德尔福 SOAP : delete temporary file after response dispatched

Question

我有一个 SOAP 方法，可以即时创建并响应 PDF 内容。

在方法finally上，临时pdf文件被删除。

它终于是执行此操作的正确位置吗？

procedure TWbModule.WbModuleGetPDFAction(Sender: TObject; Request: TWebRequest; Response: TWebResponse; var Handled: Boolean);
var
    aPDFFileTemp : string;
begin
    try
        // getTempPdf() creates and returns the PDF path, eg.: C:\files\foo.pdf
        aPDFFileTemp := getTempPdf();

        // set response content stream with file stream
        Response.ContentStream := TFileStream.Create(aPDFFileTemp, fmOpenRead or fmShareDenyNone);
        Response.ContentType   := 'application/pdf';
    finally
        // delete temporary file
        // It is the right place for perform this operation?
        if FileExists(aPDFFileTemp) then DeleteFile(aPDFFileTemp );
    end;
end;

Answer 1

如果您只想拥有一个临时文件，那么您应该将其创建为临时文件。

此类创建一个带有临时且自毁文件的流。

uses
  System.Classes;

type
  TTempFileStream = class( THandleStream )
  public
    constructor Create( );
    destructor Destroy; override;
  end;

implementation

uses
  System.IOUtils,
  System.SysUtils,
  Winapi.Windows;

{ TTempFileStream }

constructor TTempFileStream.Create;
var
  fileName  : string;
  fileHandle: THandle;
begin
  fileName := TPath.GetTempFileName( );

  fileHandle := CreateFile(
    PChar( fileName ),
    GENERIC_ALL,
    0,
    nil,
    CREATE_ALWAYS,
    FILE_ATTRIBUTE_TEMPORARY or FILE_FLAG_DELETE_ON_CLOSE,
    0 );
  if fileHandle = INVALID_HANDLE_VALUE
  then
    RaiseLastOSError( GetLastError, sLineBreak + fileName );
  inherited Create( fileHandle );
end;

destructor TTempFileStream.Destroy;
begin
  CloseHandle( Handle );
  inherited;
end;

最好的选择是将数据(PDF 内容)写入此 TTempFileStream 并从 getTempPdf() 返回实例

function getTempPdf() : TStream;
begin
  Result := TTempFileStream.Create;
  // create the PDF document and write into the result stream
end;

procedure TWbModule.WbModuleGetPDFAction(Sender: TObject; Request: TWebRequest; Response: TWebResponse; var Handled: Boolean);
begin
  Response.ContentStream := getTempPdf();
  Response.ContentType   := 'application/pdf';
end;

发送响应后，流将被释放，文件将被删除。