《WinForm开发系列之控件篇》Item16 ErrorProvider

ErrorProvider实际上并不是一个控件，而是一个组件。当把该组件拖放到设计器上时，它会显示在设计器下方的组件栏中。当存在一个错误条件时，ErrorProvider可以在控件的旁边显示一个图标。

假定有一个TextBox控件要验证正数。如果用户试图输入字符时，就必须通知用户所允许的值，需要改变输入的值。有效值的检查在文本框的Validating事件中进行。如果验证失败，就调用SetError方法，传送引起错误的控件和将该错误告知用户的字符串。然后，一个图标开始闪烁，表示出现了一个错误，用户把鼠标放在该图标上时，会显示错误文本。

图示如下

窗体编辑器：

 partial class Frm_ErrorProvider
    {
        /// <summary>
        /// Required designer variable.
        /// </summary>
        private System.ComponentModel.IContainer components = null;

        /// <summary>
        /// Clean up any resources being used.
        /// </summary>
        /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
            {
                components.Dispose();
            }
            base.Dispose(disposing);
        }

        #region Windows Form Designer generated code

        /// <summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent()
        {
            this.components = new System.ComponentModel.Container();
            this.errorProvider1 = new System.Windows.Forms.ErrorProvider(this.components);
            this.label1 = new System.Windows.Forms.Label();
            this.textBox1 = new System.Windows.Forms.TextBox();
            ((System.ComponentModel.ISupportInitialize)(this.errorProvider1)).BeginInit();
            this.SuspendLayout();
            // 
            // errorProvider1
            // 
            this.errorProvider1.ContainerControl = this;
            // 
            // label1
            // 
            this.label1.AutoSize = true;
            this.label1.Location = new System.Drawing.Point(42, 24);
            this.label1.Name = "label1";
            this.label1.Size = new System.Drawing.Size(41, 12);
            this.label1.TabIndex = 0;
            this.label1.Text = "正数：";
            // 
            // textBox1
            // 
            this.textBox1.Location = new System.Drawing.Point(80, 20);
            this.textBox1.Name = "textBox1";
            this.textBox1.Size = new System.Drawing.Size(100, 21);
            this.textBox1.TabIndex = 1;
            this.textBox1.Validating += new System.ComponentModel.CancelEventHandler(this.textBox1_Validating);
            // 
            // Frm_ErrorProvider
            // 
            this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 12F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.ClientSize = new System.Drawing.Size(292, 266);
            this.Controls.Add(this.textBox1);
            this.Controls.Add(this.label1);
            this.Name = "Frm_ErrorProvider";
            this.Text = "Frm_ErrorProvider";
            ((System.ComponentModel.ISupportInitialize)(this.errorProvider1)).EndInit();
            this.ResumeLayout(false);
            this.PerformLayout();

        }

        #endregion

        private System.Windows.Forms.ErrorProvider errorProvider1;
        private System.Windows.Forms.Label label1;
        private System.Windows.Forms.TextBox textBox1;
    }

 

代码编辑器：

引用：using System.Text.RegularExpressions;

  
 public partial class Frm_ErrorProvider : Form
    {
        public Frm_ErrorProvider()
        {
            InitializeComponent();
        }
        /// <summary>
        /// 验证控件是否输入正数
        /// </summary>
        /// <param name="obj"></param>
        /// <returns></returns>
        private bool Match(object obj)
        {
            TextBox tempText = (TextBox)obj;
            Regex r = new Regex(@"^[1-9]\d*$");
            return r.IsMatch(tempText.Text);
        }

        private void textBox1_Validating(object sender, CancelEventArgs e)
        {
            if (!Match(sender))
            {
              errorProvider1.SetError((TextBox)sender, "请输入正整数");
                e.Cancel = true;//如果输入错误，防止输入焦点移出该控件
            }
            else
            {
               errorProvider1.SetError((TextBox)sender, "");
                e.Cancel = false;
            }

        } 

    }

 

 

作者：Sue

出处：http://www.cnblogs.com/Sue_
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