Mybatis 学习记录 续

项目结构如下：

 

1、数据库建表

　　表名：user

　　结构：

　　

　　内容：

2、pom.xml文件更新如下：

注：其中build部分尤其需要重视

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.demo</groupId>
    <artifactId>Mybatis_test</artifactId>
    <packaging>pom</packaging>
    <version>1.0-SNAPSHOT</version>
    <modules>
        <module>mybatis01</module>
    </modules>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
        <!-- https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.3</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>
    </dependencies>


    <!--在build中配置resources，来防止我们资源导出失败的问题-->
    <build>
        <resources>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
            </resource>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
            </resource>
        </resources>
    </build>

</project>

3、UserMapper.xml文件更新如下

<?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">
<!--命名空间，绑定一个Dao-->
<mapper namespace="com.demo.dao.Userdao">
    <!--查询语句-->
    <select id="getUserList" resultType="com.demo.pojo.User">
        select * from calss.user
    </select>
</mapper>

4、测试类

直接上代码了

package com.demo.dao;

import com.demo.pojo.User;
import com.demo.utils.MybatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.List;

/**
 * @author June
 * @date 2022/1/7 14:16
 */
public class UserDaoTest {
    @Test
    public void test()
    {
        //第一步：获取sqlSession对象
        SqlSession sqlSession= MybatisUtils.getSqlSession();
        try {
            //getMapper     方式一
            Userdao userdao=sqlSession.getMapper(Userdao.class);
            List<User> userList=userdao.getUserList();
            //方式二
            //List<User> userList1=sqlSession.selectList("com.demo.dao.Userdao.getUserList");

            for (User user:userList) {
                System.out.println(user.getId()+user.getName()+user.getPwd());
            }

        }catch (Exception e){
            e.printStackTrace();
        }finally {
            //关闭
            sqlSession.close();
        }
    }
}

测试结果如下：

终版，完善后（即添加了CRUD后）的相关代码如下：

Userdao.java

package com.demo.dao;

import com.demo.pojo.User;

import java.util.List;

/**
 * @author June
 * @date 2022/1/6 17:44
 */
public interface Userdao {
    //获取全部用户
    List<User> getUserList();
    //根据id查询用户
    User getUserbyid(int id);
    //insert 插入一个用户
    int addUser(User user);
    //update用户
    int updateUser(User user);
    //删除一个用户
    int deleteUser(int id);
}

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">
<!--命名空间，绑定一个Dao-->
<mapper namespace="com.demo.dao.Userdao">
    <!--查询语句-->
    <select id="getUserList" resultType="com.demo.pojo.User">
        select * from calss.user
    </select>

    <select id="getUserbyid" parameterType="int" resultType="com.demo.pojo.User">
        select * from calss.user where id = #{id}
    </select>

    <insert id="addUser" parameterType="com.demo.pojo.User">
        insert into calss.user (id,name,pwd) values (#{id},#{name},#{pwd});
    </insert>

    <update id="updateUser" parameterType="com.demo.pojo.User">
        update calss.user set name = #{name},pwd = #{pwd} where id = #{id};
    </update>

    <delete id="deleteUser" parameterType="int">
        delete from calss.user where id = #{id};
    </delete>
</mapper>

UserDaoTest.java

package com.demo.dao;

import com.demo.pojo.User;
import com.demo.utils.MybatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.List;

/**
 * @author June
 * @date 2022/1/7 14:16
 */
public class UserDaoTest {
    //查询所有用户
    @Test
    public void test() {
        //第一步：获取sqlSession对象
        SqlSession sqlSession= MybatisUtils.getSqlSession();
        try {
            //getMapper     方式一
            Userdao userdao=sqlSession.getMapper(Userdao.class);
            List<User> userList=userdao.getUserList();
            //方式二
            //List<User> userList1=sqlSession.selectList("com.demo.dao.Userdao.getUserList");

            for (User user:userList) {
                System.out.println(user.getId()+user.getName()+user.getPwd());
            }

        }catch (Exception e){
            e.printStackTrace();
        }finally {
            //关闭
            sqlSession.close();
        }
    }
    //根据id查询用户
    @Test
    public void getUserbyid() {
        //第一步：获取sqlSession对象
        SqlSession sqlSession= MybatisUtils.getSqlSession();
        try {
            //getMapper     方式一
            Userdao userdao=sqlSession.getMapper(Userdao.class);
            User user=userdao.getUserbyid(1);
            //方式二
            //List<User> userList1=sqlSession.selectList("com.demo.dao.Userdao.getUserList");
            System.out.println(user.getId()+user.getName()+user.getPwd());

        }catch (Exception e){
            e.printStackTrace();
        }finally {
            //关闭
            sqlSession.close();
        }
    }
    //添加一个用户
    @Test
    public void addUser() {
        //第一步：获取sqlSession对象
        SqlSession sqlSession= MybatisUtils.getSqlSession();
        try {
            //getMapper     方式一
            Userdao userdao=sqlSession.getMapper(Userdao.class);
            int number = userdao.addUser(new User(3,"信","333"));
            if(number!=0){
                System.out.println("插入成功！！！");
            }
            //提交事务
            sqlSession.commit();
            //方式二
            //List<User> userList1=sqlSession.selectList("com.demo.dao.Userdao.getUserList");
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            //关闭
            sqlSession.close();
        }
    }
    //修改某个用户
    @Test
    public void updateUser() {
        //第一步：获取sqlSession对象
        SqlSession sqlSession= MybatisUtils.getSqlSession();
        try {
            //getMapper     方式一
            Userdao userdao=sqlSession.getMapper(Userdao.class);
            int number = userdao.updateUser(new User(3,"sndi","323243"));
            if(number!=0){
                System.out.println("修改成功！！！");
            }
            //提交事务
            sqlSession.commit();
            //方式二
            //List<User> userList1=sqlSession.selectList("com.demo.dao.Userdao.getUserList");
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            //关闭
            sqlSession.close();
        }
    }
    //删除某个用户
    @Test
    public void deleteUser() {
        //第一步：获取sqlSession对象
        SqlSession sqlSession= MybatisUtils.getSqlSession();
        try {
            //getMapper     方式一
            Userdao userdao=sqlSession.getMapper(Userdao.class);
            int number = userdao.deleteUser(3);
            if(number!=0){
                System.out.println("删除成功！！！");
            }
            //提交事务
            sqlSession.commit();
            //方式二
            //List<User> userList1=sqlSession.selectList("com.demo.dao.Userdao.getUserList");
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            //关闭
            sqlSession.close();
        }
    }
}