Mybatis的搭建

       Mybatis的搭建
1.持久化
  持久化，就是内存数据和硬盘数据状态的转换
  
2.ORM思想
Object Relation Mapping  对象关系映射
    
3.MyBatis入门案例

  3.1导入jar包
    依赖
   <!--MySQL配置-->
    <dependency>
      <groupId>MySQL</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.0.8</version>
    </dependency>

    <!--MyBatis核心jar包-->
    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis</artifactId>
      <version>3.2.2</version>
    </dependency>

  3.2书写大配置
  
  <?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/y2165"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="org/mybatis/example/BlogMapper.xml"/>
    </mappers>
</configuration>
  3.3实体类（实体类的列必须和数据库的列一致）
     public class StudentInfo {
     private Integer stuId;
     private String stuName;
     private Integer  stuAge;
     private Date stuDate;
  }

  

小配置：

<?xml version="1.0" encoding="ISO-8859-1"?><!DOCTYPE mapper        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"        "http://mybatis.org/dtd/mybatis-3-mapper.dtd"><mapper namespace="bdqn.dao.">    <select id="select" resultType="bdqn.entity.Department"> select * from department    </select>    <select id="selectid" resultType="Department">        select * from department where id=#{id}    </select></mapper>//大配置
   <?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="cn.happy.dao.IStudentInfoDAO">    <select id="findAll" resultType="cn.happy.entity.StudentInfo">        select * from studentinfo    </select></mapper>
  两个注意事项：  1.你得更新POM.xml文件中build节点  <build>    <resources>      <resource>        <directory>src/main/java</directory>        <includes>          <include>**/*.xml</include>        </includes>      </resource>    </resources>  </build>    2.需要在大配置中关联小配置文件
4.别名的使用（加在大配置里）    <typeAliases>        <!--<typeAlias type="cn.happy.entity.StudentInfo" alias="StudentInfo"></typeAlias>-->        <!--将该包中的简单类型 StudentInfo作为类的别名-->        <package name="cn.happy.entity"></package>    </typeAliases>
小配置<select id="select" resultType="bdqn.entity.Department">改为
<select id="select" resultType="Department">
5.getMapper() 动态代理数据
  class<T> 类型的类型
    is = Resources.getResourceAsStream(path);
            SqlSessionFactory factory=new SqlSessionFactoryBuilder().build(is);
            SqlSession session=factory.openSession();
            IStudentInfoDAO dao = session.getMapper(IStudentInfoDAO.class);
            StudentInfo info = dao.getStudentById(3);
            System.out.println(info.getStuName());