In the world of IO manipulation, a stream represents a chunk of data. The abstract System.IO.Stream

Apress © 2003 (1200 pages)

class defines a number of members that provide support for synchronous and asynchronous interactions

This comprehensive text starts with a brief overview of the

with the storage mediumC# language(e.g.and, anthenunderlyingquicklyfilemovesor memoryto key technicallocation)and. Figure 16-5 shows the basic stream

hierarchy. architectural issues for .NET developers.

Table

C# and

Part

Chapter

Chapter

Part

Figure 16-5: Stream-derived types

Chapter 11 - Type Reflection, Late Binding, and Attribute-Based Programming

Part Four - Leveraging the .NET Libraries

myMemStream.Close();

C# and the .NET Platform, Second Edition

by Andrew Troelsen ISBN:1590590554

The output of thisApresslogic is© 2003identical(1200 topages)that of the previous FileStream example. The only difference is where

you store the informationThis c mprehensive(to file or memory)t xt starts. Inwithadditiona brieftoovtherviewinheritedof themembers, MemoryStream supplies other membersC# language. For example,and then quicklythe previousm vescodeto keyusedt chnicalthe Capacityand property to specify how much

architectural issues for .NET developers.

memory to carve out for the streaming operation. Table 16-10 shows the core MemoryStream type members.

Table of Contents

Table 16-10: MemoryStream Core Members

C# and the .NET Platform, Second Edition

Part Three - Programming with .NET Assemblies

Notice the possible interplay between the MemoryStream and FileStream types. Using the WriteTo()

Chapter 9 - Understanding .NET Assemblies

method, you can easily transfer data stored in memory to a file. Furthermore, you can also retrieve the

Chapter 10 - Processes, AppDomains, Contexts, and Threads

memory stream as a byte array:

Chapter 11 - Type Reflection, Late Binding, and Attribute-Based Programming

Part Four - Leveraging the .NET Libraries

// Dump memory data to file.

Chapter 12 - Object Serialization and the .NET Remoting Layer

FileStream dumpFile = new FileStream("Dump.dat", FileMode.Create,

Chapter 13 - Building a Better Window (Introducing Windows Forms)

FileAccess.ReadWrite);

Chapter 14 - A Better Painting Framework (GDI+)

myMemStream.WriteTo(dumpFile);

Chapter 15 - Programming with Windows Forms Controls

// Dump memory data to a byte array.

Chapter 16 - The System.IO Namespace

byte[] bytesinMemory = myMemStream.ToArray();

Chapter 17 - Data Access with ADO.NET

myMemStream.Close();

Part Five - Web Applications and XML Web Services

Chapter 18 - ASP.NET Web Pages and Web Controls

Chapter 19 - ASP.NET Web Applications

Chapter 20 - XML Web Services

Working with BufferedStreams

Index

List of Figures

The final Stream-derived type to consider here is BufferedStream. This type can be used as a temporary

List of Tables

location to read or write information, which can later be committed to permanent storage. For example, assume you have opened a data file and need to write out a large series of bytes. While you could stuff each item directly to file using FileStream.Write(), you may wish to help optimize the process by storing the new items in a BufferedStream type and making a final commit when each addition has been accounted for. In this way, you can reduce the number of times you must hit the physical file. Here is an example:

// Build a buffer attached to a valid FileStream.

BufferedStream myFileBuffer = new BufferedStream(dumpFile);

// Add some bytes to the buffer.

byte[] str = { 127, 0x77, 0x4, 0x0, 0x0, 0x16}; myFileBuffer.Write(str, 0, str.Length);

// Commit changes to file.

SOURCE C#TheandStreamerthe .NETprojectPlatform,illustratesS condworkingEditionwith the FileStream, MemoryStream, and

CODE byBufferedStreamAndrew Troelsentypes, and is located under theISBN:1590590554Chapter 16 subdirectory.

Apress © 2003 (1200 pages)

This comprehensive text starts with a brief overview of the C# language and then quickly moves to key technical and architectural issues for .NET developers.

Table of Contents

C# and the .NET Platform, Second Edition

Introduction

Part One - Introducing C# and the .NET Platform

Chapter 1 - The Philosophy of .NET

Chapter 2 - Building C# Applications

Part Two - The C# Programming Language

Chapter 3 - C# Language Fundamentals

Chapter 4 - Object-Oriented Programming with C#

Chapter 5 - Exceptions and Object Lifetime

Chapter 6 - Interfaces and Collections

Chapter 7 - Callback Interfaces, Delegates, and Events

Chapter 8 - Advanced C# Type Construction Techniques

Part Three - Programming with .NET Assemblies

Chapter 9 - Understanding .NET Assemblies

Chapter 10 - Processes, AppDomains, Contexts, and Threads

Chapter 11 - Type Reflection, Late Binding, and Attribute-Based Programming

Part Four - Leveraging the .NET Libraries

Chapter 12 - Object Serialization and the .NET Remoting Layer

Chapter 13 - Building a Better Window (Introducing Windows Forms)

Chapter 14 - A Better Painting Framework (GDI+)

Chapter 15 - Programming with Windows Forms Controls

Chapter 16 - The System.IO Namespace

Chapter 17 - Data Access with ADO.NET

Part Five - Web Applications and XML Web Services

Chapter 18 - ASP.NET Web Pages and Web Controls

Chapter 19 - ASP.NET Web Applications

Chapter 20 - XML Web Services

Index

List of Figures

List of Tables

ChapterWriteLine()1 - The Philosophy ofWrites.NETa line to the text stream, with a new line constant.

Chapter 2 - Building C# Applications

Part Two - The C# Programming Language

The last two members of the TextWriter class probably look familiar to you. If you recall, the

Chapter 3 - C# Language Fundamentals

System.Console type has similar members that write textual data to the standard output device. (In fact

Chapter 4 - Object-Oriented Programming with C#

Console.In inherits from TextWriter and Console.Out from TextReader.) Here, TextWriter moves the

Flush() methods, as well as defines the additional AutoFlush property. This property, when set to true,

PartforcesThreeStreamWriter- Programmingto flushwithall.NETdataAssembliesevery time you perform a write operation. Be aware that you can gain

Chapterbetter performance9 - Understandingby setting.NETAutoFlushAssembliesto false, provided you always call Close() when you are done

Chapterwriting 10with- aProcStreamWritersses, AppDomains,. Contexts, and Threads

Chapter 11 - Type Reflection, Late Binding, and Attribute-Based Programming

PartWritingFour - Leveragingto a Textthe .NETFileLibraries

Chapter 12 - Object Serialization and the .NET Remoting Layer

ChapterNow for13an- exampleBuilding aofBetterworkingWindowwith the(IntroducingStreamWriterWindowstypeForms). The following class creates a new file named

Chapterthoughts14.txt- AusingBetterthePaintingFileInfoFrameworkclass. Using(GDI+)the CreateText() method, you can obtain a valid StreamWriter. ChapterAt this point,15 - PryougraddmmingsomewithtextualWindowsdataFormsto theControlsnew file, as shown here:

Chapter 16 - The System.IO Namespace

Chapterpublic17class- Data AccessMyStreamWriterReaderwith ADO.NET

Part{ Five - Web Applications and XML Web Services

Chapter public18 - ASP.NETstaticWeb Pagesint Main(string[]and Web Controls args)

Chapter {19 - ASP.NET Web Applications

// Make a file in the application directory.

Chapter 20 - XML Web Services

If you locate this new file, you should be able to double-click it to open it a la Notepad. Figure 16-7 shows

the content of your new file.

Second Edition

ISBN:1590590554

with a brief overview of the moves to key technical and

Figure 16-7:architecturalThe contentsi suesof yourfor *..NETtxt filedevelopers.

As you can see, the StreamWriter has indeed written your data to a file. Do be aware that the Write() and

Table of Contents

WriteLine() methods have each been overloaded numerous times to provide a number of ways to add

C# and the .NET Platform, Second Edition

textual and numeric data (which defaults to Unicode encoding).

Introduction

Part One - Introducing C# and the .NET Platform

ChapterReading1 - ThefromPhilosophya Textof .NETFile

Chapter 2 - Building C# Applications

Now you need to understand how to programmatically read data from a file using the corresponding

Part Two - The C# Programming Language

StreamReader type. As you probably recall, this class derives from TextReader, which offers the

Chapter 3 - C# Language Fundamentals

If you now extend the current MyStreamWriterReader class to use a StreamReader, you can read in the

Chapter 19 - ASP.NET Web Applications

textual data from the thoughts.txt file, as shown here:

Chapter 20 - XML Web Services

Index

public class MyStreamWriterReader

List of Figures

{

List of Tables

public static int Main(string[] args)

{

// Writing logic as before.

...

// Now read it all back in using a StreamReader.

Console.WriteLine("Here are your thoughts:\n"); StreamReader sr = File.OpenText("Thoughts.txt"); string input = null;

while ((input = sr.ReadLine()) != null) Console.WriteLine (input);

sr.Close(); return 0;

}

}

Running the program, you would see the output shown in Figure 16-8.

C# and the .NET Platform, Second Edition

by Andrew Troelsen ISBN:1590590554

starts with a brief overview of the moves to key technical and

developers.

Table

Figure 16-8: Reading from a file

C# and the .NET Platform, Second Edition

Introduction

Here, you obtained a valid StreamReader using the static File.OpenText() method. The read logic makes

Part One - Introducing C# and the .NET Platform

use of StreamReader.Peek() to ensure that you have an additional character ahead of the reader's current

Chapter 1 - The Philosophy of .NET

position. If so, you read the next line and pump it to the console. To obtain the contents of the entire file,

Chapter 2 - Building C# Applications

you could avoid the "peeking" and simply call ReadToEnd(), as shown here:

Part Two - The C# Programming Language

Chapter 3 - C# Language Fundamentals

// Be sure to add a reference to System.Windows.Forms.dll

Chapter 4 - Object-Oriented Programming with C#

// and specify a proper 'using' directive to access the

Chapter 5 - Exceptions and Object Lifetime

// MessageBox type.

Chapter 6 - Interfaces and Collections

string allOfTheData = sr.ReadToEnd();

Chapter 7 - Callback Interfaces, Delegates, and Events

MessageBox.Show(allOfTheData, "Here it is:");

Chapter 8 - Advanced C# Type Construction Techniques

sr.Close();

Part Three - Programming with .NET Assemblies

Chapter 9 - Understanding .NET Assemblies

As you can see, the StreamReader and StreamWriter types provide a custom implementation of the

Chapter 10 - Processes, AppDomains, Contexts, and Threads

abstract members defined by their respective base classes. Just remember that these two types are

Chapter 11 - Type Reflection, Late Binding, and Attribute-Based Programming

concerned with moving text-based data to and from a specified file.

Part Four - Leveraging the .NET Libraries

Chapter 12 - Object Serialization and the .NET Remoting Layer

SOURCE The StreamWriterReaderApp project is included under the Chapter 16 subdirectory.

Chapter 13 - Building a Better Window (Introducing Windows Forms)

CODE

Chapter 14 - A Better Painting Framework (GDI+)

Chapter 15 - Programming with Windows Forms Controls

Chapter 16 - The System.IO Namespace

Chapter 17 - Data Access with ADO.NET

Part Five - Web Applications and XML Web Services

Chapter 18 - ASP.NET Web Pages and Web Controls

Chapter 19 - ASP.NET Web Applications

Chapter 20 - XML Web Services

Index

List of Figures

List of Tables

Working withC# andStringWritersthe .NET Platform, Second Edition

Using the StringWriter and StringReader types, you can treat textual information as a stream of in-memory

Apress © 2003 (1200 pages)

characters. This can prove helpful when you wish to append character-based information to an underlying

This comprehensive text starts with a brief overview of the

buffer. To gain accessC# languageto the underlyinga then quicklybuffermovesfrom anto instancekey te hnicalof a andStringWriter type, you can call the overridden ToString()architecturalmethodissues(to receivefor .NETa Systemdev lopers.String. type) or the GetStringBuilder() method, which returns an instance of System.Text.StringBuilder.

TableTo illustrate,of Contentsreengineer the previous example to write the character information to a StringWriter instance C#ratherand tthane .NETa generatedPlatform, fileSecond. As youEditionshould notice, the two programs are nearly identical, given that both

StringWriter and StreamWriter inherit the same base class functionality, as shown here:

Introduction

Part One - Introducing C# and the .NET Platform

Chapterpublic1 class- The PhilosophyMyStringWriterReaderof .NET

Chapter{ 2 - Building C# Applications

Part Twopublic- The C#staticProgrammingt LanguageMain(string[] args)

for(int i = 0; i < 10; i++)

Part Three - Programming with .NET Assemblies

Chapter 11 - Type Reflection, Late Binding, and Attribute-Based Programming

Console.WriteLine("Stored thoughts in a StringWriter...");

Part Four - Leveraging the .NET Libraries

// Get a copy of the contents (stored in a string) and pump

Chapter 12 - Object Serialization and the .NET Remoting Layer

// to console.

Chapter 13 - Building a Better Window (Introducing Windows Forms)

Console.WriteLine("Contents: {0} ", writer.ToString());

Chapter 14 - A Better Painting Framework (GDI+)

return 0;

Chapter 15 - Programming with Windows Forms Controls

}

Chapter 16 - The System.IO Namespace

}

Chapter 17 - Data Access with ADO.NET

Part Five - Web Applications and XML Web Services

Running this program, of course, dumps out textual data to the console. To gain access to the underlying

Chapter 18 - ASP.NET Web Pages and Web Controls

StringBuilder maintained by the StringWriter, simply add the following logic:

Chapter 19 - ASP.NET Web Applications

Chapter 20 - XML Web Services

// For StringBuilder type!

Index

using System.Text;

List of Figures

...

List of Tables

public class MyStringWriterReader

{

public static int Main(string[] args)

{

// Previous logic...

...

// Get the internal StringBuilder.

StringBuilder str = writer.GetStringBuilder(); string allOfTheData = str.ToString();

Console.WriteLine("StringBuilder says:\n{0} ", allOfTheData);

// Insert item to buffer at position 20.

str.Insert(20, "INSERTED STUFF"); allOfTheData = str.ToString();

Console.WriteLine("New StringBuilder says:\n{0} ", allOfTheData);

// Remove the inserted string.

str.Remove(20, "INSERTED STUFF".Length);

Here, you can write some character data to a StringWriter type and extract and manipulate a copy of the

Table of Contents

contents using the GetStringBuilder() member function.

C# and the .NET Platform, Second Edition

Introduction

Part One - Introducing C# and the .NET Platform

Chapter 1 - The Philosophy of .NET

Chapter 2 - Building C# Applications

Part Two - The C# Programming Language

Chapter 3 - C# Language Fundamentals

Chapter 4 - Object-Oriented Programming with C#

Chapter 5 - Exceptions and Object Lifetime

Chapter 6 - Interfaces and Collections

Chapter 7 - Callback Interfaces, Delegates, and Events

Chapter 8 - Advanced C# Type Construction Techniques

Part Three - Programming with .NET Assemblies

Chapter 9 - Understanding .NET Assemblies

Chapter 10 - Processes, AppDomains, Contexts, and Threads

Chapter 11 - Type Reflection, Late Binding, and Attribute-Based Programming

Part Four - Leveraging the .NET Libraries

Chapter 12 - Object Serialization and the .NET Remoting Layer

Chapter 13 - Building a Better Window (Introducing Windows Forms)

Chapter 14 - A Better Painting Framework (GDI+)

Chapter 15 - Programming with Windows Forms Controls

Chapter 16 - The System.IO Namespace

Chapter 17 - Data Access with ADO.NET

Part Five - Web Applications and XML Web Services

Chapter 18 - ASP.NET Web Pages and Web Controls

Chapter 19 - ASP.NET Web Applications

Chapter 20 - XML Web Services

Index

List of Figures

List of Tables

Working withC# andStringReadersthe .NET Platfo m, Second Edition

Next is the StringReader type, which (as you would expect) functions identically to the related

Apress © 2003 (1200 pages)

StreamReader class. In fact, the StringReader class does nothing more than override the inherited

This comprehensive text starts with a brief overview of the members to readC#fromlanguagea blockandof characterthen quicklydata,movesratherto keythantechnicala file, asandshown here:

architectural issues for .NET developers.

// Now dump using a StringReader.

StringReader sr = new StringReader(writer.ToString());

Table of Contents

string input = null;

C# and the .NET Platform, Second Edition

while ((input = sr.ReadLine()) != null)

Introduction

{

Part One - Introducing C# and the .NET Platform

Console.WriteLine (input);

Chapter 1 - The Philosophy of .NET

}

Chapter 2 - Building C# Applications

sr.Close();

Part Two - The C# Programming Language

Chapter 3 - C# Language Fundamentals

ChapterFigure 416--9Objectshows-Orientedthe outputProgramming. with C#

Chapter 5 - Exceptions and Object Lifetime

Chapter

Chapter

Chapter

Chapter 18 - ASP.NET Web Pages and Web Controls

Figure 16-9: Manipulating the StringBuilder

Chapter 19 - ASP.NET Web Applications

Chapter 20 - XML Web Services

If you were paying attention to the previous sample applications, you may have noticed one limitation of the

Index

TextReader and TextWriter descendents. None of these types has the ability to provide random access to

List of Figures

its contents (e.g., seeking). For example, StreamReader has no members that allow you to reset the

List of Tables

internal file cursor or jump over some number of characters and begin reading from that point. To gain this sort of functionality, you need to use various descendents of the Stream type.

SOURCE The StringReaderWriterApp is included under the Chapter 16 subdirectory.

CODE

Working withC# andBinarythe .NETDataPlatform,(BinaryReadersSecond Edition and BinaryWriters)

The final two core classes provided by the System.IO namespace are BinaryReader and BinaryWriter,

Apress © 2003 (1200 pages)

both of which derive directly from System.Object. These types allow you to read and write discrete data

This comprehensive text starts with a brief overview of the

types to an underlyingC# languagestream.andThethenBinaryWriterquickly movesclasstodefineskey technicala highlyandoverloaded method named (of course) Write() toarchitplacecturala dataissuestype forin the.NETcorrespondingdevelopers. stream. The BinaryWriter class also provides some other familiar-looking members (Table 16-13).

The BinaryReader class complements the functionality offered by BinaryWriter with the members

Chapter 8 - Advanced C# Type Construction Techniques described in Table 16-14.

Part Three - Programming with .NET Assemblies

Chapter 9 - Understanding .NET Assemblies

Table 16-14: BinaryReader Core Members

Chapter 10 - Processes, AppDomains, Contexts, and Threads

BinaryReader Meaning in Life

Chapter 11 - Type Reflection, Late Binding, and Attribute-Based Programming

Member

Part Four - Leveraging the .NET Libraries

List of Tables

The following class writes a number of character types to a new *.dat file created and opened using the FileStream class. Once you have a valid FileStream, pass this object to the constructor of the BinaryWriter type. Understand that the constructor of BinaryWriter takes any Stream-derived type (for example, FileStream, MemoryStream, or BufferedStream). Once the data has been written, a corresponding BinaryReader reads each byte back, as shown here:

public class ByteTweaker

{

public static int Main(string[] args)

{

Console.WriteLine("Creating a file and writing binary data...");

FileStream myFStream

= new FileStream("temp.dat", FileMode.OpenOrCreate,

FileAccess.ReadWrite);

// Write some binary info.

BinaryWriter binWrit = new BinaryWriter(myFStream);

C# and the .NET Platform, Second Edition binWrit.Write("Hello as binary info...");

This comprehensive text starts with a brief overview of the bool myBool = false;

C# language and then quickly moves to key technical and char[] myCharArray = { 'H', 'e', 'l', 'l', 'o'} ;

architectural issues for .NET developers. binWrit.Write(myInt);

binWrit.Write(myFloat);

binWrit.Write(myBool);

Table of Contents

binWrit.Write(myCharArray);

C# and the .NET Platform, Second Edition

// Reset internal position.

Introduction

binWrit.BaseStream.Position = 0;

Part One - Introducing C# and the .NET Platform

// Read the binary info as raw bytes.

Chapter 1 - The Philosophy of .NET

Console.WriteLine("Reading binary data...");

Chapter 2 - Building C# Applications

BinaryReader binRead = new BinaryReader(myFStream);

Part Two - The C# Programming Language

int temp = 0;

Chapter 3 - C# Language Fundamentals

while(binRead.PeekChar() != -1)

Chapter 4 - Object-Oriented Programming with C#

{

Chapter 5 - Exceptions and Object Lifetime

Console.Write(binRead.ReadByte());

Chapter 6 - Interfaces and Collections

temp = temp + 1;

Chapter 7 - Callback Interfaces,if(temp Delegates,== 5) and Events

Chapter 8 - Advanced{C# Type Construction Techniques

Part Three - Programming with//.NETAddAssemba blankies line every 5 bytes.

Chapter 9 - Understanding .NETtempAssemblies= 0;

Console.WriteLine();

Chapter 10 - Processes, AppDomains, Contexts, and Threads

}

Chapter 11 - Type Reflection, Late Binding, and Attribute-Based Programming

}

Part Four - Leveraging the .NET Libraries

// Clean things up.

Chapter 12 - Object Serialization and the .NET Remoting Layer

binWrit.Close();

Chapter 13 - Building a Better Window (Introducing Windows Forms)

binRead.Close();

Chapter 14 - A Better Painting Framework (GDI+)

myFStream.Close();

Chapter 15 - Programming with Windows Forms Controls

}

Chapter 16 - The System.IO Namespace

}

Chapter 17 - Data Access with ADO.NET

Part Five - Web Applications and XML Web Services

Chapter 18 - ASP.NET Web Pages and Web Controls

ChapterSOURCE19 - ASP.NET WebThe BinaryReaderWriterApplications application is included under the Chapter 16 subdirectory.

ChapterCODE20 - XML Web Services

Index

List of Figures

List of Tables

"Watching"C#Filesand theand.NETDirectoriesPlatform, Second Edition

Now that you have a better handle on the use of various readers and writers, next we'll check out the role of the

Apress © 2003 (1200 pages)

FileSystemWatcher class. This type can be quite helpful when you wish to programmatically monitor (or "watch

This comprehensive text starts with a brief overview of the

files on your systemC#.languageSpecifically,and theth nFileSystemWatcherquickly moves to keytypetechnicalcan beandinstructed to monitor files for any of the actions specifiedarchitby thecturalNotifyFiltersissues forenumeration.NET developers(while. many of these members are selfexplanatory, check

online help for further details):

Table of Contents

public enum System.IO.NotifyFilters

C# and the .NET Platform, Second Edition

{

Introduction

Attributes, CreationTime,

Part One - Introducing C# and the .NET Platform

DirectoryName, FileName,

Chapter 1 - The Philosophy of .NET

LastAccess, LastWrite,

Chapter 2 - Building C# Applications

Security, Size,

Part Two - The C# Programming Language

}

Chapter 3 - C# Language Fundamentals

Chapter 4 - Object-Oriented Programming with C#

The first step you will need to take to work with the FileSystemWatcher type is to set the Path property to specif

Chapter 5 - Exceptions and Object Lifetime

the name (and location) of the directory that contains the files to be monitored, as well as the Filter property tha

Chapter 6 - Interfaces and Collections

defines the file extension of the files to be monitored. Next, you will set the NotifyFilter property using members

Chapter 7 - Callback Interfaces, Delegates, and Events

the System.IO.NotifyFilters enumeration.

Chapter 8 - Advanced C# Type Construction Techniques

Part Three - Programming with .NET Assemblies

At this point, you may choose to handle the Changed, Created, and Deleted events, all of which work in

Chapter 9 - Understanding .NET Assemblies

conjunction with the FileSystemEventHandler delegate. As well, the Renamed event may also be handled via t

Chapter 10 - Processes, AppDomains, Contexts, and Threads

RenamedEventHandler type. Last but not least, set the EnableRaisingEvents property to true to begin spying o

Chapter 11 - Type Reflection, Late Binding, and Attribute-Based Programming your file set.

Part Four - Leveraging the .NET Libraries

ChapterTo illustrate,12 - ObjectassumeS rializationyou haveandcreatedthe .NETa newRemotingdirectoryLayeron your C drive named ParanoidFolder that contains tw

*.txt files (named whatever you wish). The following console application will monitor the *.txt files within the

Chapter 13 - Building Better Window (Introducing Windows Forms)

ParanoidFolder, and print out messages in the event that the files are created, deleted, modified, or renamed:

Chapter 14 - A Better Painting Framework (GDI+)

Chapter 15 - Programming with Windows Forms Controls

Chapterpublic16class- The SystemTheWatcher.IO Namespace

{

Chapter 17 - Data Access with ADO.NET

public static void Main()

Part Five - Web Applications and XML Web Services

Chapter{18 - ASP.NET Web Pages and Web Controls

// Establish which directory to watch

Chapter 19 - ASP.NET Web Applications

// (assume of course you have this directory...)

Chapter 20 - XML Web Services

FileSystemWatcher watcher = new FileSystemWatcher();

Index

watcher.Path = @"C:\ParanoidFolder";

List of Figures

// Set up the things to be on the look out for.

List of Tables

watcher.NotifyFilter = NotifyFilters.LastAccess | NotifyFilters.LastWrit

| NotifyFilters.FileName | NotifyFilters.DirectoryName;

// Only watch text files.

watcher.Filter = "*.txt";

// Add event handlers.

watcher.Changed += new FileSystemEventHandler(OnChanged); watcher.Created += new FileSystemEventHandler(OnChanged); watcher.Deleted += new FileSystemEventHandler(OnChanged); watcher.Renamed += new RenamedEventHandler(OnRenamed);

// Begin watching the directory.

watcher.EnableRaisingEvents = true;

// Wait for the user to quit the program.

Console.WriteLine(@"Press 'q' to quit app.");

while(Console.Read()!='q');

}

// Event handlers (note the signature of the delegate targets!)

C# and the .NET Platform, Second Edition

private static void OnChanged(object source, FileSystemEventArgs e)

ISBN:1590590554

{

Apress © 2003 (1200 pages)

// Specify what is done when a file is changed, created, or deleted.

This comprehensive text starts with a brief overview of the

Console.WriteLine("File: {0} {1}!", e.FullPath, e.ChangeType);

C# language and then quickly moves to key technical and

}

architectural issues for .NET developers.

private static void OnRenamed(object source, RenamedEventArgs e)

{

// Specify what is done when a file is renamed.

Table of Contents

Console.WriteLine("File: {0} renamed to\n{1}", e.OldFullPath, e.FullPath

C# and the .NET Platform, Second Edition

}

Introduction

}

Part One - Introducing C# and the .NET Platform

Chapter 1 - The Philosophy of .NET

Chapter 2 - Buthislding C# Applications

Now, to test program, run the application and open up the Windows Explorer. Try renaming your files, PacreatingTwo -aThenewC#*.txtProgrammingfile, deletingLanguagea *.txt file, or whatnot. You will see the console application print out various bits Chapterinformation3 - regardingC# LanguagetheFundamentalsstate of the text files (Figure 16-10).

Chapter 4 - Object-Oriented Programming with C#

Chapter 5 - Exceptions and Object Lifetime

Chapter

Chapter

Chapter

Part

Chapter

Figure 16-10: Watching some *.txt files

Chapter 11 - Type Reflection, Late Binding, and Attribute-Based Programming

Part Four - Leveraging the .NET Libraries

ChapterSOURCE12 - Object SerializationThe MyDirectoryWatcherand the .NET RemotingapplicationLayeris included under the Chapter 16 subdirectory.

ChapterCODE13 - Building a Better Window (Introducing Windows Forms)

Chapter 14 - A Better Painting Framework (GDI+)

Chapter 15 - Programming with Windows Forms Controls

Chapter 16 - The System.IO Namespace

Chapter 17 - Data Access with ADO.NET

Part Five - Web Applications and XML Web Services

Chapter 18 - ASP.NET Web Pages and Web Controls

Chapter 19 - ASP.NET Web Applications

Chapter 20 - XML Web Services

Index

List of Figures

List of Tables

A Brief WordC# andRegardingthe .NET Platform,AsynchronousSecond Edition IO

You have already seen the asynchronous support provided by the .NET Framework during our

Apress © 2003 (1200 pages)

examination of delegates (Chapter 7) and the .NET Remoting layer (Chapter 12). Needless to say,

This comprehensive text starts with a brief overview of the

numerous types inC#thelanguageSystemand.IO namespacethen quickly movessupporttoasynchronouskey technical andoperations. Specifically, any type deriving from thearchitecturalabstract Systemissues.IOfor.Stream.NET developerstype inherits. BeginRead(), BeginWrite(), EndRead(), and EndWrite() methods. As you would expect, each of these methods works in conjunction with the IAsyncResult type:

Table of Contents

C# and the .NET Platform, Second Edition

public abstract class System.IO.Stream :

Introduction

MarshalByRefObject,

Part One - Introducing C# and the .NET Platform

IDisposable

Chapter 1 - The Philosophy of .NET

{

Chapter 2 - Building C# Applications

...

Chapter public6 - Interfacesvirtualand Collectioint EndReads (IAsyncResult asyncResult);

Chapter public7 - CallbackvirtualInterfaces,voidDelegates,EndWriteand(IAsyncResultEvents asyncResult);

}

Chapter 8 - Advanced C# Type Construction Techniques

Part Three - Programming with .NET Assemblies

Chapter 9 - Understanding .NET Assemblies

The process of working with the asynchronous behavior of Stream-derived types is identical to working with asynchronous delegates and asynchronous remote method invocations. In reality, you may never need to read or write to a Stream derivative asynchronously, unless perhaps you are building a .NET-

aware photo-editing application (where the image files can be quite large indeed). Nevertheless, should

Chapter 12 - Object Serialization and the .NET Remoting Layer

the need arise, just remember Stream-derived types automatically support this behavior.

Chapter 13 - Building a Better Window (Introducing Windows Forms) Chapter 14 - A Better Painting Framework (GDI+)

Chapter 15 - Programming with Windows Forms Controls

Chapter 16 - The System.IO Namespace

Chapter 17 - Data Access with ADO.NET

Part Five - Web Applications and XML Web Services

Chapter 18 - ASP.NET Web Pages and Web Controls

Chapter 19 - ASP.NET Web Applications

Chapter 20 - XML Web Services

Index

List of Figures

List of Tables

A WindowsC#Formsand the .CarNET Platform,LoggerSecondApplicationEdition

Speaking of Chapter 12 (see the preceding section), as you can surely surmise, the types of the System.IO

Apress © 2003 (1200 pages)

namespace work naturally with the .NET object serialization model. Given this, the remainder of this

This comprehensive text starts with a brief overview of the

chapter walks youC#throughlanguagea minimaland thenandquicklycompletemov sWindowsto key technicalFormsandapplication named CarLogApp. The CarLogApp allowsarctheitecturalend userissuesto createfor .NETandeinventorylopers.of Car types (contained in an ArrayList), which are displayed in yet another Windows Forms control, the DataGrid (Figure 16-11). To keep focused on the serialization logic, this grid is read-only.

Table of Contents

C# and the .NET Platform, Second Edition

Part

Chapter

Chapter

Part

Chapter

Chapter

Chapter 5 - Exceptions and Object Lifetime

Figure 16-11: The car logger application

Chapter 6 - Interfaces and Collections

ChapterThe topmost7 - CallbackFile menuI terfaces,providesDelegates,numberandof choicesEvents that operate on the underlying ArrayList. Table 16-15

Chapterdescribes8 -theAdvancedpossibleC#selectionsType Construction. Techniques

Part Three - Programming with .NET Assemblies

ChTablepter 169 -15:- UnderstandingFile Menu Options.NET Assembliesof the CarLogApp Project

Chapter 10 - Processes, AppDomains, Contexts, and Threads

Chapter 11 - Type Reflection, Late Binding, and Attribute-Based Programming

Item

Part Four - Leveraging the .NET Libraries

ChapterMake12New- ObjectCar SerializationDisplaysandcustomthe .NETdialogRemotingbox thatLayerallows the user to configure a new Car

Chapter 20 - XML Web Services

I will not bother to detail the menu construction logic, as you have already seen these steps during the

Index

formal discussion of Windows Forms. The first task is to define the Car type itself. This is the class that

List of Figures

represents not only a unique row in the DataGrid, but also an item in the serialized object graph. There are

List of Tables

numerous iterations of the Car class throughout this book, so this version is brutally bland (recall the role of the [Serializable] attribute!):

[Serializable]

public class Car

{

// Make public for easy access.

public string petName, make, color;

public Car(string petName, string make, string color)

{

this.petName = petName; this.color = color; this.make = make;

}

}

configured using a small set of properties, all of which have been assigned using the Properties window of

Apress © 2003 (1200 pages)

the Visual Studio .NET IDE. The most important property for this example is the ReadOnly member (set to

preventsThis comprehensive text starts with a brief overview of the

true), which the user from editing the cells in the DataGrid. The remaining configurations establish

C# language and then quickly moves to key technical and

the type's color scheme and physical dimensions (which you can explore at your leisure). architectural issues for .NET developers.

In addition, the main Form maintains a private ArrayList type, which holds each of the Car references. The

Form's constructor adds a number of default cars to allow the user to view some initial items in the grid.

Table of Contents

Once these Car types have been added to the collection, you call a helper function named UpdateGrid(), as

C# and the .NET Platform, Second Edition shown here:

Introduction

Part One - Introducing C# and the .NET Platform

public class mainForm : System.Windows.Forms.Form

Chapter 1 - The Philosophy of .NET

{

Chapter 2 - Building C# Applications

// ArrayList for object serialization.

Part Two - The C# Programming Language

private ArrayList arTheCars = null;

Chapter 3 - C# Language Fundamentals

...

Chapter 4 - Object-Oriented Programming with C# public mainForm()

Chapter 5 - Exceptions and Object Lifetime

{

Chapter 6 - Interfaces and Collections

InitializeComponent();

Chapter 7 - Callback Interfaces, Delegates, and Events

CenterToScreen();

Chapter 8 - Advanced// AddC#someType carsConstruction. Techniques

Part Three - ProgarTheCarsamming with= .NETnewAssembliesArrayList();

Chapter 9 - UnderstandingarTheCars.NETAdd(nAssembliesw Car("Siddhartha", "BMW", "Silver"));

Chapter 10 - ProcessarTheCarss, AppDomains,.Add(newContexts,Car("Chucky",and Threads "Caravan", "Pea Soup Green"));

arTheCars.Add(new Car("Fred", "Audi TT", "Red"));

Chapter 11 - Type Reflection, Late Binding, and Attribute-Based Programming

// Display data in grid.

Part Four - Leveraging the .NET Libraries

UpdateGrid();

Chapter 12 - Object Serialization and the .NET Remoting Layer

}

Chapter 13 - Building a Better Window (Introducing Windows Forms)

...

Chapter 14 - A Better Painting Framework (GDI+)

}

Chapter 15 - Programming with Windows Forms Controls Chapter 16 - The System.IO Namespace

Chapter 17 - Data Access with ADO.NET

Part Five - Web Applications and XML Web Services

The UpdateGrid() method is responsible for creating a System.Data.DataTable type that contains a row for

Chapter 18 - ASP.NET Web Pages and Web Controls

each Car in the ArrayList. Once the DataTable has been populated, you then bind it the DataGrid type.

Chapter 19 - ASP.NET Web Applications

Chapter 17 examines the ADO.NET types (such as the DataTable) in much greater detail, so here the Chapterfocus is20on-theXMLbasicsWeb Servicfor thestime being. Here is the code:

Index

List of Figures

private void UpdateGrid()

List of Tables

{

if(arTheCars != null)

{

// Make a DataTable object named Inventory.

DataTable inventory = new DataTable("Inventory");

// Create DataColumn objects that map to the fields of the Car type.

DataColumn make = new DataColumn("Car Make");

DataColumn petName = new DataColumn("Pet Name");

DataColumn color = new DataColumn("Car Color");

// Add columns to data table.

inventory.Columns.Add(petName);

inventory.Columns.Add(make);

inventory.Columns.Add(color);

// Iterate over the array list to make rows.

foreach(Car c in arTheCars)

{

DataRow newRow;

newRow["Pet Name"] = c.petName;

Apress © 2003 (1200 pages)

newRow["Car Make"] = c.make;

This comprehensive text starts with a briefcolor;verview of the newRow["Car Color"] = c.

C# language and then quickly moves to key technical and inventory.Rows.Add(newRow);

architectural issues for .NET developers.

}

// Now bind this data table to the grid.

carDataGrid.DataSource = inventory;

Table of Contents

}

C# and the .NET Platform, Second Edition

}

Introduction

Part One - Introducing C# and the .NET Platform

Chapter 1 - The Philosophy of .NET

Begin by creating a new DataTable type named Inventory. In the world of ADO.NET, a DataTable is an in-

Chapter 2 - Building C# Applications

memory representation of a single table of information. While you might assume that a DataTable would be PacreatedTwo -asThea resultC# Programmingof some SQLLanguagequery, you can also use this type as a stand-alone entity.

Chapter 3 - C# Language Fundamentals

Once you have a new DataTable, you need to establish the set of columns that should be listed in the table.

Chapter 4 - Object-Oriented Programming with C#

The System.Data.DataColumn type represents a single column. Given that this iteration of the Car type has

Chapter 5 - Exceptions and Object Lifetime

three public fields (make, color, and pet name), create three DataColumns and insert them in the table

Chapter 6 - Interfaces and Collections

using the DataTable.Columns property.

Chapter 7 - Callback Interfaces, Delegates, and Events

Chapter 8 - Advanced C# Type Construction Techniques

Next, you need to add each row to the table. Recall that the main Form maintains an ArrayList that contains

Part Three - Programming with .NET Assemblies

some number of Car types. Given that ArrayList implements the IEnumerable interface, you can fetch each

Chapter 9 - Understanding .NET Assemblies

Car from the collection, read each public field, and compose and insert a new DataRow in the table. Finally,

Chapter 10 - Processeis, AppDomains, Contexts, and Threads

the new DataTable bound to the GUI DataGrid widget using the DataSource property.

Chapter 11 - Type Reflection, Late Binding, and Attribute-Based Programming

Now then! If you run the application at this point, you will find that the grid is indeed populated with the

Part Four - Leveraging the .NET Libraries

default set of automobiles. This is a good start, but you can do better.

Chapter 12 - Object Serialization and the .NET Remoting Layer Chapter 13 - Building a Better Window (Introducing Windows Forms) ChapterImplementing14 - A Better Paintingthe AddFrameworkNew(GDI+)Car Logic

Chapter 15 - Programming with Windows Forms Controls

The CarLogApp project defines another Form-derived type (AddCarDlg) that functions as a modal dialog

Chapter 16 - The System.IO Namespace

box (Figure 16-12). From a GUI point of view, this type is composed of a TextBox (to hold the pet name)

Chapter 17 - Data Access with ADO.NET

and two ListBox types (to allow the user to select the color and make).

Part Five - Web Applications and XML Web Services

Chapter 18 - ASP.NET Web Pages and Web Controls

Chapter

Chapter

Index

List of

List of

Figure 16-12: The Add a Car dialog box

As far as the code behind the Form, the OK button has been assigned the DialogResult property DialogResult.OK. As you recall, this value marks a Button type to function as a standard OK button. Also, this Form maintains a public Car type (for easy access), which is configured when the user clicks the OK button. The remainder of the code is nothing more than some GUI control prep work. The relevant logic is as follows:

public class AddCarDlg : System.Windows.Forms.Form

C# and the .NET Platform, Second Edition

{

by Andrew Troelsen ISBN:1590590554

// Make public for easy access.

Apress © 2003 (1200 pages)

public Car theCar = null;

This comprehensive text starts with a brief overview of the

...

C# language and then quickly moves to key technical and

protected void btnOK_Click (object sender, System.EventArgs e) architectural issues for .NET developers.

{

// Configure a new Car when user clicks OK button.

Table of ContentheCars = new Car(txtName.Text, listMake.Text, listColor.Text);

C# and the} .NET Platform, Second Edition

}

Introduction

Part One - Introducing C# and the .NET Platform

Chapter 1 - The Philosophy of .NET

The main Form displays this dialog box when the user selects the Make New Car menu item. Here is the

Chapter 2 - Building C# Applications code behind that object's Clicked event:

Part Two - The C# Programming Language

Chapter 3 - C# Language Fundamentals

protected void menuItemNewCar_Click (object sender, System.EventArgs e)

Chapter 4 - Object-Oriented Programming with C#

{

Chapter 5 - Exceptions and Object Lifetime

// Show the dialog and check for OK click.

Chapter 6 - Interfaces and Collections

AddCarDlg d = new AddCarDlg();

Chapter 7 - Callback Interfaces, Delegates, and Events if(d.ShowDialog() == DialogResult.OK)

Chapter 8 - Advanced C# Type Construction Techniques

{

Part Three - Programming with .NET Assemblies

// Add new car to array list.

Chapter 9 - Understanding .NET Assemblies arTheCars.Add(d.theCar);

Chapter 10 - Processes, AppDomains, Contexts, and Threads

UpdateGrid();

Chapter 11 - Type Reflection, Late Binding, and Attribute-Based Programming

}

Part Four - Leveraging the .NET Libraries

}

Chapter 12 - Object Serialization and the .NET Remoting Layer

Chapter 13 - Building a Better Window (Introducing Windows Forms)

No surprises here. You just show the Form as a modal dialog box, and if the OK button has been clicked,

Chapter 14 - A Better Painting Framework (GDI+)

you read the public Car member variable, add it to the ArrayList, and refresh your grid.

Chapter 15 - Programming with Windows Forms Controls Chapter 16 - The System.IO Namespace

ChaptTherSerialization17 - D ta Access withLogicADO.NET

Part Five - Web Applications and XML Web Services

The core logic behind the Save Car File and Open Car File Click event handlers should pose no problems

Chapter 18 - ASP.NET Web Pages and Web Controls

at this point. When the user chooses to save the current inventory, you create a new file and use a

Chapter 19 - ASP.NET Web Applications

BinaryFormatter to serialize the object graph. However, just to keep things interesting, the user can

Chapter 20 - XML Web Services

establish the name and location of this file using a System.Windows.Forms.SaveFileDialog type. This type

Index

is yet another standard dialog box and is illustrated in Figure 16-13.

List of Figures

List of Tables

Figure 16-13: The standard File Save dialog box

C# and the .NET Platform, Second Edition

Notice that the SaveFileDialog is listing a custom file extension (*.car). While I leave the task of investigating

Apress © 2003 (1200 pages)

the complete functionality of the SaveFileDialog in your capable hands, it is worth pointing out that this has

This comprehensive text starts with a brief overview of the

been assigned usingC# languagethe Filterandpropertythen quickly. This propertymoves totakeskey technicalan OR-delimitedand string that represents the text to be used in thearchitecturaldrop-down Fileissuesnamefor .andNETSavede lopersas type. combo boxes. Here is the full implementation:

protected void menuItemSave_Click (object sender, System.EventArgs e)

Table of Contents

{

C# and the .NET Platform, Second Edition

// Configure look and feel of save dialog box.

Introduction

SaveFileDialog mySaveFileDialog = new SaveFileDialog();

Part One - Introducing C# and the .NET Platform

mySaveFileDialog.InitialDirectory = ".";

Chapter 1 - The Philosophy of .NET

mySaveFileDialog.Filter = "car files (*.car)|*.car|All files (*.*)|*.*";

Chapter 2 - Building C# Applications mySaveFileDialog.FilterIndex = 1;

Chapter if(mySaveFileDialog5 - Exceptions and Object.LifetimeShowDialog() == DialogResult.OK)

Chapter {6 - Interfaces and Collections

Chapter 7 - CallbackStreamInterfaces,myStreamDelegates,= null;and Events

if((myStream = mySaveFileDialog.OpenFile()) != null)

Chapter 8 - Advanced C# Type Construction Techniques

{

Part Three - Programming with .NET Assemblies

// Save the cars!

Chapter 9 - Understanding .NET Assemblies

BinaryFormatter myBinaryFormat = new BinaryFormatter();

Chapter 10 - Processes, AppDomains, Contexts, and Threads

myBinaryFormat.Serialize(myStream, arTheCars);

Chapter 11 - Type Reflection, Late Binding, and Attribute-Based Programming

myStream.Close();

Part Four - Leveraging the .NET Libraries

}

Chapter 12 - Object Serialization and the .NET Remoting Layer

}

Chapter 13 - Building a Better Window (Introducing Windows Forms)

}

Chapter 14 - A Better Painting Framework (GDI+) Chapter 15 - Programming with Windows Forms Controls

Chapter 16 - The System.IO Namespace

Also note that the OpenFile() member of the SaveFileDialog type returns a Stream that represents the Chapterspecified17file- DataselectedAccessbywiththe ADOend.userNET . As seen in Chapter 13, this is the very thing needed by the

PartBinaryFormatterFive - Web Applicationstype. and XML Web Services

Chapter 18 - ASP.NET Web Pages and Web Controls

The logic behind the Open Car File Click event handler looks very similar. This time you create an instance

Chapter 19 - ASP.NET Web Applications

of the System.Windows.Forms OpenFileDialog type, configure accordingly, and obtain a Stream reference

Chapter 20 - XML Web Services

based on the selected file. Next you dump the contents of the ArrayList and read in the new object graph

Index

using the BinaryFormatter.Deserialize() method, as shown here:

List of Figures

List of Tables

protected void menuItemOpen_Click (object sender, System.EventArgs e)

{

// Configure look and feel of open dialog box.

OpenFileDialog myOpenFileDialog = new OpenFileDialog(); myOpenFileDialog.InitialDirectory = ".";

myOpenFileDialog.Filter = "car files (*.car)|*.car|All files (*.*)|*.*"; myOpenFileDialog.FilterIndex = 1;

myOpenFileDialog.RestoreDirectory = true;

// Do you have a file?

if(myOpenFileDialog.ShowDialog() == DialogResult.OK)

{

// Clear current array list.

arTheCars.Clear(); Stream myStream = null;

if((myStream = myOpenFileDialog.OpenFile()) != null)

{

C# and the .NET Platform, Second Edition

// Get the cars!

by Andrew Troelsen ISBN:1590590554

BinaryFormatter myBinaryFormat = new BinaryFormatter();

Apress © 2003 (1200 pages)

arTheCars = (ArrayList)myBinaryFormat.Deserialize(myStream);

ThismyStreamcomp ehensive text starts with a brief overview of the

.Close();

C# language and then quickly moves to key technical and

UpdateGrid();

architectural issues for .NET developers.

}

}

}

Table of Contents

C# and the .NET Platform, Second Edition

Introduction

At this point, the application can save and load the entire set of Car types held in the ArrayList using a

Part One - Introducing C# and the .NET Platform

BinaryFormatter. The final menu items are self-explanatory, as shown here:

Chapter 1 - The Philosophy of .NET

Chapter 2 - Building C# Applications

protected void menuItemClear_Click (object sender, System.EventArgs e)

Part Two - The C# Programming Language

{

Chapter 3 - C# Language Fundamentals

arTheCars.Clear();

Chapter 4 - Object-Oriented Programming with C#

UpdateGrid();

Chapter 5 - Exceptions and Object Lifetime

}

Chapter 6 - Interfaces and Collections

protected void menuItemExit_Click (object sender, System.EventArgs e)

Chapter 7 - Callback Interfaces, Delegates, and Events

{

Chapter 8Application- Advanced C#.ExitType ();Construction Techniques

Part} Three - Programming with .NET Assemblies

Chapter 9 - Understanding .NET Assemblies

Chapter 10 - Processes, AppDomains, Contexts, and Threads

This wraps up our exploration of the System.IO namespace. Over the course of this chapter you have seen

Chapter 11 - Type Reflection, Late Binding, and Attribute-Based Programming

how to read and write data to binary, character-based, and memory streams. In the next chapter you will

Part Four - Leveraging the .NET Libraries

come to understand how to interact with XML-based data readers (and writers).

Chapter 12 - Object Serialization and the .NET Remoting Layer

Chapter 13 - Building a Better Window (Introducing Windows Forms)

SOURCE The CarLogApp project is included under the Chapter 16 subdirectory.

Chapter 14 - A Better Painting Framework (GDI+)

CODE

Chapter 15 - Programming with Windows Forms Controls

Chapter 16 - The System.IO Namespace

Chapter 17 - Data Access with ADO.NET

Part Five - Web Applications and XML Web Services

Chapter 18 - ASP.NET Web Pages and Web Controls

Chapter 19 - ASP.NET Web Applications

Chapter 20 - XML Web Services

Index

List of Figures

List of Tables