关于不同线程访问同一文件的问题。
UI线程和程序中的另一子线程都需要写log文件，那么我需要解决的问题是：两个线程同时访问log文件时会发生冲突，出现同时打开文件执行写操作的情况。我使用FileStream时，会发生要打开写的文件正在被其他占用的错误，那么：
1.FileStream本身就是独占的方式打开文件的么？
2.想要避免一个线程打开文件时出现上述错误，我想知道文件是否已经被打开？如果能知道，那么等待一定时间后再进行写文件操做就可以避免出错。有什么好方法么？可否提供稍详细的实现方法。
[解决办法]
如果一个进程内，你可以写个log类。这个类，写文件的地方，可以写
Monitor.Enter(me)
写文件
Monitor.Exit(me)
[解决办法]
楼主参考一下我的代码，或者浏览http://topic.csdn.net/u/20100716/11/4addfa0d-db8e-4604-9e7b-f2e14958a59e.html
Imports System.IOImports System.ThreadingImports System.TextPublic Class Form1 Private p As String = "" '文件路径 Private fLength As Integer Private fl As Integer = 102400 '定义缓冲区大小 Private fStart As Integer = 0 '定义读取起始位置 Private m As Integer = 1 Private fCount As Integer = 0 '分块数 Private cInte As Integer = 0 '当前块 Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click OpenFileDialog1.ShowDialog() TextBox1.Text = OpenFileDialog1.FileName End Sub Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click p = TextBox1.Text Dim a As New FileInfo(p) fLength = a.Length fStart = 0 Dim u As Thread fStart = -fl Dim c, d As Double c = Int(fLength / fl) d = fLength / fl If c < d Then fCount = c + 1 Else fCount = d End If For i As Integer = 1 To ThreadCount.Text u = New Thread(AddressOf Work) u.IsBackground = True u.Name = i u.Start() Next End Sub Sub Work() SyncLock Thread.CurrentThread Do While Not cInte >= fCount fStart += fl cInte += 1 ReadData(fStart, fl, cInte) Loop If cInte = fCount Then Dim temppath As String = "E:\1\" '========合并文件========= Dim pm As New System.Diagnostics.Process() pm.StartInfo.FileName = "cmd.exe" pm.StartInfo.UseShellExecute = False pm.StartInfo.CreateNoWindow = True pm.StartInfo.RedirectStandardInput = True pm.StartInfo.RedirectStandardOutput = True pm.Start() Dim temp As String = "" Dim fEx As New FileInfo(p) For i As Integer = 1 To fCount If temp = "" Then temp = "E:\1\" & fEx.Name.Replace(fEx.Extension, "." & i & fEx.Extension) Else temp = temp & " + " & "E:\1\" & fEx.Name.Replace(fEx.Extension, "." & i & fEx.Extension) End If Next 'MsgBox(temp) pm.StandardInput.WriteLine("copy /b " & temp & " " & temppath & "OK.txt") pm.StandardInput.WriteLine("exit") pm.WaitForExit() End If End SyncLock End Sub '读取指定位置的内容 Sub ReadData(ByVal Start As Integer, ByVal l As Integer, ByVal cuinte As Integer) Dim u As New FileStream(p, FileMode.Open, FileAccess.Read) Dim sBy(l - 1) As Byte u.Seek(Start, SeekOrigin.Begin) u.Read(sBy, 0, sBy.Length) u.Close() u.Dispose() writeData(cuinte, sBy) End Sub '写文件 Sub writeData(ByVal cuinte As Integer, ByVal data As Byte()) Try Dim fEx As New FileInfo(p) Dim TEMP As String = "c:\" & fEx.Name.Replace(fEx.Extension, "." & cuinte & fEx.Extension) Dim u As New FileStream(TEMP, FileMode.OpenOrCreate, FileAccess.Write) Dim Bw As New System.IO.BinaryWriter(u) Bw.Write(data) u.Close() u.Dispose() Bw.Close() Catch ex As Exception Err.Clear() Exit Sub End Try End Sub Private Sub Form1_FormClosing(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing End End Sub
[解决办法]
我已经测试过了，使用多线程分块读取同一个文件后，写成指定数量的块，再合并还原成文件。
代码是有效的。。。。
我的代码的读取线程默认为5个。。。