A SIMPLE DEMO FOR LOOKUP DISPATCH ACTION...HINTS

         In struts, there are five special  Actions.They are




                   1.ForwardAction


                   2.DispathAction


                   3.LookupDispathAction


                   4.SwitchAction


                   5.IncludeAction                   


          In these Actions first three actions (ForwardAction,DispatchAction,       LookupDispatchAction) are very important. 


I have already done  a     simple demo for DispatchAction which is about If we want to use   more than one function in Action class what we have to do. 


         LookupDispathchAction is also similar  to DispatchAction. 


       But,       Additionally we have to do  two things


                   1.Implemetation of getKeyMethodMap()  method
                   2.put entry in .properties file


  demoAction.java
 -----------------     
  public class demoAction extends LookupDispatchAction
       { 
        
//your methods


 protected   Map   getKeyMethodMap()
    {


    Map map=new  HashMap();
    map.put("operation.add","add");
    map.put("operation.sub","sub");


   //map your methods as above






    return map;
    }


  }


Application.properties file entry
----------------------------------
operation.add=Add
operation.sub=Sub
...
  

PREPARING ABSTRACT,TABLE-DESIGN, TECHNOLOGY STACK,DFD

   Yessterday( 5-2-2012), I prepared the draft Abstract  and a note on Technology stack for my project.
I prepared tables  design and  DataFlow Diagram.
      I think, the technology stack will be of interest to students like me.
I am giving that below.
=====================================================================


Brief  Overview about  Technology  Stack

       Nowadays, There is much debate between two sets
of technologies. One group consists of Spring, Struts1.1,
struts2, Hibernate, and the other group consists of JSF, JPA,
SEAM. And also for providing webservice some of them make use
of REST protocal and some of them use SOAP.
JPA, JSF are all JCP standard.
Spring, and struts are not standards.
 But, theyare used widely .
That is why we are giving equal importance to
both set of technologies.


Webserver                                          Tomcat 5.0


Enterprise Server                               JBoss4.2.2  /     JBoss5


Development Platform                       Windows  XP (service pack2)


Database                                             MySql  in WAMP server


Database Accessing                          JDBC  /   ORM(Hibernate)


Syndication                                          RSS feed


Container                                             Spring   /     SEAM


AJAX technology                                jQuery+JSON


Web Framework                                 STRUTS1.1/ STRUTS2/ JSF


Portal                                                  JBoss Portal software


Messaging                                          JBoss Messaging


Mobile Client                                      J2ME


Reports                                              Jasper Reports


XML WebService                             AXIS / JBoss webservice  and REST


IDE                                                    ECLIPSE  3,5 ( GANYMEDE)


Build-tools                                        ANT   /  MAVEN


UNIT TESTING                               JUnit


CMS                                                 JBOSS  CMS


UML                                                  STAR UML

SEQUENTIAL IMAGE LOADING FROM SERVER USING JSON & jQUERY

  Today, I successfully developed a demo for getting pictures one by one from the server automatically, by timer effect.   I made use of JSON  and jQUERY.
     This time, I have made use of JSON-Java library as a jar file. I got that from JSON.org site.
The name of the jar file that I selected is json-simple.jar. There are a lot of json-java librarries there!.
   This library is recommended in  Ajax on Java book. which I am using.
I placed this jar in tomcat\web-apps\root\web-inf\lib  folder.

--------------------------------------------------------------------------------
The jsp code is given below.


 JSONObject             ob1  =  new JSONObject();
       JSONObject       ob2  =  new JSONObject();

      String s1="";

      s1="alice.jpg";      ob1.put("alice",s1);

      s1="clinton.jpg";      ob1.put("clinton",s1);

      s1="cindy.jpg";      ob1.put("cindy",s1);

      s1="colin.jpg";      ob1.put("colin",s1);

      s1="nathan.gif";      ob1.put("nathan",s1);

      s1="mathew.gif";      ob1.put("mathew",s1);

      ob2.put("myarray",ob1);      String r=ob2.toString();


      System.out.println(r);  // for checking
      out.println(r);
----------------------------------------------------------------------------------------
 Now to the client side.


function   job5()   // jQuery Ajax
     {
      $.get("imagesender.jsp",function(r)
        {     
       a=r
      });
              a = eval('('+a+')');             
                    }

n=1
     function   job1()
     {
       if(n==7){         n=1}

       if(n==1){          s="http://localhost:8080/"+a.myarray.alice}  etc
       if(n==2)            s="http://localhost:8080/"+a.myarray.clinton
     

       setTimeout("job4()",1000)

     }
     function  job4()
          {
       $("#img1").attr({src:s});
        n=n+1
       job1();
     }
     //------------------------





     



 

DISPATCH ACTION DEMO FOR CRUD OPERATIONS

A NOTE ON DISPATCHACTION IN STRUTS1.1

    When we have a number of related methods,
instead of writing action-class for each operation,
we should use DispatchAction. Usually in Action class we
define execute(...) method.But, in DispatchAction you
can have your own methods which should resemble the
signature of the original execute(...) method.
public ActionForward execute(ActionMapping mapping,
ActionForm form,HttpServletRequest request,
HttpServletResponse response);
I am going to explain this DispatchAction with two applications.
The first one deals with databese CRUD operations and the second
one deals with simple arithmetic operations.
when you use this DispatchAction, you should be careful
while providing action mapping. We have to specify one more
attribute. that is 'parameter' which holds the method name which
we want to access.



My database table has three fields ( key, name, place).
My example has the following files.
demoInput.jsp
demoForm.java
Finally, we have demoOutput.jsp for
displaying the result in table form
using jstl for iteration.
I am giving demoAction.java here
=================================================================
package demopack;
import java.io.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
import org.apache.struts.action.*;
import org.apache.struts.actions.DispatchAction;
public class demoAction extends DispatchAction

{
public ActionForward addRecord(ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response)
{

demoForm demoform=(demoForm)form;
String a=demoform.getKey();
String b=demoform.getName();
String c=demoform.getPlace();
if(a.length()!=0)
{
querybean bean1=new querybean();
Vector vector=bean1.addRecord(a,b,c);
request.setAttribute("result",vector);
return(mapping.findForward("success"));
}
else
{ return ( mapping.findForward("failure"));}
}
//------------------------------------------
public ActionForward modifyRecord(ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response)
{
demoForm demoform=(demoForm)form;
String a=demoform.getKey();
String b=demoform.getName();
String c=demoform.getPlace();
if(a.length()!=0)
{
querybean bean1=new querybean();
Vector vector=bean1.modifyRecord(a,b,c);
request.setAttribute("result",vector);
return(mapping.findForward("success"));
}
else
{ return ( mapping.findForward("failure"));}
}
//--------------------------------------------------
public ActionForward removeRecord(ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response)
{
demoForm demoform=(demoForm)form;
String a=demoform.getKey();
String b=demoform.getName();
String c=demoform.getPlace();
if(a.length()!=0)
{
querybean bean1=new querybean();
Vector vector=bean1.removeRecord(a);
request.setAttribute("result",vector);
return(mapping.findForward("success"));
}
else
{ return ( mapping.findForward("failure")); }
}
//------------------------------------------------------------
public ActionForward showRecord(ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response)
{
demoForm demoform=(demoForm)form;
String a = demoform.getKey();
String b = demoform.getName();
String c = demoform.getPlace();
if(a.length()!=0)
{
querybean bean1=new querybean();
Vector vector1 = bean1.showRecord(a); // key
request.setAttribute("result",vector1);
return(mapping.findForward("success"));
}
else
{ return ( mapping.findForward("failure"));}
}
//-------------------------------------------------------
public ActionForward showallRecords(ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response)
{
demoForm demoform=(demoForm)form;
String a=demoform.getKey();
String b=demoform.getName();
String c=demoform.getPlace();
if(a.length()!=0)
{
querybean bean1=new querybean();
Vector vector1 =bean1.showallRecords();
request.setAttribute("result",vector1);
return(mapping.findForward("success")); }
else
{ return ( mapping.findForward("failure"));}
}

In demoOutput.jsp,I have iterated the objects
returned by the methods defined in
demoAction class
===================================================
package demopack;
import java.util.*;
import java.sql.*;
public class querybean
{
Connection connection;
Vector vector1;
public querybean()
{
vector1 = new Vector();
try
{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
String url="jdbc:odbc:keynameplace";
connection=DriverManager.getConnection(url);
}
catch(Exception e1)
{ vector1.addElement(""+e1);}
}
//-------------------------------
public Vector addRecord(String a,String b,String c)
{
Statement statement=connection.createStatement();
String sql="insert into table1 values('"+a+"','"+b+"','"+c+"')";
statement.execute(sql);
player player1 = new player();
player1.setKey("added");
player1.setName("");
player1.setPlace("");
vector1.add(player1);
connection.close();
}catch(Exception e1) {System.out.println(""+e1); }
return vector1;
}
//--------------
public Vector modifyRecord(String a,String b,String c)
{
Vector vector1 = new Vector();
try
{
Statement statement=connection.createStatement();
String sql="update table1 set table1.name='"+b+"',table1.place='"+c+"' where table1.key='"+a+"' ";
statement.execute(sql);
player player1 = new player();
player1.setKey("modified");
player1.setName("");
player1.setPlace("");
vector1.add(player1);
connection.close();
}catch(Exception e1) {vector1.addElement(""+e1); }
return vector1;
}
//======================
public Vector removeRecord(String a)
{
try
{
Statement statement=connection.createStatement();
String sql="delete from table1 where table1.key='"+a+"' ";
statement.execute(sql);
player player1 = new player();
player1.setKey("removed");
player1.setName("");
player1.setPlace("");
vector1.add(player1);
}catch(Exception e1) {System.out.println(""+e1); }
return vector1;
}
//===========================
public Vector showRecord(String a)
{
try
{
Statement statement=connection.createStatement();
System.out.println ("statement ready");
String sql="select * from table1 where key='"+a+"' ";
System.out.println(sql);
ResultSet rs=statement.executeQuery(sql);
while(rs.next())
{
String s1=rs.getString(1);
String s2=rs.getString(2);
String s3=rs.getString(3);
player player1 = new player();
player1.setKey(s1);
player1.setName(s2);
player1.setPlace(s3);
vector1.add(player1);
}
}catch(Exception e1) { vector1.addElement(""+e1); }
return vector1;
}
//======================
public Vector showallRecords()
{
try
{
Statement statement=connection.createStatement();
String sql="select * from table1";
ResultSet rs=statement.executeQuery(sql);
while(rs.next())
{
player player=new player();
String s1=rs.getString(1);
String s2=rs.getString(2);
String s3=rs.getString(3);
player.setKey(s1);
player.setName(s2);
player.setPlace(s3);
vector1.add(player);
}
}catch(Exception e1) {System.out.println(""+e1); }
return vector1;
}
//======================
}
==========================================
The following code is for the player class that we have used above.
package demopack;
public class player
{
String key;
String name;
String place;
public void setKey(String a) { key = a; }
public void setName(String b) { name = b; }
public void setPlace(String c) { place = c; }
//==================
public String getKey() { return key; }
public String getName() { return name; }
public String getPlace() { return place; }
}
how to iterate the collection of objects created in querybean.


=============================================
I tested the code and got correct results.
This demo shows how we use DispatchAction.
It also shows how the action just returns an array ( vector).
It is the job of the output.jsp to display the result as it wants.
The action class should NOT take the responsibilty of how
the result is to be displayed,
If you want to explain the purpose of DispatchAction to a beginner,
I think we should use a very simple example. We need not bring in
things jstl ,jdbc etc.
We said that we use DispatchAction when there are a number of functions
inter-related as in CRUD.
So, why not a simple calcbean ?
For this purpose I have thought of an calcbean having 4 methods
( add, subtract,multiply and divide).
So, I developed dispatchapp with simple
arithmetic operations (addidtion, subtraction,
multiplication and division.
That will better bring out the essence of DispatchAction.
This is given in my next blog.

CYCLIC DISPLAY OF IMAGES FROM SERVER-SIDE

WE CAN GET PICTURES FROM SERVER-SIDE AND DISPLAY THEM IN BROWSER PAGE AUTOMATICALLY WITH SET TIME INTERVAL. HOW?

----------

It is about simple javascript timer effect to the above program.

So, I modified the code as ,

function job1()

{

if(n==7) { n=1};

n=1;

if(n==1){ s="alice" }

if(n==2) { s="clinton"}

if(n==3){ s="cindy"}

if(n==4){ s="colin"}

if(n==5){ s="nathan"}

if(n==6){ s="mathew"}

setTimeout("job4()",1000)

}

function job4()

{

$.get("imagesender.jsp",{'combo1':s},function(r)

{

$("#img1") . attr({ src : r }); // jQuery syntax!

});

n=n+1

job1();

}

jQuery-Ajax for getting URL of selected picture from JSP

Loading An image in HTML page With the help Of

jQuery AJAX, And JSP

Today, I did a program which can load an image using jquery ajax

and jsp. The HTML code will have a combo box which lists the names of some

famous personalities. The corresponding picture will be loaded when

you select a name from the combo.( the URL of the image comes from server side)

HTML file will call jsp page with selected name as an argument.

The jsp file will return appropriate url of the selected name.

Then we can load the image in image tag using jquery code as follows.

$.get("imagesender.jsp",{'combo1':s},function(r)

{

$("#img1").attr({src:r});

});

and the jsp code will be,

String r="http://localhost:8080/images/";

if(s.equals("alice")) { r=r+"alice.jpg"; }

if(s.equals("clinton")) { r=r+"clinton.jpg"; }

if(s.equals("cindy")) { r=r+"cindy.jpg"; }

if(s.equals("colin")) { r=r+"colin.jpg"; }

if(s.equals("nathan")) { r=r+"nathan.gif"; }

if(s.equals("mathew")) { r=r+"mathew.gif"; }

System.out.println(r);

out.println(r);

and also I added some code to magnify this image when hovering.

$('#img1').attr({width:250});

I found that jQuery automatically preserves the width:height ratio!

**************************************************************************

JDBC-AJAX-Chained List Using JSON

Today(1-2-2012), I developed a chained list demo using json.js library

and raw AJAX. For this demo I required

1.combo1 -to show state names 2.List1 -to populate cities according

to the selected state. 3.List2 -the selected city in List1

to be added to list2

To store these state and cities I needed a database table. So I created a table with two fields 1.state,2.city

Then, I used 3 buttons,a)for listing the cities in list1

b) to add city to List2

c) to Remove city from List2

When user clicks “List the cities” button, the AJAX will call “jsondemo.jsp” page which gets the selected state as an input .

Using this input we form the sql query as

“select *from table1 where state=’”+selectedState+”’”

This will return the Resultset. In this ResultSet, we need the second column only which contains cities name in accordance with given state.

Then we have to iterate this String to form JSONString. Then return this String to ajax code.

(Reference: Ajax On Java -Steven douglas olson,Orielly publishers(page 49))

For populating the cities in List1 we need to access database with the help of JSP. for other remaining two tasks we can use simple javascript code.

I tested this code in IE. I got correct result. I tried this same code in Firefox and Chrome. But, It didn’t work. Though the object is initialized correctly, data could not be populated in Lists. I must find out!