mybatis新手快速入门以及一些错误汇总

一、使用maven加载依赖

加载了连接数据库的依赖、mybatis的依赖以及lombok的依赖

<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>

二、建库、建表

三、配置MyBatis的配置文件（conf.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> <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>

四、定义表所对应的实体类

@Data@NoArgsConstructor@AllArgsConstructorpublic class User { private Integer uid; private String uname; private String password;}

五、定义操作表的sql的映射文件xxxMapper.xml

见名知意，操作的user表，所以映射文件也命名为了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"><!--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>

六、在Mybatis配置文件中添加映射文件

将编写好的userMapper.xml添加到mybatis.xml配置文件，下方

<?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>

七、编写增删改查代码测试

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.commit(); }}

结果：

一些错误

编写中可能碰到的错误

1.Mapped Statements collection does not contain…

2.The server time zone value’XXXXXXXXX’ is…

在Mybatis配置文件中的jdbc连接地址后面拼接serverTimezone=Asia/Shanghai

总结

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