MyBatis框架快速入门

//1.导入maven依赖
	需要导入的有 mybatis ,mysql,log4j(日志),Junit(测试)

  
  //2.创建数据库user表   创建实体类USer
      
  //3.创建接口UserDao.java
      public interface UserDao{
      //查询所有
      	List<User> findAll();
    }

4.在maven的resources目录下创建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>
    <!--关联数据库的信息-->
    <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/mybatis_db"/>
                <property name="username" value="root"/>
                <property name="password" value="123"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <!--关联保存sql语句的配置文件-->
        <mapper resource="cn/itcast/dao/UserDao.xml"/>
    </mappers>
</configuration>

5.在resources目录下创建和dao一样的目录结构,在dao中创建保存sql语句的UserDao.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 要求是 dao接口类的全路径-->
<mapper namespace="cn.itcast.dao.UserDao">
    <!--
        id : 是当前sql语句的唯一标识, 写成方法名
        resultType : 将结果封装到指定的类型中
    -->
    <select id="queryAll" resultType="cn.itcast.domain.User">
        select * from user;
    </select>
</mapper>

6.测试

public class UserDaoTest {
    @Test
    public void queryAll() throws Exception {
        //1.读取配置文件
        InputStream in = Resources.getResourceAsStream("mybatis-config.xml");
      	// 2 根据配置文件创建工厂类
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(in);
        // 3 从工厂类获取 执行sql的对象
        SqlSession sqlSession = sqlSessionFactory.openSession();
        // 4 执行sql 获得结果 处理结果
        List<User> userList = sqlSession.selectList("cn.itcast.dao.UserDao.queryAll");
        for (User user : userList) {
            System.out.println(user);
        }
        // 5 释放资源
        sqlSession.close();
        in.close();
    }

}