咨询区

• Homam：

我先说一下我的顾虑，是这样的，我有一个 windows service 服务在不断的写入日志，同时我还有个看板程序在不断的获取 windows service 程序写入的日志。

问题是：service 程序在写日志的时候会 lock 文件，看板程序在读取的时候也会 lock 文件，这就很尴尬了，经常遇到进程被占用的异常。

服务程序代码：

void WriteInLog(string logFilePath, data)
{File.AppendAllText(logFilePath, string.Format("{0} : {1}\r\n", DateTime.Now, data));
}

看板程序代码：

int index = 0;private void Form1_Load(object sender, EventArgs e){try{using (StreamReader sr = new StreamReader(logFilePath)){while (sr.Peek() >= 0)  // reading the old data{AddLineToGrid(sr.ReadLine());index++;}sr.Close();}timer1.Start();}catch (Exception ex){MessageBox.Show(ex.Message);}}private void timer1_Tick(object sender, EventArgs e){using (StreamReader sr = new StreamReader(logFilePath)){// skipping the old data, it has read in the Form1_Load event handlerfor (int i = 0; i < index ; i++) sr.ReadLine();while (sr.Peek() >= 0) // reading the live data if exists{string str = sr.ReadLine();if (str != null){AddLineToGrid(str);index++;}}sr.Close();}}

请问大家我该如何解决此问题？

回答区

• Manfred：

你的问题在于写入和读取都是以排他的方式进行，其实 FileStream 中是可以支持共享的方式进行读写的。

比如将 service 代码改造如下：

var outStream = new FileStream(logfileName, FileMode.Open, FileAccess.Write, FileShare.ReadWrite);

看板程序改造如下：

var inStream = new FileStream(logfileName, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);

用完的时候记得 Close 一下，对了， FileStream 实现了 IDisposable 接口，可以用 using 包一下，参考如下代码：

using(var outStream = ...)
{// using outStream here...
}

点评区

????，我特意看了下 FileStream 的 FileShare.ReadWrite 参数解释。

    [ComVisible(true)][Flags]public enum FileShare{None = 0,Read = 1,Write = 2,//// Summary://     Allows subsequent opening of the file for reading or writing. If this flag is//     not specified, any request to open the file for reading or writing (by this process//     or another process) will fail until the file is closed. However, even if this//     flag is specified, additional permissions might still be needed to access the//     file.ReadWrite = 3,Delete = 4,Inheritable = 16}

我去，原来还可以这样玩，对 FileStream 用的还不透彻，学习了。