快速入门

mybatis-comfig.xml中文件介绍

<?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://127.0.0.1:3306/mybatis"/>
                <property name="username" value="****"/>
                <property name="password" value="***"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="mapper.xml"/>
    </mappers>
</configuration>

mapper.xml文件

<?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="test">

    <select id="selectAll" resultType="com.xiaonan.demo.User">
         select * from tb_user;
    </select>

</mapper>

namespace:一个称为一个工厂

id:里面的一个员工

resultType:返回值类型(精确到pojo类)

最后使用方法为:test.id(这样就可以检索到对应的sql了)

运行文件

String resource = "mybatis-comfig.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

主要是下面这三行代码
SqlSession sqlSession=sqlSessionFactory.openSession();
ist<User> users=sqlSession.selectList("test.selectAll");
System.out.println(users);

sqlSession.close();

代理开发

这里不在说mybatis-comfig.xml这个配置文件的介绍

<?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://127.0.0.1:3306/mybatis"/>
                <property name="username" value="*"/>
                <property name="password" value="*"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/xiaonan/mapper/UserMapper.xml"/>
    </mappers>
</configuration>

mapper.xml文件介绍:必须注意把mapper.xml和接口文件放在一起

比如com/xiaonan/mapper/UserMapper.xml这是mapper.xml文件

com\xiaonan\mapper\UserMapper.java这是接口文档

下面这里我放一个图片可以观察观察

mapper.xml代理开发还需要注意这个问题

<?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="com.xiaonan.mapper.UserMapper">
    <select id="selectAll" resultType="com.xiaonan.Pojo.User">
        select * from tb_user;
    </select>
</mapper>

namespace：这里是mapper.xml文件对应的接口文档，这个xml文件和接口文档必须是同级目录(目录精确到接口文档)

id：快速入门这里比作一个员工，但是这里也可以比作员工，那么对应的接口文档就比作一个工厂，什么意思呢，也就是说，接口文档是一个工厂那么id(selectAll),肯定在工厂里面，也就意味这，mapper接口文件肯定里面包含有一个selectAll的方法(函数)
**
resultType：这个和上面快速入门一样，意思一样，都是返回值类型

运行文件

String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);


注意下面这四行代码
SqlSession sqlSession=sqlSessionFactory.openSession();
这个是接口，这样写
UserMapper userMapper=sqlSession.getMapper(UserMapper.class);
List<User> list=userMapper.selectAll();
System.out.println(list);

sqlSession.close();

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