DataBindings的用法

在C#操作数据库过程中，针对一般的文本控件，比如TextBox，Label等，我们赋值直接使用类似TextBox.Text=****的方式来进行，这种方式从某种意义上来说的确是最简便的方式，但是对于复杂一些的空间，比如说DataGridView，这个时候，绑定数据源我们一般使用DataGridView1.DataSource=****的方式来进行，如果数据源稍微有更改，那么只需要重新调用绑定一遍即可。可以说这种方式是单向的，也即从数据库到UI，但是有没有一种方式能够实现数据源改变的时候，不用重新绑定DataGridView就让它能够自动刷新数据呢，当然，这里要提到的就是DataBinding了。

代码如下

Form2.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 DataBindingsTest
{
    public partial class Form2 : Form
    {
        public Form2()
        {
            InitializeComponent();
        }

        MyDataSource mydatasource = new MyDataSource();  //应用于第二种方式

        public int Num { get; set; }  //应用于第三种方式

        public List<BlogNew> blogNews { get; set; }  //应用于第四种方式

        public BindingList<BlogNew> blogNewsRegardUI { get; set; }  //应用于DataGridView界面UI更新 

        private void mainFrm_Load(object sender, EventArgs e)
        {
            #region 测试一
            /************************************************
             * 第一个值：要绑定到TextBox的什么地方
             * 第二个值：数据源是什么
             * 第三个值：应该取数据源的什么属性
             * 第四个值：是否开启数据格式化
             * 第五个值：在什么时候启用数据源绑定
             * *********************************************/
            textBox1.DataBindings.Add("Text", trackBar1, "Value", false, DataSourceUpdateMode.OnPropertyChanged);
            #endregion

            #region 测试二
            /*********************************************
             * 这个主要就是通过一个外部的类，当做数据源
             * *********************************************/

            mydatasource.Myvalue = "这是个测试";
            textBox2.DataBindings.Add("Text", mydatasource, "Myvalue", false, DataSourceUpdateMode.OnPropertyChanged);
            #endregion

            #region 测试三
            /*****************************************
             *这个主要就是通过本身拥有的属性，当做数据源
             ****************************************/
            Num = 5;
            textBox3.DataBindings.Add("Text", this, "Num", false, DataSourceUpdateMode.OnPropertyChanged);
            #endregion

            /*
             * 注意：上面的3个测试，改变文本框中的值，数据源中对应的属性值会改变   
             *       但是，数据源的属性值改变了，文本框中的值不会改变
             */
            
            #region 测试四 ： List<T>
            blogNews = new List<BlogNew>();
            blogNews.Add(new BlogNew { BlogID = 1, BlogTitle = "人生若只如初见" });
            blogNews.Add(new BlogNew { BlogID = 2, BlogTitle = "何事秋风悲画扇" });
            blogNews.Add(new BlogNew { BlogID = 3, BlogTitle = "最喜欢纳兰性德" });

            dataGridView1.DataBindings.Add("DataSource", this, "blogNews", false, DataSourceUpdateMode.OnPropertyChanged);

            #endregion

            #region 测试五 ： BindingList<T>
            blogNewsRegardUI = new BindingList<BlogNew>();
            blogNewsRegardUI.Add(new BlogNew { BlogID = 11, BlogTitle = "僵卧孤村不自哀" });
            blogNewsRegardUI.Add(new BlogNew { BlogID = 12, BlogTitle = "尚思为国戍轮台" });
            blogNewsRegardUI.Add(new BlogNew { BlogID = 13, BlogTitle = "夜阑卧听风吹雨" });

            dataGridView2.DataBindings.Add("DataSource", this, "blogNewsRegardUI", false, DataSourceUpdateMode.OnPropertyChanged);

            #endregion
        }

        private void button1_Click(object sender, EventArgs e)
        {
            //从这里可以看出，改变了TextBox2中的值，这里的值也改变了，原因是因为类属于引用类型
            MessageBox.Show(mydatasource.Myvalue);
        }

        private void button2_Click(object sender, EventArgs e)
        {
            //从这里可以看出，改变了TextBox3中的值，这里的值也改变了，
            //原因是Num被当做了当前窗体的一个属性(窗体本身就是一个类)，也属于引用类型
            MessageBox.Show(Num.ToString());
            //this.Num = 10;
            //MessageBox.Show(Num.ToString());
        }

        private void button3_Click(object sender, EventArgs e)
        {
            //在这里向DataGridView中插入一行
            var data = dataGridView1.DataSource as List<BlogNew>;
            data.Add(new BlogNew { BlogID = 4, BlogTitle = "取次花丛懒回顾，半缘修道半缘君" });

            foreach (BlogNew blogNew in dataGridView1.DataSource as List<BlogNew>)
            {
                /***********
                 * 当我们心插入一条BlogID记录为4的数据的时候，在界面上可以看出dataGridView1的dataSource已经被更新，
                 * 但是界面上依旧显示为BlogID为1,2,3三条数据，很奇怪
                 * *********************/
                MessageBox.Show(blogNew.BlogID + "--" + blogNew.BlogTitle);
            }
        }

        private void button4_Click(object sender, EventArgs e)
        {
            /*这里主要用来解决DataGridView1界面不更新的问题，其实原因在于使用了List<BlogNew>,这里我们采用BindList<BlogNew>
             *通过测试，我们发现，只要数据源改变，界面就可以自动的进行更新了，很是方便，不需要重新绑定
             */
            var dataRegardUI = dataGridView2.DataSource as BindingList<BlogNew>;
            dataRegardUI.Add(new BlogNew { BlogID = 20, BlogTitle = "竹外桃花三两枝，春江水暖鸭先知" });
        }
    }

    public class MyDataSource
    {
        public string Myvalue { get; set; }
    }

    public class BlogNew
    {
        public int BlogID { get; set; }
        public string BlogTitle { get; set; }
    }
}

Form2.Designer.cs代码：

namespace DataBindingsTest
{
    partial class Form2
    {
        /// <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.groupBox1 = new System.Windows.Forms.GroupBox();
            this.groupBox2 = new System.Windows.Forms.GroupBox();
            this.button1 = new System.Windows.Forms.Button();
            this.textBox2 = new System.Windows.Forms.TextBox();
            this.groupBox3 = new System.Windows.Forms.GroupBox();
            this.button2 = new System.Windows.Forms.Button();
            this.textBox3 = new System.Windows.Forms.TextBox();
            this.groupBox4 = new System.Windows.Forms.GroupBox();
            this.button3 = new System.Windows.Forms.Button();
            this.dataGridView1 = new System.Windows.Forms.DataGridView();
            this.groupBox5 = new System.Windows.Forms.GroupBox();
            this.button4 = new System.Windows.Forms.Button();
            this.dataGridView2 = new System.Windows.Forms.DataGridView();
            this.textBox1 = new System.Windows.Forms.TextBox();
            this.trackBar1 = new System.Windows.Forms.TrackBar();
            this.groupBox1.SuspendLayout();
            this.groupBox2.SuspendLayout();
            this.groupBox3.SuspendLayout();
            this.groupBox4.SuspendLayout();
            ((System.ComponentModel.ISupportInitialize)(this.dataGridView1)).BeginInit();
            this.groupBox5.SuspendLayout();
            ((System.ComponentModel.ISupportInitialize)(this.dataGridView2)).BeginInit();
            ((System.ComponentModel.ISupportInitialize)(this.trackBar1)).BeginInit();
            this.SuspendLayout();
            // 
            // groupBox1
            // 
            this.groupBox1.Controls.Add(this.trackBar1);
            this.groupBox1.Controls.Add(this.textBox1);
            this.groupBox1.Location = new System.Drawing.Point(12, 12);
            this.groupBox1.Name = "groupBox1";
            this.groupBox1.Size = new System.Drawing.Size(200, 100);
            this.groupBox1.TabIndex = 0;
            this.groupBox1.TabStop = false;
            this.groupBox1.Text = "方式一";
            // 
            // groupBox2
            // 
            this.groupBox2.Controls.Add(this.button1);
            this.groupBox2.Controls.Add(this.textBox2);
            this.groupBox2.Location = new System.Drawing.Point(218, 12);
            this.groupBox2.Name = "groupBox2";
            this.groupBox2.Size = new System.Drawing.Size(200, 100);
            this.groupBox2.TabIndex = 2;
            this.groupBox2.TabStop = false;
            this.groupBox2.Text = "方式二";
            // 
            // button1
            // 
            this.button1.Location = new System.Drawing.Point(22, 59);
            this.button1.Name = "button1";
            this.button1.Size = new System.Drawing.Size(157, 23);
            this.button1.TabIndex = 3;
            this.button1.Text = "查看已修改的数据源的值";
            this.button1.UseVisualStyleBackColor = true;
            this.button1.Click += new System.EventHandler(this.button1_Click);
            // 
            // textBox2
            // 
            this.textBox2.Location = new System.Drawing.Point(22, 20);
            this.textBox2.Name = "textBox2";
            this.textBox2.Size = new System.Drawing.Size(157, 21);
            this.textBox2.TabIndex = 2;
            // 
            // groupBox3
            // 
            this.groupBox3.Controls.Add(this.button2);
            this.groupBox3.Controls.Add(this.textBox3);
            this.groupBox3.Location = new System.Drawing.Point(428, 12);
            this.groupBox3.Name = "groupBox3";
            this.groupBox3.Size = new System.Drawing.Size(200, 100);
            this.groupBox3.TabIndex = 4;
            this.groupBox3.TabStop = false;
            this.groupBox3.Text = "方式三";
            // 
            // button2
            // 
            this.button2.Location = new System.Drawing.Point(22, 59);
            this.button2.Name = "button2";
            this.button2.Size = new System.Drawing.Size(157, 23);
            this.button2.TabIndex = 3;
            this.button2.Text = "查看已修改的数据源的值";
            this.button2.UseVisualStyleBackColor = true;
            this.button2.Click += new System.EventHandler(this.button2_Click);
            // 
            // textBox3
            // 
            this.textBox3.Location = new System.Drawing.Point(22, 20);
            this.textBox3.Name = "textBox3";
            this.textBox3.Size = new System.Drawing.Size(157, 21);
            this.textBox3.TabIndex = 2;
            // 
            // groupBox4
            // 
            this.groupBox4.Controls.Add(this.button3);
            this.groupBox4.Controls.Add(this.dataGridView1);
            this.groupBox4.Location = new System.Drawing.Point(12, 118);
            this.groupBox4.Name = "groupBox4";
            this.groupBox4.Size = new System.Drawing.Size(568, 157);
            this.groupBox4.TabIndex = 5;
            this.groupBox4.TabStop = false;
            this.groupBox4.Text = "方式四";
            // 
            // button3
            // 
            this.button3.Location = new System.Drawing.Point(377, 122);
            this.button3.Name = "button3";
            this.button3.Size = new System.Drawing.Size(157, 23);
            this.button3.TabIndex = 4;
            this.button3.Text = "插入一行";
            this.button3.UseVisualStyleBackColor = true;
            this.button3.Click += new System.EventHandler(this.button3_Click);
            // 
            // dataGridView1
            // 
            this.dataGridView1.ColumnHeadersHeightSizeMode = System.Windows.Forms.DataGridViewColumnHeadersHeightSizeMode.AutoSize;
            this.dataGridView1.Location = new System.Drawing.Point(18, 20);
            this.dataGridView1.Name = "dataGridView1";
            this.dataGridView1.RowTemplate.Height = 23;
            this.dataGridView1.Size = new System.Drawing.Size(516, 96);
            this.dataGridView1.TabIndex = 0;
            // 
            // groupBox5
            // 
            this.groupBox5.Controls.Add(this.button4);
            this.groupBox5.Controls.Add(this.dataGridView2);
            this.groupBox5.Location = new System.Drawing.Point(12, 281);
            this.groupBox5.Name = "groupBox5";
            this.groupBox5.Size = new System.Drawing.Size(568, 162);
            this.groupBox5.TabIndex = 6;
            this.groupBox5.TabStop = false;
            this.groupBox5.Text = "方式五";
            // 
            // button4
            // 
            this.button4.Location = new System.Drawing.Point(377, 127);
            this.button4.Name = "button4";
            this.button4.Size = new System.Drawing.Size(157, 23);
            this.button4.TabIndex = 4;
            this.button4.Text = "插入一行";
            this.button4.UseVisualStyleBackColor = true;
            this.button4.Click += new System.EventHandler(this.button4_Click);
            // 
            // dataGridView2
            // 
            this.dataGridView2.ColumnHeadersHeightSizeMode = System.Windows.Forms.DataGridViewColumnHeadersHeightSizeMode.AutoSize;
            this.dataGridView2.Location = new System.Drawing.Point(18, 20);
            this.dataGridView2.Name = "dataGridView2";
            this.dataGridView2.RowTemplate.Height = 23;
            this.dataGridView2.Size = new System.Drawing.Size(516, 91);
            this.dataGridView2.TabIndex = 0;
            // 
            // textBox1
            // 
            this.textBox1.Location = new System.Drawing.Point(18, 20);
            this.textBox1.Name = "textBox1";
            this.textBox1.Size = new System.Drawing.Size(157, 21);
            this.textBox1.TabIndex = 0;
            // 
            // trackBar1
            // 
            this.trackBar1.Location = new System.Drawing.Point(18, 47);
            this.trackBar1.Name = "trackBar1";
            this.trackBar1.Size = new System.Drawing.Size(157, 45);
            this.trackBar1.TabIndex = 1;
            // 
            // Form2
            // 
            this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 12F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.ClientSize = new System.Drawing.Size(676, 471);
            this.Controls.Add(this.groupBox5);
            this.Controls.Add(this.groupBox4);
            this.Controls.Add(this.groupBox3);
            this.Controls.Add(this.groupBox2);
            this.Controls.Add(this.groupBox1);
            this.Name = "Form2";
            this.Text = "Form2";
            this.Load += new System.EventHandler(this.mainFrm_Load);
            this.groupBox1.ResumeLayout(false);
            this.groupBox1.PerformLayout();
            this.groupBox2.ResumeLayout(false);
            this.groupBox2.PerformLayout();
            this.groupBox3.ResumeLayout(false);
            this.groupBox3.PerformLayout();
            this.groupBox4.ResumeLayout(false);
            ((System.ComponentModel.ISupportInitialize)(this.dataGridView1)).EndInit();
            this.groupBox5.ResumeLayout(false);
            ((System.ComponentModel.ISupportInitialize)(this.dataGridView2)).EndInit();
            ((System.ComponentModel.ISupportInitialize)(this.trackBar1)).EndInit();
            this.ResumeLayout(false);

        }

        #endregion

        private System.Windows.Forms.GroupBox groupBox1;
        private System.Windows.Forms.GroupBox groupBox2;
        private System.Windows.Forms.Button button1;
        private System.Windows.Forms.TextBox textBox2;
        private System.Windows.Forms.GroupBox groupBox3;
        private System.Windows.Forms.Button button2;
        private System.Windows.Forms.TextBox textBox3;
        private System.Windows.Forms.GroupBox groupBox4;
        private System.Windows.Forms.Button button3;
        private System.Windows.Forms.DataGridView dataGridView1;
        private System.Windows.Forms.GroupBox groupBox5;
        private System.Windows.Forms.Button button4;
        private System.Windows.Forms.DataGridView dataGridView2;
        private System.Windows.Forms.TrackBar trackBar1;
        private System.Windows.Forms.TextBox textBox1;
    }
}

效果图：