個人學習筆記--MyBatis官方推薦DAO開發方案

1、導入Jar包

2、編寫全局配置文件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>  
    <typeAliases>  
        <!--給實體類起一個別名 user -->  
        <typeAlias type="cn.sky.bookshop.beans.User" alias="User" />  
    </typeAliases>  
    <!--數據源配置  這塊用 mysql數據庫 -->  
    <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/ibatis" />  
                <property name="username" value="root" />  
                <property name="password" value="215890" />  
            </dataSource>  
        </environment>  
    </environments>  
    <mappers>  
        <!--userMapper.xml裝載進來  同等於把“dao”的實現裝載進來 --> 
        <mapper resource="User.xml" />   
        <mapper resource="UserMapper.xml" />  
    </mappers>  
</configuration>  

3、這裏編寫一個MyBatis工具類

package cn.sky.bookshop.utils;

import java.io.IOException;

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

public final class MyBatisUtil {

    private static SqlSessionFactory sessionFactory;
    private static String resource = "configuration.xml";

    static {
	try {
	    sessionFactory = new SqlSessionFactoryBuilder()//
	    		.build(Resources//
			.getResourceAsReader(resource));
	    // sessionFactory.getConfiguration().addMapper(UserDao.class);
	} catch (IOException e) {
	    e.printStackTrace();
	}
    }

    public static SqlSession getSqlSession() {
	return sessionFactory.openSession();
    }
}

然後接可以先建立一個測試類加載測試一番了。。

4、按Javabean規範寫的一個User類

package cn.sky.bookshop.beans;

public class User {
    private int id;
    private String userName;
    private String password;
    private String email;
    
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }

    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    public String getEmail() {
        return email;
    }
    public void setEmail(String email) {
        this.email = email;
    }
    public String getUserName() {
        return userName;
    }
    public void setUserName(String userName) {
        this.userName = userName;
    }
    @Override
    public String toString() {
	return "User [email=" + email + ", id=" + id + ", password=" + password
		+ ", username=" + userName + "]";
    }
}

5、這裏將UserDao接口命名爲UserMapper接口

package cn.sky.bookshop.dao;

import cn.sky.bookshop.beans.User;

public interface UserMapper {
    
    
    public User findUserByName(String username)throws Exception;
    
    public void insertUser(User user)throws Exception;
    
    public void updateUser(User user)throws Exception;
    
    public void deleteUserById(int id)throws Exception;
}

6 、關鍵是這裏的UserMapper.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">

<!-- namespace必須是定義的接口全限定名 -->
<mapper namespace="cn.sky.bookshop.dao.UserMapper">
	<!-- 裏面id是接口的方法名 parameterType是接口裏方法的傳入參數 -->
	<insert id="insertUser" parameterType="User">
		insert into
		t_user(id,username,password,email)values(#{id},#{userName},#{password},#{email});
	</insert>
	<!-- resultType這裏是接口裏方法返回值類型：當方法返回集合時，這裏還是設爲集合元素類型 -->
	<select id="findUserByName" parameterType="string" resultType="User">
		select * from t_user where username=#{userName};
	</select>

	<update id="updateUser" parameterType="User">
		update t_user set
		username=#{userName},password=#{password},email=#{email} where
		id=#{id};
	</update>

	<delete id="deleteUserById" parameterType="int">
		delete from t_user
		where id=#{id};
	</delete>
</mapper>

7、注意：上面的步驟配置有些嚴格。。因爲下面的接口動態代理對象（就是個接口的實現）是根據UserMapper接口和UserMapper.xml文件生成的! 下面是我的DAO測試類

UserMapperTest 

package cn.sky.bookshop.test;

import org.apache.ibatis.session.SqlSession;

import cn.sky.bookshop.beans.User;
import cn.sky.bookshop.dao.UserMapper;
import cn.sky.bookshop.utils.MyBatisUtil;

public class UserMapperTest {

    /**
     * @param args
     */
    public static void main(String[] args) {
//	    addUserMapper(); 添加
//	findUserMapper(); 查找
//	updateUserMapper();更新
	deleteUserMapper();
    }
    //添加記錄
    public static void addUserMapper(){
	SqlSession sqlSession = MyBatisUtil.getSqlSession();
	//獲取接口的動態代理對象
	UserMapper um = sqlSession.getMapper(UserMapper.class);
	User user = new User();
	user.setUserName("大俠");
	user.setPassword("daxia");
	user.setEmail("[email protected]");
	try {
	    um.insertUser(user);
	} catch (Exception e) {
	    e.printStackTrace();
	}
	sqlSession.commit();
	sqlSession.close();

    }
    //查找記錄
    public static void findUserMapper() {
	SqlSession sqlSession = MyBatisUtil.getSqlSession();
	UserMapper um = sqlSession.getMapper(UserMapper.class);
	User user = null;
	try {
	    user = um.findUserByName("大俠");
	} catch (Exception e) {
	    e.printStackTrace();
	}
	System.out.println(user);
	sqlSession.close();
    }
    //跟新紀錄
    public static void updateUserMapper(){
	SqlSession sqlSession = MyBatisUtil.getSqlSession();
	UserMapper um = sqlSession.getMapper(UserMapper.class);
	User user = new User();
	user.setId(4);
	user.setUserName("小蝦");
	user.setPassword("xiaoxia");
	user.setEmail("[email protected]");
	try {
	    um.updateUser(user);
	} catch (Exception e) {
	    e.printStackTrace();
	}
	sqlSession.commit();
	sqlSession.close();
    }
    //刪除記錄
    public static void deleteUserMapper(){
	SqlSession sqlSession = MyBatisUtil.getSqlSession();
	UserMapper um = sqlSession.getMapper(UserMapper.class);
	try {
	    um.deleteUserById(4);
	} catch (Exception e) {
	    e.printStackTrace();
	}
	sqlSession.commit();
	sqlSession.close();
    }
}