C# KeyPressEventArgs.Handled属性代码示例

//引入命名空间
using System;
using System.Windows.Forms;

public class Form1: Form
{
    public Form1()
    {
        // Create a TextBox control.
        TextBox tb = new TextBox();
        this.Controls.Add(tb);
        tb.KeyPress += new KeyPressEventHandler(keypressed);
    }

    private void keypressed(Object o, KeyPressEventArgs e)
    {
        // The keypressed method uses the KeyChar property to check 
        // whether the ENTER key is pressed. 

        // If the ENTER key is pressed, the Handled property is set to true, 
        // to indicate the event is handled.
        if (e.KeyChar == (char)Keys.Return)
        {
            e.Handled = true;
        }
    }

    public static void Main()
    {
        Application.Run(new Form1());
    }
}

//引入命名空间
using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;

public class TextCancelEventKeyEvent : System.Windows.Forms.Form
{
  private System.Windows.Forms.Label label1;
  private System.Windows.Forms.TextBox txtInput;
  private System.Windows.Forms.Label label2;
  private System.Windows.Forms.Label lblTrue;
  private System.Windows.Forms.Label label3;
  private System.Windows.Forms.Label lblCheck;
    private System.Windows.Forms.Label lblResults;

  public TextCancelEventKeyEvent()
  {
    InitializeComponent();
  }

  private void InitializeComponent()
  {
     this.label1 = new System.Windows.Forms.Label();
     this.txtInput = new System.Windows.Forms.TextBox();
     this.label2 = new System.Windows.Forms.Label();
     this.lblTrue = new System.Windows.Forms.Label();
     this.label3 = new System.Windows.Forms.Label();
     this.lblCheck = new System.Windows.Forms.Label();
     this.lblResults = new System.Windows.Forms.Label();
     this.SuspendLayout();
     // 
     // label1
     // 
     this.label1.Font = new System.Drawing.Font("Tahoma", 14.25F, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic), System.Drawing.GraphicsUnit.Point, ((System.Byte)(0)));
     this.label1.Location = new System.Drawing.Point(48, 16);
     this.label1.Name = "label1";
     this.label1.Size = new System.Drawing.Size(176, 23);
     this.label1.TabIndex = 0;
     this.label1.Text = "ISBN Validation";
     // 
     // txtInput
     // 
     this.txtInput.Location = new System.Drawing.Point(72, 64);
     this.txtInput.Name = "txtInput";
     this.txtInput.TabIndex = 1;
     this.txtInput.Text = "";
     this.txtInput.KeyPress += new System.Windows.Forms.KeyPressEventHandler(this.txtInput_KeyPress);
     this.txtInput.Validating += new System.ComponentModel.CancelEventHandler(this.handleCancleEvent);
     // 
     // label2
     // 
     this.label2.Location = new System.Drawing.Point(24, 104);
     this.label2.Name = "label2";
     this.label2.Size = new System.Drawing.Size(80, 23);
     this.label2.TabIndex = 2;
     this.label2.Text = "True Number:";
     // 
     // lblTrue
     // 
     this.lblTrue.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D;
     this.lblTrue.Location = new System.Drawing.Point(112, 104);
     this.lblTrue.Name = "lblTrue";
     this.lblTrue.TabIndex = 3;
     // 
     // label3
     // 
     this.label3.Location = new System.Drawing.Point(32, 152);
     this.label3.Name = "label3";
     this.label3.Size = new System.Drawing.Size(72, 23);
     this.label3.TabIndex = 4;
     this.label3.Text = "Check Digit:";
     // 
     // lblCheck
     // 
     this.lblCheck.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D;
     this.lblCheck.Location = new System.Drawing.Point(112, 152);
     this.lblCheck.Name = "lblCheck";
     this.lblCheck.TabIndex = 5;
     // 
     // lblResults
     // 
     this.lblResults.Location = new System.Drawing.Point(56, 192);
     this.lblResults.Name = "lblResults";
     this.lblResults.Size = new System.Drawing.Size(152, 24);
     this.lblResults.TabIndex = 8;
     // 
     // TextCancelEventKeyEvent
     // 
     this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
     this.ClientSize = new System.Drawing.Size(264, 293);
     this.Controls.AddRange(new System.Windows.Forms.Control[] {
                                                                  this.lblResults,
                                                                  this.lblCheck,
                                                                  this.label3,
                                                                  this.lblTrue,
                                                                  this.label2,
                                                                  this.txtInput,
                                                                  this.label1});
     this.ResumeLayout(false);

  }
  [STAThread]
  static void Main() 
  {
    Application.Run(new TextCancelEventKeyEvent());
  }

  private void handleCancleEvent(object sender, System.ComponentModel.CancelEventArgs e)
  {
    TextBox tb = (TextBox)sender;
    string strInput = tb.Text;
        Console.WriteLine(strInput);
  }     

  private void txtInput_KeyPress(object sender, System.Windows.Forms.KeyPressEventArgs e)
  {
     char keyChar;
     keyChar = e.KeyChar;

     if(!Char.IsDigit(keyChar)      // 0 - 9
        &&
        keyChar != 8               // backspace
        &&
        keyChar != 13              // enter
        &&
        keyChar != 'x'
        &&
        keyChar != 45              //  dash/minus
        ){
        //  Do not display the keystroke
        e.Handled = true;
     }
  }     
}