VB.NET实现图象文件和XML文件互换

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通过.NET 框架下的FromBase64String和ToBase64String方法可以很容易地实现图象文件和XML文件的互换。这样可以轻易解决以XML格式保存图片的问题。以下是利用VB.NET实现图象文件和XML文件的互换代码：


Public Class Form1   
Inherits System.Windows.Forms.Form   
#Region " Windows 窗体设计器生成的代码 "   
Public Sub New()   
MyBase.New()   
InitializeComponent()   
在 InitializeComponent() 调用之后添加任何初始化   
End Sub  
窗体重写处置以清理组件列表。   
Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)   
If disposing Then  
If Not (components Is Nothing) Then  
components.Dispose()   
End If  
End If  
MyBase.Dispose(disposing)   
End Sub  
Windows 窗体设计器所必需的   
Private components As System.ComponentModel.IContainer   
注意：以下过程是 Windows 窗体设计器所必需的   
可以使用 Windows 窗体设计器修改此过程。   
不要使用代码编辑器修改它。   
Friend WithEvents Button1 As System.Windows.Forms.Button   
Friend WithEvents Button2 As System.Windows.Forms.Button   
Friend WithEvents PictureBox1 As System.Windows.Forms.PictureBox   
Friend WithEvents Button3 As System.Windows.Forms.Button   
Friend WithEvents Label1 As System.Windows.Forms.Label   
Friend WithEvents Label2 As System.Windows.Forms.Label   
<System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()   
Me.Button1 = New System.Windows.Forms.Button()   
Me.Button2 = New System.Windows.Forms.Button()   
Me.PictureBox1 = New System.Windows.Forms.PictureBox()   
Me.Button3 = New System.Windows.Forms.Button()   
Me.Label1 = New System.Windows.Forms.Label()   
Me.Label2 = New System.Windows.Forms.Label()   
Me.SuspendLayout()   
  
Button1   
  
Me.Button1.Location = New System.Drawing.Point(365, 63)   
Me.Button1.Name = "Button1"  
Me.Button1.Size = New System.Drawing.Size(115, 23)   
Me.Button1.TabIndex = 0   
Me.Button1.Text = "将图象保存成XML"  
  
Button2   
  
Me.Button2.Location = New System.Drawing.Point(365, 98)   
Me.Button2.Name = "Button2"  
Me.Button2.Size = New System.Drawing.Size(115, 23)   
Me.Button2.TabIndex = 1   
Me.Button2.Text = "从XML中得到图象"  
  
PictureBox1   
  
Me.PictureBox1.Location = New System.Drawing.Point(18, 6)   
Me.PictureBox1.Name = "PictureBox1"  
Me.PictureBox1.Size = New System.Drawing.Size(320, 460)   
Me.PictureBox1.TabIndex = 2   
Me.PictureBox1.TabStop = False  
  
Button3   
  
Me.Button3.Location = New System.Drawing.Point(365, 28)   
Me.Button3.Name = "Button3"  
Me.Button3.Size = New System.Drawing.Size(115, 23)   
Me.Button3.TabIndex = 3   
Me.Button3.Text = "浏览图片…"  
  
Label1   
  
Me.Label1.Location = New System.Drawing.Point(369, 135)   
Me.Label1.Name = "Label1"  
Me.Label1.Size = New System.Drawing.Size(105, 95)   
Me.Label1.TabIndex = 4   
  
Label2   
  
Me.Label2.Location = New System.Drawing.Point(367, 437)   
Me.Label2.Name = "Label2"  
Me.Label2.Size = New System.Drawing.Size(130, 16)   
Me.Label2.TabIndex = 5   
Me.Label2.Text = "【孟宪会之精彩世界】"  
  
Form1   
  
Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)   
Me.ClientSize = New System.Drawing.Size(500, 480)   
Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.Label2, Me.Label1, Me.Button3, Me.PictureBox1, Me.Button2, Me.Button1})   
Me.Name = "Form1"  
Me.Text = "图象文件和XML格式文件互换例子"  
Me.ResumeLayout(False)   
End Sub  
#End Region   
Private MyFile As String = ""  
Private MyFileExt As String = ""  
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) _   
Handles Button2.Click   
Dim pic As String  
Dim MyXml As System.Xml.XmlDocument = New System.Xml.XmlDocument()   
MyXml.Load("c:\MyPhoto.xml")   
Dim picNode As System.Xml.XmlNode   
picNode = MyXml.SelectSingleNode("/pic/photo")   
pic = picNode.InnerText   
Dim memoryStream As System.IO.MemoryStream   
memoryStream = New System.IO.MemoryStream(Convert.FromBase64String(pic))   
Me.PictureBox1.Image = New System.Drawing.Bitmap(memoryStream)   
memoryStream.Close()   
End Sub  
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) _   
Handles Button1.Click   
If MyFile = "" Then  
MessageBox.Show("请选择一个图片！", "错误", MessageBoxButtons.OK, MessageBoxIcon.Warning)   
Exit Sub  
End If  
Dim MyImg As System.Drawing.Image = MyImg.FromFile(MyFile)   
Dim memoryStream As System.IO.MemoryStream = New System.IO.MemoryStream()   
MyImg.Save(memoryStream, GetImageType(MyFileExt))   
Dim b() As Byte  
b = memoryStream.GetBuffer()   
Dim pic As String = Convert.ToBase64String(b)   
memoryStream.Close()   
Dim MyXml As System.Xml.XmlDocument = New System.Xml.XmlDocument()   
MyXml.LoadXml("<pic><name>孟宪会</name><photo>" + pic + "</photo></pic>")   
MyXml.Save("c:\MyPhoto.xml")   
Label1.Text = "文件被保存到了：" + Microsoft.VisualBasic.ChrW(13) + "c:\MyPhoto.xml"  
End Sub  
Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) _   
Handles Button3.Click   
Dim openFileDialog1 As New OpenFileDialog()   
openFileDialog1.InitialDirectory = "c:\"  
openFileDialog1.Filter = "PNG(*.png)|*.png|Gif(*.gif)|*.gif|Jpg(*.jpg)|*.jpg|所有图象文件(*.*)|*.*"  
openFileDialog1.FilterIndex = 2   
openFileDialog1.RestoreDirectory = True  
If openFileDialog1.ShowDialog() = DialogResult.OK Then  
MyFile = openFileDialog1.FileName()   
MyFileExt = MyFile.Substring(MyFile.LastIndexOf(".") + 1)   
End If  
End Sub  
Public Function GetImageType(ByVal str As String) As System.Drawing.Imaging.ImageFormat   
Select Case str.ToLower()   
Case "jpg"  
Return System.Drawing.Imaging.ImageFormat.Jpeg   
Case "gif"  
Return System.Drawing.Imaging.ImageFormat.Gif   
Case "tiff"  
Return System.Drawing.Imaging.ImageFormat.Tiff()   
Case "icon"  
Return System.Drawing.Imaging.ImageFormat.Icon   
Case "image/png"  
Return System.Drawing.Imaging.ImageFormat.Png   
Case Else  
Return System.Drawing.Imaging.ImageFormat.MemoryBmp   
End Select  
End Function  
Private Sub Form1_Closing(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) _   
Handles MyBase.Closing   
System.Diagnostics.Process.Start("IExplore.exe", "http://xml.sz.luohuedu.net/")   
End Sub  
End Class