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mybatis(一)安装

2024-08-13 04:43:12   219人阅读

1.创建web项目,添加jar包

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2.创建实验表user_t

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3.在src下创建conf.xml文件,如下

<?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" />            <!-- 配置数据库连接信息 -->            <dataSource type="POOLED">                <property name="driver" value="com.mysql.jdbc.Driver" />                <property name="url" value="jdbc:mysql://localhost/mi" />                <property name="username" value="root" />                <property name="password" value="dbdaocom" />            </dataSource>        </environment>    </environments>    </configuration>

2、定义表所对应的实体类，

package com.mi.entity;public class User {    private int id;    private String userName;    private String password;    private Integer age;...}

3、定义操作users表的sql映射文件userMapper.xml

<?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.mi.dao.UserInfoMapper">         <select id="queryUserInfo" resultType="com.mi.entity.User">        SELECT id,user_name userName,age FROM user_t where 1=1    </select>    <select id="getCount" resultType="int">        SELECT count(*) FROM user_t    </select>    </mapper>

4、在conf.xml文件中注册userMapper.xml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" />            <!-- 配置数据库连接信息 -->            <dataSource type="POOLED">                <property name="driver" value="com.mysql.jdbc.Driver" />                <property name="url" value="jdbc:mysql://localhost/mi" />                <property name="username" value="root" />                <property name="password" value="dbdaocom" />            </dataSource>        </environment>    </environments>    <mappers>        <mapper resource="com/mi/mapping/UserInfoMapper.xml"/><!-- 注册userMapper.xml文件， -->    </mappers></configuration>

5、编写测试代码：执行定义的select语句

　　创建一个Test1类，编写如下的测试代码：

package com.mi.demo;import java.io.InputStream;import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactory;import org.apache.ibatis.session.SqlSessionFactoryBuilder;import com.mi.entity.User;public class Test1 {    public static void main(String[] args) {        //mybatis的配置文件        String resource = "conf.xml";         //使用类加载器加载mybatis的配置文件（它也加载关联的映射文件）        InputStream is = Test1.class.getClassLoader().getResourceAsStream(resource);         //构建sqlSession的工厂        SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);        //使用MyBatis提供的Resources类加载mybatis的配置文件（它也加载关联的映射文件）        //Reader reader = Resources.getResourceAsReader(resource);         //构建sqlSession的工厂        //SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);        //创建能执行映射文件中sql的sqlSession        SqlSession session = sessionFactory.openSession();        /**         * 映射sql的标识字符串，         * com.mi.mapping.UserInfoMapper是UserInfoMapper.xml文件中mapper标签的namespace属性的值，         * queryUserInfo是select标签的id属性值，通过select标签的id属性值就可以找到要执行的SQL         */        String statement = "com.mi.mapping.UserInfoMapper.queryUserInfo";//映射sql的标识字符串        User user = session.selectOne(statement,1);//执行查询返回一个唯一user对象的sql        System.out.println(user.getId());        System.out.println(user.getUserName());        System.out.println(user.getAge());    }}

结果如下:

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mybatis(一)安装


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