Mybatis--初见mybatis

Mybatis

ssm中连接数据库的框架

底层是jdbc

mybatis是将大量jdbc语句封装起来的框架

Mybatis前言：

准备工作：

使用mybatis要导入mybatis依赖包和jdbc依赖包

maven配置：

 <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis</artifactId>
      <version>3.5.7</version>
    </dependency>

    <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>8.0.26</version>
    </dependency>

创建一个resours目录作为资源文件夹在其中创建mybatis的全局文件

<?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="${driver}"/>
        <property name="url" value="${url}"/>
        <property name="username" value="${username}"/>
        <property name="password" value="${password}"/>
      </dataSource>
    </environment>
  </environments>
  <mappers>
    <mapper resource="org/mybatis/example/BlogMapper.xml"/>
  </mappers>
</configuration>

在dao文件下创建

一个接口用来编写所要查询的java语句

并在同一目录下实现sql语句的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="dao.daoStudent">
    <select id="selectStudents" resultType="com.demo.Student">
       select id,name,age,email from Student order by id;
    </select>
    <update id="UpdataStudent" >
        UPDATE Student set name= #{name} where id=#{id};
    </update>
    <insert id="InsertStudent" >
        insert into Student VALUES (#{id},#{name},#{age},#{email});
    </insert>
</mapper>

namespace：关联的接口类

id：最好是写接口类中实现的方法名

resultType：全限定名称返回的对象类名