最近，看到网上经常会问如何进行窗口跳转，大多数的问题都是牵扯到Login窗口。其实，在Visual Studio 6以来，比较正确的做法，是判断Login窗口的返回值，然后决定是否打开主窗体，那么在C#中也是一样的。 具体做法如下：首先，创建Login窗口，然后添加相应的输入框和按钮，设置窗口的AcceptButton为窗体的确认按钮，而CancelButton为窗体的取消按钮。例如： this.AcceptButton = this.btnOK; this.CancelButton = this.btnCancel; 定义确定按钮以及取消按钮事件，如下： private void btnOK_Click(object sender, System.EventArgs e)
...{
// Here is to use fixed username and password // You can check username and password from DB if( txtUserName.Text == "Admin" && txtPassword.Text == "nopassword" )
...{ // Save login user info uiLogin.UserName = txtUserName.Text; uiLogin.Password = txtPassword.Text; // Set dialog result with OK this.DialogResult = DialogResult.OK;
} else ...{ // Wrong username or password nLoginCount++; if( nLoginCount == MAX_LOGIN_COUNT ) // Over 3 times this.DialogResult = DialogResult.Cancel; else ...{ MessageBox.Show( "Invalid user name and password!" ); txtUserName.Focus(); } }
} private void btnCancel_Click(object sender, System.EventArgs e) ...{ // Set dialog result with Cancel this.DialogResult = DialogResult.Cancel; } 然后，在Login窗体的Closing事件中，要进行处理，如下：private void frmLogin_Closing(object sender, System.ComponentModel.CancelEventArgs e)...{ // Check whether form is closed with dialog result if( this.DialogResult != DialogResult.Cancel && this.DialogResult != DialogResult.OK ) e.Cancel = true;} 除此外，Login窗体一些辅助代码如下： private int nLoginCount = 0; private const int MAX_LOGIN_COUNT = 3; private UserInfo uiLogin; public frmLogin( ref UserInfo ui ) ...{ // // Required for Windows Form Designer support // InitializeComponent(); // Set login info to class member uiLogin = ui; } 调用的时候，要修改程序的Main函数，如下： /**//// <summary> /// The main entry point for the application. /// </summary> [STAThread] static void Main() ...{ UserInfo ui = new UserInfo(); frmLogin myLogin = new frmLogin( ref ui ); if( myLogin.ShowDialog() == DialogResult.OK ) ...{ //Open your main form here MessageBox.Show( "Logged in successfully!" ); } else ...{ MessageBox.Show( "Failed to logged in!" ); } } 而附加的UserInfo类如下： /**//// <summary> /// User info class /// </summary> public class UserInfo ...{ private string strUserName; private string strPassword; public string UserName ...{ get...{ return strUserName;} set...{ strUserName = value; } } public string Password ...{ get...{ return strPassword;} set...{ strPassword = value;} } public UserInfo() ...{ strUserName = ""; strPassword = ""; } }