Use Model View Controller framework
Parse parameters into domain objects
Send trouble ticket emails
A Web App Framework WEB4J
HttpServletare sometimes informally called Controller classes (or Action classes). They form the entry point of client HTTP requests into a web app.
A common problem with Controllers is that they become too large. Since the flow of control starts out in the Controller, there's a strong tendency to keep adding more and more code to the same place. But that's usually a mistake. You should not really think of the Controller as being in control. Rather, you should think of the Service as being in control. (From this perspective, the term Controller is a bit of a misnomer.)
Here's a summary of the distinction between Controller and Service:
(The distinction between Controller and Service can be more than just a desire for clear design.
When using the Spring framework, there are actually some important functional differences between Controller and Service classes.)