Input/Output with .NET Framework Class Library pps

a Navigating the File System FileSystemI|nfo class Phương thức Name |Description Delete \Removes the file or directory from the file system Refresh \Updates the data in the class with

Input/Output with

m NET Framework Class Library

Pham Minh Tuan

BỘ môn CNPM — Khoa CNTT

a a dung trinh bay

=» Navigating the File System

=» Reading and Writing Files

=» Compressing Streams

DriveFormat Drive Type isReady

Name RootDirectory

TotalPreeSpace Totaisize

VobhbumeLabel

be different from the amount returned by TotalFreeSpace (described later in this table), depending on disk quotas

Gets the format of the drive, such as NIFS or FAT32

Gets the type of drive in the form of the DriveType enumeration (which is described in the following section)

Gets the status of the drive, indicating whether it is ready to be accessed

Gets the name of the drive

Gets a Directoryinfo object that represents the root directory of the

drive |

Gets the total amount of free space on the drive

Gets the total size of the drive

Gets or sets the label of the drive It might be set only on drives that are not readonly

Navigating the File System

Drivel nfo class

DriveType enum

Name Description

CDRom An optical drive It can be CD-ROM, DVD, and so on

Fixed A fixed disk

Network A network mapped drive

NoRootDirectory |A drive that does not have a root directory

Ram ARAM drive

Removable A drive that has removable media

Unknown The drive could not be determined

Phương thức Name Description CetDrives |A static method (or a shared one in Visual Basic) that returns

allthe drives on the current system

Attributes Gets or sets FileAttributes of the current file or directory

CreationTime |Gets or sets the time that the current file or directory was created

Exists Determines whether the file or directory exists

Extension Gets a string representation of the extension part of the file or directory

PullName Gets the full path to the file or directory

LastAccessTime |Gets or sets the time the file or directory was accessed

LastWriteTime |Gets or sets the time the file or directory was last written to

Name Gets the simple name for the file or directory For a file, this is the name

within the directory For a directory, this is the last directory name in the directory hierarchy

a Navigating the File System

FileSystemI|nfo class Phương thức

Name (|Description Delete \Removes the file or directory from the file system Refresh \Updates the data in the class with the most current information from the file

system

a Navigating the File System

Directoryl nfo class Thuộc tính

Name Description Parent \Gets the Directoryinfo object for the parent directory of the

current directory in the directory hierarchy

Root |Gets the root part of the directory's path as a string

Lirectorylnfo object CreateSubdirectory |Creates a new directory as a child directory of the

current directory in the directory hierarchy GetDirectories Retrieves an array of Directoryinfo objects that

represent subdirectories of the current directory Get Files Retrieves an array of File/nyfo objects that represent

all the files in the current directory GethileSysteminjfos |Retrieves an array of FileSystemlnfo objects that

represent both files and subdirectories in the current directory

Moves the current directory to a new location

Navigating the File System

Filelnfo class

Thuộc tính Name Description Lirectory Gets the Directory/nfo object that represents the directory

that this file 1s stored within

LirectoryName \Gets the name ofthe directory that this file is stored

CapyTo Create CreateText Decrypt

Open Write Replace

Makes a copy of the file in a new location

Creates a file based on the current file information

Creates a new Stream Writer and a new file for writing text

Decrypts a file that was encrypted by the current user

Encrypts a file so that only the current user can decrypt the information within the file

Moves the file to a new location

Opens the file with specific privileges (read, read/write, and so on)

Opens the file with read-only access

Opens the file and returns a Stream Reader to allow reading of text within the file

Opens the file with write-only access

Replaces a file with the information in the current Pile/nfo object

changes, not the actual file name extension.) Combines two compatible path strings

Returns the name of the directory in the specified path

Returns the name of the file extension in the specified path

Returns the name of the file in the specified path

Returns the file name without the extension in the

specified path

Returns a full path to the specified path This method can

be used to resolve relative paths

GetTempPileName

GetTempPath

HasHxtension

isPathRooted

Returns the root directory name in the specified path

Generates arandom file name

Generates a temporary file in the file system and returns the full path to the file

Returns the path to the temporary file directory for the

current user or system

Indicates whether a specified path's file name has an extension

Indicates whether the specified path includes a root directory

a Navigating the File System

|

FileSystemWatcher class Thuộc tính

Normally, it's used to turn on and off the watching ofa directory and/or files

Gets or sets the file filter to use to determine which file changes to monitor A blank filter indicates "all files."

Gets or sets an indicator of whether the watching ofa directory 1s

to include subdirectories or only the directory specified in the Path

property

Gets or sets the type of changes to watch for By default, all

changes (creation, deletion, renamed files, and modifications) are notified

Gets or sets the path to the directory to monitor

Navigating the File System

FileSystemWatcher class Phương thức

WaithorChanged |Synchronous method for watching a directory for changes and for

returning a structure that contains all the changes

Su kiện

Name (|Description Changed |Occurs when a file or directory has changed in the watched directory Created |Occurs when a file or directory has been created in the watched directory Deleted \Occurs when a file or directory has been deleted in the watched directory Renamed |Occurs when a file or directory has been renamed in the watched directory

a the File System

» Lam sao biết được trên hệ thống có những ổ đĩa

nào?

Drivelnfo[] drives = Drivelnfo.GetDrives();

foreach (Drivelnfo drive in drives)

Console.WriteLine("Drive: {0}", drive.Name);

Console.WriteLine("Type: {0}",

drive.DriveType) ;

a the File System

„ Làm sao lẫy được danh sách tập tin và thư mục con của một thư mục nào đó?

Directorylnfo ourDir = new

a the File System

m Làm sao truy xuất được các thuộc tính của mội tập tin, thư mục?

Filelnfo ourFile = new Filelnfo(@"c:\boot.ini ");

a the File System

= Lam sao giam sat được sự thay đổi của một tập tin, thư mục?

FilesystemWatcher watcher = new FileSystemWatcher();

a the File System

Cung cấp tất cả các phương thức cần thiết

cho việc tạo file, xóa file, di chuyển file, sao chep file

Cung cấp tất cả các phương thức cần thiết

cho việc tạo thư mục, xóa thư mục, dị chuyển thư mục, lấy danh sách tập tin, thư mục con

ac: and Writing Files

=» Stream class

=» FileStream class

» StreamReader class, StreamWriter class

» BinaryReader class, BinaryWriter class

» Memorystream class

» BufferedStream class

CanSeek Determines whether the stream supports seeking

CanTimeout Determines whether the stream can time out

CanWrite Determines whether the stream can be written to

Length Gets the length (in bytes) of the stream

Position Gets or sets the virtual cursor for determining where in the stream the

current position is The value of Position cannot be greater than the value

of the stream's Length

ReadTimeout |Gets or sets the stream's timeout for read operations

Write Timeout |Gets or sets the stream's timeout for write operations

Plush Clears any buffers within the stream and forces changes to be written to the

underlying system or device

Read Performs a sequential read of a specified number of bytes from the current

position and updates the position to the end of the read upon completion of the operation

Read Byte Performs the read of a single byte and updates the position by moving it by

one Identical to calling Read to read a single byte

Sets the position within the stream

setLength |Specifies the length of the stream Will truncate the stream if the new length is

less than the old length and will expand the stream if the reverse 1s true

Write Writes information to the stream as a number of bytes and updates the current

position to reflect the new write position

WriteByte |Writes a single byte to the stream and updates the position Identical to calling

Write with a single byte

§) Reading and Writing Files

FileStream class: ké thUfa Stream class

Thuộc tính Name Description Handle Gets the stream's underlying file handle

Name Gets the name of the file

Phương thức Name Description Lock Prevents other processes from changing all or part of the

file

Unlock Allows other processes to change all or part of the

underlying file.

§) Reading and Writing Files

Stream Reader class

Kể thửa TextReader class

Dùng để đọc các file văn bản

Thuộc tính Name Description BasesStream Gets the underlying stream that the reader 1s reading Current#xucoding |Gets the current encoding used for the underlying

stream

EndOfstream Determines whether the reader has encountered the end

of the stream

§) Reading and Writing Files

Stream Reader class

Phương thức

Name Description Close Closes the reader and the underlying stream

Peek Returns the next character in the stream without moving the

stream's current position Read Reads the next set of characters in the stream ReadBlock \Reads the next block of characters in the stream Readiine \Reads the next line of characters in the stream Read loHnd \Reads all the characters through to the end of the stream

ac: and Writing Files

= Doc file van ban

FileStream theFile = File.-Open(@"C:\boot.ini",

FileMode.Open, FileAccess Read);

Stream Reader rdr = new StreamReader(theFile) ; while (!rdr.EndOfStream)

string line = rdr.ReadLine();

Console.WriteLine(line) ;

} rdr.Close();

theFile.Close();

§) Reading and Writing Files

StreamWriter class

Kể thửa TextWriter class

Dùng để ghi các file văn bản

Thuộc tính

AutoPlush \Gets or sets an indicator that shows whether every call to the Write method

should flush changes to the underlying stream

SaseStream |Gets the underlying stream that the reader 1s reading

Encoding |Gets the current encoding used for the underlying stream

Newline — |Gets or sets a string that contains the line terminator string Normally used

only if you need to change the string that terminates an individual line.

§) Reading and Writing Files

StreamWriter class

Phương thức

Close Closes the writer and the underlying stream

WriteLine |\Writes data to the stream followed by the string that

terminates an individual line

ac: and Writing Files

» Vi du

„ Ghi file văn bản

FileStream theFile = File.COpoen(Œ@”c:\somefile.tx{”,

ac: and Writing Files

=» BinaryReader class

= Dung dé doc file nhi phan

= Cung cap cac phuong thức có dạng ReadXxXx(ReadByte, ReadInt32 ) dé doc noi dung file

byte[] bytes = reader.ReadBytes(4) ;

string s = reader.ReadString();

ac: and Writing Files

=» BinaryWriter class

= Dung dé ghi file nhi phan

= Cung cap cac phương thức Write với nhiêu

dạng tham số khác nhau để ghi nội dung

II:

ac: and Writing Files

» Vi du

a Ghi file nhi phan

FileStream theFile = File.Open(@"c:\somefile.bin",

FileMode.OpenOrCreate, FileAccess Write);

BinaryWriter writer = new

BIinaryWriter(theFile) ;

lòng number = 100;

byte[] bytes = new byte[] { 10, 20, 50, 100 };

string s= “Toi di hoc’;

writer.Write(number);

writer Write(bytes);

writer.Write(s);

§) Reading and Writing Files

Phương thức

Name Description

CetSuffer Retrieves the array of unsigned bytes that were used to

create the stream

foArray |Writes the entire stream to an array of bytes

Writefo \Writes the MemoryStream to another stream.

ac: and Writing Files

MemoryStream memStrm = new MemoryStream();

StreamWriter writer = new StreamWriter(memStrm) ; writer WriteLine("Hello") ;

ac: and Writing Files

=» BufferedStream class

= Thuong dung cho NetworkStream

= Tang hiéu qua doc/ghi du liệu

he Streams

= Cho phép nén dữ liệu gốc tối đa là 4GB

„ Kiểu nén: GZIP và DEFLATE

'N©-:|© lele ho tro

» GZipStream class

=» DeflateStream class

he Streams

=» GZipStream class

„ KẾ thừa Stream class

« Dùng để nén/giải nén tập tin theo GZIP

=» Neén tap ale

FileStream sourceFile = File OQoenRead(inFilename);

FileStream destFile = File.Create(outFilename) ;

GZipStream compStream = new GZipStream(sourceFile,

CompressionMode.Compress):

byte[] Arr = new byte[4096];

int theByte = sourceFile.Read(Arr, 0, 4096);

while(theByte!= 0)

{

compstream.Write(Arr, 0, theByte) ; theByte = sourceFile.Read(Arr, 0, 4096);

he Streams

=» GZipStream class

= Giai nén tap tin

FileStream sourceFile = File OQoenRead(inFilename) ;

FileStream destFile = File.Create(outFilename) ;

GZipStream compStream = new

GZipStream(sourceFile, CompressionMode.Decompress) ; byte[] Arr = new byte[4096] ;

int theByte = compStream.Read(Arr, 0, 4096);

while (theByte != 0)

|

destFile.Write(Arr, 0, theByte);

theByte = compsStream.Read(Arr, 0, 4096);