如何使用jsp+servlet实现增删改查代码功能
- 作者: 左医生
- 来源: 51数据库
- 2021-09-22
如何使用jsp+servlet实现增删改查代码功能
package ceet.ac.cn.dao;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import ceet.ac.cn.model.*****;
public class *****Dao {
public List*****> getAll*****(){ //查询所有信息
List*****> list = new ArrayList*****>(); //创建集合
Connection conn = DbHelper.getConnection();
String sql = "select * from *****"; //SQL查询语句
try {
PreparedStatement pst = conn.prepareStatement(sql);
ResultSet rst = pst.executeQuery();
while (rst.next()) {
***** ***** = new *****();
*****.setId(rst.getInt("id")); //得到ID
*****.setUsername(rst.getString("username"));
*****.setUserpwd(rst.getString("userpwd"));
list.add(*****);
}
rst.close(); //关闭
pst.close(); //关闭
} catch (SQLException e) {
e.printStackTrace(); //抛出异常
}
return list; //返回一个集合
}
public boolean add*****(***** *****){ //添加信息
String sql = "INSERT INTO `*****`(`id`,`username`,`userpwd`) VALUES (?,?,?)"; //添加的SQL语句
Connection conn = DbHelper.getConnection();
try {
PreparedStatement pst = conn.prepareStatement(sql);
pst.setInt(1, *****.getId());
pst.setString(2, *****.getUsername());
pst.setString(3, *****.getUserpwd());
int count = pst.executeUpdate();
pst.close();
return count>0?true:false; //是否添加的判断
} catch (SQLException e) {
e.printStackTrace();
}
return false;
}
public boolean update*****(***** *****){ //修改
String sql = "UPDATE `*****` SET `username`=?,`userpwd`=? WHERE `id` = ?"; //修改的SQL语句，根据ID修改
Connection conn = DbHelper.getConnection();
try {
PreparedStatement pst = conn.prepareStatement(sql);
pst.setString(1, *****.getUsername());
pst.setString(2, *****.getUserpwd());
pst.setInt(3, *****.getId()); //根据的ID
int count = pst.executeUpdate();
pst.close(); //关闭
return count>0?true:false; //是否修改的判断
} catch (SQLException e) {
e.printStackTrace();
}
return false;
}
public boolean delete*****(int id){ //删除
String sql = "delete from ***** where id = ?"; //删除的SQL语句，根据ID删除
Connection conn = DbHelper.getConnection();
try {
PreparedStatement pst = conn.prepareStatement(sql);
pst.setInt(1, id);
int count = pst.executeUpdate();
pst.close();
return count>0?true:false; //是否删除的判断
} catch (SQLException e) {
e.printStackTrace();
}
return false;
}
public ***** select*****ById(int id){ //根据ID进行查询
Connection conn = DbHelper.getConnection();
String sql = "select * from ***** where id = "+id;
***** ***** = null;
try {
PreparedStatement pst = conn.prepareStatement(sql);
ResultSet rst = pst.executeQuery();
while (rst.next()) {
***** = new *****();
*****.setId(rst.getInt("id"));
*****.setUsername(rst.getString("username"));
*****.setUserpwd(rst.getString("userpwd"));
}
rst.close();
pst.close();
} catch (SQLException e) {
e.printStackTrace();
}
return *****; //返回
}
}
package ceet.ac.cn.dao;
import java.sql.Connection;
import java.sql.DriverManager;
/**
* 连接数据库
* @author 画船听雨眠
*
*/
public class DbHelper {
private static String url = "jdbc:mysql://localhost:3306/*****"; //数据库地址
private static String userName = "root"; //数据库用户名
private static String passWord = "359129127"; //数据库密码
private static Connection conn = null;
private DbHelper(){
}
public static Connection getConnection(){
if(null == conn){
try {
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection(url, userName, passWord);
} catch (Exception e) {
e.printStackTrace();
}
}
return conn;
}
public static void main(String[] args) { //测试数据库是否连通
System.err.println(getConnection());
}
}
package ceet.ac.cn.model;
import java.io.Serializable;
public class ***** implements Serializable{ //数据封装类
