关于Stream的知识分享

 1 public class MyStreamExample : Stream 
 2     {
 3 
 4         public override bool CanRead
 5         {
 6             get { throw new NotImplementedException(); }
 7         }
 8 
 9         public override bool CanSeek
10         {
11             get { throw new NotImplementedException(); }
12         }
13 
14         public override bool CanWrite
15         {
16             get { throw new NotImplementedException(); }
17         }
18 
19         public override void Flush()
20         {
21             throw new NotImplementedException();
22         }
23 
24         public override long Length
25         {
26             get { throw new NotImplementedException(); }
27         }
28 
29         public override long Position
30         {
31             get
32             {
33                 throw new NotImplementedException();
34             }
35             set
36             {
37                 throw new NotImplementedException();
38             }
39         }
40 
41         public override int Read(byte[] buffer, int offset, int count)
42         {
43             throw new NotImplementedException();
44         }
45 
46         public override long Seek(long offset, SeekOrigin origin)
47         {
48             throw new NotImplementedException();
49         }
50 
51         public override void SetLength(long value)
52         {
53             throw new NotImplementedException();
54         }
55 
56         public override void Write(byte[] buffer, int offset, int count)
57         {
58             throw new NotImplementedException();
59         }
60     }

 1 static void Main(string[] args)
 2         {
 3             byte[] buffer = null;
 4 
 5             string testString = "Stream!Hello world";
 6             char[] readCharArray = null;
 7             byte[] readBuffer = null;
 8             string readString = string.Empty;
 9             //关于MemoryStream 我会在后续章节详细阐述
10             using (MemoryStream stream = new MemoryStream()) 
11             {
12                 Console.WriteLine("初始字符串为：{0}", testString);
13                 //如果该流可写
14                 if (stream.CanWrite)
15                 {
16                     //首先我们尝试将testString写入流中
17                     //关于Encoding我会在另一篇文章中详细说明，暂且通过它实现string->byte[]的转换
18                     buffer = Encoding.Default.GetBytes(testString);
19                     //我们从该数组的第一个位置开始写，长度为3，写完之后 stream中便有了数据
20                     //对于新手来说很难理解的就是数据是什么时候写入到流中，在冗长的项目代码面前，我碰见过很
21                     //多新手都会有这种经历，我希望能够用如此简单的代码让新手或者老手们在温故下基础
22                     stream.Write(buffer, 0,3);
23 
24                     Console.WriteLine("现在Stream.Postion在第{0}位置",stream.Position+1);
25 
26                     //从刚才结束的位置（当前位置）往后移3位，到第7位
27                     long newPositionInStream =stream.CanSeek? stream.Seek(3, SeekOrigin.Current):0;
28 
29                     Console.WriteLine("重新定位后Stream.Postion在第{0}位置", newPositionInStream+1);
30                     if (newPositionInStream < buffer.Length)
31                     {
32                         //将从新位置（第7位）一直写到buffer的末尾，注意下stream已经写入了3个数据“Str”
33                         stream.Write(buffer, (int)newPositionInStream, buffer.Length - (int)newPositionInStream);
34                     }
35 
36                     
37                     //写完后将stream的Position属性设置成0，开始读流中的数据
38                     stream.Position = 0;
39 
40                     // 设置一个空的盒子来接收流中的数据，长度根据stream的长度来决定
41                     readBuffer = new byte[stream.Length];
42 
43 
44                     //设置stream总的读取数量 ，
45                     //注意！这时候流已经把数据读到了readBuffer中
46                     int count = stream.CanRead?stream.Read(readBuffer, 0, readBuffer.Length):0;
47          
48 
49                     //由于刚开始时我们使用加密Encoding的方式,所以我们必须解密将readBuffer转化成Char数组，这样才能重新拼接成string
50 
51                     //首先通过流读出的readBuffer的数据求出从相应Char的数量
52                     int charCount = Encoding.Default.GetCharCount(readBuffer, 0, count);
53                     //通过该Char的数量 设定一个新的readCharArray数组
54                     readCharArray = new char[charCount];
55                     //Encoding 类的强悍之处就是不仅包含加密的方法，甚至将解密者都能创建出来（GetDecoder()），
56                     //解密者便会将readCharArray填充（通过GetChars方法，把readBuffer 逐个转化将byte转化成char，并且按一致顺序填充到readCharArray中）
57                     Encoding.Default.GetDecoder().GetChars(readBuffer, 0, count, readCharArray, 0);
58                     for (int i = 0; i < readCharArray.Length; i++)
59                     {
60                         readString += readCharArray[i];
61                     }
62                     Console.WriteLine("读取的字符串为：{0}", readString);
63                 }
64 
65                 stream.Close();
66             }
67 
68             Console.ReadLine();
69 
70         }