C#實現(xiàn)用戶登錄功能

1、.C#實現(xiàn)用戶登錄功能usingSystem;usingSystem.Collections.Generic;usingSystem.ComponentModel;usingSystem.Data;usingSystem.Drawing;usingSystem.Linq;usingSystem.Text;usingSystem.Windows.Forms;usingMrCy.BaseClass; / 引入文件夾 BaseClassusingSystem.Data.SqlClient;/ 引入連接數(shù)據(jù)庫所需的類namespace MrCypublicpartialclassfrmLogin:Fo

2、rmpublicfrmLogin()InitializeComponent();/ <summary>/ 用戶點擊 “登錄 ”觸發(fā)的事件/ </summary>/ <param name="sender"></param>/ <param name="e"></param>privatevoid btnLogin_Click(objectsender,EventArgs e)trystringUserName = txtUserName.Text.Trim();/ 獲取用戶名stri

3、ngPassWord = 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elseif(PassWord ="" ) / 如果密碼為空值MessageBox.Show( " 請輸入密碼 " ," 提示 " ,MessageBoxBu

4、ttons .OK,MessageBoxIcon.Information);/ 彈出消息對話框1 / 4.elseSqlConnectionconn =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stringstr ="select count(*) from tb_User where UserName='"+ UserName +"' and UserPwd='"+ PassWord +"'" ; / 建立查詢數(shù)據(jù)庫中tb_User 表的用

5、戶名和對應密碼的SQL字符串SqlCommandcmd =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)intn = (int )cmd.ExecuteScalar();if(n >= 1)/ 判斷是否有匹配的用戶名和密碼stringstr1= "select* from tb_User where UserName='" + UserName+ "'" ; /根據(jù)用戶名查

6、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)stringUserPower = 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 (); / 建立主窗體對象Main.Uname

7、= 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UpowerMain.Show();/ 顯示 frmMain 窗體this .Hide();/ 隱藏當前登錄窗體elseMessageBox.Show( " 用戶名或密碼錯誤" ," 警告 " ,MessageBoxButtons .OK,MessageBoxIcon.Warnin

8、g);/ 彈出警告提示框catch ( Exceptionex) / 拋出異常MessageBox.Show(ex.Message);/ 彈出消息對話框2 / 4./ <summary>/ 單擊 “取消 ”按鈕，清空文本框內(nèi)容/ </summary>/ <param name="sender"></param>/ <param name="e"></param>privatevoid btnCancel_Click(objectsender,EventArgs e)/txtUserN

9、ame.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 Click 事

10、件/ </summary>/ <param name="sender"></param>/ <param name="e"></param>privatevoid txtUserName_KeyPress(objectsender,KeyPressEventArgse)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>/ &