(1)依赖:mysql,mybatis,junit
(2)建数据库对应实体类
(3)pom.xml中build中配置resources,来防止我们资源导出失败的问题
(4)我的IDEA中还要加:具体看之前的博客
<properties>
<project.build.sourceEncoding>UTF-8project.build.sourceEncoding>
properties>
<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&serverTimezone=UTC" />
<property name="username" value="root"/>
<property name="password" value="18170021"/>
dataSource>
environment>
environments>
configuration>
注意:后面写的mapper.xml要在mybatis-config.xml文件注册
例如:
<mappers>
<mapper resource="cn/edu/hbue/wmp/dao/UserMapper.xml"/>
mappers>
public class MybatisUtil {
private static SqlSessionFactory sqlSessionFactory ;
static{
//1.从XML 配置文件配置的 Configuration 实例来构建出 SqlSessionFactory 实例
String resource = "mybatis-config.xml";
try {
InputStream inputStream = Resources.getResourceAsStream(resource);
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
} catch (IOException e) {
e.printStackTrace();
}
}
//既然有了 SqlSessionFactory,顾名思义,我们可以从中获得 SqlSession 的实例
//获取SqlSession ,SqlSession 完全包含了面向数据库执行 SQL 命令所需的所有方法。
public static SqlSession getSqlSession(){
return sqlSessionFactory.openSession();
}
}
dao层中userMapper写抽象类UserMapper和接口
public interface UserMapper {
List<User> getUserList();
}
dao层中userMapper.xml实现接口,然后去配置文件中注册
<mapper namespace="cn.edu.hbue.wmp.dao.UserMapper">
<select id="getUserList" resultType="cn.edu.hbue.wmp.entity.User">
select * from mybatis.user
select>
mapper>
@Test
public void test(){
//获取sqlSession对象
SqlSession sqlSession = MybatisUtil.getSqlSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
List<User> userList = userMapper.getUserList();
for (User user : userList) {
System.out.println(user);
}
//关闭SqlSession
sqlSession.close();
}
值得注意的是:Mybatis中的事务是默认开启的,因此我们在完成操作以后,需要我们手动去提交事务!,也就是在插入删除更新时要sqlSession.commit();
提交事务.
后面学习中将采用如下配置mybatis(需要写外部配置文件properties文件)
mybatis-config.xml
<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>
configuration>
db.properties文件
#这里的&不需要转义
driver=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://localhost:3306/mybatis?useUnicode=true&characterEncoding=utf8&serverTimezone=UTC
username=root
password=18170021