We create one controller class named TestCtrl:

As you can see, there are two new files, TestCtrl.h and TestCtrl.cc. Now, let’s have a look at them:

TestCtrl.cc:

Each HttpSimpleController class can only define one Http request handler, and it is defined by a virtual function override.

The first parameter is the path to be mapped, and parameters beyond the path are constraints on this path. Currently, two types of constraints are supported. One is the HttpMethod enum Type, which means the Http method allowed. The other type is the name of the HttpFilter class. One can configure any number of these two types of constraints, and there are no order requirements for them. For Filter, please refer to .

Users can register the same Simple Controller to multiple paths, or register multiple Simple Controllers on the same path (using different HTTP methods).

The mapping from the above path to the handler is done at compile time. In fact, the drogon framework also provides an interface for runtime completion mapping. The runtime mapping allows the user to map or modify the mapping through configuration files or other user interfaces without recompiling this program (For performance reasons, it is forbidden to add any controller mapping after running the app().run() method).

04.2