在C＃中读取（/写入）文件

Question

I recently wanted to track progress of a HTTPWebRequest Upload progress. So I started small and started with buffered read of a simple text file. I then discovered that a simple task like

File.ReadAllText("text.txt");

becomes something like below, with all the streams, readers, writers etc. Or can somethings be removed? Also the code below is not working. Maybe I did something wrong, whats the way to read (i guess write will be similar) into buffer so that I can track progress, assuming the stream are not local eg. WebRequest

byte[] buffer = new byte[2560]; // 20KB Buffer, btw, how should I decide the buffer size?
int bytesRead = 0, read = 0;
FileStream inStream = new FileStream("./text.txt", FileMode.Open, FileAccess.Read);
MemoryStream outStream = new MemoryStream();
BinaryWriter outWriter = new BinaryWriter(outStream);

// I am getting "Offset and length were out of bounds for the array or count is greater than the number of elements from index to the end of the source collection."
// inStream.Length = Length = 9335092
// bytesRead = 2560
// buffer.Length = 2560
while ((read = inStream.Read(buffer, bytesRead, buffer.Length)) > 0)
{
    outWriter.Write(buffer);
    //outStream.Write(buffer, bytesRead, buffer.Length);
    bytesRead += read;
    Debug.WriteLine("Progress: " + bytesRead / inStream.Length * 100 + "%");
}
outWriter.Flush();

txtLog.Text = outStream.ToString(); 

Update: Solution

byte[] buffer = new byte[2560];
int bytesRead = 0, read = 0;
FileStream inStream = File.OpenRead("text.txt");
MemoryStream outStream = new MemoryStream();

while ((read = inStream.Read(buffer, 0, buffer.Length)) > 0)
{
    outStream.Write(buffer, 0, buffer.Length);
    bytesRead += read;
    Debug.WriteLine((double)bytesRead / inStream.Length * 100);
}

inStream.Close();
outStream.Close();

Answer 1

应该是

outWriter.Write(buffer,0,read);

Answer 2

Since you seem to be reading text (although I could be wrong), it seems that your program could be a lot simpler if you read character by character instead of calling the standard Read():

BinaryReader reader = new BinaryReader(File.Open("./text.txt", FileMode.Open));
MemoryStream outStream = new MemoryStream();
StreamWriter outWriter = new StreamWriter(outStream);

while (Reader.BaseStream.Position < Reader.BaseStream.Length)
{
    outWriter.Write(reader.ReadChar());
    Debug.WriteLine("Progress: " + ((double)reader.BaseStream.Position) / (double)(reader.BaseStream.Length) + "%");
}
outWriter.Close();
txtLog.Text = outStream.ToString();

Answer 3

Since you only need to check the progress of the upload operation you can just check the size of the file using a fileinfo object.

In the FileInfo class theres a property called length that returns the file size in bytes. Not sure if it gives the current size when the file being written. But I think it'll be worth giving a try as it is more simple and efficient than the method that you are using