《（学习笔记）两天进步一点点》（2） ——BindingSource基础操作
以前在进行数据绑定的时候，通常用的数据源有DataSet、DataTable、BindingList<T>、还有强类型数据源。今天呢、我看了一下BindingSource组建，感觉还不错特将学习笔记分大家分享。
一、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
增删改查
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。
绑定 DBNull 值
//***********************************************************************
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。
//***********************************************************************
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());
}
}
}
《（学习笔记）两天进步一点点》持续更新中… 望大侠们指点一二，谢谢！
