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我正在使用以下代碼進行登錄。登錄時發生NullReferenceException
public logininfo ViewLoginByUsernameAndPassword(logininfo linfo)
{
logininfo linf = null;
SqlDataReader dr = null;
try
{
con.Open();
SqlCommand com = new SqlCommand("adminlogin", con);
com.CommandType = CommandType.StoredProcedure;
SqlParameter q = new SqlParameter();
q = com.Parameters.AddWithValue("@username", linfo.username);
q = com.Parameters.AddWithValue("@password", linfo.password);
dr = com.ExecuteReader();
linf = new logininfo();
while (dr.Read())
{
linf.username = dr["username"].ToString();
linf.password = dr["password"].ToString();
}
}
catch (Exception ex)
{
return new logininfo();
}
finally
{
dr.Close();
con.Close();
}
return linf;
}
當我試圖登錄，我發現了一個NullReferenceException..And的例外是
See the end of this message for details on invoking
just-in-time (JIT) debugging instead of this dialog box.
************** Exception Text **************
System.NullReferenceException: Object reference not set to an instance of an
object.
at
chitty.App_Code.DAL.SERVICES.loginservice.ViewLoginByUsernameAndPassword
(logininfo linfo)
at chitty.frmlogin.btn_login_Click(Object sender, EventArgs e)
at System.Windows.Forms.Control.OnClick(EventArgs e)
at System.Windows.Forms.Button.OnClick(EventArgs e)
at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32
clicks)
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.ButtonBase.WndProc(Message& m)
at System.Windows.Forms.Button.WndProc(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr
wparam, IntPtr lparam)
************** Loaded Assemblies **************
mscorlib
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.1 (RTMRel.030319-0100)
CodeBase: file:///C:/WINDOWS/Microsoft.NET/Framework/v4.0.30319/mscorlib.dll
----------------------------------------
chitty
Assembly Version: 1.0.0.0
Win32 Version: 1.0.0.0
CodeBase: file:///C:/Program%20Files/itek/chittysoft/chitty.exe
----------------------------------------
System.Windows.Forms
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.1 built by: RTMRel
CodeBase:
file:///C:/WINDOWS/Microsoft.Net/assembly/GAC_MSIL/System.Windows.Forms
/v4.0_4.0.0.0__b77a5c561934e089/System.Windows.Forms.dll
----------------------------------------
System.Drawing
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.1 built by: RTMRel
CodeBase: file:///C:/WINDOWS/Microsoft.Net/assembly/GAC_MSIL/System.Drawing/
v4.0_4.0.0.0__b03f5f7f11d50a3a/System.Drawing.dll
----------------------------------------
System
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.1 built by: RTMRel
CodeBase: file:///C:/WINDOWS/Microsoft.Net/assembly/GAC_MSIL/System/
v4.0_4.0.0.0__b77a5c561934e089/System.dll
----------------------------------------
System.Data
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.1 (RTMRel.030319-0100)
CodeBase: file:///C:/WINDOWS/Microsoft.Net/assembly/GAC_32/System.Data/
v4.0_4.0.0.0__b77a5c561934e089/System.Data.dll
----------------------------------------
System.Core
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.1 built by: RTMRel
CodeBase:
file:///C:/WINDOWS/Microsoft.Net/assembly/GAC_MSIL/System.Core/
v4.0_4.0.0.0__b77a5c561934e089/System.Core.dll
----------------------------------------
System.Configuration
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.1 (RTMRel.030319-0100)
CodeBase:
file:///C:/WINDOWS/Microsoft.Net/assembly/GAC_MSIL/System.Configuration/
v4.0_4.0.0.0__b03f5f7f11d50a3a/System.Configuration.dll
----------------------------------------
System.Xml
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.1 built by: RTMRel
CodeBase: file:///C:/WINDOWS/Microsoft.Net/assembly/GAC_MSIL/System.Xml/
v4.0_4.0.0.0__b77a5c561934e089/System.Xml.dll
----------------------------------------
System.Transactions
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.1 (RTMRel.030319-0100)
CodeBase: file:///C:/WINDOWS/Microsoft.Net/assembly/GAC_32/System.Transactions/
v4.0_4.0.0.0__b77a5c561934e089/System.Transactions.dll
----------------------------------------
System.EnterpriseServices
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.1 (RTMRel.030319-0100)
CodeBase:
file:///C:/WINDOWS/Microsoft.Net/assembly/GAC_32/System.EnterpriseServices/
v4.0_4.0.0.0__b03f5f7f11d50a3a/System.EnterpriseServices.dll
----------------------------------------
************** JIT Debugging **************
To enable just-in-time (JIT) debugging, the .config file for this
application or computer (machine.config) must have the
jitDebugging value set in the system.windows.forms section.
The application must also be compiled with debugging
enabled.
For example:
<configuration>
<system.windows.forms jitDebugging="true" />
</configuration>
When JIT debugging is enabled, any unhandled exception
will be sent to the JIT debugger registered on the computer
rather than be handled by this dialog box.
我還設置「jitdebugging =真」在app.config.But仍然出現此錯誤。請爲此找到解決方案。