Mybatis入门（一）之操作数据库

Whats Mybatis

持久层框架， 替代MVC层中DAO，因为DAO 层的需求就是 ：能与数据库交互的对象、 能执行SQL语句。

不同于JDBC的connection，MyBatis 中有个SqlSession ,什么是SqlSession，以及它的作用是什么：

◆

1 向SQL语句传入参数

2执行SQL语句

3 获取执行SQL语句的结果

4 事务的控制

如何获得SqlSession

1 通过配置文件获取数据库连接的相关需求

2 通过配置文件构建SqlSessionFactory

3 通过SqlSessionFactory 打开openSession

下面看代码具体操作：

 

目录结构：

MyBatis 配置文件

MySQL-connector…….对应的驱动文件

Ojdbc14.jar……..oracle 对应的驱动文件

Userinfo.java(数据库对应的实体类)

package bean;

public class Userinfo {

    private String uname;
    private String upass;
    private int id;

    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getUname() {
        return uname;
    }
    public void setUname(String uname) {
        this.uname = uname;
    }
    public String getUpass() {
        return upass;
    }
    public void setUpass(String upass) {
        this.upass = upass;
    }

}

Mapper

 <?xml version="1.0" encoding="UTF-8" standalone="no"?>
 <!DOCTYPE mapper
     PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
     "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

 <mapper namespace="UserinfoMapper">
     <!--
     public String getuser (int id){}
     -->
     <select id="getuser" parameterType="int" resultType="java.lang.String" >
          select uname from userinfo where id=#{id}
     </select>
 </mapper>

Test

 package Test;

 import java.io.InputStream;

 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 class Demo {

     /**
      *
      * 测试连接数据库，执行SQL语句
      */
     public static void main(String[] args) throws Exception {
         // TODO Auto-generated method stub

         // 加载Mybatis的主配置文件
         InputStream is = Resources.getResourceAsStream("SqlMapConfig.xml");

         // 创建生产session的工厂类 session不是作用域 -- 相当于connection
         SqlSessionFactoryBuilder sfb = new SqlSessionFactoryBuilder();
         SqlSessionFactory ssf = sfb.build(is);
         // 打开session
         SqlSession session=ssf.openSession();
         //执行sql语句
         /**
          * UserinfoMapper 是UserinfoMapper.xml namespace 的名字
          * getuser select id 对应的方法名字
          * 3 是传的参数
          */

         String  name=session.selectOne("UserinfoMapper.getuser", 3);
         System.out.println("name:"+ name);
         session.close();
         System.out.println("over");

     }

 }

SqlMapConfig.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" />
            <!-- 配置数据源 相当于JDBC连接数据库
              Class.forName("oracle.jdbc.driver.OracleDriver");
              String user = "scott";
               String password = "tiger";
              String url = "jdbc:oracle:thin:@localhost:1521:orcl";
            -->
            <dataSource type="POOLED">
                <property name="driver" value="oracle.jdbc.driver.OracleDriver"/>
                <property name="url" value="jdbc:oracle:thin:@localhost:1521:orcl"/>
                <property name="username" value="scott" />
                <property name="password" value="tiger" />
            </dataSource>
        </environment>
    </environments>
    <!-- 读取Mapper包下的UserinfoMapper.xml文件 -->
    <mappers>
        <mapper resource="Mapper/UserinfoMapper.xml" />
    </mappers>
</configuration>

控制台输出的文件