ファイルにロックをかける方法とロックをかけない方法

ファイルにロックをかける方法
VB.NET

Dim fileName As String = "C:\lock.txt"
Dim fs As New System.IO.FileStream(fileName, _
    System.IO.FileMode.Open, _
    System.IO.FileAccess.Read, _
    System.IO.FileShare.None)
Dim bs(fs.Length - 1) As Byte
fs.Read(bs, 0, bs.Length)
fs.Close()

C#

string fileName = @"C:\lock.txt";
System.IO.FileStream fs = new System.IO.FileStream(
    fileName,
    System.IO.FileMode.Open,
    System.IO.FileAccess.Read,
    System.IO.FileShare.None);
byte[] bs = new byte[fs.Length];
fs.Read(bs, 0, bs.Length);
fs.Close();

ファイルをロックしない方法
VB.NET

Dim fileName As String = "C:\lock.txt"
Dim fs As New System.IO.FileStream(fileName, _
    System.IO.FileMode.Open, _
    System.IO.FileAccess.Read, _
    System.IO.FileShare.ReadWrite)
Dim enc As System.Text.Encoding = _
    System.Text.Encoding.GetEncoding("shift_jis")
Dim sr As New System.IO.StreamReader(fs, enc)
Dim s As String = sr.ReadToEnd()
sr.Close()

C#

string fileName = @"C:\lock.txt";
System.IO.FileStream fs = new System.IO.FileStream(
    fileName,
    System.IO.FileMode.Open,
    System.IO.FileAccess.Read,
    System.IO.FileShare.ReadWrite);
System.Text.Encoding enc =
    System.Text.Encoding.GetEncoding("shift_jis");
System.IO.StreamReader sr = new System.IO.StreamReader(fs, enc);
string s = sr.ReadToEnd();
sr.Close();

ファイル内の一部だけにロックをかける方法
VB.NET

Private testStream As New System.IO.FileStream("C:\lock.txt", _
                                               System.IO.FileMode.Open, _
                                               System.IO.FileAccess.Read, _
                                               System.IO.FileShare.ReadWrite, _
                                               10)

Private Sub btn1_Click(ByVal sender As System.Object, _
        ByVal e As System.EventArgs) Handles btn1.Click
    Try
        testStream.Lock(10, 20)
        MessageBox.Show("Lock完了")
    Catch ex As System.IO.IOException
        MessageBox.Show(ex.Message)
    End Try
End Sub

Private Sub btn2_Click(ByVal sender As System.Object, _
        ByVal e As System.EventArgs) Handles btn2.Click
    Try
        testStream.Unlock(10, 20)
        MessageBox.Show("Unlock完了")
    Catch ex As System.IO.IOException
        MessageBox.Show(ex.Message)
    End Try
End Sub

Private Sub Button3_Click(ByVal sender As System.Object, _
        ByVal e As System.EventArgs) Handles Button3.Click
    Try
        testStream.Seek(0, System.IO.SeekOrigin.Begin)
        MessageBox.Show(testStream.ReadByte().ToString())
    Catch ex As System.IO.IOException
        MessageBox.Show(ex.Message)
    End Try
End Sub

Private Sub Button4_Click(ByVal sender As System.Object, _
        ByVal e As System.EventArgs) Handles Button4.Click
    Try
        testStream.Seek(29, System.IO.SeekOrigin.Begin)
        MessageBox.Show(testStream.ReadByte().ToString())
    Catch ex As System.IO.IOException
        MessageBox.Show(ex.Message)
    End Try
End Sub

Protected Overrides Sub OnFormClosed( _
        ByVal e As System.Windows.Forms.FormClosedEventArgs)
    testStream.Close()
    MyBase.OnFormClosed(e)
End Sub

C#

private System.IO.FileStream testStream = new System.IO.FileStream(
        @"C:\test.txt",
        System.IO.FileMode.Open,
        System.IO.FileAccess.Read,
        System.IO.FileShare.ReadWrite,
        10);

private void btn1_Click(object sender, EventArgs e)
{
    try
    {
        testStream.Lock(10, 20);
        MessageBox.Show("Lock完了");
    }
    catch (System.IO.IOException ex)
    {
        MessageBox.Show(ex.Message);
    }
}

private void btn2_Click(object sender, EventArgs e)
{
    try
    {
        testStream.Unlock(10, 20);
        MessageBox.Show("Unlock完了");
    }
    catch (System.IO.IOException ex)
    {
        MessageBox.Show(ex.Message);
    }
}

private void Button3_Click(object sender, EventArgs e)
{
    try
    {
        testStream.Seek(0, System.IO.SeekOrigin.Begin);
        MessageBox.Show(testStream.ReadByte().ToString());
    }
    catch (System.IO.IOException ex)
    {
        MessageBox.Show(ex.Message);
    }
}

private void Button4_Click(object sender, EventArgs e)
{
    try
    {
        testStream.Seek(29, System.IO.SeekOrigin.Begin);
        MessageBox.Show(testStream.ReadByte().ToString());
    }
    catch (System.IO.IOException ex)
    {
        MessageBox.Show(ex.Message);
    }
}

protected override void OnFormClosed(FormClosedEventArgs e)
{
    testStream.Close();
    base.OnFormClosed(e);
}