C實現(xiàn)用戶登錄功能

1、C#實現(xiàn)用戶登錄功能using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Linq;using System.Text;using System.Windows.Forms;using MrCy.BaseClass;/引入文件夾BaseClassusing System.Data.SqlClient;/引入連接數(shù)據(jù)庫所需的類namespace MrCy public partial class fr

2、mLogin : Form public frmLogin() InitializeComponent(); / <summary> / 用戶點擊“登錄”觸發(fā)的事件 / </summary> / <param name="sender"></param> / <param name="e"></param> private void btnLogin_Click(object sender, EventArgs e) try string UserName = txtUserName

3、.Text.Trim();/獲取用戶名 string PassWord = txtPwd.Text.Trim();/獲取密碼 if (UserName = "")/如果用戶名為空值 MessageBox.Show("請輸入用戶名", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);/彈出消息對話框 else if (PassWord = "")/如果密碼為空值 MessageBox.Show("請輸入密碼", "提示&qu

4、ot;, MessageBoxButtons.OK, MessageBoxIcon.Information);/彈出消息對話框 else SqlConnection conn = DBconn.Connection();/創(chuàng)建數(shù)據(jù)庫連接對象 conn.Open();/打開數(shù)據(jù)庫連接 string str = "select count(*) from tb_User where UserName='" + UserName + "' and UserPwd='" + PassWord + "'"/建立查

5、詢數(shù)據(jù)庫中tb_User表的用戶名和對應(yīng)密碼的SQL字符串 SqlCommand cmd = new SqlCommand(str, conn);/創(chuàng)建命令對象; /SqlDataReader sdr = cmd.ExecuteReader();/創(chuàng)建數(shù)據(jù)讀取器對象 /sdr.Read();/讀取數(shù)據(jù) int n = (int)cmd.ExecuteScalar(); if (n >= 1)/判斷是否有匹配的用戶名和密碼 string str1 = "select * from tb_User where UserName='" + UserName + &q

6、uot;'"/根據(jù)用戶名查詢tb_User表中數(shù)據(jù) cmd = new SqlCommand(str1, conn);/創(chuàng)建命令對象; SqlDataReader sdr = cmd.ExecuteReader();/創(chuàng)建數(shù)據(jù)讀取器對象 sdr.Read();/讀取數(shù)據(jù) string UserPower = sdr"Power".ToString().Trim();/獲取數(shù)據(jù)庫中tb_User表的Power字段 sdr.Close();/關(guān)閉數(shù)據(jù)讀取器 conn.Close();/關(guān)閉數(shù)據(jù)庫連接 frmMain Main = new frmMain();/

7、建立主窗體對象 Main.Uname = UserName;/將用戶名賦值給frmMain窗體的Uname對象 Main.Utime = DateTime.Now.ToString();/獲取登錄時間并賦值給主窗體的Utime對象 Main.Upower = UserPower;/將用戶權(quán)限賦值給主窗體的對象Upower Main.Show();/顯示frmMain窗體 this.Hide();/隱藏當前登錄窗體 else MessageBox.Show("用戶名或密碼錯誤", "警告", MessageBoxButtons.OK, MessageBox

8、Icon.Warning);/彈出警告提示框 catch (Exception ex)/拋出異常 MessageBox.Show(ex.Message);/彈出消息對話框 / <summary> / 單擊“取消”按鈕，清空文本框內(nèi)容 / </summary> / <param name="sender"></param> / <param name="e"></param> private void btnCancel_Click(object sender, EventArgs e

9、) /txtUserName.Text = "" /txtPwd.Text = "" if (MessageBox.Show("確定退出本系統(tǒng)嗎？", "提示", MessageBoxButtons.OKCancel, MessageBoxIcon.Exclamation) = DialogResult.OK)/如果點擊了消息對話框中的“確定” Application.Exit();/退出應(yīng)用程序 / <summary> / 當用戶輸入用戶名之后判斷是否按了“Enter”鍵，按了的話就激發(fā)“登錄”按鈕的

10、Click事件 / </summary> / <param name="sender"></param> / <param name="e"></param> private void txtUserName_KeyPress(object sender, KeyPressEventArgs e) if (e.KeyChar = 13) btnLogin_Click(sender, e); / <summary> / 當用戶輸完密碼，判斷用戶是否按了“Enter”鍵，按了就調(diào)用登錄事件 / </summary> / <param name="sender"></param>