Delphi - 需要XE2代码到Delphi7。使用wininet下载文件 [英] Delphi - XE2 code to Delphi7 needed. Using wininet to download a file

问题描述

注意：我只想使用wininet，而不是urlmon-urldownloadtofile。

Note: I only want to use wininet, not urlmon-urldownloadtofile.

嗯，我有以下代码在XE2中完美的下载文件： / p>

Well, I have the following code which works perfectly in XE2 to download a file:

procedure DownloadFile(URL: string; Path: string);
const
  BLOCK_SIZE = 1024;
var
  InetHandle: Pointer;
  URLHandle: Pointer;
  FileHandle: Cardinal;
  BytesRead: Cardinal;
  DownloadBuffer: Pointer;
  Buffer: array [1 .. BLOCK_SIZE] of byte;
  BytesWritten: Cardinal;
begin
  InetHandle := InternetOpen(PWideChar(URL), 0, 0, 0, 0);
  URLHandle := InternetOpenUrl(InetHandle, PWideChar(URL), 0, 0, 0, 0);
  FileHandle := CreateFile(PWideChar(Path), GENERIC_WRITE, FILE_SHARE_WRITE, 0,
CREATE_NEW, FILE_ATTRIBUTE_NORMAL, 0);
  DownloadBuffer := @Buffer;
  repeat
    InternetReadFile(URLHandle, DownloadBuffer, BLOCK_SIZE, BytesRead);
    if not WriteFile(FileHandle, DownloadBuffer, BytesRead, BytesWritten, 0) or
  (BytesWritten <> BytesRead) then
      RaiseLastOSError;
  until BytesRead < BLOCK_SIZE;
  CloseHandle(FileHandle);
  InternetCloseHandle(URLHandle);
  InternetCloseHandle(InetHandle);
end;

上述代码的学分转到 jachguate 。他编辑我的代码来纠正它，我感谢他。

The above code's credits go to jachguate. He edited my code to correct it, and I thank him for that.

现在，这段代码只能在Delphi XE2下正常工作。我试图在Delphi 7下使用它，它不能正常工作。似乎在文件中存储相同的行或字节序列超过几次。

Now, this code only works correctly under Delphi XE2. I try to use it under Delphi 7 and it is not working correctly. It seems to store the same "line" or "byte sequence" to the file over and over a few times.

以下是上述代码的两个重新设置已经考虑在Delphi 7中使用 - 这两个都不正常。

The following are the two reformations of the above code I have attemted to use in Delphi 7 - neither of which worked properly.

procedure DownloadFile(URL: string; Path: string);
const
  BLOCK_SIZE = 1024;
var
  InetHandle: Pointer;
  URLHandle: Pointer;
  FileHandle: Cardinal;
  BytesRead: Cardinal;
  DownloadBuffer: Pointer;
  Buffer: array [1 .. BLOCK_SIZE] of byte;
  BytesWritten: Cardinal;
begin
  InetHandle := InternetOpen(PChar(URL), 0, 0, 0, 0);
  URLHandle := InternetOpenUrl(InetHandle, PChar(URL), 0, 0, 0, 0);
  FileHandle := CreateFile(PChar(Path), GENERIC_WRITE, FILE_SHARE_WRITE, 0,
CREATE_NEW, FILE_ATTRIBUTE_NORMAL, 0);
  DownloadBuffer := @Buffer;
  repeat
    InternetReadFile(URLHandle, DownloadBuffer, BLOCK_SIZE, BytesRead);
    if not WriteFile(FileHandle, DownloadBuffer, BytesRead, BytesWritten, 0) or
  (BytesWritten <> BytesRead) then
      RaiseLastOSError;
  until BytesRead < BLOCK_SIZE;
  CloseHandle(FileHandle);
  InternetCloseHandle(URLHandle);
  InternetCloseHandle(InetHandle);
end;

---

---

procedure DownloadFile(URL: string; Path: string);
const
  BLOCK_SIZE = 1024;
var
  InetHandle: Pointer;
  URLHandle: Pointer;
  FileHandle: Cardinal;
  BytesRead: Cardinal;
  DownloadBuffer: Pointer;
  Buffer: array [1 .. BLOCK_SIZE] of byte;
  BytesWritten: Cardinal;
begin
  InetHandle := InternetOpen(PAnsiChar(URL), 0, 0, 0, 0);
  URLHandle := InternetOpenUrl(InetHandle, PAnsiChar(URL), 0, 0, 0, 0);
  FileHandle := CreateFile(PAnsiChar(Path), GENERIC_WRITE, FILE_SHARE_WRITE, 0,
CREATE_NEW, FILE_ATTRIBUTE_NORMAL, 0);
  DownloadBuffer := @Buffer;
  repeat
    InternetReadFile(URLHandle, DownloadBuffer, BLOCK_SIZE, BytesRead);
    if not WriteFile(FileHandle, DownloadBuffer, BytesRead, BytesWritten, 0) or
  (BytesWritten <> BytesRead) then
      RaiseLastOSError;
  until BytesRead < BLOCK_SIZE;
  CloseHandle(FileHandle);
  InternetCloseHandle(URLHandle);
  InternetCloseHandle(InetHandle);
end;

只有编辑的内容才是数据类型转换。例如使用PChar，并使用了两个PAnsiChar。

Only thing edited was the data type conversions. Example one "PChar" was used, and example two "PAnsiChar" was used.

推荐答案

您需要使用 ^ char来取消引用指针 DownloadBuffer ，因此要修复您的方法，只需替换此代码

You are getting garbage in the file because you need dereference the pointer DownloadBuffer using the ^ char, so to fix your method just replace this code

WriteFile(FileHandle, DownloadBuffer, BytesRead, BytesWritten, 0)

这个

WriteFile(FileHandle, DownloadBuffer^, BytesRead, BytesWritten, 0)

。

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