《Unity虚拟现实技术及其应用》 课件 20 IO

FileTextfilescontaindatathatcanbereadinatexteditorbecausethedatahasbeenencodedusingaschemesuchasASCIIorUnicode.•Binaryfilescontaindatathathasnotbeenencodedastext.Theircontentsareinbinaryformat,whichmeansthatyoucannotunderstandthembyviewingtheminatexteditorC#FileclassandstaticmethodsusingSystem.IO;publicclassFileStatistics{publicstaticvoidMain(){stringfileName;Console.Write("Enterafilename>>");fileName=Console.ReadLine();if(File.Exists(fileName)){Console.WriteLine("Fileexists");Console.WriteLine("Filewascreated"+File.GetCreationTime(fileName));Console.WriteLine("Filewaslastaccessed"+File.GetLastAccessTime(fileName));Console.WriteLine("Filewaslastwrittento"+File.GetLastWriteTime(fileName));}else{Console.WriteLine("Filedoesnotexist");}}}FilesandStreamsWhenyoureadfromorwritetoafile,youuseafileprocessingclassinsteadofConsole.ManyfileprocessingclassesareavailableinC#,including:•StreamReader,fortextinputfromafile•StreamWriter,fortextoutputtoafile•FileStream(whichisusedaloneandwithbothStreamReaderandStreamWriter),forbothinputfromandoutputtoafileFileModeFileAccessYoucanuseaFileStreamobjectasanargumenttheStreamWriterconstructor.ThenyouuseWriteLine()orWrite()tosendastringtotheFileStreamfile.WritingdatatoatextfileReadingfromatextfileSearchingasequentialtextfileAfileisreadinorderthroughafilepositionpointer.Seek()methodtorepositionthefilepointer,inFile.Seek(0,SeekOrigin.Begin);UsingFileStream.Writeand.ReadFileStreamfs=null;stringfileName=@"C:\Users\Shine\Desktop\ConsoleApplication1\1.txt";Try{fs=newFileStream(fileName,FileMode.OpenOrCreate);//fs=newFileStream(fileName,FileMode.Append);stringwriteStr="asdf";fs.Write(Encoding.UTF8.GetBytes(writeStr),0,writeStr.Length);fs.Close();}catch(Exceptione){Console.WriteLine(e.Message.ToString());}try{fs=newFileStream(fileName,FileMode.OpenOrCreate);byte[]s=newbyte[10];fs.Read(s,0,10);stringreadStr=Encoding.UTF8.GetString(s);Console.WriteLine(readStr);fs.Close();}catch(Exceptione){Console.WriteLine(e.Message.ToString());}fs.Close();Console.ReadKey();SerializationanddeserializationSerializationistheprocessofconvertingobjectsintostreamsofbytes.Deserializationisthereverseprocess;itconvertsstreamsofbytesbackintoobjects.publicdelegatevoidPriceChangedHandler(decimaloldPrice,decimalnewPrice);publicclassStock

{stringsymbol;decimalprice;publicStock(stringsymbol){this.symbol=symbol;}publiceventPriceChangedHandlerPriceChanged;publicdecimalPrice

{get{returnprice;}set{if(price==value)return;//fireeventifinvocationlistisnotemptyif(PriceChanged!=null)PriceChanged(price,value);price=value;

}

}

}publicstaticvoidchange(decimalx,decimaly)

{Console.WriteLine(y);

}publicstaticvoidup(decimalx,decimaly)

{Console.WriteLine("up");Console.WriteLine(y);

}staticvoidMain(string[]args)

{Stockst=newStock("LIU");st.PriceChanged+=change;st.PriceChanged+=up;st.Price=20;

}StandardEventPatternTheNetFrameworkdefinesastandardpatternforwritingevents.eventsarebasedontheEventHandlerdelegateandtheEventArgsbaseclass.publicdelegatevoidEventHandler<TEventArgs>(objectsource,TEventArgse)whereTEventArgs:EventArgs;derivefromEventArgspublicclassPriceChangedEventArgs:EventArgs

{publicreadonlydecimalLastPrice,NewPrice;publicPriceChangedEventArgs(decimallastPrice,decimalnewPrice){LastPrice=lastPrice;NewPrice=newPrice;}

}definepublisherclasspublicclassStock

{stringsymbol;decimalprice;publicStock(stringsymbol){this.symbol=symbol;}publiceventEventHandler<PriceChangedEventArgs>PriceChanged;//EventHandlerisadelegateprotectedvirtualvoidOnPriceChanged(PriceChangedEventArgse)//here,fireanevent

{if(PriceChanged!=null)PriceChanged(this,e);

}publicdecimalPrice

{get{returnprice;}set

{if(price==value)return;OnPriceChanged(newPriceChangedEventArgs(price,value));price=value;

}

}

}definesubscribersstaticvoidstock_price_changed(objectsender,PriceChangedEventArgse)

{if((e.NewPrice-e.LastPrice)/e.LastPrice>0.1M)Console.WriteLine("Alert,10%priceincrease!");

}staticvoidMain(string[]args)

{Stockst=newStock("LIU");st.Price=27.10M;Console.WriteLine("OK");st.PriceChanged+=stock_price_changed;st.Price=31.59M;

}nongenericEventHandlerdelegateThismeansthatnoadditionalinformationneedbetransmittedwithevent.publiceventEventHandlerPriceChanged;EventAccessorsAnevent’saccessorsaretheimplementationsofits+=and−=functions.publiceventEventHandlerPriceChanged;//默认产生下面的代码EventHandler_priceChanged;//PrivatedelegatepubliceventEventHandlerPriceChanged{add{_priceChanged+=value;}remove{_priceChanged−=value;}}public