Package javax.servlet.http does not exist when you use Ant package

Obviously, the reason for this error is that the corresponding jar package is missing. This is because Servlets and JSPs are not part of the Java Platform Javase (Standard Edition), but are part of Java EE (Enterprise Edition), so you must tell the location of the compiler servlet. There are three ways to solve the problem:

First, add the Apache-tomcat-7.0.55\lib\servlet-api.jar to the environment variable.

Second, add the Servlet-api.jar directly to the Lib folder.

Third, add the corresponding fileset in Build.xml, the corresponding Servlet-api.jar included, in fact, for a single project classpath increase the path of the jar package, the principle and the first method is the same.

Package javax.servlet.http does not exist when you use Ant package