mybatis 连接mysql 实现CRUD

2022-09-22 106

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简介： mybatis 连接mysql 实现CRUD

新建maven项目

在IDEA里新建一个maven项目。依赖里下载相关的包

<?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>org.example</groupId>
    <artifactId>mybatis</artifactId>
    <version>1.0-SNAPSHOT</version>
    <properties>
        <maven.complier.source>11</maven.complier.source>
        <maven.complier.target>11</maven.complier.target>
    </properties>
    <dependencies>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.29</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.5</version>
        </dependency>
    </dependencies>
</project>

接着在java 里面新建一个包里面新建一个User类定义一个实体类
并输出set 和get 方法快捷键alt+ins

在resources目录下创建一个mapper包用来配置UserMapper.xml文件
并且创建 db.properties 和 mybatis-config.xml

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="cn.wxz.mybatistest.pojo.User">
    <select id="findUserById" parameterType="int" resultType="cn.wxz.mybatistest.pojo.User">
 select * from user where uid = #{uid}
 </select>
    <insert id="addUser" parameterType="cn.wxz.mybatistest.pojo.User">
        insert  into user (uname,uage)values(#{uname},#{uage});
    </insert>
    <update id="updateUser" parameterType="cn.wxz.mybatistest.pojo.User">
        update user set uname=#{uname},uage=#{uage} where uid=#{uid};
    </update>
    <delete id="deleteUser" parameterType="int">
        delete from user  where uid=#{uid};
    </delete>
</mapper>

db.properties

driver=com.mysql.cj.jdbc.Driver
//端口号默认3306
url=jdbc:mysql://localhost:3306/mybatis?serverTimezone=UTC 
username=root //账号
password=root //密码

mybatis-config.xml

<?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>
    <properties resource="db.properties"/>
    <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="mapper/UserMapper.xml"/>
    </mappers>
</configuration>

然后打开mysql 创建一个user表

DROP TABLE IF EXISTS `user`;
CREATE TABLE `user`  (
  `uid` int(0) NOT NULL AUTO_INCREMENT,
  `uname` varchar(20) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NOT NULL,
  `uage` int(0) NOT NULL,
  PRIMARY KEY (`uid`) USING BTREE
)

接着创建一个UserTest类实现我们的增删改查

addUserTest

    @Test
    public void  addUserTest() {
        String  resouces="mybatis-config.xml";
        Reader reader=null;
        try {
            reader= Resources.getResourceAsReader(resouces);
        } catch (IOException e) {
            e.printStackTrace();
        }
        SqlSessionFactory sqlMapper=new   SqlSessionFactoryBuilder().build(reader);
        SqlSession sqlSession=sqlMapper.openSession();
        User user=new User();
        user.setUname("王五");
        user.setUage(19);
        int ret = sqlSession.insert("addUser",user);
        sqlSession.commit();
        if(ret>0) System.out.println("添加成功！！");
        else System.out.println("添加失败！！");
        sqlSession.close();
    }

然后我们查看当前user表

输入

select * from user

updateUserTest

  @Test
    public void  updateUserTest() {
        String  resouces="mybatis-config.xml";
        Reader reader=null;
        try {
            reader= Resources.getResourceAsReader(resouces);
        } catch (IOException e) {
            e.printStackTrace();
        }
        SqlSessionFactory sqlMapper=new   SqlSessionFactoryBuilder().build(reader);
        SqlSession sqlSession=sqlMapper.openSession();
        User user=new User();
        user.setUid(1);
        user.setUname("小王同学");
        user.setUage(12);
       int ret=sqlSession.update("updateUser",user);
       if(ret>0) System.out.println("修改成功");
       else System.out.println("修改失败");
        sqlSession.commit();
        sqlSession.close();
    }

原来的张三变成了小王同学 uage从原来的19变成12了
成功！~

表里多出了一条数据
操作成功

findUserById

 @Test
    public  void findUserById(){
        String  resouces="mybatis-config.xml";
        Reader reader=null;
        try {
            reader= Resources.getResourceAsReader(resouces);
        } catch (IOException e) {
            e.printStackTrace();
        }
        SqlSessionFactory sqlMapper=new   SqlSessionFactoryBuilder().build(reader);
        SqlSession sqlSession=sqlMapper.openSession();
        User user=sqlSession.selectOne("findUserById",2);
        System.out.println(user.getUname());
        sqlSession.close();
    }

uid 为2 的时候对应的uname是李四
成功！~

deleteUserTest

 @Test
    public void  deleteUserTest() {
        String  resouces="mybatis-config.xml";
        Reader reader=null;
        try {
            reader= Resources.getResourceAsReader(resouces);
        } catch (IOException e) {
            e.printStackTrace();
        }
        SqlSessionFactory sqlMapper=new   SqlSessionFactoryBuilder().build(reader);
        SqlSession sqlSession=sqlMapper.openSession();
       int result=sqlSession.delete("deleteUser",1);
       if(result>0) System.out.println("删除成功");
       else System.out.println("删除失败！");
        sqlSession.commit();
        sqlSession.close();
    }

原来的uid为1 的小王同学的一列删除成功！！~

完整代码附上：

package cn.wxz.mybatistest.test;
import cn.wxz.mybatistest.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.Test;
import java.io.IOException;
import java.io.Reader;
public class UserTest {
    @Test
    public  void findUserById(){
        String  resouces="mybatis-config.xml";
        Reader reader=null;
        try {
            reader= Resources.getResourceAsReader(resouces);
        } catch (IOException e) {
            e.printStackTrace();
        }
        SqlSessionFactory sqlMapper=new   SqlSessionFactoryBuilder().build(reader);
        SqlSession sqlSession=sqlMapper.openSession();
        User user=sqlSession.selectOne("findUserById",2);
        System.out.println(user.getUname());
        sqlSession.close();
    }
    @Test
    public void  addUserTest() {
        String  resouces="mybatis-config.xml";
        Reader reader=null;
        try {
            reader= Resources.getResourceAsReader(resouces);
        } catch (IOException e) {
            e.printStackTrace();
        }
        SqlSessionFactory sqlMapper=new   SqlSessionFactoryBuilder().build(reader);
        SqlSession sqlSession=sqlMapper.openSession();
        User user=new User();
        user.setUname("王五");
        user.setUage(19);
        int ret = sqlSession.insert("addUser",user);
        sqlSession.commit();
        if(ret>0) System.out.println("添加成功！！");
        else System.out.println("添加失败！！");
        sqlSession.close();
    }
    @Test
    public void  updateUserTest() {
        String  resouces="mybatis-config.xml";
        Reader reader=null;
        try {
            reader= Resources.getResourceAsReader(resouces);
        } catch (IOException e) {
            e.printStackTrace();
        }
        SqlSessionFactory sqlMapper=new   SqlSessionFactoryBuilder().build(reader);
        SqlSession sqlSession=sqlMapper.openSession();
        User user=new User();
        user.setUid(1);
        user.setUname("小王同学");
        user.setUage(12);
       int ret=sqlSession.update("updateUser",user);
       if(ret>0) System.out.println("修改成功");
       else System.out.println("修改失败");
        sqlSession.commit();
        sqlSession.close();
    }
    @Test
    public void  deleteUserTest() {
        String  resouces="mybatis-config.xml";
        Reader reader=null;
        try {
            reader= Resources.getResourceAsReader(resouces);
        } catch (IOException e) {
            e.printStackTrace();
        }
        SqlSessionFactory sqlMapper=new   SqlSessionFactoryBuilder().build(reader);
        SqlSession sqlSession=sqlMapper.openSession();
       int result=sqlSession.delete("deleteUser",1);
       if(result>0) System.out.println("删除成功");
       else System.out.println("删除失败！");
        sqlSession.commit();
        sqlSession.close();
    }
}

以上就是王同学给大家带来的mybatis连接mysql 实现CRUD！

mybatis 连接mysql 实现CRUD

新建maven项目

UserMapper.xml

db.properties

mybatis-config.xml

addUserTest

updateUserTest

findUserById

deleteUserTest

完整代码附上：

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