我正在尝试向流中添加一些数据。这对于FileStream
来说效果很好,但对于MemoryStream
来说却不行,因为它具有固定的缓冲区大小。
写入数据到流的方法与创建流的方法分离(在下面的示例中已大大简化)。创建流的方法不知道要写入流的数据长度。
public void Foo(){
byte[] existingData = System.Text.Encoding.UTF8.GetBytes("foo");
Stream s1 = new FileStream("someFile.txt", FileMode.Append, FileAccess.Write, FileShare.Read);
s1.Write(existingData, 0, existingData.Length);
Stream s2 = new MemoryStream(existingData, 0, existingData.Length, true);
s2.Seek(0, SeekOrigin.End); //move to end of the stream for appending
WriteUnknownDataToStream(s1);
WriteUnknownDataToStream(s2); // NotSupportedException is thrown as the MemoryStream is not expandable
}
public static void WriteUnknownDataToStream(Stream s)
{
// this is some example data for this SO query - the real data is generated elsewhere and is of a variable, and often large, size.
byte[] newBytesToWrite = System.Text.Encoding.UTF8.GetBytes("bar"); // the length of this is not known before the stream is created.
s.Write(newBytesToWrite, 0, newBytesToWrite.Length);
}
我的一个想法是将可扩展的MemoryStream
发送到函数中,然后将返回的数据附加到现有数据中。
public void ModifiedFoo()
{
byte[] existingData = System.Text.Encoding.UTF8.GetBytes("foo");
Stream s2 = new MemoryStream(); // expandable capacity memory stream
WriteUnknownDataToStream(s2);
// append the data which has been written into s2 to the existingData
byte[] buffer = new byte[existingData.Length + s2.Length];
Buffer.BlockCopy(existingData, 0, buffer, 0, existingData.Length);
Stream merger = new MemoryStream(buffer, true);
merger.Seek(existingData.Length, SeekOrigin.Begin);
s2.CopyTo(merger);
}
有更好(更高效)的解决方案吗?
MemoryStream
,将existingData
附加到该流中,然后继续向其中附加数据即可。 - Peter Ritchie