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(Unicode C) HTTP GET -- Read Response from StreamDemonstrates how to send an HTTP GET for a web page, and then read the response from a Stream. The purpose is to fulfill a situation such as the following: "I have a URL and just want the <head> </head> portion of the HTML. This would avoid having to download a potentially enormous web page just to get at header information, such as the <styles>."
#include <C_CkRestW.h> #include <C_CkUrlW.h> #include <C_CkStreamW.h> #include <C_CkTaskW.h> #include <C_CkStringBuilderW.h> void ChilkatSample(void) { HCkRestW rest; HCkUrlW url; BOOL bAutoReconnect; BOOL success; int responseStatusCode; const wchar_t *errResponse; HCkStreamW bodyStream; HCkTaskW readResponseBodyTask; HCkStringBuilderW sbBody; BOOL exitLoop; const wchar_t *bodyText; int maxWaitMs; // This example requires the Chilkat API to have been previously unlocked. // See Global Unlock Sample for sample code. rest = CkRestW_Create(); // In this example, we'll get the web page at http://www.nytimes.com/pages/business/index.html // The domain is "www.nytimes.com", and the path is "/pages/business/index.html" // If we have only the full URL to begin with, it can be loaded into the Chilkat URL object to // access the parts: url = CkUrlW_Create(); CkUrlW_ParseUrl(url,L"http://www.nytimes.com/pages/business/index.html"); bAutoReconnect = TRUE; success = CkRestW_Connect(rest,CkUrlW_host(url),CkUrlW_getPort(url),CkUrlW_getSsl(url),bAutoReconnect); // Send the GET request (This sends the GET request, but does not read the response.) success = CkRestW_SendReqNoBody(rest,L"GET",CkUrlW_path(url)); if (success != TRUE) { wprintf(L"%s\n",CkRestW_lastErrorText(rest)); CkRestW_Dispose(rest); CkUrlW_Dispose(url); return; } // Read the response header. responseStatusCode = CkRestW_ReadResponseHeader(rest); if (responseStatusCode < 0) { wprintf(L"%s\n",CkRestW_lastErrorText(rest)); CkRestW_Dispose(rest); CkUrlW_Dispose(url); return; } wprintf(L"Response status code = %d\n",responseStatusCode); // We expect a 200 response status. if (responseStatusCode != 200) { // If the response status code is not 200, we could check for a redirect status code and // then follow it, read the entire response (as shown here), or just call rest.Disconnect errResponse = CkRestW_readRespBodyString(rest); if (CkRestW_getLastMethodSuccess(rest) != TRUE) { wprintf(L"%s\n",CkRestW_lastErrorText(rest)); } else { wprintf(L"%s\n",errResponse); } CkRestW_Dispose(rest); CkUrlW_Dispose(url); return; } bodyStream = CkStreamW_Create(); // Set a 10 second read timeout for the stream. // (Give up if no data arrives within 10 seconds after calling a read method.) CkStreamW_putReadTimeoutMs(bodyStream,10000); // Create a background thread task to read the response body (which feeds // it to the bodyStream object.) readResponseBodyTask = CkRestW_ReadRespBodyStreamAsync(rest,bodyStream,TRUE); // Start the task. success = CkTaskW_Run(readResponseBodyTask); // Read the HTTP response body until the "</head>" is seen, or until // the end-of-stream is reached. sbBody = CkStringBuilderW_Create(); exitLoop = FALSE; while (!exitLoop && (CkStreamW_getEndOfStream(bodyStream) != TRUE)) { bodyText = CkStreamW_readString(bodyStream); if (CkStreamW_getLastMethodSuccess(bodyStream) == TRUE) { CkStringBuilderW_Append(sbBody,bodyText); if (CkStringBuilderW_Contains(sbBody,L"</head>",FALSE)) { exitLoop = TRUE; } } else { exitLoop = TRUE; } } // Cancel the remainder of the task... CkTaskW_Cancel(readResponseBodyTask); CkTaskW_Dispose(readResponseBodyTask); // Ensure we're disconnected from the server. maxWaitMs = 50; CkRestW_Disconnect(rest,maxWaitMs); wprintf(L"----\n"); wprintf(L"%s\n",CkStringBuilderW_getAsString(sbBody)); wprintf(L"----\n"); wprintf(L"Successfully received the body up to the desired point.\n"); CkRestW_Dispose(rest); CkUrlW_Dispose(url); CkStreamW_Dispose(bodyStream); CkStringBuilderW_Dispose(sbBody); } |
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