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>

 <?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>

 3.5测试类   public class DepartmentTest {    @Test    public void show(){        //查询列表     /*   try {            InputStream stream=Resources.getResourceAsStream("mybatis-config.xml.tld");            SqlSessionFactory sqlSessionFactory=new SqlSessionFactoryBuilder().build(stream);            SqlSession session=sqlSessionFactory.openSession();            List<Department> list=session.selectList("select");            for (Department item:list                 ) {                System.out.println(item.getName());            }        } catch (IOException e) {            e.printStackTrace();        }*/     //根据id查部门        try {            InputStream stream=Resources.getResourceAsStream("mybatis-config.xml.tld");            SqlSessionFactory sqlSessionFactory=new SqlSessionFactoryBuilder().build(stream);            SqlSession session=sqlSessionFactory.openSession();            Department one=session.selectOne("selectid",1);            System.out.println(one.getName());        } catch (IOException e) {            e.printStackTrace();        }    }}             结论：   1. 注意小配置的命名空间的名称  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());