Servlet method execution sequence

[Steven Marco]

If I have the following two classes:

public abstract class ServletOne extends HttpServlet{
 
public void doPost(HttpServletRequest req, HttpServletResponse resp){
methodOne(req,resp);
}
public abstract void methodOne(HttpServletRequest req, HttpServletResponse resp){
//.........................
}
public void init(ServletConfig myconfig){
super.init(myconfig)
}
public void service(javax.servlet.ServletRequest req, javax.servlet.ServletResponse resp){
super.service(req,resp)
}
}
 
public abstract class ServletTwo extends ServletOne{
 
public void methodOne(HttpServletRequest req, HttpServletResponse resp){
methodOne(req,resp);
}
public void init(ServletConfig myconfig){
super.init(myconfig)
}
public void service(javax.servlet.ServletRequest req, javax.servlet.ServletResponse resp){
super.service(req,resp)
}
}

Now when I have a POST request coming in from a JSP form where "action" is ServletTwo, is the following sequence of method calls correct?

1. init() of ServletTwo is called which in turns calls init() in ServletOne which in turns calls init() in HttpServlet
2. service() of ServletTwo is called which in turns calls service() in ServletOne which in turns calls service() in HttpServlet
3. doPost() of ServletOne is called.
4. methodOne() is called in ServletTwo ???

[Bear Bibeault]

A few logging statements will help you track the execution.

[Jignesh Patel]

It seems your assumption is techically correct, but why don't you follow Bear.

[sven studde]

Now when I have a POST request coming in from a JSP form where "action" is ServletTwo, is the following sequence of method calls correct?

No.
[ October 13, 2006: Message edited by: sven studde ]

[Jignesh Patel]

As I said your assumption is correct as per j2ee specification but almost all server has a different way to handle the request.

[sven studde]

Originally posted by Jignesh Patel:
As I said your assumption is correct as per j2ee specification...

Incorrect. This is wrong per specification of Java 1.5:

init() of ServletTwo is called

[ October 14, 2006: Message edited by: sven studde ]

[Ben Souther]

I suggest you follow Bear's advice; if for no other reason that doing so would point out any other issues that your code may have.

The first issue is that ServletTwo is abstract so will not run at all.
You can not instanciate abstract classes.

If you remove the abstract keyword and recompile, then yes, number one is correct.

Number two is also correct (but you do realize that there is no need to override the service method, correct?).

Number three is correct, methodOne will be called.
It will then be called again, and again, until your app blows up with a StackOverflowError.


Sven,
"No" and "Incorrect. This is wrong per specification of Java 1.5" aren't really helpful answers. If there is something that we're missing, maybe you could point out what it is?

[sven studde]

The first issue is that ServletTwo is abstract so will not run at all.