CN103092590A - DLL sealing and invoking method of Delphi - Google Patents

Abstract

According to a DLL (Dynamic Link Library) sealing and invoking method of Delphi, DLL is a dynamic linking technique with the most widely application range. Due to the fact that sealing and invoking objects in DLL meet object dynamic binding mechanism limits, accordingly, DLL has a certain technical difficulties in encapsulated objects, and some Delphi programmers misunderstand that DLL just supports encapsulated function but not the encapsulated objects. The DLL sealing and invoking method of Delphi focuses on a special principle and idea of the sealing and invoking objects in DLL.

Description

DLL encapsulation and the call method of a kind of Delphi

Technical field

The present invention relates to DLL encapsulation and the call method of a kind of Delphi, particularly be the way of thinking that how to encapsulate and call in DELPHI.

Background technology

So if the modules of program is kept at respectively in different unit files and by the taking-up subroutine compiled code and adding in execute file from unit that Delphi compile or static library of connector after uses instruction each the static subroutine compiling of a typical static linkage of calling mutually that Here it is in Delphi.Static linkage can't realize that physically cutting is connected with encapsulation in case wherein certain unit or module are changed other all unit or module and all got and recompilate and be connected thereupon.

Summary of the invention

Based on the above issues, hereby invent a Delphi DLL package and call the method; first is the physical package with dynamic linking, for the realization of the physical cutting and packaging bpl package dynamic link library DLL or COM + components are in the form of a dynamic link dynamic link connector case subroutine external use only statement that the information in the executable file generated some data tables loaded into memory when Windows executable file when it is first loaded all required DLL and the program will start in the process of loading Windows use the function in memory address shim internal tables whenever the program calls an external function it will use the internal data tables directly on the DLL code it is currently loaded in the program's address space to call attention to this mode will not be involved in two different application DLL has become a part of the application and loaded in the same address space, all parameters are passed on the stack occurs with any other function call, like we do not intend to discuss here the DLL compiled because we first want to focus on Delphi the DLL package and object technology.

The secondth, use the DLL encapsulated object, the example of DLL encapsulated object is CarObj and the BicycleObj function creation that creates in DLL and has exported the such DemoSvr dynamic link library of quoting of Car object and Bicycle object and just can export Car object and Bicycle object by CarObj and BicycleObj function.

The 3rd is the dynamic binding that utilizes object in Delphi Interface realization DLL.The application program of calling DLL can only use the method for the dynamic binding of object in DLL understand this point be the key that realizes the DLL encapsulation and use object so the Delphi interfacing provide an optimal selection for us.Using interface also to bring more benefit at first to need not to use virtual and abstract qualifier to revise the object method statement has avoided the illusion on the program reading secondly to utilize the lifetime of the automatic management object of interface instance counter to avoid the programmer to forget the memory overflow that the destruction object causes.

The 4th is to use abstract class to realize the dynamic binding of object in DLL.Since restriction that in DLL, encapsulation and allocating object have been subject to the object binding mechanism so except utilizing the Delphi interfacing we it is also conceivable that with abstract class realize object in DLL binding mechanism it encapsulated outer appearnce TfrmUsers I service part comprise data module be designed to provide service server this be the thought of its interface that encapsulated service class TuserMaint and this design indicates of database access class TuserDM of a dynamic link library file UserSvr.dll and service detach.Due to the application program of calling DLL can only use the dynamic binding of object in DLL method we might as well specialized designs abstract class TIUserMaint as the interface that object method is provided in abstract class TIUserMaint by for the object method of application program only they be all empty abstract method purpose be the support dynamic binding and need not to provide realize a general abstract class defining interface it by empty abstract method form there is no reality data in order to realize abstract class

The original TUserMaint class of the abstract method of TIUserMaint need to be inherited the TIUserMaint class and cover that they are all

The TUserMaint class declaration that empty abstract method is new is as follows

TUserMaint＝class(TIUserMaint)

private

UserDM:TUserDM；

public

function?GetDepList:TStrings；override；

function?GetUserList(strName:String):OLEVariant；override；

procedure?UpdateUserData(UserData:OleVariant；out?ErrCount:Integer)；

override；

constructor?create；override；

destructor?Destroy；override；

end；

But in fact the TUserMaint class original to realize that so part does not need to change our workload little.

Claims (2)

1. the DLL of a Delphi encapsulates and call method: the method is mainly encapsulation technology and the dynamic call method of the DELL of DELPHI.

2. according to claim 1 DLL encapsulation and the call method of Delphi, the method is mainly realized the dynamic binding of object in DLL by the dynamic binding that utilizes object in Delphi Interface realization DLL with the DLL encapsulated object and use abstract class.