An elegant way to consume (all bytes of a) BinaryReader?

问题

Is there an elegant to emulate the StreamReader.ReadToEnd method with BinaryReader? Perhaps to put all the bytes into a byte array?

I do this:

read1.ReadBytes((int)read1.BaseStream.Length);

...but there must be a better way.

回答1:

Simply do:

byte[] allData = read1.ReadBytes(int.MaxValue);

The documentation says that it will read all bytes until the end of the stream is reached.

Update

Although this seems elegant, and the documentation seems to indicate that this would work, the actual implementation (checked in .NET 2, 3.5, and 4) allocates a full-size byte array for the data, which will probably cause an OutOfMemoryException on a 32-bit system.

Therefore, I would say that actually there isn't an elegant way.

Instead, I would recommend the following variation of @iano's answer. This variant doesn't rely on .NET 4:
Create an extension method for BinaryReader (or Stream, the code is the same for either).

public static byte[] ReadAllBytes(this BinaryReader reader)
{
    const int bufferSize = 4096;
    using (var ms = new MemoryStream())
    {
        byte[] buffer = new byte[bufferSize];
        int count;
        while ((count = reader.Read(buffer, 0, buffer.Length)) != 0)
            ms.Write(buffer, 0, count);
        return ms.ToArray();
    }

}

回答2:

There is not an easy way to do this with BinaryReader. If you don't know the count you need to read ahead of time, a better bet is to use MemoryStream:

public byte[] ReadAllBytes(Stream stream)
{
    using (var ms = new MemoryStream())
    {
        stream.CopyTo(ms);
        return ms.ToArray();
    }
}

To avoid the additional copy when calling ToArray(), you could instead return the Position and buffer, via GetBuffer().

回答3:

To copy the content of a stream to another, I've solved reading "some" bytes until the end of the file is reached:

private const int READ_BUFFER_SIZE = 1024;
using (BinaryReader reader = new BinaryReader(responseStream))
{
    using (BinaryWriter writer = new BinaryWriter(File.Open(localPath, FileMode.Create)))
    {
        int byteRead = 0;
        do
        {
            byte[] buffer = reader.ReadBytes(READ_BUFFER_SIZE);
            byteRead = buffer.Length;
            writer.Write(buffer);
            byteTransfered += byteRead;
        } while (byteRead == READ_BUFFER_SIZE);                        
    }                
}

回答4:

Another approach to this problem is to use C# extension methods:

public static class StreamHelpers
{
   public static byte[] ReadAllBytes(this BinaryReader reader)
   {
      // Pre .Net version 4.0
      const int bufferSize = 4096;
      using (var ms = new MemoryStream())
      {
        byte[] buffer = new byte[bufferSize];
        int count;
        while ((count = reader.Read(buffer, 0, buffer.Length)) != 0)
            ms.Write(buffer, 0, count);
        return ms.ToArray();
      }

      // .Net 4.0 or Newer
      using (var ms = new MemoryStream())
      {
         stream.CopyTo(ms);
         return ms.ToArray();
      }
   }
}

Using this approach will allow for both reusable as well as readable code.

来源：https://stackoverflow.com/questions/8613187/an-elegant-way-to-consume-all-bytes-of-a-binaryreader

标签

.net

stream

streamreader

binaryreader