Google App Engine Java部署和Servlet / jsp关系

Question

I am trying to understand application deployment on Google App Engine using java. Looks like if java is used it is more like deployment of a web application which extends java servlet ( HttpServlet ). Let me know if java application can be deployed without using servlet or jsp.

I agree in addition to standard web application deployment it will require GAE specific configuration ie appengine-web.xml. But my question is mainly on requirement of servlet for java based deployment.

Sorry for very basic question, but all code samples pointed me to servlet but in document there is no mention about servlet.

Answer 1

Depending on which tools (frameworks) you are using in App Engine you may OR NOT write Servlets and JSPs. For example if you use Google Endpoints ( https://cloud.google.com/endpoints/docs/frameworks/java/about-cloud-endpoints-frameworks ), you will not write any servlet yourself: they will be automatically generated by the framework itself.

On the other hand it is totally possible to deploy your own servlets and JSPs, and adapt the web.xml file accordingly.

Answer 2

As I understand you want to communicate with the server via HTTP. Servlets are most common way to support this protocol in JVM, unless you want to implement protocol in something low level, like in Netty.

Servlet is a set of java interfaces, but it is not required to implement them by yourself. Most Java web frameworks provide some implementation for you. I mean someone should write this servlet once, but most likely it was written by frameworks authors many years ago, you don't even need to think about its implementation.

For example I don't remember writing any Servlet since 2003, but I have plenty of working web apps on GAE. Most of them are Spring based, it have Spring Dispatcher Servlet which does all processing HTTP request/response for you.

So the answer is: yes App Engine is Servlet based app container and you need one, but it's very unlikely you'll write any servlet by yourself