isNew() method

[Shanthi Murugeson]

Hi,
I have a servlet program in which i am checking whether the session created is new or not. But the isNew() method always returns false even if i redeploy my application.
I am using BEA weblogic 8.1 server
Can anyone please tell me the reason.
Thanks in advance.

I have attached my code with this..

public class DatabaseServlet extends HttpServlet
{
 
int numRec=0;
int numCols=0;
String cnames[];
ResourceBundle properties = null;
ResultSet rs=null;
HttpSession session;

//Inner class 
class NewSession{
int count=0;
int pkeyindex = 0;
int rownum;
String primDataType=null;
String tablename = null;
String resultset = null;
String colnames = null;
String bpressed = null;
String query = null;
String primkey = null;
String pkey = "";
String order=null;
String subquery=null;
String end=null;
String url=null;
String pkeyval = null;
Connection conn = null;
PreparedStatement pstmt = null;
Statement stmt;
ResultSet rs=null;
ResultSet rscoltype=null;
HttpSession session;
RequestDispatcher dispatcher;
ResultSetMetaData rmd=null;
DatabaseMetaData dmd = null;
boolean flag;
}
 
public void init() {
properties = ResourceBundle.getBundle(DBConstants.PROPERTY);//getting properties from property file
numRec = Integer.parseInt(properties.getString(DBConstants.NUMOFRECORDS));
numCols = Integer.parseInt(properties.getString(DBConstants.NUMOFCOLUMNS));
cnames = new String[numCols];
System.out.println("init() of dbs");
}
 
public void destroy() {
System.out.println("destroy()");
}
 
public void doGet(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException
{
session=request.getSession(true);
NewSession newSession;
System.out.println(session.isNew());
[B]if( session.isNew() ){
System.out.println("newsession");
newSession=new NewSession();
newSession.flag=false;
DBConnect dbconn = new DBConnect();
newSession.conn=dbconn.getConnection();
newSession.bpressed=request.getParameter("button");
try {
newSession.dmd = newSession.conn.getMetaData();
} catch(SQLException sq) {
sq.printStackTrace();
   }
session.setAttribute("newsession",newSession);
}
else
{
newSession=(NewSession)session.getAttribute("newsession");
newSession.bpressed=request.getParameter("button");
}[/B]
        int cnt=0;
try {
if (newSession.bpressed == null) {
newSession.flag=true;
newSession.colnames = "";
newSession.url=null;
newSession.rownum = numRec;
newSession.order="asc";
newSession.tablename = request.getParameter("comboTableName").toUpperCase();
System.out.println("TableName :"+newSession.tablename);
newSession.rs = newSession.dmd.getColumns(null,null,newSession.tablename,null);
System.out.println("No. of Cols from Property File : " + numCols);
newSession.rmd=newSession.rs.getMetaData();
rs=newSession.rs;
while(rs.next())
cnt++;
if ( cnt < numCols )
{
numCols = cnt;
}
System.out.println("No. of Cols in " +newSession.tablename + " is :" +  numCols);
newSession.primkey = getPrimaryKeys(newSession);
rs=getColumnNames(newSession);
System.out.println("number of cols--"+rs.getFetchSize());
for(int i=0;i<numCols;i++){
rs.next();
cnames[i]=rs.getString(4);
newSession.colnames += cnames[i] + "!";
if (cnames[i].equals(newSession.primkey))
newSession.pkeyindex = i+1;
}
System.out.println("Column Names inserted in result string");
System.out.println("Primary Key is :"+ newSession.primkey + " and Primary Key Index : "+newSession.pkeyindex);
newSession.resultset = newSession.colnames + "#";
rs=getData(newSession);
while(rs.next()) {
for (int k=1; k<=numCols; k++) {
newSession.resultset += rs.getString(k)+"!";
}
}
newSession.rmd=rs.getMetaData();
newSession.primDataType=newSession.rmd.getColumnTypeName(newSession.pkeyindex);
System.out.println(newSession.pkeyindex+"********"+newSession.primDataType);
System.out.println();System.out.println();
System.out.println("Complete Value bein Passed : " + newSession.resultset);
System.out.println();System.out.println();
session.setAttribute("sessionTableName",newSession.tablename);
session.setAttribute("PrimaryKeyIndex",newSession.pkeyindex + "");//sending name of primary key index
session.setAttribute("PrimaryKeyDataType",newSession.primDataType);
session.setAttribute("noCols",numCols+"");
session.setAttribute("noRec",numRec+"");
session.setAttribute("value",newSession.resultset);
session.setAttribute("session_primarykey",newSession.primkey);//sending name of primary key column
newSession.url=response.encodeURL("/second.jsp");
newSession.dispatcher = getServletContext().getRequestDispatcher(newSession.url);
if (newSession.dispatcher != null){
newSession.dispatcher.forward(request,response);
}
}//end of if
//the else part is reached when the control comes from the jsp, where there are four buttons to access first,last,previous and next records
else {
newSession.rs= null;
newSession.resultset = newSession.colnames + "#";
System.out.println("Result String only with Column Names :"+newSession.resultset);
newSession.bpressed = request.getParameter("button").toUpperCase();
 
System.out.println(newSession.bpressed);
/****************************First button is Pressed **********************************/
if(newSession.bpressed.equals("FIRST")) {
System.out.println("order :"+newSession.order+", rownum :"+newSession.rownum+" ,numRec :"+numRec);
if((newSession.order.equals("asc")) && (newSession.rownum==numRec)){}
else{
newSession.order="asc";
newSession.rownum =numRec;
getString(newSession);
}
newSession.url=response.encodeURL("/second.jsp");
newSession.dispatcher = getServletContext().getRequestDispatcher(newSession.url);
if (newSession.dispatcher != null)
newSession.dispatcher.forward(request,response);
}//end of if
/****************************Next Button is Pressed************************************/
else if(newSession.bpressed.equals("NEXT")){
if(newSession.order.equals("asc"))
newSession.rownum+=numRec;
else
newSession.rownum-=numRec;
System.out.println("Value of RowNum on clicking next :"+ newSession.rownum + " and NumRec :"+numRec);
if(newSession.rownum == 0)
newSession.rownum =numRec;
else
getString(newSession);
newSession.url=response.encodeURL("/second.jsp");
newSession.dispatcher = getServletContext().getRequestDispatcher(newSession.url);
if (newSession.dispatcher != null)
newSession.dispatcher.forward(request,response);
}
/**************************Previous buuton is Pressed *************************************/
else if (newSession.bpressed.equals("PREVIOUS")) {
if(newSession.order.equals("asc"))
newSession.rownum-=numRec;
else
newSession.rownum+=numRec;
System.out.println(newSession.rownum);
if(newSession.rownum == 0)
newSession.rownum =numRec;
else
getString(newSession);
newSession.url=response.encodeURL("/second.jsp");
newSession.dispatcher = getServletContext().getRequestDispatcher(newSession.url);
if(newSession.dispatcher != null)
newSession.dispatcher.forward(request,response);
}
/***************************Last Button is Pressed****************************************/
else if(newSession.bpressed.equals("LAST")){
if(((newSession.order).equals("desc"))&& (newSession.rownum==numRec)){}
else{
newSession.order="desc";
newSession.rownum =numRec;
getString(newSession);
}
newSession.url=response.encodeURL("/second.jsp");
newSession.dispatcher = getServletContext().getRequestDispatcher(newSession.url);
if(newSession.dispatcher != null)
newSession.dispatcher.forward(request,response);
}
/***************************Search Button is Pressed***************************************/
else if(newSession.bpressed.equals("SEARCH")){
newSession.url=response.encodeURL("/search.jsp");
newSession.dispatcher=getServletContext().getRequestDispatcher(newSession.url);
if(newSession.dispatcher != null)
newSession.dispatcher.forward(request,response);
}
/***************************Edit Button is Pressed***************************************/
else if(newSession.bpressed.equals("EDIT/DELETE")) {
System.out.println(request.getParameter("chk"));
newSession.pkeyval = request.getParameter("chk");
System.out.println("******"+newSession.pkeyval);
session.setAttribute("pkeyvalue",newSession.pkeyval);
session.setAttribute("flag1",new Integer(1));
newSession.url=response.encodeURL("/third");
newSession.dispatcher = getServletContext().getRequestDispatcher(newSession.url);
if (newSession.dispatcher != null) {
newSession.dispatcher.forward(request,response);
}
}//END FOR EDIT
else if(newSession.bpressed.equals("HOME")){
newSession.url=response.encodeURL("/DBCombo.jsp");
newSession.dispatcher = getServletContext().getRequestDispatcher(newSession.url);
if (newSession.dispatcher != null) {
newSession.dispatcher.forward(request,response);
}
}//END FOR HOME
}//end of if
}catch(SQLException se){
se.printStackTrace();
}
catch(IOException ie){
ie.printStackTrace();
}
}
 
public int getCount(NewSession newSession){
try{
newSession.pstmt=newSession.conn.prepareStatement("select count(*) from "+newSession.tablename );
rs=newSession.pstmt.executeQuery();
rs.next();
newSession.count=rs.getInt(1);
}catch(Exception e){
e.printStackTrace();
}
return newSession.count;
}
 
public void getString(NewSession newSession){
try{
rs=getData(newSession);
if(newSession.order.equals("asc")){
for (int i=0;i<newSession.rownum-numRec;i++ )
{
rs.next();
}
}
//while(rs.next()) {
for (int i=0;i<numRec;i++){
rs.next();
for(int k=1;k<=numCols;k++) {
newSession.resultset += rs.getString(k)+"!";
}
}
session.setAttribute("value",newSession.resultset);
System.out.println("*****************************************************************************");
System.out.println("Result String for next :"+newSession.resultset);
System.out.println("*****************************************************************************");
}catch(SQLException sqle){
sqle.printStackTrace();
}//end of catch
}//end of connect
 
public ResultSet getData(NewSession newSession){
try{
newSession.query="";
rs=null;
for(int k=0;k<numCols-1;k++) {
newSession.query+=cnames[k] + ",";
}
newSession.query+= cnames[numCols-1];
System.out.println("Select String in getData : " + newSession.query);
if(newSession.order.equals("asc")){
newSession.subquery=newSession.tablename;
newSession.end="";
}
else{
newSession.subquery="( select "+newSession.query+" from "+newSession.tablename+" order by "+newSession.primkey+" "+ newSession.order+" )";
newSession.end= " order by "+newSession.primkey;
}
newSession.pstmt=newSession.conn.prepareStatement(" select "+newSession.query+ " from  "+newSession.subquery+"  where rownum <= " + newSession.rownum+" "+newSession.end);
 
System.out.println("Inside getData :  select "+newSession.query+ " from  "+newSession.subquery+"  where rownum <= " +newSession.rownum+" "+newSession.end);
rs=newSession.pstmt.executeQuery();
 
}catch(SQLException sqle){
sqle.printStackTrace();
}
return rs;
}//end of getData
 
public ResultSet getColumnNames(NewSession newSession){//method to get the column names of a table
try {
rs = newSession.dmd.getColumns(null,null,newSession.tablename,null);
}//end of try
catch(SQLException sqle){
System.out.println(newSession.tablename+" Table NOT found ");
sqle.printStackTrace();
}//end ofcatch
return rs;
}//end of getColumnNames
 
 
 
public String getPrimaryKeys(NewSession newSession) {
try {
rs = newSession.dmd.getPrimaryKeys(null,null,newSession.tablename);
rs.next();
System.out.println("*********Inside getPrimaryKeys***********");
System.out.println("one : "+rs.getString(1) + "2. : "+ rs.getString(2)+"3. : "+rs.getString(3)+"4 : "+rs.getString(4));
System.out.println("*********Inside getPrimaryKeys***********");
newSession.pkey = rs.getString(4);
} catch(SQLException sqle) {
System.out.println("Exception in getPrimaryKeys");
sqle.printStackTrace();
   }//end of catch
return newSession.pkey;
}//end of getPrimaryKeys
}//end of class

[EDIT - code tags added]
[ February 06, 2006: Message edited by: David O'Meara ]

[David O'Meara]

You may find that the comtainer if creating the session before your code gets run, but you can still manage this. Just modify your code to see if the session has been initialised yet and add your code there instead:

NewSession newSession = (NewSession)session.getAttribute("newsession");
System.out.println(session.isNew());
if( newSession ==null ){
//not initialised
System.out.println("newsession");
newSession=new NewSession();
newSession.flag=false;
DBConnect dbconn = new DBConnect();
newSession.conn=dbconn.getConnection();
newSession.bpressed=request.getParameter("button");
try {
newSession.dmd = newSession.conn.getMetaData();
} catch(SQLException sq) {
sq.printStackTrace();
   }
session.setAttribute("newsession",newSession);
}
else
{
newSession.bpressed=request.getParameter("button");
}

Note that attaching a connection to a session is a bad idea, as a database connection is a heavy object, and it is better to limit the number created. They are also utilised fairly sparingly, so getting them from a ConnectionPool is much more efficient.

Dave