"Fitting The Pieces Into The Enterprise Java Jigsaw, by Tony Loton"
Vol. 6, Issue 5, p. 72

	


Listing 1: Writing User Options as Applet Parameters
 
//-- write the options out as an applet -- 

out.println( 
 "<applet code=com.lotontech.applets.OptionsApplet 
  height=30, width=600>"); 

out.println("<param name=user value="+user+"></param>"); 

for (int opNum=0; opNum<options.size(); opNum++) 
{ 
  String thisOption=(String) options.elementAt(opNum); 

  out.println("<param name=option"+(opNum+1) 
   +" value="+thisOption+"></param>"); 
} 

out.println("</applet>"); 
  

Listing 2: Options Applet Java Code
 
public class OptionsApplet extends Applet 
 implements ActionListener 
{ 
 public void init() 
 { 
  // -- get the user from parameter -- 
  String user=getParameter("user"); 

  // -- GUI would be initialized here -- 

  int opNum=0; 
  boolean finished=false; 
  while (!finished) 
  { 
   opNum++; 

   String thisOption=getParameter 
    ("option"+opNum); 

   if (thisOption==null) finished=true; 
   else 
   { 
    Button newButton=new Button(thisOption); 
    this.add(newButton); 
    newButton.addActionListener(this); 
   } 

  } 

 } 

 // -- ActionListener Method -- 
 public void actionPerformed(ActionEvent event) 
 { 

  if (event.getSource() instanceof Button) 
  { 
   Button sourceButton=(Button)event.getSource(); 

   // -- tell browser to launch selected app. -- 

   AppletContext theBrowser 
    =this.getAppletContext(); 

   try 
   { 
     URL documentBase=getCodeBase(); 

     URL newURL=new 
      URL(documentBase,sourceButton.getLabel()); 

     theBrowser.showDocument(newURL,"main"); 
   } 
   catch (Exception ex) {ex.printStackTrace();} 
  } 

 } 

} 

Listing 3: TaskServlet
 
public class TaskServlet extends HttpServlet 
{ 
 public void doGet(HttpServletRequest req 
  , HttpServletResponse res) throws IOException 
 { 

  // -- get the current http session -- 
  HttpSession session=req.getSession(true); 

  String user=(String) 
   session.getAttribute("user"); 

  // -- check for null user omitted - 

  String getdata=req.getParameter("getdata"); 
  if (getdata==null) getdata="false"; 

  if (!getdata.equals("true")) 
  { 
   // -- download HTML with task applet tag 
  } 
  else 
  { 
   // --task applet calling me again for data -- 

   Vector tasks=new Vector(); 

   // -- get connection from datasource -- 
   InitialContext ic = new InitialContext(); 

   DataSource ds = (DataSource) 
    ic.lookup("java:comp/env/jdbc/LOTONtech"); 

   Connection con = ds.getConnection(); 

   // -- select user tasks from the database -- 
   Statement st=con.createStatement(); 

   ResultSet results=st.executeQuery( 
    "SELECT username, task , priority 
    FROM usertasks WHERE username='"+user+"'"); 

   while (results.next()) 
   { 
    Task thisTask=new Task(results.getString(2) 
     , results.getString(3)); 

    tasks.addElement(thisTask); 
   } 

   // -- return serialized vector to the applet -- 
   ObjectOutputStream taskStream = new 
    ObjectOutputStream(res.getOutputStream()); 

   taskStream.writeObject(tasks); 
  } 
 } 
} 
  

Listing 4: TaskApplet
 
public class TaskApplet extends Applet 
{ 
 public void init() 
 { 
  // -- get the user from parameter -- 
  String user=getParameter("user"); 

  // -- set up the GUI Lists -- 

  this.setBackground(new Color(0,0,128)); 
  setLayout(new GridLayout(1,2)); 

  java.awt.List highList=new java.awt.List(); 
  highList.add("HIGH PRIORITY"); 
  highList.add(""); 
  add(highList); 

  java.awt.List lowList=new java.awt.List(); 
  lowList.add("LOW PRIORITY"); 
  lowList.add(""); 
  add(lowList); 

  try 
  { 
   // -- get user tasks from task servlet -- 

   URL servletURL=new URL(this.getCodeBase() 
    ,"getTasks?getdata=true"); 

   ObjectInputStream taskStream= 
    new ObjectInputStream(servletURL.openStream()); 

   Vector tasks=(Vector) taskStream.readObject(); 

   // -- and display them in 2 lists -- 

   for (int taskNum=0; taskNum<tasks.size(); 
   taskNum++) 
   { 
    Task thisTask=(Task) tasks.elementAt(taskNum); 

    if (thisTask.priority.equals("high")) 
     highList.add(thisTask.taskName); 
    else if (thisTask.priority.equals("low")) 
     lowList.add(thisTask.taskName); 
   } 

  } 
  catch (Exception ex) 
  { 
   // -- send error to Java Console -- 
   ex.printStackTrace(); 
  } 

 } 
}