[英]HTTP POST with Wininet API on Delphi
我正在使用Delphi 2010向Java應用程序發送HTTP請求。 具體來說,我正在發送一個JSON對象。 但是,在發送請求時,我不知道發生了什么,但對象不正確。
我像這樣發送對象:
{"entidad":"1","username":"A","password":"1234"}
我的嗅探器讀取這樣的對象:
%�7�B�%�2�2�e�n�t�i�d�a�d�%�2�2�%�3�A�%�2�2�8�3�0�0�2�3�0�0�0�%�2�2�%�2�C�
因此,我的Java應用程序不會讀取該對象,而是導致空指針異常。
我的代碼在這里:
function TFormMain.JSONPostRequest(Server,Url,jo : String; blnSSL: Boolean): String;
var
aBuffer : Array[0..4096] of Char;
Header : TStringStream;
BufStream : TMemoryStream;
BytesRead : Cardinal;
pSession : HINTERNET;
pConnection : HINTERNET;
pRequest : HINTERNET;
port : Integer;
flags : DWord;
begin
Result := '';
pSession := InternetOpen(nil, INTERNET_OPEN_TYPE_PRECONFIG, nil, nil, 0);
if Assigned(pSession) then
try
if blnSSL then
Port := INTERNET_DEFAULT_HTTPS_PORT
else
Port := 9000;
pConnection := InternetConnect(pSession, PChar(Server), port, nil, nil, INTERNET_SERVICE_HTTP, 0, 0);
if Assigned(pConnection) then
try
if blnSSL then
flags := INTERNET_FLAG_SECURE or INTERNET_FLAG_KEEP_CONNECTION
else
flags := INTERNET_SERVICE_HTTP;
pRequest := HTTPOpenRequest(pConnection, 'POST', PChar(Url), nil, nil, nil, flags, 0);
if Assigned(pRequest) then
try
Header := TStringStream.Create('');
try
with Header do
begin
WriteString('Host: ' + Server + ':' + IntToStr(Port) + sLineBreak);
end;
HttpAddRequestHeaders(pRequest, PChar(Header.DataString), Length(Header.DataString), HTTP_ADDREQ_FLAG_ADD);
if HTTPSendRequest(pRequest, nil, 0, Pointer(jo), Length(jo)) then
begin
BufStream := TMemoryStream.Create;
try
while InternetReadFile(pRequest, @aBuffer, SizeOf(aBuffer), BytesRead) do
begin
if (BytesRead = 0) then Break;
BufStream.Write(aBuffer, BytesRead);
end;
aBuffer[0] := #0;
BufStream.Write(aBuffer, 1);
Result := WideCharToString(PChar(BufStream.Memory));
finally
BufStream.Free;
end;
end
else
raise Exception.Create('HttpOpenRequest failed. ' + SysErrorMessage(GetLastError));
finally
Header.Free;
end;
finally
InternetCloseHandle(pRequest);
end;
finally
InternetCloseHandle(pConnection);
end;
finally
InternetCloseHandle(pSession);
end;
end;
JSON默認使用UTF-8,Delphi(2009及更新版本)使用UTF-16作為默認編碼。 您的代碼需要在將JSON傳遞給HTTPSendRequest之前將其轉換為UTF-8字符串。
我還會添加一個請求標頭來指示編碼,以便Java端知道它是UTF-8。
我的嗅探器讀取這樣的對象:
% 7 B % 2 2 e n t i d a d % 2 2 % 3 A % 2 2 8 3 0 0 2 3 0 0 0 % 2 2 % 2 C
您的JSON數據以UTF-16編碼,因為string
是Delphi 2010中UnicodeString
的別名。您正在發送該字符串的原始字節,而不是將它們編碼為UTF-8,這是JSON的默認字符集。 正如mjn所說,你在這方面濫用HttpSendRequest()
。
此外,您的輸入JSON字符串似乎在傳遞給JSONPostRequest()
之前已經過url編碼( HTTPSendRequest()
不會對原始數據進行url編碼)。 不要對JSON進行URL編碼,按原樣傳遞原始JSON。
此外, INTERNET_SERVICE_HTTP
不是HTTPOpenRequest()
的有效標志。
您沒有顯示調用JSONPostRequest()
的代碼,因此我無法向您展示如何修復url編碼問題。 但是對於實際的帖子,嘗試更像這樣的東西:
function WinInetErrorMsg(Err: DWORD): string;
var
ErrMsg: array of Char;
ErrLen: DWORD;
begin
if Err = ERROR_INTERNET_EXTENDED_ERROR then
begin
ErrLen := 0;
InternetGetLastResponseInfo(Err, nil, ErrLen);
if GetLastError() = ERROR_INSUFFICIENT_BUFFER then
begin
SetLength(ErMsg, ErrLen);
InternetGetLastResponseInfo(Err, PChar(ErMsg), ErrLen);
SetString(Result, PChar(ErrMsg), ErrLen);
end else begin
Result := 'Unknown WinInet error';
end;
end else
Result := SysErrorMessage(Err);
end;
function TFormMain.JSONPostRequest(const Server, Url: string; const jo : UTF8String; blnSSL: Boolean): String;
var
aBuffer : Array of Byte;
Header : String;
BufStream : TStringStream;
BytesRead : DWORD;
pSession : HINTERNET;
pConnection : HINTERNET;
pRequest : HINTERNET;
port : Integer;
flags : DWORD;
begin
Result := '';
pSession := InternetOpen(nil, INTERNET_OPEN_TYPE_PRECONFIG, nil, nil, 0);
if not Assigned(pSession) then
raise Exception.Create('InternetOpen failed. ' + WinInetErrorMsg(GetLastError));
try
if blnSSL then
Port := INTERNET_DEFAULT_HTTPS_PORT
else
Port := 9000;
pConnection := InternetConnect(pSession, PChar(Server), port, nil, nil, INTERNET_SERVICE_HTTP, 0, 0);
if not Assigned(pConnection) then
raise Exception.Create('InternetConnect failed. ' + WinInetErrorMsg(GetLastError));
try
if blnSSL then
flags := INTERNET_FLAG_SECURE
else
flags := 0;
pRequest := HTTPOpenRequest(pConnection, 'POST', PChar(Url), nil, nil, nil, flags, 0);
if not Assigned(pRequest) then
raise Exception.Create('HttpOpenRequest failed. ' + WinInetErrorMsg(GetLastError));
try
Header := 'Host: ' + Server + ':' + IntToStr(Port) + #13#10 +
'Content-Type: application/json; charset=UTF-8'#13#10;
if not HttpAddRequestHeaders(pRequest, PChar(Header), Length(Header), HTTP_ADDREQ_FLAG_ADD) then
raise Exception.Create('HttpAddRequestHeaders failed. ' + WinInetErrorMsg(GetLastError));
if not HTTPSendRequest(pRequest, nil, 0, PAnsiChar(jo), Length(jo)) then
raise Exception.Create('HTTPSendRequest failed. ' + WinInetErrorMsg(GetLastError));
SetLength(aBuffer, 4096);
BufStream := TStringStream.Create('', TEncoding.Default);
try
repeat
if not InternetReadFile(pRequest, PByte(aBuffer), Length(aBuffer), BytesRead) then
raise Exception.Create('InternetReadFile failed. ' + WinInetErrorMsg(GetLastError));
if (BytesRead = 0) then Break;
BufStream.WriteBuffer(PByte(aBuffer)^, BytesRead);
until False;
Result := BufStream.DataString;
finally
BufStream.Free;
end;
finally
InternetCloseHandle(pRequest);
end;
finally
InternetCloseHandle(pConnection);
end;
finally
InternetCloseHandle(pSession);
end;
end;
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