MyBatis 入门

#创建数据库create database mybatis_demo;#创建user表create table user(	uid int primary key auto_increment,    username varchar(40),    sex varchar(10),    birthday date,    address varchar(40));

<dependencies>    <dependency>      <groupId>junit</groupId>      <artifactId>junit</artifactId>      <version>4.12</version>      <scope>test</scope>    </dependency>        <!--引入lombok的依赖-->    <dependency>      <groupId>org.projectlombok</groupId>      <artifactId>lombok</artifactId>      <version>1.18.10</version>    </dependency>        <!--mysql驱动-->    <dependency>      <groupId>mysql</groupId>      <artifactId>mysql-connector-java</artifactId>      <version>5.1.47</version>    </dependency>        <!--mybatis的依赖-->    <dependency>      <groupId>org.mybatis</groupId>      <artifactId>mybatis</artifactId>      <version>3.5.3</version>    </dependency></dependencies>

package com.nengli51.pojo;
import lombok.Data;
import java.util.Date;
/** * @Date 2021/2/4 */@Datapublic class User {
    private int uid;    private String username;    private String sex;    private Date birthday;    private String address;}

package com.nengli51.dao;
import com.nengli51.pojo.User;
import java.util.List;
public interface UserDao {    /**     * 添加用户     *     * @param user     */    void addUser(User user);
    /**     * 删除用户     *     * @param uid     */    void deleteUser(int uid);
    /**     * 修改用户     *     * @param user     */    void updateUser(User user);
    /**     * 查找用户     *     * @param uid     * @return     */    User findUser(int uid);
    /**     * 查找所有     *     * @return     */    List<User> findAll();}

<?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.nengli51.dao.UserDao">    <select id="findUser" resultType="com.nengli51.pojo.User" parameterType="int">        select *        from user        where uid = #{id};    </select>    <select id="findAll" resultType="com.nengli51.pojo.User">        select *        from user    </select>
    <insert id="addUser" parameterType="com.nengli51.pojo.User">        insert into user        values (null, #{username}, #{sex}, #{birthday}, #{address})    </insert>
    <delete id="deleteUser" parameterType="int">        delete        from user        where uid = #{uid}    </delete>
    <update id="updateUser" parameterType="com.nengli51.pojo.User">        update user        set username=#{username},            sex=#{sex},            birthday=#{birthday},            address=#{address}        where uid = #{uid}    </update></mapper>

<?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="dev">        <environment id="dev">            <transactionManager type="JDBC"></transactionManager>            <dataSource type="POOLED">                <property name="driver" value="com.mysql.jdbc.Driver"/>                <property name="url" value="jdbc:mysql://localhost:3306/mybatis?characterEncoding=utf-8"/>                <property name="username" value="root"/>                <property name="password" value="root"/>            </dataSource>        </environment>    </environments>
    <mappers>        <mapper resource="com/nengli51/UserDao.xml"></mapper>    </mappers></configuration>

import com.nengli51.dao.UserDao;import com.nengli51.pojo.User;import org.apache.ibatis.io.Resources;import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactory;import org.apache.ibatis.session.SqlSessionFactoryBuilder;import org.junit.After;import org.junit.Before;import org.junit.Test;
import java.io.IOException;import java.io.InputStream;import java.util.Date;import java.util.List;
/** * @Author MaLi * @Date 2021/2/4 */public class TestMybatis {
    private UserDao userDao;    private SqlSession sqlSession;    private InputStream is;
    @Before    public void init() {        try {            //1. 创建SqlSessionFactoryBuilder对象            SqlSessionFactoryBuilder sessionFactoryBuilder = new SqlSessionFactoryBuilder();
            //2. 读取核心配置文件，转换成字节输入流            is = Resources.getResourceAsStream("SqlMapConfig.xml");
            //3. 创建SqlSessionFactory对象            SqlSessionFactory sessionFactory = sessionFactoryBuilder.build(is);
            //4. 创建SqlSession对象            sqlSession = sessionFactory.openSession();
            //5. 创建UserDao的代理对象            userDao = sqlSession.getMapper(UserDao.class);
        } catch (IOException e) {            e.printStackTrace();        }    }
    @Test    public void testAddUser() {        User user = new User();        user.setUsername("小马哥");        user.setAddress("Beijing");        user.setBirthday(new Date());        user.setSex("Male");        userDao.addUser(user);        user = userDao.findUser(4);        System.out.println(user);    }
    @Test    public void testDeleteUser() {        userDao.deleteUser(1);    }
    @Test    public void testUpdateUser() {        User user = userDao.findUser(1);        user.setUsername("马斯克");        userDao.updateUser(user);        user = userDao.findUser(1);        System.out.println(user);    }
    @Test    public void testFindUser() {        User user = userDao.findUser(1);        System.out.println(user);    }
    @Test    public void testFindAll() {        List<User> userList = userDao.findAll();        //6, 使用UserDao进行操作        for (User user : userList) {            System.out.println(user);        }
    }
    @After    public void destroy() throws IOException {        //7.提交事务, 关闭资源        sqlSession.commit();        sqlSession.close();        is.close();    }}