How to pre-compile JSP?

Add jsp_precompile as a request parameter and send a request to the JSP file. This will make the jsp pre-compile. Why it is mentioned as pre compile instead of compilation is that, the request is not served. That is, the JSP will not be executed and the request will not be serviced. Just it will be compiled and the implementation class will be generated.

The jsp_precompile parameter may have no value, or may have values true or false. It should not have any other values like ?jsp_precompile=yes – this will result in HTTP error 500.

So the example for query strings to pre compile jsp files are
?jsp_precompile
?jsp_precompile=true
?jsp_precompile=false
?foobar=foobaz&jsp_precompile=true
?foobar=foobaz&jsp_precompile=false

How to do pre compile for a bunch of JSP files? for all JSPs in a folder or application?
There are no special features available for this in the JSP specification. But the application servers (JSP containers) provide methods to do this on their own way. At the end of this tutorial we will see how to pre compile JSP files for Apache Tomcat 6.

But if you want to pre compile in server independent manner you have to use jsp_precompile request parameter and no other option available. To do it for the whole application, you can custome write a servlet or jsp file which will raise a request for all the JSPs available with jsp_precompile added as parameter.