MyBatis小试牛刀

 

今天刚听说iBATIS改名为MyBatis，实际上就是iBATIS 3.0.1。以前都是用hibernate或者JPA，同时听说iBATIS 3与iBATIS 2 相比，变化挺大的，于是今天花了点时间学习了一下，做了个小例子。

 

准备工作：建立相应的数据库，表，添加一条记录用于测试。

 

第一步当然是建立项目，导入jar包，导入mybatis-3.0.1.jar，和mysql的jdbc驱动。

 

第二步 新建一个类User，包含主键，用户名，密码等属性

 

package cn.dcr.mybatis.entity;

public class User {
    private Long id;
    private String userName;
    private String password;
    private int age;

    public Long getId() {
        return id;
    }

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

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public String getPassword() {
        return password;
    }

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

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

}

package cn.dcr.mybatis.entity;

public class User {
	private Long id;
	private String userName;
	private String password;
	private int age;

	public Long getId() {
		return id;
	}

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

	public String getUserName() {
		return userName;
	}

	public void setUserName(String userName) {
		this.userName = userName;
	}

	public String getPassword() {
		return password;
	}

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

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}

}

 第三步，写sql映射的xml文件

 

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//ibatis.apache.org//DTD Mapper 3.0//EN"
"http://ibatis.apache.org/dtd/ibatis-3-mapper.dtd">

<mapper namespace="cn.dcr.mybatis.entity.UserMapper">
    <select id="selectOne" parameterType="long" resultType="cn.dcr.mybatis.entity.User">
        select * from user where id = #{id}
    </select>
</mapper>

<?xml version="1.0" encoding="UTF-8" ?>  
<!DOCTYPE mapper  
PUBLIC "-//ibatis.apache.org//DTD Mapper 3.0//EN"  
"http://ibatis.apache.org/dtd/ibatis-3-mapper.dtd">  
  
<mapper namespace="cn.dcr.mybatis.entity.UserMapper">  
    <select id="selectOne" parameterType="long" resultType="cn.dcr.mybatis.entity.User">  
        select * from user where id = #{id}  
    </select>  
</mapper>

 

 第四步，写MyBatis配置文件，configuration.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"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/test"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="cn/dcr/mybatis/entity/User.xml"/>
    </mappers>
</configuration>

<?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"/> 
			<dataSource type="POOLED"> 
				<property name="driver" value="com.mysql.jdbc.Driver"/> 
				<property name="url" value="jdbc:mysql://localhost:3306/test"/> 
				<property name="username" value="root"/> 
				<property name="password" value="root"/> 
			</dataSource> 
		</environment> 
	</environments> 
	<mappers> 
		<mapper resource="cn/dcr/mybatis/entity/User.xml"/> 
	</mappers>
</configuration>

 

第五步，编写Util类，用于初始化SqlSessionFactory

 

package cn.dcr.mybatis.util;

import java.io.IOException;
import java.io.Reader;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

public class Util {

    private static SqlSessionFactory sqlSessionFactory = null;

    static {
        String resource = "configuration.xml";

        Reader reader = null;
        try {
            reader = Resources.getResourceAsReader(resource);
        } catch (IOException e) {
            e.printStackTrace();
        }

        sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
    }

    public static SqlSessionFactory getSqlSessionFactory(){
        return sqlSessionFactory;
    }
}

package cn.dcr.mybatis.util;

import java.io.IOException;
import java.io.Reader;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

public class Util {
	
	private static SqlSessionFactory sqlSessionFactory = null;
	
	static {
		String resource = "configuration.xml"; 
		
		Reader reader = null;
		try {
			reader = Resources.getResourceAsReader(resource);
		} catch (IOException e) {
			e.printStackTrace();
		}		
		
		sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
	}
	
	public static SqlSessionFactory getSqlSessionFactory(){
		return sqlSessionFactory;
	}
}

 

 

第六步，编写Dao类，用于封装增删改查等操作（为简单起见，这个类只有一个根据id查询出对应的User对象的方法）

 

package cn.dcr.mybatis.dao;

import org.apache.ibatis.session.SqlSession;

import cn.dcr.mybatis.entity.User;
import cn.dcr.mybatis.util.Util;

public class UserDao {
    public User query(Long id){
        SqlSession session = Util.getSqlSessionFactory().openSession();
        User user = null;
        try{
             user = (User)session.selectOne("cn.dcr.mybatis.entity.UserMapper.selectOne", id);
        }catch(Exception e){
            e.printStackTrace();
        }finally{
            session.close();
        }
        return user;
    }
}

package cn.dcr.mybatis.dao;

import org.apache.ibatis.session.SqlSession;

import cn.dcr.mybatis.entity.User;
import cn.dcr.mybatis.util.Util;

public class UserDao {
	public User query(Long id){
		SqlSession session = Util.getSqlSessionFactory().openSession();
		User user = null;
		try{
			 user = (User)session.selectOne("cn.dcr.mybatis.entity.UserMapper.selectOne", id);
		}catch(Exception e){
			e.printStackTrace();
		}finally{
			session.close();
		}
		return user;
	}
}

 

第七步，编写测试类

 

package cn.dcr.mybatis.test;

import cn.dcr.mybatis.dao.UserDao;
import cn.dcr.mybatis.entity.User;

public class UserTest {
    public static void main(String[] args){
        UserDao userDao = new UserDao();
        User user = userDao.query(1L);

        System.out.println(user.getId());
        System.out.println(user.getUserName());
        System.out.println(user.getPassword());
        System.out.println(user.getAge());
    }
}

package cn.dcr.mybatis.test;

import cn.dcr.mybatis.dao.UserDao;
import cn.dcr.mybatis.entity.User;

public class UserTest {
	public static void main(String[] args){
		UserDao userDao = new UserDao();
		User user = userDao.query(1L);
		
		System.out.println(user.getId());
		System.out.println(user.getUserName());
		System.out.println(user.getPassword());
		System.out.println(user.getAge());
	}
}

 

 

运行一下，能够成功查询出对应的记录。

 

先到这，等有功夫在研究一下详细用法。