Goos Servllet Design

Question

Firstly let me say i am not keen on using JSP's because they mix scripting language with Java and that can only be bad,
What i would like to know is if you have servlet(pure) and you wish to output data to the client-how do you do this,
If any developer suggests that i should use PrintWriter instance as i have seen in many book/tutorial they should go home and sleep.
You see the problem with PrintWriter instance is that if your boss says i want the page to look like x,z and y you have a huge task in front of you.
A better approach is to have a HTML template page and insert content in dynamically using a find and replace stratergy.
At least then you can make modifications to the layout without touching your java code.
Can anyone suuggest how they have designed a scalable complex servlet in Java such as this one (devshed forums) so that it is maintaible and doesnt contain hunderds of if then else block which have to deal with all the possiblilities.
For example look at this website-you have regisetre , sumbitNewMessage,ForumList etch etc.
Do you mean totell me that the code is written as
code:
if(currentRequest.equals(newMessage)){
//do something
}else if(...){
//do something else
}else if(){
//do something
Any sensible answers welcome

Answer 1

Daryl,
Apologies for not returning to you yestaerday. I wa busy drawing uml and class diagrams which my organisation requires.
I went away and asked my colleagues why one would use multiple servlets for one project. They could not answer. By using multiple servlets the server becomes much less efficient- you have difficulty maintaining security of each servlet and seeing when and if ay has been broken into amd more importantly:
you still need a main controller servlet to take in the request and deal with it appropriately- ie
the if else scenario decribed above and then dispatch it to the correct servlet.
Let me make my example concrete with a simple example:
A servlet can have four operations logOut, payForbasket, addToBasket and removeFromBasket.
Now your method would be that each operation has a different servlet. My approach would be to have a handleResponse() method with a if else blockas explained before.
This is bad design surely.!!
As a side note lets say you have a from which needs filling in- and four fields you must make sure are not blank inputs. My naive approach is to get all the parameters and check if the are equal to "" -if one is blank then build the form again with all the fields which were not empty in place- there must be abetter way to do this.
String notify=httpRequest.getParameter("submitNewBug.notify");
         String version=httpRequest.getParameter("submitNewBug.version");
         String platform=httpRequest.getParameter("submitNewBug.platform");
         String os=httpRequest.getParameter("submitNewBug.os");
         String severity=httpRequest.getParameter("submitNewBug.severity");
         String component=httpRequest.getParameter("submitNewBug.component");
         String description=httpRequest.getParameter("submitNewBug.description");
if(title.equals("")){
          StringBuffer errorString=new StringBuffer("The title was not filled out ");
          return submitNewBug(responsePage,errorString,projectID,title,notify,version,platform,os,severity,component,description);
         }else if(notify.equals("")){
          StringBuffer errorString=new StringBuffer("The notify field  was not filled out ");
          return submitNewBug(responsePage,errorString,projectID,title,notify,version,platform,os,severity,component,description);
         }else if(version.equals("")){
          StringBuffer errorString=new StringBuffer("The version field  was not filled out ");
          return submitNewBug(responsePage,errorString,projectID,title,notify,version,platform,os,severity,component,description);
         }else if(platform.equals("")){
          StringBuffer errorString=new StringBuffer("The platform field  was not filled out ");
          return submitNewBug(responsePage,errorString,projectID,title,notify,version,platform,os,severity,component,description);
         }else if(os.equals("")){
          StringBuffer errorString=new StringBuffer("The OS field  was not filled out ");
          return submitNewBug(responsePage,errorString,projectID,title,notify,version,platform,os,severity,component,description);
         else if(severity.equals("")){
          StringBuffer errorString=new StringBuffer("The severity field  was not filled out ");
          return submitNewBug(responsePage,errorString,projectID,title,notify,version,platform,os,severity,component,description);
         }else if(component.equals("")){
          StringBuffer errorString=new StringBuffer("The severity field  was not filled out ");
          return submitNewBug(responsePage,errorString,projectID,title,notify,version,platform,os,severity,component,description);
         }else if(description.equals("")){
          StringBuffer errorString=new StringBuffer("The severity field  was not filled out ");
          return submitNewBug(responsePage,errorString,projectID,title,notify,version,platform,os,severity,component,description);
    //else form correctly filled in!-so can carry onIf you have a big servlet then i do not believe this is how you retain form fields the cient has submitted- Remember i am using a template HTML file where i do a find and replace strtergy