The @RequestMapping annotation

The @RequestMapping annotation is used at class level to map the /calculation URI to the CalculationController class; that is, it ensures that the HTTP request to /calculation is mapped to the CalculationController class. Based on the path defined using the @RequestMapping annotation of the URI (postfix of /calculation, for example, /calculation/sqrt/144), it would be mapped to the respective methods. Here, the request mapping, /calculation/sqrt, is mapped to the sqrt() method, and /calculation/power is mapped to the pow() method.

You might have also observed that we have not defined what request method (GET/POST/PUT, and so on) these methods would use. The @RequestMapping annotation maps all the HTTP request methods by default. You could use specific methods by using the method property of RequestMapping. For example, you could write a @RequestMethod annotation in the following way to use the POST method:

@RequestMapping(value = "/power", method = POST) 

For passing the parameters along the way, the sample demonstrates both request parameters and path parameters using the @RequestParam and @PathVariable annotations, respectively.