MyBatis,快速入门

1.创建项目

创建一个JavaWeb项目

2.到入相关的Jar包

1. mybatis:mybatis-3.1.1.jar
2. mysql驱动包:mysql-connector-java-5.1.7-bin.jar

3.编写data.sql

drop database if exists mybatistest;
create database mybatistest;
use mybatistest;
create table t_user(
user_id int primary key auto_increment,
username varchar(30),
password varchar(30)
)engine=innobd auto_increment=1 character set utf8;

4. mybatis-config.xml 和 jdbc.properties配置文件

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>
    <!-- 读取jdbc.properties -->
    <properties resource="jdbc.properties"></properties>


    <!-- 开发环境配置：
                development：开发阶段
                work：工作阶段
     -->
    <environments default="development">
        <environment id="development">
            <!-- 事务管理配置：jdbc -->
            <transactionManager type="JDBC" />
            <!-- 数据源配置： -->
            <dataSource type="POOLED">
                <property name="driver" value="${mysql.driver}" />
                <property name="url" value="${mysql.url}" />
                <property name="username" value="${mysql.username}" />
                <property name="password" value="${mysql.password}" />
            </dataSource>
        </environment>
    </environments>

    <!-- 引入映射文件 -->
    <mappers>
        <mapper resource="com/test/dao/UserMapper.xml" />
    </mappers>
</configuration>

jdbc.properties

mysql.driver=com.mysql.jdbc.Driver
mysql.url=jdbc:mysql://localhost:3306/mybatistest?characterEncoding=utf-8
mysql.username=root
mysql.password=123456

5. 根据数据库表编写User实体类

注意:构造函数和setter,getter方法

6. UserDao接口和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">
<mapper namespace="com.test.dao">
    <!-- 自定义结果集映射： -->
    <resultMap type="com.test.po.User" id="userMap">
        <id column="user_id" property="userId"/>
        <result column="username" property="username"/>
        <result column="password" property="password"/>
    </resultMap>


    <!-- CRUD:UserDao -->

    <insert id="addUser" parameterType="com.test.po.User">
        insert into t_user(username,password) values(#{username},#{password});
    </insert>

    <delete id="delUser" parameterType="java.lang.Integer">
        delete from t_user where user_id = #{userId}
    </delete>

    <update id="updateUser" parameterType="com.test.po.User">
        update t_user set username = #{username}, password = #{password}
        where user_id = #{userId}
    </update>

    <select id="findById" parameterType="java.lang.Integer" resultMap="userMap">
        select user_id,username,password
        from t_user
        where user_id = #{userId}
    </select>

    <select id="findAll" resultMap="userMap">
        select user_id,username,password from t_user
    </select>

</mapper>

7. 编写M3Util.java类

用于获取session

public class M3Util {
    private static SqlSessionFactory sqlSessionFactory = null;
    static{
        try {
            //读取mybatis配置文件
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static SqlSession getSession(){
        return sqlSessionFactory.openSession();
    }
}

8. 编写测试类

public class TestMybatis {
    @Test
    public void add() throws IOException{
        SqlSession session = M3Util.getSession();
        String statement = "com.test.dao
        .addUser";
        session.insert(statement, new User(null, "张三", "2324"));

        //提交事务关闭session
        session.commit();
        session.close();

    }
    @Test
    public void del() throws IOException{
        SqlSession session = M3Util.getSession();
        String statement = "com.test.dao.delUser";
        session.delete(statement, 2);

        //提交事务关闭session
        session.commit();
        session.close();

    }
    @Test
    public void update() throws IOException{
        SqlSession session = M3Util.getSession();
        String statement = "com.test.dao.updateUser";

        User user = new User(3, "李四", "111111", new Date());

        session.update(statement, user);

        //提交事务关闭session
        session.commit();
        session.close();
    }

    @Test
    public void find() throws IOException{
        SqlSession session = M3Util.getSession();
        String statement = "com.test.dao.findById";

        User user = session.selectOne(statement, 3);
        System.out.println(user);

        //提交事务关闭session
        session.commit();
        session.close();
    }
    @Test
    public void findAll() throws IOException{
        SqlSession session = M3Util.getSession();
        String statement = "com.test.dao.findAll";

        List<User> list = session.selectList(statement);

        for (User user : list) {
            System.out.println(user);
        }

        //提交事务关闭session
        session.commit();
        session.close();
    }
}

关于起别名
typeAlias 是为单一类起别名,type=”类名”,alias=”别名”
package 是为包下所有类起别名,别名为类名或者类名小写.

<typeAliases>
           <typeAlias type="com.test.po.User" alias="User"/>
           <package name="com.test.po"/>
    </typeAliases>