Want detailed sample code(value list handler pattern) for my case

Question

I am trying to write a Session Facade Bean with getAllUsers() method which get Collection pased from my UserBean(entity), to get all my users info.and I have a helper class called UserInfo
public class UserInfo implements java.io.Serializable
public String userid;
public String username;
public String password;
     public UserInfo()
     public void setUserInfo(String userid,String username,String password)
          this.userid=userid;
          this.username=username;
          this.password=password;
I dont' know How my ejb client(jsp maybe) to use value list handler pattern to implement getting all users shown.
I found http://java.sun.com/blueprints/corej2eepatterns/Patterns/ValueListHandler.html the sample code is to complex.
any one could help me figure out ...
what helper class do i need .or maybe interface
what is the best practice?
thanks in advanced.

Answer 1

Hi,
For a J2EE system with session facades, I've implemented that pattern based on the DTO pattern.
The idea is based on Sun's blueprint Pet Store implementation.
For that' I've created a DTO called "ListChunk", which holds a chunk of the complete list. In the Pet Store
application v1.3.2 it's called "Page".
So, those facade methods that would possibly return a huge list (such as getAllXXX and findXXX)
return a ListChunk. As arguments, those methods take start index and the maximum size.
If you want a value-list handler to control the iteration on your client side, you code such a class that
uses the facade method.
Here's some code:
public class ListChunk implements Serializable {
     private List list;
     private int startIndex;     // starts on '0'
     private int totalSize;
     public ListChunk(List list, int startIndex, int totalSize)  {
          this.list = list;
          this.startIndex = startIndex;
          this.totalSize = totalSize;
     public List getList()  {
          return list;
     public int size()  {
          return list.size();
     public boolean hasNext()  {
          return totalSize > (startIndex + list.size());
     public boolean hasPrevious()  {
          return startIndex > 0;
     public int getTotalSize()  {
          return totalSize;
}And a method in the facade could look like this:
     public ListChunk getAllCoWorkers(int startIndex, int maxSize, CoWorkerSortBy sortBy) {...}