ProgrammingC#3.0-23-of1A.ppt

Chapter23Programming NETandCOM 天津大学软件学院章亦葵email zhangyk 05 45 1 Chapter23Programming NETandCOMIntroduction IntroductionProgrammersloveacleanslate 程序员都喜欢从头开始 Butthistypicallyisn taviableoptionformostcompanies ManydevelopmentorganizationshavemadeasubstantialinvestmentindevelopingandpurchasingCOMcomponentsandActiveXcontrols Microsofthasmadeacommitmenttoensurethattheselegacycomponentsareusablefromwithin NETapplications andthat NETcomponentsareeasilycallablefromCOM ThisChapterdescribessomeofthe NETprovidedsupportsImportingActiveXcontrolsandCOMcomponentsintoyourapplication MakingdirectcallstoWin32APIs LearnaboutC pointers keywordsforaccessingmemorydirectly 05 45 2 Chapter23Programming NETandCOM 05 45 3 ImportingActiveXControlsActiveXcontrolsareCOMcomponents typicallydroppedintoaform whichmightormightnothaveauserinterface WhenMicrosoftdevelopedtheOCXstandard whichalloweddeveloperstobuildActiveXcontrolsinVBandusethemwithC andviceversa theActiveXcontrolrevolutionbegan Overthepastfewyears thousandsofsuchcontrolshavebeendeveloped sold andused Chapter23Programming NETandCOM 05 45 4 CreatinganActiveXControlDevelopasimple4functioncalculatorasanActiveXcontrolCalcControl OcxinVB6 因为没有用户界面 可以把控件的尺寸设定为较小的尺寸 File NewProject ActiveXControl 控件的Form Right clickUserControl1andchoosePropertiesRenametoCalculator UserControl1 CalculatorClicktheProjectintheProjectExplorer andinthePropertieswindow renameit Project1 CalcControl File Saveproject nameboththefileandtheprojectCalcControl 05 45 5 Chapter23Programming NETandCOM AddCodeforCalcControlCompiletoOCX 05 45 6 ViewCode EditCode Chapter23Programming NETandCOM Chapter23Programming NETandCOM 05 45 7 CreateanewProjecttotestOCXControlinVB6 Component selectCalcControl addCalcControlonform AddOtherControlsonformandrelatedcode Chapter23Programming NETandCOM 05 45 8 InvokethatActiveXcontrolfromwithinaC applicationImportingaControlin NET RegisterCalcControl ocxBuildingaC WondowsFormApplication C ocxSample Regsvr32CalcControl ocx ImportingaControlin NET 05 45 9 Chapter23Programming NETandCOM ToolBox AddTab AddaCOMTab ImportingaControlin NET 05 45 10 Chapter23Programming NETandCOM MouseRightClick Select ChoseItem InItemListselect COMComponents Tab Selectitem CalcControl Calculator Chapter23Programming NETandCOM 05 45 11 ManuallyimportingthecontrolRun AximpCalcControl ocx atDosPromptManuallyadd NetComponent doesnotwork AddCalcControlonForm Drag Drop 05 45 12 AddingOthercontrols ForExample buttonADDChangePropertiestoTxet Add Name btnAdd DragButtoncontrol DropitonForm Chapter23Programming NETandCOM Addsourcecodeforthecontrols 05 45 13 Chapter23Programming NETandCOM DoubleClickhere letC adddefault Click eventforbuttonADD AddsourcecodeforbtnADD Click Chapter23Programming NETandCOM 05 45 14 Addsourcecodeforthecontrols privatevoidbtnADD Click objectsender EventArgse doubleleft double Parse textBox1 Text doubleright double Parse textBox2 Text label1 Text axCalculator1 Add refleft refright ToString 调用Vb6的CalcControl控件的Add方法 RunC CalculatorApplication 05 45 15 Chapter23Programming NETandCOM Chapter23Programming NETandCOM 05 45 16 P Invoke PlatforminvokefacilityItispossibletoinvokeunmanagedcodefromwithinC The NETP InvokewasoriginallyintendedonlytoprovideaccesstotheWindowsAPI butyoucanuseittocallfunctionsinanyDLL TheDllImportattributeclassisusedtoindicatethatanunmanagedmethodwillbeinvokedthroughP Invoke Chapter23Programming NETandCOM 05 45 17 P InvokeExampleExample22 3 FileInfoclassMoveTo methodSamethingcanbeaccomplishedbyusingtheWindowskernel32 dllandinvokingtheMoveFilemethod FileInfoclassfile MoveTo fullName bak ClassTester DllImport kernel32 dll EntryPoint MoveFile ExactSpelling false CharSet CharSet Unicode SetLastError true staticexternboolMoveFile stringsrcFile stringdestFile staticvoidMain Tester MoveFile fullName fullName bak P InvokeDLLmethod 05 45 18 Chapter23Programming NETandCOM DllImport kernel32 dll EntryPoint MoveFile ExactSpelling false CharSet CharSet Unicode SetLastError true staticexternboolMoveFile stringsourceFile stringdestinationFile DLLname ThenameoftheDLLyouareinvoking EntryPoint IndicatesthenameoftheDLLentrypoint themethod tocall ExactSpelling AllowstheCLRtomatchmethodswithslightlydifferentnamesbasedontheCLR sknowledgeofnamingconventions CharSet Indicateshowthestringargumentstothemethodshouldbemarshaled SetLastError SettingthistotrueallowsyoutocallMarshal GetLastWin32Error andcheckwhetheranerroroccurredwheninvokingthismethod Methodreturntypeandsignature P Invokereferenceresourceshttp ja wikipedia org wiki P Invoke 05 45 19 Chapter23Programming NETandCOM Chapter23Programming NETandCOM 05 45 20 Pointers 1 Chapter23Programming NETandCOM 05 45 21 Pointers 2 Theuseofpointersisalmostneverrequired andisnearlyalwaysdiscouragedinC NET Whenyoudousepointers youmustmarkyourcodewiththeC unsafemodifier becauseyoucanmanipulatememorylocationsdirectlywithpointers Inexchange yougiveupgarbagecollectionandprotectionagainstuninitializedvariables beyondboundsofanarray etc Pointersexample 3 InvokingWin32APIcalls CreateFileandReadFile 05 45 22 Chapter23Programming NETandCOM DllImport kernel32 SetLastError true staticexternunsafeintCreateFile stringfilename uintdesiredAccess uintshareMode uintattributes uintcreationDisposition uintflagsAndAttributes uinttemplateFile DllImport kernel32 SetLastError true staticexternunsafeboolReadFile inthFile void lpBuffer intnBytesToRead int nBytesRead intoverlapped Pointer Chapter23P