mybatis新手快速入门以及一些错误汇总
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2022-06-24 22:27:20
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 junit
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&characterencoding=utf8&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 @allargsconstructor public 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&characterencoding=utf8&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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