlSession() {
		if(sqlSessionFactory==null) {
			initSqlSessionFactory();
		}
		return sqlSessionFactory.openSession();
	}
	

}

3.接着我们要编写对应的pojo对象和映射文件和操作接口

pojo

package mybaits.pojo;
public class Role {
	private Long id;
	private String roleName;
	private String note;
	public Long getId() {
		return id;
	}
	public void setId(Long id) {
		this.id = id;
	}
	public String getRoleName() {
		return roleName;
	}
	public void setRoleName(String roleName) {
		this.roleName = roleName;
	}
	public String getNote() {
		return note;
	}
	public void setNote(String note) {
		this.note = note;
	}
}

mysql创建表的语句：

mysql> create table t_role(
    -> id int,
    -> role_name varchar(40),
    -> note varchar(50));
Query OK, 0 rows affected (0.25 sec)

映射文件：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper
 PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
 "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
 
 <mapper namespace="mybaits.mapper.RoleMapper">
 
   <select id="getRole" parameterType="long" resultType="role">
    select id,role_name as roleName,note from t_role where id = #{id}
   </select>
   
   <insert id="insertRole" parameterType="role">
     insert into t_role(role_name,note) values (#{roleName},#{note})
   </insert>
   
   <delete id="deleteRole" parameterType="long">
    delete from t_role where id = #{id}
   </delete>
 </mapper>

操作接口：

package mybaits.mapper;

import mybaits.pojo.Role;

public interface RoleMapper {

	public Role getRole(Long id);
	public int deleteRole(Long id);
	public int insertRole(Role role);
}

最后，编写主类测试：

package mybaits.main;
import java.io.IOException;
import org.apache.ibatis.session.SqlSession;

import mybaits.mapper.RoleMapper;
import mybaits.pojo.Role;
import mybaits.util.SqlSessionFactoryUtil;

public class Main {
public static void main(String[] args) throws IOException {
	SqlSession sqlSession = null;
	try {
		sqlSession = SqlSessionFactoryUtil.openSqlSession();
		RoleMapper roleMapper=sqlSession.getMapper(RoleMapper.class);
		Role role = new Role();
		role.setRoleName("testName");
		role.setNote("testNote");
		roleMapper.insertRole(role);
		sqlSession.commit();
	}catch(Exception ex) {
		System.err.println(ex.getMessage());
		sqlSession.rollback();
	}finally {
		if(sqlSession!=null) {
			sqlSession.close();
		}
	}
}
}

测试结果：