Delphi System.net.HTTPClient: 读取数据时出错 (12002) 操作超时
Delphi System.net.HTTPClient: Error reading data (12002) The operation timed out
我使用 System.net.HTTPClient 在 Berlin Update 2 上使用此设备从 AWS S3 下载大文件（>500 MB）：
unit AcHTTPClient;
interface
uses
System.Net.URLClient, System.net.HTTPClient;
type
TAcHTTPProgress = procedure(const Sender: TObject; AStartPosition : Int64; AEndPosition: Int64; AContentLength: Int64; AReadCount: Int64; ATimeStart : Int64; ATime : Int64; var Abort: Boolean) of object;
TAcHTTPClient = class
private
FOnProgress: TAcHTTPProgress;
FHTTPClient: THTTPClient;
FTimeStart: cardinal;
FCancelDownload: boolean;
FStartPosition: Int64;
FEndPosition: Int64;
FContentLength: Int64;
private
procedure SetProxySettings(AProxySettings: TProxySettings);
function GetProxySettings : TProxySettings;
procedure OnReceiveDataEvent(const Sender: TObject; AContentLength: Int64; AReadCount: Int64; var Abort: Boolean);
public
constructor Create;
destructor Destroy; override;
property ProxySettings : TProxySettings read FProxySettings write SetProxySettings;
property OnProgress : TAcHTTPProgress read FOnProgress write FOnProgress;
property CancelDownload : boolean read FCancelDownload write FCancelDownload;
function Download(const ASrcUrl : string; const ADestFileName : string): Boolean;
end;
implementation
uses
System.Classes, System.SysUtils, Winapi.Windows;
constructor TAcHTTPClient.Create;
// -----------------------------------------------------------------------------
// Constructor
begin
inherited Create;
// create an THTTPClient
FHTTPClient := THTTPClient.Create;
FHTTPClient.OnReceiveData := OnReceiveDataEvent;
// setting the timeouts
FHTTPClient.ConnectionTimeout := 5000;
FHTTPClient.ResponseTimeout := 15000;
// initialize the class variables
FCancelDownload := false;
FOnProgress := nil;
FEndPosition := -1;
FStartPosition := -1;
FContentLength := -1;
end;
destructor TAcHTTPClient.Destroy;
// -----------------------------------------------------------------------------
// Destructor
begin
FHTTPClient.free;
inherited Destroy;
end;
procedure TAcHTTPClient.SetProxySettings(AProxySettings: TProxySettings);
// -----------------------------------------------------------------------------
// Set FHTTPClient.ProxySettings with AProxySettings
begin
FHTTPClient.ProxySettings := AProxySettings;
end;
function TAcHTTPClient.GetProxySettings : TProxySettings;
// -----------------------------------------------------------------------------
// Get FHTTPClient.ProxySettings
begin
Result := FHTTPClient.ProxySettings;
end;
procedure TAcHTTPClient.OnReceiveDataEvent(const Sender: TObject; AContentLength: Int64; AReadCount: Int64; var Abort: Boolean);
// -----------------------------------------------------------------------------
// HTTPClient.OnReceiveDataEvent become OnProgress
begin
Abort := CancelDownload;
if Assigned(OnProgress) then
OnProgress(Sender, FStartPosition, FEndPosition, AContentLength, AReadCount, FTimeStart, GetTickCount, Abort);
end;
function TAcHTTPClient.Download(const ASrcUrl : string; const ADestFileName : string): Boolean;
// -----------------------------------------------------------------------------
// Download a file from ASrcUrl and store to ADestFileName
var
aResponse: IHTTPResponse;
aFileStream: TFileStream;
aTempFilename: string;
aAcceptRanges: boolean;
aTempFilenameExists: boolean;
begin
Result := false;
FEndPosition := -1;
FStartPosition := -1;
FContentLength := -1;
aResponse := nil;
aFileStream := nil;
try
// raise an exception if the file already exists on ADestFileName
if FileExists(ADestFileName) then
raise Exception.Create(Format('the file %s alredy exists', [ADestFileName]));
// reset the CancelDownload property
CancelDownload := false;
// set the time start of the download
FTimeStart := GetTickCount;
// until the download is incomplete the ADestFileName has *.parts extension
aTempFilename := ADestFileName + '.parts';
// get the header from the server for aSrcUrl
aResponse := FHTTPClient.Head(aSrcUrl);
// checks if the response StatusCode is 2XX (aka OK)
if (aResponse.StatusCode < 200) or (aResponse.StatusCode > 299) then
raise Exception.Create(Format('Server error %d: %s', [aResponse.StatusCode, aResponse.StatusText]));
// checks if the server accept bytes ranges
aAcceptRanges := SameText(aResponse.HeaderValue['Accept-Ranges'], 'bytes');
// get the content length (aka FileSize)
FContentLength := aResponse.ContentLength;
// checks if a "partial" download already exists
aTempFilenameExists := FileExists(aTempFilename);
// if a "partial" download already exists
if aTempFilenameExists then
begin
// re-utilize the same file stream, with position on the end of the stream
aFileStream := TFileStream.Create(aTempFilename, fmOpenWrite or fmShareDenyNone);
aFileStream.Seek(0, TSeekOrigin.soEnd);
end else begin
// create a new file stream, with the position on the beginning of the stream
aFileStream := TFileStream.Create(aTempFilename, fmCreate);
aFileStream.Seek(0, TSeekOrigin.soBeginning);
end;
// if the server doesn't accept bytes ranges, always start to write at beginning of the stream
if not(aAcceptRanges) then
aFileStream.Seek(0, TSeekOrigin.soBeginning);
// set the range of the request (from the stream position to server content length)
FStartPosition := aFileStream.Position;
FEndPosition := FContentLength;
// if the range is incomplete (the FStartPosition is less than FEndPosition)
if (FEndPosition > 0) and (FStartPosition < FEndPosition) then
begin
// ... and if a starting point is present
if FStartPosition > 0 then
begin
// makes a bytes range request from FStartPosition to FEndPosition
aResponse := FHTTPClient.GetRange(aSrcUrl, FStartPosition, FEndPosition, aFileStream);
end else begin
// makes a canonical GET request
aResponse := FHTTPClient.Get(aSrcUrl, aFileStream);
end;
// check if the response StatusCode is 2XX (aka OK)
if (aResponse.StatusCode < 200) or (aResponse.StatusCode > 299) then
raise Exception.Create(Format('Server error %d: %s', [aResponse.StatusCode, aResponse.StatusText]));
end;
// if the FileStream.Size is equal to server ContentLength, the download is completed!
if (aFileStream.Size > 0) and (aFileStream.Size = FContentLength) then begin
// free the FileStream otherwise doesn't renames the "partial file" into the DestFileName
FreeAndNil(aFileStream);
// renames the aTempFilename file into the ADestFileName
Result := RenameFile(aTempFilename, ADestFileName);
// What?
if not(Result) then
raise Exception.Create(Format('RenameFile from %s to %s: %s', [aTempFilename, ADestFileName, SysErrorMessage(GetLastError)]));
end;
finally
if aFileStream <> nil then aFileStream.Free;
aResponse := nil;
end;
end;
end.
有时我会看到这个异常：
Error reading data: (12002) The operation timed out
我在 System.NetConsts.pas:
中找到了这个错误字符串
SNetHttpRequestReadDataError = 'Error reading data: (%d) %s';
并且错误被引发到 System.Net.HttpClient.Win.pas（参见 @SNetHttpRequestReadDataError）：
procedure TWinHTTPResponse.DoReadData(const AStream: TStream);
var
LSize: Cardinal;
LDownloaded: Cardinal;
LBuffer: TBytes;
LExpected, LReaded: Int64;
LStatusCode: Integer;
Abort: Boolean;
begin
LReaded := 0;
LExpected := GetContentLength;
if LExpected = 0 then
LExpected := -1;
LStatusCode := GetStatusCode;
Abort := False;
FRequestLink.DoReceiveDataProgress(LStatusCode, LExpected, LReaded, Abort);
if not Abort then
repeat
// Get the size of readed data in LSize
if not WinHttpQueryDataAvailable(FWRequest, @LSize) then
raise ENetHTTPResponseException.CreateResFmt(@SNetHttpRequestReadDataError, [GetLastError, SysErrorMessage(GetLastError, FWinHttpHandle)]);
if LSize = 0 then
Break;
SetLength(LBuffer, LSize + 1);
if not WinHttpReadData(FWRequest, LBuffer[0], LSize, @LDownloaded) then
raise ENetHTTPResponseException.CreateResFmt(@SNetHttpRequestReadDataError, [GetLastError, SysErrorMessage(GetLastError, FWinHttpHandle)]);
// This condition should never be reached since WinHttpQueryDataAvailable
// reported that there are bits to read.
if LDownloaded = 0 then
Break;
AStream.WriteBuffer(LBuffer, LDownloaded);
LReaded := LReaded + LDownloaded;
FRequestLink.DoReceiveDataProgress(LStatusCode, LExpected, LReaded, Abort);
until (LSize = 0) or Abort;
end;
是什么导致了这个错误？
您可以尝试将 ConnectTimeout、SendTimeout 和 ReceiveTimeout 增加到 15000 以上吗？例如说 300000（5 分钟）
即：
FHTTPClient.ConnectionTimeout := 300000;
FHTTPClient.ResponseTimeout := 300000;
我使用 System.net.HTTPClient 在 Berlin Update 2 上使用此设备从 AWS S3 下载大文件（>500 MB）：
unit AcHTTPClient;
interface
uses
System.Net.URLClient, System.net.HTTPClient;
type
TAcHTTPProgress = procedure(const Sender: TObject; AStartPosition : Int64; AEndPosition: Int64; AContentLength: Int64; AReadCount: Int64; ATimeStart : Int64; ATime : Int64; var Abort: Boolean) of object;
TAcHTTPClient = class
private
FOnProgress: TAcHTTPProgress;
FHTTPClient: THTTPClient;
FTimeStart: cardinal;
FCancelDownload: boolean;
FStartPosition: Int64;
FEndPosition: Int64;
FContentLength: Int64;
private
procedure SetProxySettings(AProxySettings: TProxySettings);
function GetProxySettings : TProxySettings;
procedure OnReceiveDataEvent(const Sender: TObject; AContentLength: Int64; AReadCount: Int64; var Abort: Boolean);
public
constructor Create;
destructor Destroy; override;
property ProxySettings : TProxySettings read FProxySettings write SetProxySettings;
property OnProgress : TAcHTTPProgress read FOnProgress write FOnProgress;
property CancelDownload : boolean read FCancelDownload write FCancelDownload;
function Download(const ASrcUrl : string; const ADestFileName : string): Boolean;
end;
implementation
uses
System.Classes, System.SysUtils, Winapi.Windows;
constructor TAcHTTPClient.Create;
// -----------------------------------------------------------------------------
// Constructor
begin
inherited Create;
// create an THTTPClient
FHTTPClient := THTTPClient.Create;
FHTTPClient.OnReceiveData := OnReceiveDataEvent;
// setting the timeouts
FHTTPClient.ConnectionTimeout := 5000;
FHTTPClient.ResponseTimeout := 15000;
// initialize the class variables
FCancelDownload := false;
FOnProgress := nil;
FEndPosition := -1;
FStartPosition := -1;
FContentLength := -1;
end;
destructor TAcHTTPClient.Destroy;
// -----------------------------------------------------------------------------
// Destructor
begin
FHTTPClient.free;
inherited Destroy;
end;
procedure TAcHTTPClient.SetProxySettings(AProxySettings: TProxySettings);
// -----------------------------------------------------------------------------
// Set FHTTPClient.ProxySettings with AProxySettings
begin
FHTTPClient.ProxySettings := AProxySettings;
end;
function TAcHTTPClient.GetProxySettings : TProxySettings;
// -----------------------------------------------------------------------------
// Get FHTTPClient.ProxySettings
begin
Result := FHTTPClient.ProxySettings;
end;
procedure TAcHTTPClient.OnReceiveDataEvent(const Sender: TObject; AContentLength: Int64; AReadCount: Int64; var Abort: Boolean);
// -----------------------------------------------------------------------------
// HTTPClient.OnReceiveDataEvent become OnProgress
begin
Abort := CancelDownload;
if Assigned(OnProgress) then
OnProgress(Sender, FStartPosition, FEndPosition, AContentLength, AReadCount, FTimeStart, GetTickCount, Abort);
end;
function TAcHTTPClient.Download(const ASrcUrl : string; const ADestFileName : string): Boolean;
// -----------------------------------------------------------------------------
// Download a file from ASrcUrl and store to ADestFileName
var
aResponse: IHTTPResponse;
aFileStream: TFileStream;
aTempFilename: string;
aAcceptRanges: boolean;
aTempFilenameExists: boolean;
begin
Result := false;
FEndPosition := -1;
FStartPosition := -1;
FContentLength := -1;
aResponse := nil;
aFileStream := nil;
try
// raise an exception if the file already exists on ADestFileName
if FileExists(ADestFileName) then
raise Exception.Create(Format('the file %s alredy exists', [ADestFileName]));
// reset the CancelDownload property
CancelDownload := false;
// set the time start of the download
FTimeStart := GetTickCount;
// until the download is incomplete the ADestFileName has *.parts extension
aTempFilename := ADestFileName + '.parts';
// get the header from the server for aSrcUrl
aResponse := FHTTPClient.Head(aSrcUrl);
// checks if the response StatusCode is 2XX (aka OK)
if (aResponse.StatusCode < 200) or (aResponse.StatusCode > 299) then
raise Exception.Create(Format('Server error %d: %s', [aResponse.StatusCode, aResponse.StatusText]));
// checks if the server accept bytes ranges
aAcceptRanges := SameText(aResponse.HeaderValue['Accept-Ranges'], 'bytes');
// get the content length (aka FileSize)
FContentLength := aResponse.ContentLength;
// checks if a "partial" download already exists
aTempFilenameExists := FileExists(aTempFilename);
// if a "partial" download already exists
if aTempFilenameExists then
begin
// re-utilize the same file stream, with position on the end of the stream
aFileStream := TFileStream.Create(aTempFilename, fmOpenWrite or fmShareDenyNone);
aFileStream.Seek(0, TSeekOrigin.soEnd);
end else begin
// create a new file stream, with the position on the beginning of the stream
aFileStream := TFileStream.Create(aTempFilename, fmCreate);
aFileStream.Seek(0, TSeekOrigin.soBeginning);
end;
// if the server doesn't accept bytes ranges, always start to write at beginning of the stream
if not(aAcceptRanges) then
aFileStream.Seek(0, TSeekOrigin.soBeginning);
// set the range of the request (from the stream position to server content length)
FStartPosition := aFileStream.Position;
FEndPosition := FContentLength;
// if the range is incomplete (the FStartPosition is less than FEndPosition)
if (FEndPosition > 0) and (FStartPosition < FEndPosition) then
begin
// ... and if a starting point is present
if FStartPosition > 0 then
begin
// makes a bytes range request from FStartPosition to FEndPosition
aResponse := FHTTPClient.GetRange(aSrcUrl, FStartPosition, FEndPosition, aFileStream);
end else begin
// makes a canonical GET request
aResponse := FHTTPClient.Get(aSrcUrl, aFileStream);
end;
// check if the response StatusCode is 2XX (aka OK)
if (aResponse.StatusCode < 200) or (aResponse.StatusCode > 299) then
raise Exception.Create(Format('Server error %d: %s', [aResponse.StatusCode, aResponse.StatusText]));
end;
// if the FileStream.Size is equal to server ContentLength, the download is completed!
if (aFileStream.Size > 0) and (aFileStream.Size = FContentLength) then begin
// free the FileStream otherwise doesn't renames the "partial file" into the DestFileName
FreeAndNil(aFileStream);
// renames the aTempFilename file into the ADestFileName
Result := RenameFile(aTempFilename, ADestFileName);
// What?
if not(Result) then
raise Exception.Create(Format('RenameFile from %s to %s: %s', [aTempFilename, ADestFileName, SysErrorMessage(GetLastError)]));
end;
finally
if aFileStream <> nil then aFileStream.Free;
aResponse := nil;
end;
end;
end.
有时我会看到这个异常：
Error reading data: (12002) The operation timed out
我在 System.NetConsts.pas:
SNetHttpRequestReadDataError = 'Error reading data: (%d) %s';
并且错误被引发到 System.Net.HttpClient.Win.pas（参见 @SNetHttpRequestReadDataError）：
procedure TWinHTTPResponse.DoReadData(const AStream: TStream);
var
LSize: Cardinal;
LDownloaded: Cardinal;
LBuffer: TBytes;
LExpected, LReaded: Int64;
LStatusCode: Integer;
Abort: Boolean;
begin
LReaded := 0;
LExpected := GetContentLength;
if LExpected = 0 then
LExpected := -1;
LStatusCode := GetStatusCode;
Abort := False;
FRequestLink.DoReceiveDataProgress(LStatusCode, LExpected, LReaded, Abort);
if not Abort then
repeat
// Get the size of readed data in LSize
if not WinHttpQueryDataAvailable(FWRequest, @LSize) then
raise ENetHTTPResponseException.CreateResFmt(@SNetHttpRequestReadDataError, [GetLastError, SysErrorMessage(GetLastError, FWinHttpHandle)]);
if LSize = 0 then
Break;
SetLength(LBuffer, LSize + 1);
if not WinHttpReadData(FWRequest, LBuffer[0], LSize, @LDownloaded) then
raise ENetHTTPResponseException.CreateResFmt(@SNetHttpRequestReadDataError, [GetLastError, SysErrorMessage(GetLastError, FWinHttpHandle)]);
// This condition should never be reached since WinHttpQueryDataAvailable
// reported that there are bits to read.
if LDownloaded = 0 then
Break;
AStream.WriteBuffer(LBuffer, LDownloaded);
LReaded := LReaded + LDownloaded;
FRequestLink.DoReceiveDataProgress(LStatusCode, LExpected, LReaded, Abort);
until (LSize = 0) or Abort;
end;
是什么导致了这个错误？
您可以尝试将 ConnectTimeout、SendTimeout 和 ReceiveTimeout 增加到 15000 以上吗？例如说 300000（5 分钟）
即：
FHTTPClient.ConnectionTimeout := 300000;
FHTTPClient.ResponseTimeout := 300000;