C# 中的 IpBox

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引言

这只是一个简单的 IpBox 控件，就像 MFC 中的一样。

使用代码

这个简单的 IpBox 实际上由一个 Panel 作为背景、四个 TextBox 控件放置在适当的位置以收集用户输入，以及三个 Label 控件表示句点组成，就像所有其他的 IP 地址控件一样。将四个 TextBox 控件和三个 Label 控件添加到面板中并按顺序排列。然后，基本上就完成了界面。剩下的只是验证地址输入逻辑。

让我们来看一下代码

// The class which inherits this interface will have
// to declare all the abstract functions in the interface
// it is implemented outside the class and inside the same namespace
// with the class which suppose to inherit this interface.
public interface IpBox_Control
{
    IPAddress GetIPAddress { set; get; }
}

// NOTE: this is just a portion of declared variables.
private TextBox ip1;
private TextBox ip2;
private TextBox ip3;
private TextBox ip4;
private string address;

// This function is inherited from the interface. It has no other purpose
// getting the ip address into string form and then convert it to IPAddress form
public IPAddress GetIPAddress
{
    get
    {
        // if the respective textbox is empty, it returns 0.
        address = 
         int.Parse( ( this.ip1.Text.Length > 0 ) ? this.ip1.Text : "0" ).ToString()
         + "." + 
         int.Parse( ( this.ip2.Text.Length > 0 ) ? this.ip2.Text : "0" ).ToString() 
         + "." + 
         int.Parse( ( this.ip3.Text.Length > 0 ) ? this.ip3.Text : "0" ).ToString() 
         + "." + 
         int.Parse( ( this.ip4.Text.Length > 0 ) ? this.ip4.Text : "0" ).ToString();

        return IPAddress.Parse( address );
    }
    set{ }
}

// this function is to validate input from user.
// Everytime a user input a value, it will go through this function
// If the value is not integer value, it will erase the value in the textbox
// If the value inserted is bigger than 255, the value will be set to 255.
// Each textbox can only accomodate a maximum of 3 characters to restrict
// the maximum value.
private void OnTextChange(object sender, System.EventArgs e)
{
    int box_type = 0;

    CultureInfo MyCultureInfo = new CultureInfo("en-GB");

    double d;

    // performing simple check to determine which textbox is currently
    // on focus
    if( sender.Equals( ip1 ) )
        box_type = 1;
    if( sender.Equals( ip2 ) )
        box_type = 2;
    if( sender.Equals( ip3 ) )
        box_type = 3;
    if( sender.Equals( ip4 ) )
        box_type = 4;

    switch( box_type )
    {
        case 1:
        // this is to check whether the user has inserted '.'
        // so that the focus can shift to the next textbox
        if( this.ip1.Text.Length > 0 && 
            this.ip1.Text.ToCharArray()[this.ip1.Text.Length - 1] == '.' )
        {
                // before we shift focus, we must first
                // erase the '.' inserted
                this.ip1.Text = this.ip1.Text.TrimEnd( '.' );
                this.ip1.Text = this.Parse( this.ip1.Text ).ToString();
                // set focus to the next textbox
                ip2.Focus();
            }

            // validate input whether it is still an integer value or not
            if( double.TryParse(
                this.ip1.Text,
                System.Globalization.NumberStyles.Integer,
                MyCultureInfo,
                out d ) == false
                )
            {
                // erase the whole textbox and wait for input again
                // as the previous input was invalid
                this.ip1.Text = this.ip1.Text.Remove( 0, this.ip1.Text.Length );
                return;
            }

            // change focus to the next textbox if the textbox
            // is fully occupied.
            if( this.ip1.Text.Length == 3 )
            {
                if( int.Parse( this.ip1.Text ) >= 255 )
                    this.ip1.Text = "255";
                else
                    this.ip1.Text = int.Parse( this.ip1.Text ).ToString();
                ip2.Focus();
            }
            break;
        case 2:
            if( this.ip2.Text.Length > 0 && 
              this.ip2.Text.ToCharArray()[this.ip2.Text.Length - 1] == '.' )
            {
                this.ip2.Text = this.ip2.Text.TrimEnd( '.' );
                this.ip2.Text = this.Parse( this.ip2.Text ).ToString();
                ip3.Focus();
            }

            if( double.TryParse(
                this.ip2.Text,
                System.Globalization.NumberStyles.Integer,
                MyCultureInfo,
                out d ) == false
                )
            {
                this.ip2.Text = this.ip2.Text.Remove( 0, this.ip2.Text.Length );
                return;
            }

            if( this.ip2.Text.Length == 3 )
            {
                if( int.Parse( this.ip2.Text ) >= 255 )
                    this.ip2.Text = "255";
                else
                    this.ip2.Text = int.Parse( this.ip2.Text ).ToString();
                ip3.Focus();
            }
            break;
        case 3:
            if( this.ip3.Text.Length > 0 && 
              this.ip3.Text.ToCharArray()[this.ip3.Text.Length - 1] == '.' )
            {
                this.ip3.Text = this.ip3.Text.TrimEnd( '.' );
                this.ip3.Text = this.Parse( this.ip3.Text ).ToString();
                ip4.Focus();
            }

            if( double.TryParse(
                this.ip3.Text,
                System.Globalization.NumberStyles.Integer,
                MyCultureInfo,
                out d ) == false
                )
            {
                this.ip3.Text = this.ip3.Text.Remove( 0, this.ip3.Text.Length );
                return;
            }

            if( this.ip3.Text.Length == 3 )
            {
                if( int.Parse( this.ip3.Text ) >= 255 )
                    this.ip3.Text = "255";
                else
                    this.ip3.Text = int.Parse( this.ip3.Text ).ToString();
                ip4.Focus();
            }
            break;
        case 4:

            if( double.TryParse(
                this.ip4.Text,
                System.Globalization.NumberStyles.Integer,
                MyCultureInfo,
                out d ) == false
                )
            {
                this.ip4.Text = this.ip4.Text.Remove( 0, this.ip4.Text.Length );
                return;
            }

            if( this.ip4.Text.Length == 3 )
            {
                if( int.Parse( this.ip4.Text ) >= 255 )
                    this.ip4.Text = "255";
                else
                    this.ip4.Text = int.Parse( this.ip4.Text ).ToString();
            }
            break;
    }
}

就这样。您可以参考源代码获取完整代码。要使用它，只需遵循以下三个步骤：

1. 将您的 DLL 添加为引用。
2. 在您的 using 部分添加一行："using IpBox;"
3. 声明

   private IpBox.IpBox ipbox = new IpBox.IpBox();
   ipbox.GetIPAddress();// it returns System.Net.IPAddress

三个步骤就完成了。

更新

由于这是我的第一篇文章，而且我仍在学习，请提供有关需要修改的部分的评论以及对不良编程技术的更正。

附言：我将一个位图添加到资源中，以便您可以将其添加到工具箱中，并使用一个简单的 ipbox 图片 :) 享受吧！