When do you use a JSP and when a Servlet? [duplicate]

Answer 1

A JSP is compiled to a servlet the first time it is run. That means that there's no real runtime difference between them.

However, most have a tradition to use servlets for controllers and JSPs for views. Since controllers are just java classes you can get full tool support (code completion etc.) from all IDEs. That gives better quality and faster development times compared to JSPs. Some more advanced IDE's (IntelliJ IDEA springs to mind) have great JSP support, rendering that argument obsolete.

If you're making your own framework or just making it with simple JSPs, then you should feel free to continue to use JSPs. There's no performance difference and if you feel JSPs are easier to write, then by all means continue.

Answer 2

i think its up to you? because JSP is Java inside of HTML and Servlet is a Java that can do the HTML inside

hmmm... servlet is more sercure than jsp because if you submit to Servlet and forward to another JSP there is no file extension appear and also you cant see what Page it is..

but the advantage of JSP is you can code there easily.

Answer 3

JSPs: To present data to the user. No business logic should be here, and certainly no database access.

Servlets: To handle input from a form or specific URL. Usually people will use a library like Struts/Spring on top of Servlets to clear up the programming. Regardless the servlet should just validate the data that has come in, and then pass it onto a backend business layer implementation (which you can code test cases against). It should then put the resulting values on the request or session, and call a JSP to display them.

Model: A data model that holds your structured data that the website handles. The servlet may take the arguments, put them into the model and then call the business layer. The model can then interface with back-end DAOs (or Hibernate) to access the database.

Any non-trivial project should implement a MVC structure. It is, of course, overkill for trivial functionality. In your case I would implement a servlet that called a DAO to update the status, etc, or whatever is required.

Answer 4

Most java applications nowadays are build on the MVC pattern... In the controller side (servlet) you implement business logic. The servlet controller usually forward the request to a jsp that will generate the actual html response (the View in MVC). The goal is to separate concerns... Thousands of books have been written on that subject.

Answer 5

In an MVC architecture, servlets are used as controller and JSPs as view. But both are technically the same. JSP will be translated into servlet, either in compile time (like in JDeveloper) or when accessed for the first time (like in Tomcat). So the real difference is in the ease of use. I'm pretty sure that you'll have a hard time rendering HTML page using servlet; but opposite to common sense, you'll actually find it pretty easy to code even a fairly complex logic all inside JSP (with the help of some prepared helper class maybe). PHP guys do this all the time. And so they fall into the pitfall of creating spaghetti codes. So my solution to your problem: if you found it easier to code in JSP and it wouldn't involve too many code, feel free to code in JSP. Otherwise, use servlet.

Answer 6

In java servlet the HTML tags are embeded in java coding. In JSP the java codings are embeded in HTML tags.

For big application for big problem the servlet is complex to read,understand,debug,etc because of unreadability of embeding more html tags inside the java coding..So we use jsp.In jsp it is easy to understand,debug,etc.

Thanks & Regards, Sivakumar.j