Csharp/CSharp Tutorial/File Directory Stream/Stream
Содержание
- 1 C#"s I/O Is Built Upon Streams
- 2 Implementing Binary Read Write To File
- 3 Reading from a stream buffer at a time
- 4 Reading from a stream, casting to chars
- 5 Stream seeking: SeekOrigin.Current, SeekOrigin.Begin, SeekOrigin.End
- 6 The Byte Stream Classes and The Character Stream Wrapper Classes
- 7 The Stream Classes
- 8 Using streamreader to decode streams
- 9 Using streamreader to read entire lines at a time
- 10 Using streamreader to read the entire stream at once
C#"s I/O Is Built Upon Streams
- C# programs perform I/O through streams.
- A stream is linked to a physical device by the C# I/O system.
- The I/O classes and methods can be applied to many types of devices.
At the lowest level, all C# I/O systems operate on bytes.
The Predefined Streams
- Console.Out: the standard output stream.
- Console.In: standard input, which is by default the keyboard.
- Console.Error: the standard error stream, which is also the console by default.
15.18.Stream 15.18.1. C#"s I/O Is Built Upon Streams 15.18.2. <A href="/Tutorial/CSharp/0300__File-Directory-Stream/TheStreamClasses.htm">The Stream Classes</a> 15.18.3. <A href="/Tutorial/CSharp/0300__File-Directory-Stream/TheByteStreamClassesandTheCharacterStreamWrapperClasses.htm">The Byte Stream Classes and The Character Stream Wrapper Classes</a> 15.18.4. <A href="/Tutorial/CSharp/0300__File-Directory-Stream/StreamseekingSeekOriginCurrentSeekOriginBeginSeekOriginEnd.htm">Stream seeking: SeekOrigin.Current, SeekOrigin.Begin, SeekOrigin.End</a> 15.18.5. <A href="/Tutorial/CSharp/0300__File-Directory-Stream/Usingstreamreadertodecodestreams.htm">Using streamreader to decode streams</a> 15.18.6. <A href="/Tutorial/CSharp/0300__File-Directory-Stream/Usingstreamreadertoreadentirelinesatatime.htm">Using streamreader to read entire lines at a time</a> 15.18.7. <A href="/Tutorial/CSharp/0300__File-Directory-Stream/Usingstreamreadertoreadtheentirestreamatonce.htm">Using streamreader to read the entire stream at once</a> 15.18.8. <A href="/Tutorial/CSharp/0300__File-Directory-Stream/Readingfromastreamcastingtochars.htm">Reading from a stream, casting to chars</a> 15.18.9. <A href="/Tutorial/CSharp/0300__File-Directory-Stream/Readingfromastreambufferatatime.htm">Reading from a stream buffer at a time</a> 15.18.10. <A href="/Tutorial/CSharp/0300__File-Directory-Stream/ImplementingBinaryReadWriteToFile.htm">Implementing Binary Read Write To File</a>
Implementing Binary Read Write To File
<source lang="csharp">using System; using System.IO;
class Tester
{
public static void Main()
{
int SizeBuff = 1024;
Stream inputStream = File.OpenRead("test1.cs");
Stream outputStream = File.OpenWrite("test1.bak");
byte[] buffer = new Byte[SizeBuff];
int bytesRead;
while ((bytesRead =
inputStream.Read(buffer, 0, SizeBuff)) > 0)
{
outputStream.Write(buffer, 0, bytesRead);
}
inputStream.Close();
outputStream.Close();
}
}</source>
Reading from a stream buffer at a time
<source lang="csharp">using System; using System.Collections.Generic; using System.Collections.Specialized; using System.IO; using System.IO.rupression; using System.Net; using System.Net.Mail; using System.Runtime.InteropServices; using System.Text; using System.Threading; public class MainClass {
public static void Main()
{
using (Stream s = new FileStream("c:\\test.txt", FileMode.Open))
{
int readCount;
byte[] buffer = new byte[4096];
while ((readCount = s.Read(buffer, 0, buffer.Length)) != 0)
{
for (int i = 0; i < readCount; i++)
{
Console.Write("{0} ", buffer[i]);
}
}
}
}
}</source>
Reading from a stream, casting to chars
<source lang="csharp">using System; using System.Collections.Generic; using System.Collections.Specialized; using System.IO; using System.IO.rupression; using System.Net; using System.Net.Mail; using System.Runtime.InteropServices; using System.Text; using System.Threading; public class MainClass {
public static void Main()
{
using (Stream s = new FileStream("c:\\test.txt", FileMode.Open))
{
int read;
while ((read = s.ReadByte()) != -1)
{
Console.Write("{0} ", (char)read);
}
}
}
}</source>
Stream seeking: SeekOrigin.Current, SeekOrigin.Begin, SeekOrigin.End
<source lang="csharp">using System; using System.Collections.Generic; using System.Collections.Specialized; using System.IO; using System.IO.rupression; using System.Net; using System.Net.Mail; using System.Net.Sockets; using System.Runtime.InteropServices; using System.Text; using System.Threading; public class MainClass {
public static void Main()
{
using (Stream s = new FileStream("c:\\test.txt", FileMode.Open))
{
s.Seek(8, SeekOrigin.Current);
Console.WriteLine(s.ReadByte());
s.Seek(0, SeekOrigin.Begin);
Console.WriteLine(s.ReadByte());
s.Seek(-1, SeekOrigin.End);
Console.WriteLine(s.ReadByte());
}
}
}</source>
The Byte Stream Classes and The Character Stream Wrapper Classes
The Byte Stream Classes
Stream Class Description BufferedStream Wraps a byte stream and adds buffering. FileStream A byte stream designed for file I/O. MemoryStream A byte stream that uses memory for storage.
The Character Stream Wrapper Classes.
To create a character stream, wrap a byte stream inside one of C#"s character stream wrappers.
- The abstract classes TextReader and TextWriter are at the top of the character stream hierarchy.
- TextReader handles input.
- TextWriter handles output.
The Stream Classes
- System.IO.Stream represents a byte stream
- System.IO.Stream is a base class for all other stream classes.
- System.IO.Stream is abstract.
Some of the Methods Defined by Stream
Method Description void Close() Closes the stream. void Flush() Flush the stream. int ReadByte() Returns an integer representation of a byte of input. Returns -1 if no byte is available. int Read(byte[ ] buf,int offset, int numBytes) Attempts to read up to numBytes bytes into buf starting at buf[offset], returning the number of bytes successfully read. long Seek(long offset,SeekOrigin origin) Sets the current position in the stream to the specified offset from the specified origin. void WriteByte(byte b) Writes a single byte to an output stream. void Write(byte[ ] buf,int offset, int numBytes) Writes a subrange of numBytes bytes from the array buf, beginning at buf[offset].
The Properties Defined by Stream
Method Description bool CanRead can be read or not. (read-only) bool CanSeek supports position requests or not. (read-only) bool CanWrite can be written or not. (read-only) long Length the length of the stream. (read-only) long Position the current position of the stream. (read/write)
Using streamreader to decode streams
<source lang="csharp">using System; using System.Collections.Generic; using System.Collections.Specialized; using System.IO; using System.IO.rupression; using System.Net; using System.Net.Mail; using System.Net.Sockets; using System.Runtime.InteropServices; using System.Text; using System.Threading; public class MainClass {
public static void Main()
{
Stream s = new FileStream("c:\\test.txt", FileMode.Open);
using (StreamReader sr = new StreamReader(s, Encoding.UTF8))
{
int readCount;
char[] buffer = new char[1024];
while ((readCount = sr.Read(buffer, 0, 1024)) != 0)
{
for (int i = 0; i < readCount; i++)
{
Console.Write("{0} ", buffer[i]);
}
}
}
}
}</source>
Using streamreader to read entire lines at a time
<source lang="csharp">using System; using System.Collections.Generic; using System.Collections.Specialized; using System.IO; using System.IO.rupression; using System.Net; using System.Net.Mail; using System.Net.Sockets; using System.Runtime.InteropServices; using System.Text; using System.Threading; public class MainClass {
public static void Main()
{
Stream s = new FileStream("c:\\test.txt", FileMode.Open);
using (StreamReader sr = new StreamReader(s, Encoding.UTF8))
{
string line;
while ((line = sr.ReadLine()) != null)
{
Console.WriteLine(line);
}
}
}
}</source>
Using streamreader to read the entire stream at once
<source lang="csharp">using System; using System.Collections.Generic; using System.Collections.Specialized; using System.IO; using System.IO.rupression; using System.Net; using System.Net.Mail; using System.Net.Sockets; using System.Runtime.InteropServices; using System.Text; using System.Threading; public class MainClass {
public static void Main()
{
Stream s = new FileStream("c:\\test.txt", FileMode.Open);
using (StreamReader sr = new StreamReader(s, Encoding.UTF8))
{
Console.WriteLine(sr.ReadToEnd());
}
}
}</source>
