Delphi處理高速檔案上傳下載的代碼及思路-有解無憂

Delphi處理高速檔案上傳下載的代碼及思路

上傳和下載是一對方向不同的概念，下面對應的客戶端和服務器代碼：掉個頭，它就是下載；再掉個頭，它就是上傳，

一、思路

1、將大檔案：分段（即常說的“斷點”上傳或下載）上傳或下載

2、分別上傳或下載這些分段

3、將上傳或下載后的各“分段”檔案流合并還原

4、關于加速（網上你經常看到“高速”上傳或下載）：若多執行緒分別上傳或下載這些分段，即可提速，

你們去使用高勇老師的代碼，它是完全無問題；這里僅僅給大家提供一種提速的方案，高勇老師的代碼，你按照這個思路稍作改裝，即可高速上傳或下載，

二、代碼

2.1、客戶端：

  ///<summary>RestFull上傳檔案函式(檔案流方法)：
    ///上傳單個檔案(TFileStream實體化抽象流:檔案分段傳參給服務器):
  ///</summary>
function CopyFileTFileStream(const Path: string;
    const BufSize :Integer= (13*1024*1024); //Buffer大小默認值13MB
    const ServerPath:string='api\upload\';
    const ServerFileName:string='A1.pdf' ):string;  
var Buffer: TBytes; ReadCount,FileSize,FileBufferCount,iCircle: Integer;
    ATStream,AWriteStream: TFileStream; ACopyStream:TStream;
    AResultStr:string; ifResult: Boolean;
begin
  if (Path.Trim='') 
    or (ServerPath.Trim='') 
    or (ServerFileName.Trim='') then
  begin
    AResultStr:='檔案不能為空！';
    Result := AResultStr ;  
    exit;  
  end;
  if FileExists(Path) =true then
  begin
    AResultStr:='檔案存在！';
    //AWriteStream:讀本地大檔案的流:
    AWriteStream := TFileStream.Create( Path,fmOpenRead );
    iCircle:=ceil( AWriteStream.Size /BufSize );
      //:分幾段讀取,就寫幾個臨時檔案.tmp:

    //大檔案：已知大于最小設定值,則分段讀取,直到讀完為止:
    if AWriteStream.Size > BufSize then
      //:不能用FileSize顯式的判斷
    begin //:需要分資料包處理，如果是服務端是Datasnap默認32k的緩沖區(快取，太JB小啦):
      //檔案流無需SetSize,而是設定其Buffer:TBytes位元組陣列的長度://SetLength(Buffer, BufSize);
      SetLength( Buffer,(500*1024*1024) ); 
        //$F000;//$F000:61440:60kb//:System.Classes.fmCreate
        //:印象中好像最大緩沖區就這個大小，你自己核實吧，500兆我夠了
      FileBufferCount:=0;  FileSize:=BufSize;
      AResultStr:=''; 

      for FileBufferCount := 1 to iCircle do
      begin  //檔案流無需SetSize:
        //ATStream:將大檔案流AWriteStream拆分成:
          //三位數的小臨時檔案.tmp的檔案流：
        ACopyStream:= TMemoryStream.Create;
        {ATStream:=TFileStream.Create( Path
            + FillBeforeString(IntToStr(FileBufferCount),3,'0')+'.tmp',
          fmCreate );
        try
        finally
          ATStream.disposeOf;
        end;//}
        ATStream:=TFileStream.Create( Path
          +FillBeforeString(IntToStr(FileBufferCount),3,'0')+'.tmp'
          ,fmCreate or fmOpenReadWrite);//:FillBeforeString:自寫函式,字串末尾向左補齊字符
          //:檔案流,沒有就產生、有就打開
        try
          if FileSize < AWriteStream.Size then FileSize:= BufSize;
          if FileSize >= AWriteStream.Size then
            FileSize:=AWriteStream.Size - (iCircle-1) * BufSize;
          ReadCount := AWriteStream.Read( Buffer[0], FileSize );

          AResultStr:=AResultStr+','+IntToStr(FileSize); 

          if ReadCount > 0 then
            ATStream.WriteBuffer(Buffer[0], ReadCount);
          ACopyStream.CopyFrom(ATStream,0);
            //:ACopyStream:由CopyFrom的呼叫者自己來釋放
          try 
            ifResult:=ServerMethods
             .upLoadFileFromTStreamBufferRead(ACopyStream,( ServerPath +ServerFileName
                +FillBeforeString(IntToStr(FileBufferCount),3,'0')+'.tmp') );
            //:服務器方法成功執行需要時間:
            //while ifResult<>true do sleep(0);//:需要的場景才這樣做
          except
            AWriteStream.disposeOf; ATStream.disposeOf; ACopyStream.disposeOf; 
            Result := '流加載錯誤'; exit;
          end;  
          FileSize:=FileSize + BufSize;
        finally
          //傳完該臨時分段檔案流釋放它的句柄，并洗掉它對應的臨時檔案:
          ATStream.disposeOf; 
          System.IOUtils.TFile.Delete(Path
            +FillBeforeString(IntToStr(FileBufferCount),3,'0')+'.tmp');
        end;
      end;
      //確保:全部臨時分段檔案流處理完成之后,發出合并檔案請求，
        //將分段檔案流還原為原始檔案:
      if ifResult=true then
      begin 
        try 
          ifResult:=ServerMethods
           .mergeFilesUseTFileStream(ServerPath + ServerFileName);
          //while ifResult <>true do sleep(0);//:服務器方法成功執行需要時間,需要的場景才做
        except
          AWriteStream.disposeOf; ATStream.disposeOf; ACopyStream.disposeOf; 
          Result := '檔案流合并錯誤'; exit;
        end;
        AResultStr:=  '檔案上傳成功';
        AWriteStream.disposeOf;
      end;
    end else
    begin
      //小檔案：已知小于最小設定值,則直接復制資料:
      ACopyStream:= TMemoryStream.Create;
      ACopyStream.CopyFrom(AWriteStream,0);
      try  
        ifResult:=ServerMethods
         .upLoadFileFromTStreamBufferRead( ACopyStream,(ServerPath+ServerFileName) );
        //:服務器方法成功執行需要時間
        //while ifResult<>true do sleep(0);//:需要的場景才這樣做
        AResultStr:=IntToStr(AWriteStream.Size);
      except
        AWriteStream.disposeOf; ACopyStream.disposeOf; 
        Result := '服務器出錯了'; exit;
      end;
      if ifResult=true then
      begin
        AResultStr:= '檔案上傳成功';
        AWriteStream.disposeOf; 
      end;
    end;

  end else AResultStr:='檔案不存在！';

  System.IOUtils.TDirectory.SetCurrentDirectory
    (System.IOUtils.TPath.GetLibraryPath);

  Result := AResultStr ;
end;

2.2、服務端上傳的接收流、合并檔案流：

function mergeFilesUseTFileStream(const toFilePath:string): Boolean;
var filesCount:Integer; SearchRec: TSearchRec; currPath:string;
  fileName:string; filesName:TStringList; 
  FileTStream,tmpTStream:TStream;
begin
  TDirectory.SetCurrentDirectory(System.IOUtils.TPath.GetLibraryPath);
  fileName:=System.IOUtils.TPath.GetLibraryPath + toFilePath;
  if TDirectory.Exists(TDirectory.GetParent(fileName)) then
  begin
    currPath:=TDirectory.GetParent(fileName);
    TDirectory.SetCurrentDirectory(currPath);
      //:進入該路徑（設定當前路徑并進入）
    if FileExists(fileName)=true then TFile.Delete(fileName);
  end;
  filesCount := FindFirst(currPath + '\' + '*.tmp', faAnyFile, SearchRec);//:搜索成功回傳0
  if filesCount<>0 then
  begin
    System.SysUtils.FindClose(SearchRec);//?不識別:需要帶上前綴:System.SysUtils.
    TDirectory.SetCurrentDirectory(System.IOUtils.TPath.GetLibraryPath);
    Result :=false; exit;
  end;                      
  FileTStream:=TFileStream.Create(fileName,fmCreate);
  filesName:=TStringList.Create;

  while filesCount = 0 do
  begin
    filesName.Add(SearchRec.Name);
    tmpTStream:=TFileStream.Create(SearchRec.Name,fmOpenRead);
    try
      Vcl.Forms.Application.ProcessMessages;
        //:不卡界面：將執行緒池TServerMethods1的訊息事件交給應用的主執行緒
        //:本函式：如果用于客戶端，下面兩句的處理，請使用執行緒同步TThread.Synchronize（服務端也可這樣），因為硬碟IO需要確切的時間來處理完畢：
      FileTStream.CopyFrom(tmpTStream,0);
      filesCount := FindNext(SearchRec);
    finally
      tmpTStream.Free; 
    end;
  end;
  try
    for filesCount := 0 to filesName.Count-1 do
    begin
      if FileExists(filesName[filesCount].Trim)=true then System.IOUtils.TFile.Delete(filesName[filesCount].Trim);
    end;
  finally
    System.SysUtils.FindClose(SearchRec);//?不識別:需要帶上前綴:System.SysUtils.
    filesName.Free; FileTStream.Free; 
    TDirectory.SetCurrentDirectory(System.IOUtils.TPath.GetLibraryPath);
  end;
    //幾個常用的路徑方法:
    //強制路徑產生：//ForceDirectories(currPath) ;uses System.SysUtils;
    //DirectoryExists:路徑是否存在uses System.SysUtils;
    //FileExists:檔案是否存在:uses System.SysUtils;
    //設定當前（進入該）路徑：TDirectory.SetCurrentDirectory(Path);
    //路徑中是否什么檔案都沒有：TDirectory.IsEmpty(Path)
    //是同級的路徑：TDirectory.IsRelativePath(Path)
    //移動檔案夾：TDirectory.Move(const SourceDirName, DestDirName: string)
  Result :=true;
end;

2.2、服務端：

/// <summary>大檔案上傳到服務器的函式；
   ///引數為檔案資料流和服務器端應用庫路徑下的子路徑 </summary>
function TServerMethods1.upLoadFileFromTStreamBufferRead(
    const ATStream:TStream; const toFilePath:string): Boolean;
const BufSize = $F000; //:BufferSize //System.Classes.fmCreate
var Buffer: TBytes; ReadCount,times: Integer; FS: TFileStream;
begin
  if FileExists(toFilePath)=true then
  begin
    TThread.Synchronize(nil,
    procedure
    begin
      TFile.Delete(toFilePath);
      MainServerForm.Memo_Errors.Lines.Add('洗掉檔案:'+toFilePath.Trim);
    end
    );
  end;//:存在就先洗掉
  //洗掉后然后產生新檔案:
  FS := TFileStream.Create(toFilePath, System.Classes.fmCreate); 
    //:常量默認fmCreate = $FF00; //: TFileStream create mode
  TThread.Synchronize(nil,
  procedure
  begin//測驗:
    //MainServerForm.Memo_Errors.Lines.Add('新產生檔案:'+toFilePath.Trim);
  end
  );

  try
    //if ATStream.Size = -1 then//:大小未知則一直讀取到沒有資料為止:
    begin
      SetLength( Buffer, BufSize );
      repeat
        ReadCount := ATStream.Read( Buffer[0], BufSize );
        if ReadCount > 0 then
          FS.WriteBuffer( Buffer[0], ReadCount );
        if ReadCount < BufSize then
          break;
      until ReadCount < BufSize;
    end //else FS.CopyFrom(ATStream, 0)
    ; //:大小已知則直接復制資料
  finally
    FS.Free;
    Result := True;
  end;
end;


/// <summary>多檔案流合并(用檔案流方法實體化抽象流):</summary>
function TServerMethods1.mergeFilesUseTFileStream(const toFilePath:string): Boolean;
var filesCount :Integer;  SearchRec :TSearchRec;  currPath :string;
  fileName :string;  filesName :TStringList; 
  FileTStream,tmpTStream :TStream;
begin
  TDirectory.SetCurrentDirectory(System.IOUtils.TPath.GetLibraryPath);
  fileName:=System.IOUtils.TPath.GetLibraryPath + toFilePath;
  if TDirectory.Exists(TDirectory.GetParent(fileName)) then
  begin
    currPath:=TDirectory.GetParent(fileName);
      //強制路徑產生：//ForceDirectories(currPath) 
      //DirectoryExists:路徑是否存在//FileExists:檔案是否存在:uses System.SysUtils;
    TDirectory.SetCurrentDirectory(currPath);
      //:進入該路徑（設定當前路徑并進入）
    if FileExists(fileName)=true then TFile.Delete(fileName);
  end;
  filesCount := FindFirst(currPath + '\' + '*.tmp', faAnyFile, SearchRec);//:搜索成功回傳0
  if filesCount<>0 then
  begin
    System.SysUtils.FindClose(SearchRec);//?不識別:需要帶上前綴:System.SysUtils.
    TDirectory.SetCurrentDirectory(System.IOUtils.TPath.GetLibraryPath);
    Result :=false; exit;
  end;     
  FileTStream:=TFileStream.Create(fileName,fmCreate);
  filesName:=TStringList.Create;
 
  while filesCount = 0 do
  begin
    filesName.Add(SearchRec.Name);
    tmpTStream:=TFileStream.Create(SearchRec.Name,fmOpenRead);
    try
      //Vcl.Forms.Application.ProcessMessages;
        //:不卡界面：VCL將執行緒池TServerMethods1的訊息事件交給應用的主執行緒
        //:不卡界面：FMX用執行緒同步方法TThread.Synchronize
      FileTStream.CopyFrom(tmpTStream,0);
      filesCount := FindNext(SearchRec);
    finally
      tmpTStream.disposeOf;  
    end;
  end;
  try
    for filesCount := 0 to filesName.Count-1 do
    begin
      if FileExists(filesName[filesCount].Trim)=true then
        TFile.Delete(filesName[filesCount].Trim);
    end;
  finally
    System.SysUtils.FindClose(SearchRec);//?不識別:需要帶上前綴:System.SysUtils.
    filesName.disposeOf;  FileTStream.disposeOf; 
    TDirectory.SetCurrentDirectory(System.IOUtils.TPath.GetLibraryPath);
  end;

  Result :=true;
end;

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