delphi 创建dll_从Delphi创建和使用DLL

左手的ㄟ右手 2022-12-06 15:44 288阅读 0赞

delphi 创建dll

A Dynamic Link Library (DLL) is a collection of routines (small programs) that that can be called by applications and other DLLs. Like units, they contain code or resources that can be shared between multiple applications.

动态链接库(DLL)是例程(小程序)的集合，可以由应用程序和其他DLL调用。 像单元一样，它们包含可以在多个应用程序之间共享的代码或资源。

The concept of DLLs is the core of the Windows architectural design, and for the most part, Windows is simply a collection of DLLs.

DLL的概念是Windows体系结构设计的核心，并且在大多数情况下，Windows只是DLL的集合。

With Delphi, you can write and use your own DLLs and even call functions regardless of whether or not they were developed with other systems or developers, like [Visual Basic][], or [C/C++][C_C].

使用Delphi，您可以编写和使用自己的DLL，甚至可以调用函数，而不管它们是否由其他系统或开发人员(例如[Visual Basic][]或[C / C ++)开发][C_C] 。

## 创建动态链接库 **(** Creating a Dynamic Link Library **)** ##

The following few lines will demonstrate how to create a simple DLL using Delphi.

以下几行代码将演示如何使用Delphi创建简单的DLL。

For the beginning start Delphi and navigate to **File > New > DLL** to build a new DLL template. Select the default text and replace it with this:

首先，请启动Delphi并导航至“ **文件”>“新建”>“ DLL”**以构建新的DLL模板。 选择默认文本，并用以下内容替换：

library TestLibrary;

uses SysUtils, Classes, Dialogs;

procedure DllMessage; export;begin

ShowMessage('Hello world from a Delphi DLL') ;

end;

exports DllMessage;

beginend.

If you look at the [project file][] of any Delphi application, you’ll see that it starts with the reserved word *program*. By contrast, DLLs always start with *library* and then a *uses* clause for any units. In this example, the *DllMessage* procedure follows, which doesn't do anything but show a simple message.

如果查看任何Delphi应用程序的[项目文件][project file] ，都会看到它以保留字*program*开头。 相比之下，DLL总是以*库*开头，然后是任何单元的*using*子句。 在此示例中，将*遵循DllMessage*过程，该过程除了显示一条简单消息外不执行任何操作。

At the end of the source code is an *exports* statement which lists the routines that are actually exported from the DLL in a way that they can be called by another application. What this means is that you can have, say, five procedures in a DLL and only two of them (listed in the *exports* section) can be called from an external program (the remaining three are "sub procedures").

在源代码到底是一个*出口*声明，列出实际上从DLL导出的方式，他们可以被其他应用程序调用的程序。 这意味着您可以在一个DLL中拥有五个过程，并且只能从一个外部程序中调用其中两个过程(在“ *导出”*部分中列出)(其余三个过程是“子过程”)。

In order to use this DLL, we have to compile it by pressing **Ctrl+F9**. This should create a DLL called *SimpleMessageDLL.DLL* in your projects folder.

为了使用此DLL，我们必须按**Ctrl + F9**进行编译。 这应该在您的项目文件夹中创建一个名为*SimpleMessageDLL.DLL*的DLL。

Finally, let's take a look at how to call the DllMessage procedure from a statically loaded DLL.

最后，让我们看一下如何从静态加载的DLL中调用DllMessage过程。

To import a procedure contained in a DLL, you can use the keyword *external* in the procedure declaration. For example, given the DllMessage procedure shown above, the declaration in the calling application would look like this:

要导入DLL中包含的过程，可以在过程声明中使用关键字*external* 。 例如，给定上面显示的DllMessage过程，调用应用程序中的声明将如下所示：

procedure DllMessage; external 'SimpleMessageDLL.dll'

The actual call to a procedure is nothing more than:

对过程的实际调用无非是：

DllMessage;

The entire code for a Delphi form (name: *Form1*), with a TButton (named *Button1*) that calls the DLLMessage function, looks something like this:

具有调用DLLMessage函数的TButton(名为*Button1* )的Delphi表单(名称： *Form1* )的完整代码如下所示：

unit Unit1;

interface

uses

Windows, Messages, SysUtils, Variants, Classes,

Graphics, Controls, Forms, Dialogs, StdCtrls;

type

TForm1 = class(TForm)

Button1: TButton;

procedure Button1Click(Sender: TObject) ;private{ Private declarations }public{ Public declarations }end;

var

Form1: TForm1;

procedure DllMessage; external 'SimpleMessageDLL.dll'

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject) ;begin

DllMessage;

end;

end.

> 翻译自: [https://www.thoughtco.com/creating-and-using-dlls-from-delphi-1058459][https_www.thoughtco.com_creating-and-using-dlls-from-delphi-1058459]

delphi 创建dll

[Visual Basic]: https://www.thoughtco.com/visual-basic-4133468
[C_C]: https://www.thoughtco.com/c-and-c-plus-programming-4133470
[project file]: https://www.thoughtco.com/understanding-delphi-project-files-dpr-1057652
[https_www.thoughtco.com_creating-and-using-dlls-from-delphi-1058459]: https://www.thoughtco.com/creating-and-using-dlls-from-delphi-1058459