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2、 第一个Mybatis程序
思路:搭建环境->导入mybatis->编写代码->测试
CREATE SCHEMA `mybatis` DEFAULT CHARACTER SET utf8;
CREATE TABLE `mybatis`.`user` (
`id` INT NOT NULL AUTO_INCREMENT,
`name` VARCHAR(45) NOT NULL,
`pwd` VARCHAR(45) NOT NULL,
PRIMARY KEY (`id`))
DEFAULT CHARACTER SET = utf8;
INSERT INTO `mybatis`.`user` (`id`, `name`, `pwd`) VALUES ('1', '狂神', '123456');
INSERT INTO `mybatis`.`user` (`id`, `name`, `pwd`) VALUES ('2', '张三', '123456');
INSERT INTO `mybatis`.`user` (`id`, `name`, `pwd`) VALUES ('3', '李四', '123456');
新建普通的Maven项目
删除src
加入Maven依赖(mybatis,juint,mysql)
参考官方文档[https://mybatis.org/mybatis-3/zh/index.html
<?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">
<!--核心配置文件-->
<configuration>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="com.mysql.cj.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/mybatis?useUnicode=true&characterEncoding=utf8&useSSL=true"/>
<property name="username" value="root"/>
<property name="password" value="12345678"/>
</dataSource>
</environment>
</environments>
<!-- 每一个mapper.xml都需要在该核心配置文件中注册-->
<mappers>
<mapper resource="com/bao/dao/UserMapper.xml"/>
</mappers>
</configuration>
package com.bao.utils;
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.InputStream;
public class MybatisUtils {
public static SqlSessionFactory sqlSessionFactor;
// 从 XML 中构建 SqlSessionFactory
static {
try {
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
sqlSessionFactor = new SqlSessionFactoryBuilder().build(inputStream);
}catch (Exception e){
e.printStackTrace();
}
}
// 获取SqlSession
//SqlSession中包含面向数据库执行SQL命令的所有方法
public static SqlSession getSqlSession(){
return sqlSessionFactor.openSession();
}
}
实体类
Dao接口
package com.bao.dao;
import com.bao.pojo.User;
import java.util.List;
public interface UserDao {
List<User> getUserList();
}
Dao接口实现类
<?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">
<!--使用namespace=绑定一个对应的接口-->
<mapper namespace="com.bao.dao.UserDao">
<select id="getUserList" resultType="com.bao.pojo.User">
select * from mybatis.user
</select>
</mapper>
测试
import java.util.List;
public class UserDaoTest {
@Test
public void test(){
// 获取sqlSession对象
SqlSession sqlSession = MybatisUtils.getSqlSession();
// 执行 Sql语句
UserDao mapper = sqlSession.getMapper(UserDao.class);
List<User> userList = mapper.getUserList();
for (User user : userList) {
System.out.println(user);
}
sqlSession.close();
}
}
可能遇到的问题
<!--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>
<filtering>true</filtering>
</resource>
<resource>
<directory>src/main/java</directory>
<includes>
<include>**/*.properties</include>
<include>**/*.xml</include>
</includes>
<filtering>true</filtering>
</resource>
</resources>
</build>
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