流(2)--流

BinaryReader,BinaryWriter

Writer的方法主要有--Seek主要用來選取插入的位置，Write方法重載了寫入bool,decimal,double,float,int,long,sbyte,short,string,unit,ulong,ushort,byte,byte[],char,char[]的方法。

 

可以看見其中的幾個方法--PeekChar,Read,Readxxx,對於byte和char有Readxxxs。Readxxx和Readxxxs行爲基本一致，讀一個類型，往後移，而且當讀到盡頭，再調用這個方法將拋出異常。Read有3個重載方法,第一個是Read，返回int，int是讀取的值，當讀到流的末尾時返回的是-1.第二個是Read到一個char[]中指定讀到char[]的什麼位置，要讀幾個字符，返回的是讀取字符的個數，當讀到流的末尾返回0，還有一個重載是byte[]類似於char[]。PeekChar是獲取下一個char，返回讀取的東東，但是流不往後走，也就是下次讀還是這個字符。

StringWriter,StringReader

StringWriter類提供一個類似於Stream的方法連接字符串。字符串連接是一個開銷很大的操作，因爲字符串本身是不變的（immutable）類型。用 StringWriter來連接字符串會提供更好的性能。StringWriter類只是另一個對象 -- StringBuilder 的封裝，StringBuilder纔是真正用來執行字符串連接的類。你可以將StringBuilder作爲一個參數構造器傳入 StringWriter (否則會在其內部生成一個實例)，並用GetStringBuilder方法返回StringBuilder。這是一個基類型，只接受和操作string，不參與修飾別的流。

http://topic.csdn.net/u/20090927/11/499c6042-df94-4345-93bc-afeaf7c49ee5.html

class Program { static void Main(string[] args) { StringWriter sw = new StringWriter(); sw.WriteLine("xuxu"); Console.WriteLine(sw); StringReader sr = new StringReader("xuxu"); Console.WriteLine( sr.ReadLine() ); } }

FileStream --以byte[]數組形式操作，所以是二進制的。支持Seek，支持異步

class Program { static void Main(string[] args) { FileInfo info = new FileInfo("D:/a.txt"); FileInfo info1 = new FileInfo("D:/b.bat"); FileStream fr = info.OpenRead(); FileStream fw = info1.OpenWrite(); byte[] read = new byte[5]; int count = 0; while ( (count=fr.Read( read,0,5))>0 ) fw.Write(read, 0, count); } }

BufferedStream-- 帶緩衝的流，是修飾類流。注意使用flush。

class Program { static void Main(string[] args) { FileInfo info = new FileInfo("D:/a.txt"); FileInfo info1 = new FileInfo("D:/b.bat"); FileStream fr = info.OpenRead(); FileStream fw = info1.OpenWrite(); BufferedStream bfr = new BufferedStream(fr); BufferedStream bfw = new BufferedStream(fw); byte[] read = new byte[1024]; int count = 0; while ( (count=fr.Read( read,0,1024))>0 ) fw.Write(read, 0, count); bfr.Flush(); bfw.Flush(); bfr.Close(); bfw.Close(); } }

StreamWriter,StreamReader --操作文本，提供了ReadLine,WriteLine方法就是證明。StreamReader構造器接受一個Stream對象或者一個文件路徑 （你可以使用Universal Naming Convention [UNC] 路徑，但不能用URL）。你還可以指定這些參數：比如編碼類型（encoding type）（如果沒有特別指定，系統會默認使用UTF8編碼）；作爲緩存的內置緩衝器大小（很可能通過BufferedStream對象來實現）；還有一 個布爾值，它用來指示是否應通過該Stream的第一個字節來判斷編碼類型。可以看到，StreamReader是個很有用的封裝（wrapper）類

class Program { static void Main(string[] args) { FileInfo info = new FileInfo("D:/a.txt"); FileInfo info1 = new FileInfo("D:/b.bat"); StreamReader sr = info.OpenText(); StreamWriter sw = new StreamWriter("D:/b.bat",false,Encoding.Unicode);//info.AppendText(); //info.CreateText(); string result = null; do { result = sr.ReadLine(); sw.WriteLine(result); } while (result != null); sr.Close(); sw.Close(); } }

TextReader,TextWriter --表示可讀取連續字符系列的讀取器。TextReader 爲 StreamReader 和 StringReader 的抽象基類，它們分別從流和字符串讀取字符。使用這些派生類可打開一個文本文件以讀取指定範圍的字符，或基於現有的流創建一個讀取器。

class TextRW { static void Main() { TextWriter stringWriter = new StringWriter(); using(TextWriter streamWriter = new StreamWriter("InvalidPathChars.txt")) { WriteText(stringWriter); WriteText(streamWriter); } TextReader stringReader = new StringReader(stringWriter.ToString()); using(TextReader streamReader = new StreamReader("InvalidPathChars.txt")) { ReadText(stringReader); ReadText(streamReader); } } static void WriteText(TextWriter textWriter) { textWriter.Write("Invalid file path characters are: "); textWriter.Write(Path.InvalidPathChars); textWriter.Write('.'); } static void ReadText(TextReader textReader) { Console.WriteLine("From {0} - {1}", textReader.GetType().Name, textReader.ReadToEnd()); } }

MemoryStream --創建其支持存儲區爲內存的流。 MemoryStream 類創建這樣的流，該流以內存而不是磁盤或網絡連接作爲支持存儲區。MemoryStream 封裝以無符號字節數組形式存儲的數據，該數組在創建 MemoryStream 對象時被初始化，或者該數組可創建爲空數組。可在內存中直接訪問這些封裝的數據。內存流可降低應用程序中對臨時緩衝區和臨時文件的需要。

class MemStream { static void Main() { int count; byte[] byteArray; char[] charArray; UnicodeEncoding uniEncoding = new UnicodeEncoding(); // Create the data to write to the stream. byte[] firstString = uniEncoding.GetBytes( "Invalid file path characters are: "); byte[] secondString = uniEncoding.GetBytes( Path.InvalidPathChars); using(MemoryStream memStream = new MemoryStream(100)) { // Write the first string to the stream. memStream.Write(firstString, 0 , firstString.Length); // Write the second string to the stream, byte by byte. count = 0; while(count < secondString.Length) { memStream.WriteByte(secondString[count++]); } // Write the stream properties to the console. Console.WriteLine( "Capacity = {0}, Length = {1}, Position = {2}/n", memStream.Capacity.ToString(), memStream.Length.ToString(), memStream.Position.ToString()); // Set the position to the beginning of the stream. memStream.Seek(0, SeekOrigin.Begin); // Read the first 20 bytes from the stream. byteArray = new byte[memStream.Length]; count = memStream.Read(byteArray, 0, 20); // Read the remaining bytes, byte by byte. while(count < memStream.Length) { byteArray[count++] = Convert.ToByte(memStream.ReadByte()); } // Decode the byte array into a char array // and write it to the console. charArray = new char[uniEncoding.GetCharCount( byteArray, 0, count)]; uniEncoding.GetDecoder().GetChars( byteArray, 0, count, charArray, 0); Console.WriteLine(charArray); } } }

異步IO --不解釋，看代碼

class Program { static void Main(string[] args) { new AsyncReader().Read(); for (int i = 0; i < 100000; i++) if (i % 10000 == 0) Console.WriteLine(i); } } public class AsyncReader { public static readonly string FILENAME = "D:/a.txt"; public static readonly int BUFFER_SIZE = 128; public byte[] buffer_array = new byte[BUFFER_SIZE]; public Stream stream; public void Read() { stream = new FileInfo(FILENAME).OpenRead(); stream.BeginRead(buffer_array, 0, BUFFER_SIZE, OnReadCompleted, null); } private void OnReadCompleted(IAsyncResult result) { int bytesRead = stream.EndRead(result); if (bytesRead > 0) { string s = Encoding.ASCII.GetString(buffer_array,0,bytesRead); Console.WriteLine(s); stream.BeginRead(buffer_array,0,BUFFER_SIZE,OnReadCompleted,null); } } }

網頁流--代碼

class Program { static void Main(string[] args) { //WebRequest is a factory,when param is a uri,return the HttpWebRequest sub class. //create a connection to the website.what you get back from the host is encapsulate in the HttpWebRequest object. HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://www.baidu.com"); HttpWebResponse response = (HttpWebResponse)request.GetResponse(); StreamReader reader = new StreamReader( response.GetResponseStream(),Encoding.ASCII ); string content = reader.ReadToEnd(); Console.WriteLine(content); } }