Mybatis

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

public class StudentInfo {

private Integer stuId;

private String stuName;

private Integer stuAge;

private Date stuDate;

}

3.4小配置

<?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.你得在大配置中关联小配置文件

<mappers>

<mapper resource="cn/happy/dao/IStudentInfoDAO.xml"/>

</mappers>

3.5 写测试类

3.5.1 String path="大配置的路径名";

InputStream is=Resources.getResourcesAsStream(path);

SessionFactory factory=new SessionFactoryBuilder().build(is);

SqlSession session=factory.openSession();

结论：

1. 注意小配置的命名空间的名称

4.别名的使用

<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>

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());