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  • C#教程之WinForm之BindingSource基础操作实例教程

通常我们在进行数据绑定的时候，常用的数据源有DataSet、DataTable、BindingList<T>、还有强类型数据源。今天我们来通过实例了解一下BindingSource组建，分享给大家供大家参考借鉴之用。

BindingSource的两个用途：

（1）首先，它提供一个将窗体上的控件绑定到数据的间接层。这是通过将 BindingSource 组件绑定到数据源，然后将窗体上的控件绑定到 BindingSource 组件来完成的。与数据的所有进一步交互（包括导航、排序、筛选和更新）都是通过调用 BindingSource 组件来完成的。
（2）其次，BindingSource 组件可以充当强类型数据源。使用 Add 方法向 BindingSource 组件添加类型会创建一个该类型的列表。

一、对BindingSource的基础操作——增删改查

实例代码如下：

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public partial class Form1 : Form
{
  //注当前DGV已经绑定到 ID 和 Name 列
  private BindingSource source = new BindingSource();
  public Form1()
  {
    InitializeComponent();
  }
  //窗体加载
  private void Form1_Load(object sender, EventArgs e)
  {
    this.source.DataSource = typeof(Custom);
    this.dataGridView1.DataSource = this.source;
  }
  //添加
  private void button1_Click(object sender, EventArgs e)
  {
    this.source.Add(new Custom(1,"A"));
    this.source.Add(new Custom(2,"B"));
  }
  //删除
  private void button2_Click(object sender, EventArgs e)
  {
    this.source.RemoveAt(0);
  }
  //排序 【有问题】
  private void button3_Click(object sender, EventArgs e)
  {
    this.source.Sort = "ID ASC";
    this.source.ResetBindings(false);
  }
  //筛选 【有问题】
  private void button4_Click(object sender, EventArgs e)
  {
    this.source.Filter = "ID = 1";
    this.source.ResetBindings(false);
  }
  //向下移动
  private void button5_Click(object sender, EventArgs e)
  {
    this.source.MoveNext();
    MessageBox.Show(this.source.Position.ToString());
  }
  //向上移动
  private void button9_Click(object sender, EventArgs e)
  {
    this.source.MovePrevious();
    MessageBox.Show(this.source.Position.ToString());
  }
  //获取当前项
  private void button6_Click(object sender, EventArgs e)
  {
    Custom custom = (Custom)this.source.Current;
    MessageBox.Show(" 所处的位置 : " + this.source.IndexOf(custom).ToString());
    MessageBox.Show("custom.Name : " + custom.Name);
  }
  //修改当前项
  private void button7_Click(object sender, EventArgs e)
  {
    Custom custom = (Custom)this.source.Current;
    custom.Name = "修改后的值";
    this.source.ResetCurrentItem();
  }
  //删除当前项
  private void button8_Click(object sender, EventArgs e)
  {
    Custom custom = (Custom)this.source.Current;
    this.source.Remove(custom);
  }
}
//自定义类 字段必须属性公开化
public class Custom
{
  public Custom()
  { }
  public Custom(int ID, string Name)
  {
    this.ID = ID;
    this.Name = Name;
  }
  private int id;
  public int ID
  {
    get { return id; }
    set { id = value; }
  }
  private string name;
  public string Name
  {
    get { return name; }
    set { name = value; }
  }
}

二、  下面的示例演示如何在两种不同情况下绑定 DBNull 值。

第一种情况演示如何设置字符串属性的 NullValue；第二种情况演示如何设置图像属性的 NullValue。

下面的示例演示如何在两种不同情况下绑定 DBNull 值。第一种情况演示如何设置字符串属性的 NullValue；第二种情况演示如何设置图像属性的 NullValue。

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using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Data.SqlClient;
using System.Windows.Forms;
namespace DBNullCS
{
  public class Form1 : Form
  {
    public Form1()
    {   
      this.Load += new EventHandler(Form1_Load);
    }
    // The controls and components we need for the form.
    private Button button1;
    private PictureBox pictureBox1;
    private BindingSource bindingSource1;
    private TextBox textBox1;
    private TextBox textBox2;
    // Data table to hold the database data.
    DataTable employeeTable = new DataTable();
    void Form1_Load(object sender, EventArgs e)
    {
      // Basic form setup.
      this.pictureBox1 = new PictureBox();
      this.bindingSource1 = new BindingSource();
      this.textBox1 = new TextBox();
      this.textBox2 = new TextBox();
      this.button1 = new Button();
      this.pictureBox1.Location = new System.Drawing.Point(20, 20);
      this.pictureBox1.Size = new System.Drawing.Size(174, 179);
      this.textBox1.Location = new System.Drawing.Point(25, 215);
      this.textBox1.ReadOnly = true;
      this.textBox2.Location = new System.Drawing.Point(25, 241);
      this.textBox2.ReadOnly = true;
      this.button1.Location = new System.Drawing.Point(200, 103);
      this.button1.Text = "Move Next";
      this.button1.Click += new System.EventHandler(this.button1_Click);
      this.ClientSize = new System.Drawing.Size(292, 273);
      this.Controls.Add(this.button1);
      this.Controls.Add(this.textBox2);
      this.Controls.Add(this.textBox1);
      this.Controls.Add(this.pictureBox1);
      this.ResumeLayout(false);
      this.PerformLayout();
      // Create the connection string and populate the data table
      // with data.
      string connectionString = "Integrated Security=SSPI;" +
        "Persist Security Info = False;Initial Catalog=Northwind;" +
        "Data Source = localhost";
      SqlConnection connection = new SqlConnection();
      connection.ConnectionString = connectionString;
      SqlDataAdapter employeeAdapter =
        new SqlDataAdapter(new SqlCommand("Select * from Employees", connection));
      connection.Open();
      employeeAdapter.Fill(employeeTable);
      // Set the DataSource property of the BindingSource to the employee table.
      bindingSource1.DataSource = employeeTable;
      // Set up the binding to the ReportsTo column.
      Binding reportsToBinding = textBox2.DataBindings.Add("Text", bindingSource1,
        "ReportsTo", true);
      // Set the NullValue property for this binding.
      reportsToBinding.NullValue = "No Manager";
      // Set up the binding for the PictureBox using the Add method, setting
      // the null value in method call.
      pictureBox1.DataBindings.Add("Image", bindingSource1, "Photo", true,
        DataSourceUpdateMode.Never, new Bitmap(typeof(Button), "Button.bmp"));
      // Set up the remaining binding.
      textBox1.DataBindings.Add("Text", bindingSource1, "LastName", true);
    }
    // Move through the data when the button is clicked.
    private void button1_Click(object sender, EventArgs e)
    {
      bindingSource1.MoveNext();
    }
    [STAThread]
    static void Main()
    {
      Application.EnableVisualStyles();
      Application.Run(new Form1());
    }
  }
}

希望本文实例对大家C#程序设计的学习有所帮助！


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