我写了一个使用WinInet库的程序。该程序每天运行约8-12小时。首先，它连接到Internet，然后使用FTP下载/上传文件。之后，它将启动一个循环，该循环在不同的时间间隔内启动多达两个线程。两个线程都对同一台服务器执行GET -requests，看起来像这样:
private void Thread()
{
if(!InternetGetConnectedState(NULL, NULL))
{
connectToInternet();
}
// some code...
HINTERNET httpOpenRequest = HttpOpenRequest(
hHTTPConnection, // InternetConnect-Handle
L"GET", // HTTP-Verb
request_target, // FileName
L"HTTP/1.1", // HTTP-Version
NULL, // Referer
NULL, // AcceptTypes
INTERNET_FLAG_RELOAD, // Flags
0 // Context
);
BOOL httpsRequest = HttpSendRequest(
httpOpenRequest, // Handle of HttpOpenRequest
NULL, // Headers
0, // Headers-Length
NULL, // Optional
0 // Optional-Length
);
InternetCloseHandle(httpOpenRequest); // App-Crash sometimes here!
}
我的
connectToInternet-功能在这里:int connectToInternet()
{
DWORD InetTest1 = 16000;
while (InetTest1 != 0)
{
InetTest1 = InternetAttemptConnect(0);
// wait 1 second for next attempt
if (InetTest1 != 0)
{
Sleep(1000);
}
}
BOOL InetTest2 = FALSE;
while (!InetTest2)
{
InetTest2 = InternetCheckConnection(
L"http://www.example.com", // URL
FLAG_ICC_FORCE_CONNECTION, // Flags
0 // Reserved
);
// wait 1 second for next attempt
if (!InetTest2)
{
Sleep(1000);
}
}
while (hInternetOpen == NULL)
{
hInternetOpen = InternetOpen(
L"Custom-Agent", // Agent
INTERNET_OPEN_TYPE_DIRECT, // AccessType
NULL, // ProxyName
NULL, // ProxyBypass
0 // Flags
);
// wait 1 second for next attempt
if (hInternetOpen == NULL)
{
Sleep(1000);
}
}
while (hHTTPConnection == NULL)
{
hHTTPConnection = InternetConnect(
hInternetOpen, // InternetOpen-Handle
L"www.example.com", // ServerName
INTERNET_DEFAULT_HTTP_PORT, // ServerPort
NULL, // Username
NULL, // Password
INTERNET_SERVICE_HTTP, // Service
0, // Flags
0 // Context
);
// wait 1 second for next attempt
if (hHTTPConnection == NULL)
{
Sleep(1000);
}
}
return 0;
}
(我在这里找到此功能的基本工作流程:https://msdn.microsoft.com/en-us/library/windows/desktop/aa383996(v=vs.85).aspx)
现在的问题:
Q1:当两个线程之一调用
InternetCloseHandle(httpOpenRequest)时，似乎很少遇到应用崩溃的情况。我找不到这些应用程序崩溃的原因...您有任何想法吗？第2季度:运行该程序的便携式计算机似乎存在Internet连接问题，因为它经常使连接断开几秒钟到几分钟甚至几小时。因此，如果
connectToInternet()是InternetGetConnectedState(NULL, NULL)，那么我首先在两个线程中都调用false。这是必需步骤吗，或者如果我不调用connect函数，它也可以工作吗？如果连接断开，全局HINTERNET -Handles是否无效？[编辑] ，与此同时，我怀疑我的程序引起了连接问题，因为我家里的有线网络也没有互联网访问权限!我有什么错误吗？
最佳答案
看来我的问题是由同时运行多个线程并尝试调用InternetCloseHandle()引起的。
同时，我重新编写了代码。我还尝试涉及Remy Lebeau的评论。我的代码现在看起来像以下示例:
void Thread()
{
// access-control
if (ThreadRunning == true)
{
return 99;
}
ThreadRunning = true;
// variables
HINTERNET hInternetOpen = NULL;
HINTERNET hHTTPConnection = NULL;
HINTERNET httpOpenRequest = NULL;
int connectionAttempts;
string target_string;
wstring target_wstring;
LPCWSTR request_target;
BOOL httpSendRequestSuccessful;
BOOL httpQueryInfoReceived;
DWORD statusCode = 0;
DWORD statusCodeLen = sizeof(statusCode);
BOOL dataAvailable;
DWORD numberOfBytesAvailable;
BOOL internetReadFileSuccessful;
char buffer[4096] = { "" };
DWORD numberOfBytesRead;
// Connect to Internet
connectionAttempts = 0;
DWORD InetTest1 = 16000;
while (InetTest1 != 0)
{
InetTest1 = InternetAttemptConnect(0);
if (InetTest1 != 0)
{
connectionAttempts++;
// prevent an infinite loop
if (connectionAttempts >= 5)
{
// reset access-control
ThreadRunning = false;
return 1;
}
// wait 1 second if it fails
Sleep(1000);
}
}
// reset connectionAttempts
connectionAttempts = 0;
BOOL InetTest2 = FALSE;
while (!InetTest2)
{
InetTest2 = InternetCheckConnection(
L"http://www.example.com", // URL
FLAG_ICC_FORCE_CONNECTION, // Flags
0 // Reserved
);
if (InetTest2 == FALSE)
{
connectionAttempts++;
// prevent an infinite loop
if (connectionAttempts >= 5)
{
// reset access-control
ThreadRunning = false;
return 2;
}
// wait 1 second if it fails
Sleep(1000);
}
}
// reset connectionAttempts
connectionAttempts = 0;
while (hInternetOpen == NULL)
{
hInternetOpen = InternetOpen(
L"Custom-Agent", // Agent
INTERNET_OPEN_TYPE_DIRECT, // AccessType
NULL, // ProxyName
NULL, // ProxyBypass
0 // Flags
);
if (hInternetOpen == NULL)
{
connectionAttempts++;
// prevent an infinite loop
if (connectionAttempts >= 5)
{
// reset access-control
ThreadRunning = false;
return 3;
}
// wait 1 second if it fails
Sleep(1000);
}
}
// reset connectionAttempts
connectionAttempts = 0;
while (hHTTPConnection == NULL)
{
hHTTPConnection = InternetConnect(
hInternetOpen, // InternetOpen-Handle
L"www.example.com", // ServerName
INTERNET_DEFAULT_HTTP_PORT, // ServerPort
NULL, // Username
NULL, // Password
INTERNET_SERVICE_HTTP, // Service
0, // Flags
0 // Context
);
if (hHTTPConnection == NULL)
{
connectionAttempts++;
// prevent an infinite loop
if (connectionAttempts >= 5)
{
// reset access-control
onlineSettingsThreadRunning = false;
// Handle-Cleanup
InternetCloseHandle(hInternetOpen);
return 4;
}
// wait 1 second if it fails
Sleep(1000);
}
}
// some code...
// open HTTP-Request
httpOpenRequest = HttpOpenRequest(
hHTTPConnection, // InternetConnect-Handle
L"GET", // HTTP-Verb (GET or POST)
request_target, // FileName
L"HTTP/1.1", // HTTP-Version
NULL, // Referer
NULL, // AcceptTypes
INTERNET_FLAG_RELOAD, // Flags
0 // Context
);
if (httpOpenRequest == NULL)
{
// Handle-Cleanup
InternetCloseHandle(hHTTPConnection);
InternetCloseHandle(hInternetOpen);
// reset access-control
onlineSettingsThreadRunning = false;
return 5;
}
// send HTTP-Request
httpSendRequestSuccessful = HttpSendRequest(
httpOpenRequest, // Handle von HttpOpenRequest
NULL, // Headers
0, // Headers-Length
NULL, // Optional
0 // Optional-Length
);
if (httpSendRequestSuccessful == FALSE)
{
// Handle-CleanUp
InternetCloseHandle(httpOpenRequest);
InternetCloseHandle(hHTTPConnection);
InternetCloseHandle(hInternetOpen);
// reset access-control
onlineSettingsThreadRunning = false;
return 6;
}
// read Server-Status
httpQueryInfoReceived = HttpQueryInfo(
httpOpenRequest,
HTTP_QUERY_STATUS_CODE | HTTP_QUERY_FLAG_NUMBER,
&statusCode,
&statusCodeLen,
NULL
);
if (httpQueryInfoReceived == FALSE || statusCode != 200)
{
// Handle-CleanUp
InternetCloseHandle(httpOpenRequest);
InternetCloseHandle(hHTTPConnection);
InternetCloseHandle(hInternetOpen);
// reset access-control
onlineSettingsThreadRunning = false;
return 7;
}
// test, how much bytes are readable
dataAvailable = InternetQueryDataAvailable(
httpOpenRequest,
&numberOfBytesAvailable,
0,
0
);
if (dataAvailable == FALSE)
{
// Handle-CleanUp
InternetCloseHandle(httpOpenRequest);
InternetCloseHandle(hHTTPConnection);
InternetCloseHandle(hInternetOpen);
// reset access-control
onlineSettingsThreadRunning = false;
return 8;
}
// some code...
// Close internet-connection
InternetCloseHandle(httpOpenRequest);
InternetCloseHandle(hHTTPConnection);
InternetCloseHandle(hInternetOpen);
// reset access-control
ThreadRunning = false;
return 0;
}
因此，我的
connectToInternet() -function不再存在。现在，它是每个需要Internet访问的线程的一部分。它也不再使用GetLastError()，因为这可能会传递错误的结果...我仍在测试我的代码，但它似乎很有希望:-)