Delphi_ShareMem在dll中使用

原文链接

Delphi ShareMem在dll中使用

千里之行_12 2017-05-06 22:42:06 浏览39 评论0

string dll delphi ShareMem在dll中使用

摘要： Delphi ShareMem在dll中使用

dll项目

library Project2;

{ Important note about DLL memory management: ShareMem must be the
first unit in your library's USES clause AND your project's (select
Project-View Source) USES clause if your DLL exports any procedures or
functions that pass strings as parameters or function results. This
applies to all strings passed to and from your DLL--even those that
are nested in records and classes. ShareMem is the interface unit to
the BORLNDMM.DLL shared memory manager, which must be deployed along
with your DLL. To avoid using BORLNDMM.DLL, pass string information
using PChar or ShortString parameters. }

uses
System.ShareMem,
System.SysUtils,
System.Classes,
Winapi.Windows;

//简繁体装换函数
function Cn2Big(CnStr: string): string; stdcall ;
var
Len: Integer;
begin
Len := Length(CnStr);
SetLength(Result, Len);
LCMapString(GetUserDefaultLCID, LCMAP_TRADITIONAL_CHINESE, PChar(CnStr), Len, PChar(Result), Len);
end;

function Big2Cn(bigStr: string): string; stdcall ;
var
Len: Integer;
begin
Len := Length(bigStr);
SetLength(Result, Len);
LCMapString(GetUserDefaultLCID, LCMAP_SIMPLIFIED_CHINESE, PChar(bigStr), Len, PChar(Result), Len);
end;

{$R *.res}

exports
Cn2Big,
Big2Cn;

begin
end.

在项目中第一种调用方式：

type
TForm4 = class(TForm)
Button1: TButton;
edt1: TEdit;
edt2: TEdit;
Button2: TButton;
procedure Button1Click(Sender: TObject);
procedure Button2Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form4: TForm4;

function Cn2Big(CnStr: string): string; stdcall ; external 'Project2.dll';

implementation

{$R *.dfm}

procedure TForm4.Button1Click(Sender: TObject);
begin
edt2.Text :=  Cn2Big(edt1.Text);
end;

这种调用方式在dll和项目中都不用shareMem，不爆异常。

第二种调用方式（动态加载dll）：

procedure TForm4.Button2Click(Sender: TObject);
type
TAddc= function(const input: string): string; stdcall;
var
hh: THandle;
addc: TAddc;
begin
hh:= LoadLibrary('Project2.dll');
try
if hh<>0 then
@addc:= GetProcAddress(hh, PChar('Cn2Big'));
if not (@addc = nil) then
begin
edt2.Text :=  addc(edt1.Text);
end;
finally
FreeLibrary(hh);
end;
end;

在dll和项目中都不用shareMem，报异常。

在dll和项目中都用shareMem，不抛异常。