Question

我在其他人的计算机上运行我的程序时遇到此异常。

The invocation of the constructor on type TCPp2pTutorialWPF.MainWindow that matches the specified binding constraints threw an exception.来自PresentationFramework，方法：Void RewrapException(System.Exception, System.Xaml.IXamlLineInfo, System.Uri)

内部异常Object reference not set to an instance of an object来自Finalize()

我无法在我自己的系统或虚拟机上重现这一点，或找出导致它的原因。我很困惑，因为我没有写过Finalize（）

C＃代码：

namespace TCPp2pTutorialWPF
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
    {
    p2pchat network = null;
    SelectUsername name = new SelectUsername ();


    public void MessageRecieved(string username, string message, bool isDisconnect)
        {
        ChatText.Dispatcher.Invoke((Action) ( () =>
            {
            ChatText.AppendText(username + ": " + message+"\r");


            try
                {
                if (isDisconnect)
                    {
                    Users.Dispatcher.Invoke((Action) ( () =>
                        {
                            Users.Items.Remove(username);
                        } ));

                    }
                }
            catch (NullReferenceException f)
                {
                MessageRecieved("ERROR", "We tried accessing the name list when it was null or something (??) "+f.Message + " " + f.Source, false);
                }
            } ));



        }


    public void NewUser(string user)
        {
        ChatText.Dispatcher.Invoke(new Action(() =>
            {
            Users.Items.Add(user);
            } ));
        }


    public MainWindow()
        {

        try
            {
            InitializeComponent();
            }
        catch (Exception e)
            {
            MessageBox.Show("Error initializing main chat window " + e.Message + " " + e.Source + " " + e.HelpLink.ToString() + " " + e.TargetSite);
            }

        if (string.IsNullOrEmpty(name.UserName))
            try
                {
                name.ShowDialog();
                }
            catch (Exception e)
                {
                MessageRecieved("ERROR", e.Message, false);
                }
        network = new p2pchat();
        ChatText.AppendText("port " + network.Port + " may need to be forwarded to accept incoming connections\r");

        //add the handlers
        network.ReceivedMessageHandler += MessageRecieved;
        network.NewUserHandler += NewUser;
        network.MyUserName = name.UserName;
        network.Start();

        }



    private void ListBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {

        }



    private void Button_Click(object sender, RoutedEventArgs e)
        {
        Window1 getip = new Window1();
        try
            {
            getip.ShowDialog();
            }
        catch (Exception ee)
            {
            MessageRecieved("ERROR", ee.Message, false);
            }

        string Ip = getip.Ip;

        if (!string.IsNullOrEmpty(Ip))
            network.MakeConnection(Ip);
        }




    private void SendBox_KeyDown(object sender, KeyEventArgs e)
        {
        if (e.Key.Equals(Key.Enter))
            {
            network.SendMessage(new TextRange(SendBox.Document.ContentStart, SendBox.Document.ContentEnd).Text);
            SendBox.Document.Blocks.Clear();
            }
        }


    }
}

XAML：

<Window x:Class="TCPp2pTutorialWPF.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Chat" Height="379.439" Width="716.9" WindowStartupLocation="CenterScreen">
<Grid x:Name="Chat_Window">

    <RichTextBox x:Name="ChatText" HorizontalAlignment="Left" Height="280" Margin="0,23,0,0" VerticalAlignment="Top" Width="553" SpellCheck.IsEnabled="True" IsReadOnly="True" IsUndoEnabled="False" VerticalScrollBarVisibility="Auto" AcceptsReturn="False">
        <RichTextBox.Effect>
            <DropShadowEffect/>
        </RichTextBox.Effect>
        <FlowDocument AllowDrop="False"/>
    </RichTextBox>
    <ListBox x:Name="Users" HorizontalAlignment="Left" Height="280" Margin="558,23,0,0" VerticalAlignment="Top" Width="141" SelectionChanged="ListBox_SelectionChanged"/>
    <Menu x:Name="Menu" HorizontalAlignment="Left" Height="23" VerticalAlignment="Top" Width="699">
        <Button Content="User name"/>
        <Button x:Name="addip" Content="Add IP" Click="Button_Click"/>
    </Menu>
    <RichTextBox x:Name="SendBox" HorizontalAlignment="Left" Height="30" Margin="0,318,0,0" VerticalAlignment="Top" Width="699" SpellCheck.IsEnabled="True" KeyDown="SendBox_KeyDown" AcceptsReturn="False">
        <FlowDocument>
            <Paragraph>
                <Run Text=""/>
            </Paragraph>
        </FlowDocument>
    </RichTextBox>

</Grid>

编辑：添加堆栈跟踪的屏幕截图，而不是输入。现在将它记录到文件中。

并添加upnp_helper代码，因为它似乎引用它。

namespace TCPp2pTutorialWPF
{
class UPNP_Helper
    {
    UPnPNAT NatMgr;
    List<int> ports = new List<int>();

    public UPNP_Helper()
        {
        NatMgr = new UPnPNAT();
        }


    ~UPNP_Helper()
        {
        foreach (int i in ports)
            {
            try
                {
                NatMgr.StaticPortMappingCollection.Remove(i, "TCP");
                }
            catch
                {
                }
            }
        }





    public bool AddMappingToThisLocalIp(int port)
        {
        try
            {
            NatMgr.StaticPortMappingCollection.Add(port, "TCP", port, LocalIPAddress().ToString(), true, "p2pChat");
            ports.Add(port);
            return true;
            }
        catch
            {
            return false;
            }
        }




    private IPAddress LocalIPAddress()
        {
        if (!System.Net.NetworkInformation.NetworkInterface.GetIsNetworkAvailable())
            {
            return null;
            }

        IPHostEntry host = Dns.GetHostEntry(Dns.GetHostName());
        return host
            .AddressList
            .FirstOrDefault(ip => ip.AddressFamily == AddressFamily.InterNetwork);
        }

    }
}

Answer 1

这是一种常见的开发方案。在另一台机器上运行时，代码中的某些内容为null ...但是什么？最简单的方法是向MessageBox.Show添加一堆调用：

public MainWindow()
{

try
    {
    InitializeComponent();
    }
catch (Exception e)
    {
    MessageBox.Show("Error initializing main chat window " + e.Message + " " + e.Source + " " + e.HelpLink.ToString() + " " + e.TargetSite);
    }

MessageBox.Show(string.Format("name: {0}, UserName: {1}", name, name.UserName));

if (string.IsNullOrEmpty(name.UserName))
    try
        {
        name.ShowDialog();
        }
    catch (Exception e)
        {
        MessageRecieved("ERROR", e.Message, false);
        }
network = new p2pchat();

MessageBox.Show(string.Format("ChatText: {0}, network: {1}", ChatText, network));

ChatText.AppendText("port " + network.Port + " may need to be forwarded to accept incoming connections\r");

//add the handlers
network.ReceivedMessageHandler += MessageRecieved;
network.NewUserHandler += NewUser;
network.MyUserName = name.UserName;
network.Start();

}

现在，您应该获得一些MessageBox es弹出相关值，其中一个应该是null。所以问题的一半已经解决了......下一步你只需要解决为什么这个值是null并修复它。

Answer 2

Windows 4.5 for Windows 8.1中包含的WPF似乎比.NET 4.5 for Windows 7中包含的版本略微更新，我的测试对象声称拥有最新版本，但找不到安装的实际版本。此问题是由app.Run();引起的，并通过定位早期版本的.NET来解决。

在MainWindow类型上调用构造函数引发了异常

2 个答案: