标签:改查 Studenting studenting 增删 static MyBatis studenting1 public
MyBatis查询数据
1、配置好maven项目
配置步骤点击 MyBatis使用
<--------------------------------->
2、接口实现类写查询数据代码
<!-- 查询全部数据-->
<select id="allStudenting" resultType="com.dh.entity.Studenting">
select * from studenting
</select>
<!-- 以id为条件查询单个数据-->
<select id="checkStudenting" resultType="com.dh.entity.Studenting">
select * from studenting where id = #{id}
</select>
3、新建service接口层和接口实现类
4、在service层的接口实现类实现dao层业务
5、封装MyBatis工具类(增删改查都要用的MyBatis工具类,封装在一起减少代码重复)
package com.dh.util;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionManager;
import java.io.IOException;
import java.io.InputStream;
public class MyBatis {
static SqlSessionManager sqlSessionManager;
static {
String mybatis = "mybatis.xml";
InputStream resourceAsStream = null;
try {
resourceAsStream = Resources.getResourceAsStream(mybatis);
sqlSessionManager = SqlSessionManager.newInstance(resourceAsStream);
} catch (IOException e) {
e.printStackTrace();
sqlSessionManager = null;
}
}
public static <T> T getMapper(Class<T> var1) {
return sqlSessionManager.getMapper(var1);
}
// 获取sqlSession对象
public static SqlSessionManager getSqlSessionManager() {
if (sqlSessionManager != null) {
return sqlSessionManager;
}
return null;
}
}
6、全部查询和单个查询代码:
@Override
public List<Studenting> allStudenting() {
// 调用MyBatis工具类
StudentingDao studentingDao = MyBatis.getMapper(StudentingDao.class);
List<Studenting> studentings = studentingDao.allStudenting();
return studentings;
}
@Override
public Studenting checkStudenting(Studenting studenting) {
// 调用MyBatis工具类
StudentingDao studentingDao = MyBatis.getMapper(StudentingDao.class);
Studenting studenting1 = studentingDao.checkStudenting(studenting);
return studenting1;
}
7、测试
测试类调用接口实现类时注意设为静态(在类中,使用 static 修饰符修饰的属性(成员变量)称为静态变量,也可以称为类变量,常量称为静态常量,方法称为静态方法或类方法,它们统称为静态成员,归整个类所有。
静态成员不依赖于类的特定实例,被类的所有实例共享,就是说 static 修饰的方法或者变量不需要依赖于对象来进行访问,只要这个类被加载,Java 虚拟机就可以根据类名找到它们。)
static StudentServiceDao studentServiceDao = new StudentingServiceDaoImpl();
public static void main(String[] args) {
// 单个查询
Studenting studenting4 = new Studenting();
studenting4.setId(10);
Studenting studenting = studentServiceDao.checkStudenting(studenting4);
// 全部查询
List<Studenting> studentings = studentServiceDao.allStudenting();
}
MyBatis增加数据
1、接口实现类写增加数据代码
<insert id="addStudenting">
<!-- 注意传入的id,name值要以#{}表示-->
insert into studenting (id,name) values (#{id},#{name})
</insert>
2、在service层的接口实现类写人增加数据代码
@Override
public int addStudenting(Studenting studenting) {
// 调用MyBatis工具类
StudentingDao studentingDao = MyBatis.getMapper(StudentingDao.class);
int studenting1 = studentingDao.addStudenting(studenting);
return studenting1;
}
3、测试
static StudentServiceDao studentServiceDao = new StudentingServiceDaoImpl();
public static void main(String[] args) {
// 增加数据库数据
Studenting studenting1 = new Studenting();
studenting1.setName("小李");
int i = studentServiceDao.addStudenting(studenting1);
}
MyBatis删除数据
1、接口实现类写删除数据代码
<delete id="deleteStudenting">
delete from studenting where id = #{id}
</delete>
2、在service层的接口实现类写人删除数据代码
@Override
public int deleteStudenting(Studenting studenting) {
// 调用MyBatis工具类
StudentingDao studentingDao = MyBatis.getMapper(StudentingDao.class);
int studenting1 = studentingDao.deleteStudenting(studenting);
return studenting1;
}
3、测试
static StudentServiceDao studentServiceDao = new StudentingServiceDaoImpl();
public static void main(String[] args) {
// 删除数据库数据
int i1 = studentServiceDao.changeStudenting(studenting2);
Studenting studenting3 = new Studenting();
studenting3.setId(9);
int i3 = studentServiceDao.deleteStudenting(studenting3);
}
MyBatis更改数据
1、接口实现类写更改数据代码
<update id="changeStudenting">
update studenting set name = #{name} where id = #{id}
</update>
2、在service层的接口实现类写人更改数据代码
@Override
public int changeStudenting(Studenting studenting) {
// 调用MyBatis工具类
StudentingDao studentingDao = MyBatis.getMapper(StudentingDao.class);
int studenting1 = studentingDao.changeStudenting(studenting);
return studenting1;
}
3、测试
static StudentServiceDao studentServiceDao = new StudentingServiceDaoImpl();
public static void main(String[] args) {
// 更改数据库数据
Studenting studenting2 = new Studenting();
studenting2.setId(8);
studenting2.setName("小丽");
int i1 = studentServiceDao.changeStudenting(studenting2);
}
标签:改查,Studenting,studenting,增删,static,MyBatis,studenting1,public 来源: https://blog.csdn.net/lijianyu51314/article/details/119806332
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