焦点变色

示例中包含一个遍历当前窗体中所有控件并选择一个控件的方法，值得借鉴。

1.Designer.cs代码

namespace FocusChangeColor
{
    partial class Form1
    {
        /// <summary>
        /// 必需的设计器变量。
        /// </summary>
        private System.ComponentModel.IContainer components = null;

        /// <summary>
        /// 清理所有正在使用的资源。
        /// </summary>
        /// <param name="disposing">如果应释放托管资源，为 true；否则为 false。</param>
        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
            {
                components.Dispose();
            }
            base.Dispose(disposing);
        }

        #region Windows 窗体设计器生成的代码

        /// <summary>
        /// 设计器支持所需的方法 - 不要
        /// 使用代码编辑器修改此方法的内容。
        /// </summary>
        private void InitializeComponent()
        {
            this.label1 = new System.Windows.Forms.Label();
            this.label2 = new System.Windows.Forms.Label();
            this.label3 = new System.Windows.Forms.Label();
            this.label4 = new System.Windows.Forms.Label();
            this.label5 = new System.Windows.Forms.Label();
            this.label6 = new System.Windows.Forms.Label();
            this.textBox1 = new System.Windows.Forms.TextBox();
            this.textBox2 = new System.Windows.Forms.TextBox();
            this.textBox3 = new System.Windows.Forms.TextBox();
            this.textBox4 = new System.Windows.Forms.TextBox();
            this.textBox5 = new System.Windows.Forms.TextBox();
            this.textBox6 = new System.Windows.Forms.TextBox();
            this.SuspendLayout();
            //
            // label1
            //
            this.label1.AutoSize = true;
            this.label1.Location = new System.Drawing.Point(10, 22);
            this.label1.Name = "label1";
            this.label1.Size = new System.Drawing.Size(65, 12);
            this.label1.TabIndex = 0;
            this.label1.Text = "职工编号：";
            //
            // label2
            //
            this.label2.AutoSize = true;
            this.label2.Location = new System.Drawing.Point(159, 22);
            this.label2.Name = "label2";
            this.label2.Size = new System.Drawing.Size(65, 12);
            this.label2.TabIndex = 1;
            this.label2.Text = "职工姓名：";
            //
            // label3
            //
            this.label3.AutoSize = true;
            this.label3.Location = new System.Drawing.Point(10, 64);
            this.label3.Name = "label3";
            this.label3.Size = new System.Drawing.Size(65, 12);
            this.label3.TabIndex = 2;
            this.label3.Text = "职工性别：";
            //
            // label4
            //
            this.label4.AutoSize = true;
            this.label4.Location = new System.Drawing.Point(159, 64);
            this.label4.Name = "label4";
            this.label4.Size = new System.Drawing.Size(65, 12);
            this.label4.TabIndex = 3;
            this.label4.Text = "职工年龄：";
            //
            // label5
            //
            this.label5.AutoSize = true;
            this.label5.Location = new System.Drawing.Point(10, 110);
            this.label5.Name = "label5";
            this.label5.Size = new System.Drawing.Size(65, 12);
            this.label5.TabIndex = 4;
            this.label5.Text = "出生年月：";
            //
            // label6
            //
            this.label6.AutoSize = true;
            this.label6.Location = new System.Drawing.Point(159, 110);
            this.label6.Name = "label6";
            this.label6.Size = new System.Drawing.Size(65, 12);
            this.label6.TabIndex = 5;
            this.label6.Text = "职工职务：";
            //
            // textBox1
            //
            this.textBox1.Location = new System.Drawing.Point(81, 17);
            this.textBox1.Name = "textBox1";
            this.textBox1.Size = new System.Drawing.Size(72, 21);
            this.textBox1.TabIndex = 6;
            this.textBox1.Tag = "1";
            this.textBox1.KeyDown += new System.Windows.Forms.KeyEventHandler(this.textBox1_KeyDown);
            this.textBox1.Leave += new System.EventHandler(this.textBox1_Leave);
            this.textBox1.Enter += new System.EventHandler(this.textBox1_Enter);
            //
            // textBox2
            //
            this.textBox2.Location = new System.Drawing.Point(228, 17);
            this.textBox2.Name = "textBox2";
            this.textBox2.Size = new System.Drawing.Size(72, 21);
            this.textBox2.TabIndex = 7;
            this.textBox2.Tag = "2";
            this.textBox2.KeyDown += new System.Windows.Forms.KeyEventHandler(this.textBox1_KeyDown);
            this.textBox2.Leave += new System.EventHandler(this.textBox1_Leave);
            this.textBox2.Enter += new System.EventHandler(this.textBox1_Enter);
            //
            // textBox3
            //
            this.textBox3.Location = new System.Drawing.Point(81, 59);
            this.textBox3.Name = "textBox3";
            this.textBox3.Size = new System.Drawing.Size(72, 21);
            this.textBox3.TabIndex = 8;
            this.textBox3.Tag = "3";
            this.textBox3.KeyDown += new System.Windows.Forms.KeyEventHandler(this.textBox1_KeyDown);
            this.textBox3.Leave += new System.EventHandler(this.textBox1_Leave);
            this.textBox3.Enter += new System.EventHandler(this.textBox1_Enter);
            //
            // textBox4
            //
            this.textBox4.Location = new System.Drawing.Point(228, 59);
            this.textBox4.Name = "textBox4";
            this.textBox4.Size = new System.Drawing.Size(72, 21);
            this.textBox4.TabIndex = 9;
            this.textBox4.Tag = "4";
            this.textBox4.KeyDown += new System.Windows.Forms.KeyEventHandler(this.textBox1_KeyDown);
            this.textBox4.Leave += new System.EventHandler(this.textBox1_Leave);
            this.textBox4.Enter += new System.EventHandler(this.textBox1_Enter);
            //
            // textBox5
            //
            this.textBox5.Location = new System.Drawing.Point(81, 105);
            this.textBox5.Name = "textBox5";
            this.textBox5.Size = new System.Drawing.Size(72, 21);
            this.textBox5.TabIndex = 10;
            this.textBox5.Tag = "5";
            this.textBox5.KeyDown += new System.Windows.Forms.KeyEventHandler(this.textBox1_KeyDown);
            this.textBox5.Leave += new System.EventHandler(this.textBox1_Leave);
            this.textBox5.Enter += new System.EventHandler(this.textBox1_Enter);
            //
            // textBox6
            //
            this.textBox6.Location = new System.Drawing.Point(228, 105);
            this.textBox6.Name = "textBox6";
            this.textBox6.Size = new System.Drawing.Size(72, 21);
            this.textBox6.TabIndex = 11;
            this.textBox6.Tag = "6";
            this.textBox6.KeyDown += new System.Windows.Forms.KeyEventHandler(this.textBox1_KeyDown);
            this.textBox6.Leave += new System.EventHandler(this.textBox1_Leave);
            this.textBox6.Enter += new System.EventHandler(this.textBox1_Enter);
            //
            // Form1
            //
            this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 12F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.ClientSize = new System.Drawing.Size(312, 141);
            this.Controls.Add(this.textBox6);
            this.Controls.Add(this.textBox5);
            this.Controls.Add(this.textBox4);
            this.Controls.Add(this.textBox3);
            this.Controls.Add(this.textBox2);
            this.Controls.Add(this.textBox1);
            this.Controls.Add(this.label6);
            this.Controls.Add(this.label5);
            this.Controls.Add(this.label4);
            this.Controls.Add(this.label3);
            this.Controls.Add(this.label2);
            this.Controls.Add(this.label1);
            this.Name = "Form1";
            this.Text = "焦点变色";
            this.ResumeLayout(false);
            this.PerformLayout();

        }

        #endregion

        private System.Windows.Forms.Label label1;
        private System.Windows.Forms.Label label2;
        private System.Windows.Forms.Label label3;
        private System.Windows.Forms.Label label4;
        private System.Windows.Forms.Label label5;
        private System.Windows.Forms.Label label6;
        private System.Windows.Forms.TextBox textBox1;
        private System.Windows.Forms.TextBox textBox2;
        private System.Windows.Forms.TextBox textBox3;
        private System.Windows.Forms.TextBox textBox4;
        private System.Windows.Forms.TextBox textBox5;
        private System.Windows.Forms.TextBox textBox6;
    }
}

2.cs代码

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace FocusChangeColor
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void textBox1_Enter(object sender, EventArgs e)
        {
            ((TextBox)sender).BackColor = Color.CornflowerBlue;
        }

        private void textBox1_Leave(object sender, EventArgs e)
        {
            ((TextBox)sender).BackColor = Color.White;
        }

        private void textBox1_KeyDown(object sender, KeyEventArgs e)
        {
            if (e.KeyValue == 13)
            {
                int n = Convert.ToInt32(((TextBox)sender).Tag.ToString());
                Clear_Control(this.Controls, n, 6);
            }
        }

        #region  遍历指定的控件
        /// <summary>
        /// 遍历指定的控件
        /// </summary>
        /// <param Con="ControlCollection">可视化控件</param>
        /// <param n="int">控件标识</param>
        /// <param m="int">最大标识</param>
        public void Clear_Control(Control.ControlCollection Con, int n, int m)
        {
            int tem_n=0;
            foreach (Control C in Con)
            { //遍历可视化组件中的所有控件
                if (C.GetType().Name == "TextBox")  //判断是否为TextBox控件
                {
                    if (n == m)
                        tem_n = 1;
                    else
                        tem_n = n + 1;
                    if (Convert.ToInt32(((TextBox)C).Tag.ToString())==tem_n)
                        ((TextBox)C).Focus();   //清空当前控件
                }
            }
        }
        #endregion
    }
}