向窗体上添加一个TButton组件，它用于激活清空回收站的操作。
首先在程序的implementation段中定义3个常数和一个类型声明，代码如下：
const SHERB_NOCONFIRMATION = $00000001 ; SHERB_NOPROGRESSUI = $00000002 ; SHERB_NOSOUND = $00000004 ; type TSHEmptyRecycleBin= function(Wnd:HWND;LPCTSTR:PChar;DWORD:Word):Integer;stdcall;
程序运行初期，程序首先会通过LoadLibrary函数加载动态链接库Shell32.dll，并且把加载后的操作句柄存储在LibHandle中。然后通过@SHEmptyRecycleBin:=GetProcAddress (LibHandle, ’SHEmptyRecycleBinA’)语句读取SHEmptyRecycleBinA函数的地址，如果以上语句能够正确执行(也就是@SHEmptyRecycleBin不等于nil)，那么就调用SHEmptyRecycleBin完成清空回收站的操作。最后释放动态链接库。响应代码如下：
procedure TForm1.Button1Click(Sender: TObject); var SHEmptyRecycleBin:TSHEmptyRecycleBin; LibHandle:THandle; begin LibHandle := LoadLibrary(PChar(’Shell32.dll’)) ; if LibHandle <> 0 then begin @SHEmptyRecycleBin := GetProcAddress(LibHandle, ’SHEmptyRecycleBinA’); end else begin MessageDlg(’Failed to load Shell32.dll.’, mtError, [mbOK], 0); Exit ; end ; if @SHEmptyRecycleBin <> nil then begin SHEmptyRecycleBin(Application.Handle,’’,SHERB_NOCONFIRMATION or SHERB_NOPROGRESSUI or SHERB_NOSOUND) ; end; FreeLibrary(LibHandle); @SHEmptyRecycleBin := nil ; end; 程序代码如下： 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; implementation const SHERB_NOCONFIRMATION = $00000001 ; SHERB_NOPROGRESSUI = $00000002 ; SHERB_NOSOUND = $00000004 ; type TSHEmptyRecycleBin=function(Wnd:HWND;LPCTSTR:PChar;DWORD:Word):Integer;stdcall; {$R *.dfm} procedure TForm1.Button1Click(Sender: TObject); var SHEmptyRecycleBin:TSHEmptyRecycleBin; LibHandle:THandle; begin LibHandle := LoadLibrary(PChar(’Shell32.dll’)) ; if LibHandle <> 0 then begin @SHEmptyRecycleBin := GetProcAddress(LibHandle, ’SHEmptyRecycleBinA’); end else begin MessageDlg(’Failed to load Shell32.dll.’, mtError, [mbOK], 0); Exit ; end ; if @SHEmptyRecycleBin <> nil then begin SHEmptyRecycleBin(Application.Handle,’’,SHERB_NOCONFIRMATION or SHERB_NOPROGRESSUI or SHERB_NOSOUND) ; end; FreeLibrary(LibHandle); @SHEmptyRecycleBin := nil ; end; end.
（T127）
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