Add some comments

lib/inc/drogon/CacheMap.h

@@ -360,4 +360,5 @@ class CacheMap
         }
     }
 };
+
 } // namespace drogon

lib/inc/drogon/HttpRequest.h

@@ -111,10 +111,25 @@ class HttpRequest
     virtual void setContentTypeCodeAndCharacterSet(ContentType type, const std::string &charSet = "utf-8") = 0;
     virtual ContentType getContentTypeCode() = 0;
 
-    /// Create a request object.
+    /// The following methods are a series of factory methods that help users create request objects.
+
+    /// Create a normal request with http method Get and version Http1.1.
     static HttpRequestPtr newHttpRequest();
+    /// Create a http request with:
+    /// Method: Get
+    /// Version: Http1.1
+    /// Content type: application/json, the @param data will be serialized into the content of the request.
     static HttpRequestPtr newHttpJsonRequest(const Json::Value &data);
+    /// Create a http request with:
+    /// Method: Post
+    /// Version: Http1.1
+    /// Content type: application/x-www-form-urlencoded
     static HttpRequestPtr newHttpFormPostRequest();
+    /// Create a http file upload request with:
+    /// Method: Post
+    /// Version: Http1.1
+    /// Content type: multipart/form-data
+    /// The @param files represents pload files which will be transferred to the server via the multipart/form-data format
     static HttpRequestPtr newFileUploadRequest(const std::vector<UploadFile> &files);
     virtual ~HttpRequest() {}
 };

lib/inc/drogon/HttpSimpleController.h

@@ -30,6 +30,7 @@
     }
 namespace drogon
 {
+    
 class HttpSimpleControllerBase : public virtual DrObjectBase
 {
   public:

lib/inc/drogon/HttpViewBase.h

@@ -22,6 +22,7 @@
 
 namespace drogon
 {
+
 class HttpViewBase : virtual public DrObjectBase
 {
   public:
@@ -33,4 +34,5 @@ class HttpViewBase : virtual public DrObjectBase
   protected:
     virtual HttpResponsePtr genHttpResponse(const HttpViewData &) = 0;
 };
+
 } // namespace drogon

lib/inc/drogon/HttpViewData.h

@@ -27,9 +27,11 @@
 typedef std::unordered_map<std::string, any> ViewDataMap;
 namespace drogon
 {
+/// This class represents the data set displayed in views.
 class HttpViewData
 {
   public:
+    /// The function template is used to get an item in the data set by the @param key.
     template <typename T>
     const T get(const std::string &key, T &&nullVal = T()) const
     {
@@ -47,6 +49,8 @@ class HttpViewData
         }
         return nullVal;
     }
+
+    /// Insert an item identified by the @param key into the data set;
     void insert(const std::string &key, any &&obj)
     {
         viewData_[key] = std::move(obj);
@@ -55,6 +59,8 @@ class HttpViewData
     {
         viewData_[key] = obj;
     }
+
+    /// Insert an item identified by the @param key into the data set; The item will be converted to a string.
     template <typename T>
     void insertAsString(const std::string &key, T &&val)
     {
@@ -62,6 +68,8 @@ class HttpViewData
         ss << val;
         viewData_[key] = ss.str();
     }
+
+    /// Insert a formated string identified by the @param key.
     void insertFormattedString(const std::string &key,
                                const char *format, ...)
     {
@@ -105,6 +113,7 @@ class HttpViewData
         viewData_[key] = std::move(strBuffer);
     }
 
+    /// Get the 'any' object by the @param key.
     any &operator[](const std::string &key) const
     {
         return viewData_[key];
@@ -113,4 +122,5 @@ class HttpViewData
   protected:
     mutable ViewDataMap viewData_;
 };
+
 } // namespace drogon