[C#]Stream.Write Extension Method

在处理Stream型态时常会使用到Stream.Write这个方法，每次都会有种疑问就是，大多数的处理都是要将Buffer整个写入，為何偏偏每次都要将索引带0，长度带為Buffer的大小呢?另外在处理Stream时，若要显示其处理进度，是否能有更為简单的方法?这边将我為了解决这些问题所写的扩充方法整裡如下：

using System;

02	using System.Reflection;

03	using System.ComponentModel;

04	using System.Linq;

05	using System.IO;

06

07	public static class StreamExtension

08

{

09	public static void Write(this Stream targetStream, byte[] buffer)

10

{

11	if (!targetStream.CanWrite)

12	throw new ArgumentException("targetStream", "Unwritable stream");

13

14	targetStream.Write(buffer, 0, buffer.Length);

15

}

16

17	public static void Write(this Stream targetStream, Stream sourceStream)

18

{

19	if (!targetStream.CanWrite)

20	throw new ArgumentException("targetStream", "Unwritable stream");

21

22	if (sourceStream == null)

23	throw new ArgumentNullException("sourceStream");

24

25	if (!sourceStream.CanRead)

26	throw new ArgumentException("sourceStream", "Unreadable stream");

27

28	targetStream.Write(sourceStream, 1024, null);

29

}

30

31	public static void Write(this Stream targetStream, Stream sourceStream, int bufferSize, Action<object, System.ComponentModel.ProgressChangedEventArgs> progressChangedCallBack)

32

{

33	if (sourceStream == null)

34	throw new ArgumentNullException("sourceStream");

35

36	if (!sourceStream.CanRead)

37	throw new ArgumentException("sourceStream", "Unreadable stream");

38

39	if (!targetStream.CanWrite)

40	throw new ArgumentException("targetStream", "Unwritable stream");

41

42	if (bufferSize < 1024)

43	throw new ArgumentOutOfRangeException("bufferSize", "Must bigger than 1024");

44

45	byte[] buffer = new byte[bufferSize];

46

47	int offset = 0;

48	int readByteCount = 0;

49	int percent = 0;

50

51	while ((readByteCount = sourceStream.Read(buffer, 0, bufferSize)) > 0)

52

{

53	targetStream.Write(buffer, 0, readByteCount);

54

55	if (progressChangedCallBack != null)

56

{

57	offset += readByteCount;

58

59	var currentPercent = (int)(((double)offset) / sourceStream.Length * 100);

60	if (currentPercent == percent)

61

continue;

62

63	percent = currentPercent;

64	progressChangedCallBack(targetStream, new System.ComponentModel.ProgressChangedEventArgs(percent, null));

65

}

66

}

67

}

68

}

使用上Write方法會多三個多載版本，一個是將buffer整個寫入、一個是將stream的內容整個讀出並寫入、一個則是用來寫入整個stream內容，並可帶入處理的Buffer大小，與處理進度回報的Callback，用以處理進度的顯示。

view source

 

print?

1	targetStream.Write(buffer);

2	targetStream.Write(sourceStream);

3	targetStream.Write(sourceStream, 1024, (sender, e) => { Console.WriteLine(e.ProgressPercentage.ToString ()); });

這邊針對進度處理的擴充方法示範個較為詳細的範例，這邊我會讀取C槽下的test.data檔案，檔案大小為5MB多，開啟後將其寫入c槽下的test_copy.data。處理的buffer大小為1024，每當在處理時偵測到進度改變時會顯示出當前處理的進度比例。

view source

 

print?

01	using System;

02	using System.Collections.Generic;

03	using System.Linq;

04	using System.Text;

05	using System.IO;

06

07	namespace ConsoleApplication11

08

{

09	class Program

10

{

11	static void Main(string[] args)

12

{

13	using (FileStream targetStream = File .Create (@"c:\test_copy.dat"))

14

{

15	using (FileStream sourceStream= File.Open (@"c:\test.dat", FileMode.Open))

16

{

17	targetStream.Write(sourceStream, 1024, (sender, e) => { Console.WriteLine(e.ProgressPercentage.ToString()); });

18

}

19

}

20

}

21

}

22

}

運行結果如下：