datasnap 上传/下载大文件(本Demo以图传片文件为例)

function TServerMethods1.DownLoadFile(AfileName: string): TStream;
const
SaveFolder = 'FSimage\';
defaultName = 'Default.png'; // 此文件必须有
//用默认文件处理不存在图片
var
ALLpath: string;
begin
ALLpath := LocalPath + SaveFolder + AfileName;
if not FileExists(ALLpath) then
ALLpath := LocalPath + SaveFolder + defaultName;
Result := TFileStream.Create(ALLpath, fmOpenRead);
Result.Position := ;
//此处也可以加错误处理 或 释放默认文件 再生成流
end;function TServerMethods1.PutFile(AfileName: string; Stream: TStream): Boolean;
const
BufSize = $F000;
SaveFolder = 'FSimage\';
var
Buffer: TBytes;
ReadCount: Integer;
FS: TFileStream;
begin
if not DirectoryExists(LocalPath + SaveFolder) then
CreateDir(LocalPath + SaveFolder);
FS := TFileStream.Create(LocalPath + SaveFolder + AfileName, FmCreate);
try
if Stream.Size = - then // 大小未知则一直读取到没有数据为止
begin
SetLength(Buffer, BufSize);
repeat
ReadCount := Stream.Read(Buffer[], BufSize);
if ReadCount > then
FS.WriteBuffer(Buffer[], ReadCount);
if ReadCount < BufSize then
break;
until ReadCount < BufSize;
end
else // 大小已知则直接复制数据
FS.CopyFrom(Stream, );
Result := True;
finally
FS.Free;
end;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
cs: TServerMethods1Client;
memoryStream: TMemoryStream;
begin
cs := TServerMethods1Client.Create(self.SQLConnection1.DBXConnection);
try
memoryStream := TMemoryStream.Create;
try
// Image1.Picture.Graphic.SaveToStream(memoryStream);
SaveAs(Image1.Picture.Graphic, memoryStream, gptPNG);
memoryStream.Position := ;
// memoryStream.Seek(, TSeekOrigin.soBeginning);
if cs.PutFile('1.png', memoryStream) then
ShowMessage('保存成功')
else
ShowMessage('保存失败');
finally
if memoryStream <> nil then
memoryStream := nil;
end;
finally
cs.free;
end;
end;procedure TForm1.Button2Click(Sender: TObject);
begin
DownLoadfs(Image1.Picture,'1.png')
end;procedure TForm1.DownLoadfs(Ggs:TPicture;fsName: string);
const
BufSize = $F000;
var
Stream, FS: TStream;
cs: TServerMethods1Client;
syn: TSynPicture;
Buffer: TBytes;
ReadCount: Integer;
begin
cs := TServerMethods1Client.Create(self.SQLConnection1.DBXConnection);
try
Stream := cs.DownLoadFile(fsName);
FS := TMemoryStream.Create;
try
if Stream.Size = - then // 大小未知则一直读取到没有数据为止
begin
SetLength(Buffer, BufSize);
repeat
ReadCount := Stream.Read(Buffer[], BufSize);
if ReadCount > then
FS.WriteBuffer(Buffer[], ReadCount);
if ReadCount < BufSize then
break;
until ReadCount < BufSize;
end
else // 大小已知则直接复制数据
FS.CopyFrom(Stream, );
syn := TSynPicture.Create;
try
syn.LoadFromStream(FS);
Ggs.Assign(syn);
finally
syn.free;
end;
finally
FS.free;
end;
finally
cs.free;
end;end;procedure TForm1.FormCreate(Sender: TObject);
begin
self.SQLConnection1.Connected := True;
gdip := TGDIPlusFull.Create('gdiplus.dll');
end;procedure TForm1.Image1DblClick(Sender: TObject);
var
syn: TSynPicture;
begin
if self.OpenDialog1.Execute then
begin
if self.OpenDialog1.FileName = '' then
Exit
else
begin
syn := TSynPicture.Create;
try
syn.LoadFromFile(self.OpenDialog1.FileName);
self.Image1.Picture.Assign(syn);
finally
syn.free;
end;
end;
end;
end;