Difference between getLocalPort() and getServerPort() in servlets

In a simple setup (where your application server/servlet container accepts the request of the client directly) both methods will return the same value.

When the servlet container is not the application that accepts the client request (for example when you use an Apache HTTP server with mod_jk to accept the request and forward the request to a Tomcat instance via AJP), then getServerPort() will return the port the client connected to (probably 80, when the default port is used) and getLocalPort() will return the port that Tomcat used to accept the connection from the HTTP server (probably 8009 or something similar).