fixed #1475, use vector::insert instead of vector::clear + assign in CCHttpClient::writeData, to prevent losing data

extensions/network/HttpClient.cpp

@@ -74,12 +74,10 @@ size_t writeData(void *ptr, size_t size, size_t nmemb, void *stream)
 {
     std::vector<char> *recvBuffer = (std::vector<char>*)stream;
     size_t sizes = size * nmemb;
-
-    recvBuffer->clear();
-    // someone reported a bug of losting data potentially here
-    // use recvBuffer->insert(recvBuffer->end(), (char*)ptr, (char*)ptr+sizes); can resolve.
     
-    recvBuffer->assign((char*)ptr, (char*)ptr + sizes);
+    // add data to the end of recvBuffer
+    // write data maybe called more than once in a single request
+    recvBuffer->insert(recvBuffer->end(), (char*)ptr, (char*)ptr+sizes);
     
     return sizes;
 }

extensions/network/HttpClient.h

@@ -55,6 +55,7 @@ public:
     /**
      * Add a get request to task queue
      * @param request a CCHttpRequest object, which includes url, response callback etc.
+                      please make sure request->_requestData is clear before calling "send" here.
      * @return NULL
      */
     void send(CCHttpRequest* request);