一、接口方法
/**
* 删除、修改、添加操作都可以返回三种类型
* Integer、Long、Boolean
*/
public interface MyUserMapper {
public MyUser selectMyUser(Integer id); public Integer updateMyUser(MyUser user); public Boolean addMyUser(MyUser user); public Long deleteMyUser(Integer id);
}
二、对应的 SQL 映射文件
<?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">
<!-- namespace 对应接口文件的全路径 -->
<mapper namespace="com.dao.MyUserMapper">
<!--resultType 返回参数类型,可用别名-->
<select id="selectMyUser" resultType="myUser">
select * from myuser where id = #{id}
</select> <!--parameterType 输入参数类型,可用别名-->
<update id="updateMyUser" parameterType="myUser">
update myuser set name=#{name},age=#{age} where id=#{id}
</update> <!--useGeneratedKeys 返回插入主键 , keyProperty 把主键封装到 Bean 的那个字段-->
<insert id="addMyUser" parameterType="myUser" useGeneratedKeys="true" keyProperty="id">
insert into myuser(name,age) values (#{name},#{age})
</insert> <delete id="deleteMyUser" parameterType="integer">
delete from myuser where id=#{id}
</delete>
</mapper>
三、测试
单独使用 mybatis 框架进行增、删、改操作时,要显示的提交事务。session.commit(),不然会出现如下日志,且无法对数据库成功操作。
Rolling back JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@291ae]
Resetting autocommit to true on JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@291ae]
测试代码
public static void main(String[] args) {
SqlSession session = null;
try {
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
session = sqlSessionFactory.openSession(); MyUserMapper mapper = session.getMapper(MyUserMapper.class); MyUser myUser = new MyUser(null,"zhangsan",21);
mapper.addMyUser(myUser);
session.commit();
System.out.println("主键:"+myUser.getId());
} catch (IOException e) {
e.printStackTrace();
} finally {
if (session != null) {
session.close();
}
}
}
若为非自增主键(oracle)
<!-- 获取非自增主键的值:每次插入数据的主键是从另一张表中拿到的值 -->
<insert id="addUser" databaseId="oracle">
<!--
keyProperty 把查出主键封装到 Bean 的那个字段
order
BEFORE:先运行 selectKey 查询 id 的 SQL,查出 id 值封装给 javaBean 的 id 属性
AFTER:先运行插入的 SQL,再运行 selectKey 查询 id 的 SQL
resultType 查出的数据的返回值类型 -->
<selectKey keyProperty="id" order="BEFORE" resultType="Integer">
<!-- 查询主键的sql语句 -->
select EMPLOYEES_SEQ.nextval from dual
</selectKey>
insert into myuser(name,age) values (#{name},#{age})
</insert>
http://www.mybatis.org/mybatis-3/zh/sqlmap-xml.html#insert_update_and_delete