mybatis新手快速入门以及一些错误汇总

<dependency>

   <groupid>junit</groupid>

   <artifactid>junit</artifactid>

   <version> 4.11 </version>

   <scope>test</scope>

  </dependency>

  <dependency>

   <groupid>mysql</groupid>

   <artifactid>mysql-connector-java</artifactid>

   <version> 5.1 . 47 </version>

  </dependency>

  <dependency>

   <groupid>org.mybatis</groupid>

   <artifactid>mybatis</artifactid>

   <version> 3.5 . 4 </version>

  </dependency>

  <dependency>

   <groupid>org.projectlombok</groupid>

   <artifactid>lombok</artifactid>

   <version> 1.18 . 12 </version>

  </dependency>

<?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= "com.mysql.jdbc.driver" />

     <property name= "url" value= "jdbc:mysql://localhost:3306/数据库名字?/useunicode=true&amp;characterencoding=utf8&amp;usessl=false" />

     <property name= "username" value= "root" />

     <property name= "password" value= "数据库密码" />

    </datasource>

   </environment>

  </environments>

</configuration>

@data

@noargsconstructor

@allargsconstructor

public class user {

  private integer uid;

  private string uname;

  private string password;

}

<?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" >

<!--tuser是我自己定的名字-->

<mapper namespace= "tuser" >

  <!--id自己设置，等会调用方法名使用，resulttype查询结果类型-->

  <select id= "getuserbyid" resulttype= "com.hongda.space.entity.user" >

   <!--sql语句，#{}是参数格式，注意字段要与实体类属性一致-->

   select * from t_user where uid=#{uid}

  </select>

  <!--parametertype参数类型-->

  <insert id= "insertuser" parametertype= "com.hongda.space.entity.user" >

   insert into t_user(uname,password) values(#{uname},#{password});

  </insert>

</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 = "development" >

   <environment id= "development" >

    <transactionmanager type= "jdbc" />

    <datasource type= "pooled" >

     <property name= "driver" value= "com.mysql.jdbc.driver" />

     <property name= "url" value= "jdbc:mysql://localhost:3306/数据库名字?/useunicode=true&amp;characterencoding=utf8&amp;usessl=false" />

     <property name= "username" value= "root" />

     <property name= "password" value= "数据库密码" />

    </datasource>

   </environment>

  </environments>

  <mappers>

   <mapper resource= "mapper/usermapper.xml" />

  </mappers>

</configuration>

import com.hongda.space.entity.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 java.io.ioexception;

import java.io.reader;

/**

  * @classname test01

  * @description todo

  * @author whd

  * @date 2021/3/19 14:45

  */

public class test01 {

  public static void main(string[] args) throws ioexception {

   //1.读取配置文件

   reader reader = resources.getresourceasreader( "conf.xml" );

   //2.获取sqlsessionfactory

   sqlsessionfactory sessionfactory = new sqlsessionfactorybuilder().build(reader);

   //3.获取sqlsession对象 执行sql

   sqlsession session = sessionfactory.opensession();

   //4.执行sql

   user user = session.selectone( "tuser.getuserbyid" , 1 );

   system.out.println(user);

   int i = session.insert( "tuser.insertuser" , new user( null , "小刘" , "4545" ));

   system.out.println(i+ "------------" );

   session测试数据mit();

  }

}