Java exception The type javax.servlet.http.HttpServletRequest cannot be resolved

The type javax.servlet.http.HttpServletRequest cannot be resolved. It is indirectly referenced from required. class files. The meaning of this error is not clear, perhaps, MyEclipse will not automatically find this package Servlet.jar, even in the corresponding project/webroot/web-inf/lib inside, and it is strange that the error is always at the front of the code (the first line position)

Workaround: Add the relevant class jar package to your classpath (right click on a jar package--build path--config build path ...---liberary---add external jar library), join here Servelet-api.jar (This package can be found in the Eclipse/plugins directory, other similar errors are resolved in the same way) to Classpath, OK.

Java exception The type javax.servlet.http.HttpServletRequest cannot be resolved