加载远程映像时出现Delphi异常错误
嗨,我有以下代码:加载远程映像时出现Delphi异常错误,delphi,Delphi,嗨,我有以下代码: procedure TformInvoiceDetails.ReadWebImage(imgAddress: string); var memStream: TMemoryStream; begin memStream := TMemoryStream.Create; try IdHTTP1.Get (imgAddress,memStream); //sleep(5000); except imageContProduct.Visibl
procedure TformInvoiceDetails.ReadWebImage(imgAddress: string);
var
memStream: TMemoryStream;
begin
memStream := TMemoryStream.Create;
try
IdHTTP1.Get (imgAddress,memStream);
//sleep(5000);
except
imageContProduct.Visible := false;
ShowMessage('Image not found at:'+imgAddress);
memStream.Free;
exit;
end;
try
memStream.Position := 0;
imageContProduct.Visible := true;
imageContProduct.Bitmap.LoadFromStream(memStream);
finally
memStream.Free;
end;
end;
大多数情况下,它工作正常,但我不断得到一个验证错误,有时一个“图像未在”虽然图像确实存在
如果我把钥匙放好,一切正常
因此,在我尝试添加到TImage之前,我假设尚未收到该图像
有更好的方法吗?您可以使用其他组件加载图片:
uses WinInet, JPEG;
...
function DownloadToStream(Url: string; Stream: TStream): Boolean;
var
hNet: HINTERNET;
hUrl: HINTERNET;
Buffer: array[0..10240] of Char;
BytesRead: DWORD;
begin
Result := FALSE;
hNet := InternetOpen('agent', INTERNET_OPEN_TYPE_PRECONFIG, nil, nil, 0);
if (hNet <> nil) then
begin
hUrl := InternetOpenUrl(hNet, PChar(Url), nil, 0,
INTERNET_FLAG_RELOAD, 0);
if (hUrl <> nil) then
begin
while (InternetReadFile(hUrl, @Buffer, sizeof(Buffer), BytesRead)) do
begin
if (BytesRead = 0) then
begin
Result := TRUE;
break;
end;
Stream.WriteBuffer(Buffer,BytesRead);
end;
InternetCloseHandle(hUrl);
end;
InternetCloseHandle(hNet);
end;
end;
procedure TformInvoiceDetails.ReadWebImage(imgAddress: string);
var
memStream: TMemoryStream;
Jpg:= TJPEGImage;
begin
memStream:= TMemoryStream.Create;
try
if DownloadToStream(imgAddress, memStream) then
begin
memStream.Seek(0, soFromBeginning);
if (LowerCase(RightStr(imgAddress, 4))='.jpg') or (LowerCase(RightStr(imgAddress, 5))='.jpeg')
try //do the same operation for *.png
Jpg:= TJPEGImage.Create;
Jpg.LoadFromStream(memStream);
imageContProduct.Picture.Bitmap.Assign(Jpg);
imageContProduct.Visible := true;
finally
Jpg.Free;
end
else
try
imageContProduct.Picture.Bitmap.LoadFromStream(memStream);
imageContProduct.Visible := true;
finally
end;
end;
finally
memStream.Free;
end;
end;
那么,您在异常中丢弃了诊断信息,因此,…..在地址01014323处的访问冲突。。。读取地址00000030在您的问题图像中报告的错误在。。。是您自己的错误消息。正如所指出的,异常处理程序完全忽略了实际的异常,只是假设没有找到您的映像,而事实上,它可能是其他的。现在你提到访问冲突。这就是你在这里发现的例外吗?调试时断点正是在这里停止的吗?我的建议是花一些时间改进调试skills@Frank读取地址00000030-访问接近0的地址通常意味着某个地方正在使用nil指针