Delphi_ShareMem在dll中使用

2017/05/09 15:27
阅读数 769

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。

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