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Servlets

page gets hang on runtime

Megha Singhal

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Posts: 225

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posted 12 years ago

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after running following servlets the web page is get hanged
"ServletRecord.java"

import java.io.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
import java.lang.String;
import java.sql.Connection;
import javax.servlet.RequestDispatcher;

import java.sql.Statement;
import java.sql.ResultSet;
import javax.naming.*;
import javax.naming.directory.*;
import oracle.jdbc.pool.OracleDataSource;

public class ServletRecord extends HttpServlet{

public void doGet(HttpServletRequest request, HttpServletResponse response)
                                   throws ServletException,IOException{
        doPost(request,response);
    }
   public void doPost(HttpServletRequest request, HttpServletResponse response)
                                   throws ServletException,IOException{
            response.setContentType("text/html");
            PrintWriter out = response.getWriter();

Connection con = null;
                Statement st1 = null;

ResultSet rs = null;

try {

Context initContext = new InitialContext();
                 Context envContext = (Context) initContext.lookup("java:/comp/env");
                OracleDataSource ds = (OracleDataSource) envContext.lookup("jdbc/abc");
                 if (envContext == null)throw new Exception("Error: No Context");
                if (ds == null) throw new Exception("Error: No DataSource");
                if (ds != null)
                 con = ds.getConnection();

st1 = con.createStatement();

ArrayList al=null;
                ArrayList userList =new ArrayList();
                String query = "select * from ABC.PERSONS order by P_ID";
                System.out.println("query " + query);

rs = st1.executeQuery(query);

while(rs.next())
                {
                    al  = new ArrayList();

al.add(rs.getInt(1));
                  al.add(rs.getString(2));
                  al.add(rs.getString(4));
                  al.add(rs.getString(5));
                  System.out.println("al :: "+al);
                  userList.add(al);
                }

request.setAttribute("userList",userList);

String nextJSP = "Home";

RequestDispatcher dispatcher = request.getRequestDispatcher(nextJSP);
                dispatcher.forward(request,response);

rs.close();
                    st1.close();
                 con.close();

} catch (SQLException se) {
            out.println("An Error Had occurred while accessing the database");
            out.println("<HR>");

out.println(se.getMessage());
        }

catch (Exception e) {
            e.printStackTrace();

} finally {
            try {
                if (rs != null)
                    rs.close();
                if (st1 != null)
                    st1.close();

if (con != null)
                    con.close();
            } catch (Exception e) {
                out.println(e);
            }
        }

}
}

"Home.java"

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.sql.*;
import java.sql.*;
import java.util.*;

public class Home extends HttpServlet{

public void service(HttpServletRequest request, HttpServletResponse response)
                                   throws ServletException,IOException{
            response.setContentType("text/html");
            PrintWriter out = response.getWriter();
out.println("<HTML>");
 out.println("<HEAD>");
  out.println("<TITLE>Servlet Application</TITLE>");

out.println("<script language=\"javascript\">");
out.println("function editRecord(id){");

out.println("window.location.href=\"editUser.jsp?\"+id; }");

out.println("function deleteRecord(id){");

out.println("window.location.href=\"../edit/DeleteUser?\"+id;  }");
out.println("</script>");
 out.println("</HEAD>");

out.println("<BODY>");
 out.println("<br>");
out.println("<table align=\"center\">");

out.println("</table>");
out.println("<br>");
out.println("<table width=\"600px\"  align=\"center\" style=\"background-color:#EDF6EA;border:1px solid #000000;\">");
out.println("<tr><td colspan=9 align=\"center\" height=\"10px\"></td></tr>");

out.println("<tr><td colspan=9 align=\"center\"><a href=\"addUser.jsp\" style=\"font-weight:bold;color:#cc0000;\">Add New User</a></td></tr>");
out.println("<tr><td colspan=9 align=\"center\" height=\"10px\"></td></tr>");
  out.println("<tr style=\"background-color:#7BA88B;font-weight:bold;\">");
     out.println("<td>Person Id</td><td>LastName</td><td>FirstName</td>");
     out.println("<td>Address</td><td>City</td>");
     out.println("<td>Edit</td><td>Delete</td>");

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

String bgcolor="";
    int count=0;
    List viewList = new ArrayList();
    Iterator  viewItr;

if(request.getAttribute("userList")!=null && request.getAttribute("userList")!="")
    {
        List userList =  (ArrayList)request.getAttribute("userList");
        Iterator itr = userList.iterator();

while(itr.hasNext())
        {

if(count%2==0)
            {
             bgcolor = "#C8E2D1";
            }
            else
            {

bgcolor = "#EAF8EF";
            }

viewList = (ArrayList)itr.next();
            int P_ID = Integer.parseInt(viewList.get(0).toString());
            viewItr = viewList.iterator();

out.println("<tr style=\"background-color:bgcolor;\">");

while(viewItr.hasNext())
            {

out.println("<td>viewItr.next()</td>");

}
            count++;

out.println("<td><input type=\"button\" name=\"edit\" value=\"Edit\" style=\"background-color:#49743D;font-weight:bold;color:#ffffff;\" onclick=\"editRecord(P_ID);\" ></td>");
                out.println("<td><input type=\"button\" name=\"delete\" style=\"background-color:#ff0000;font-weight:bold;;color:#ffffff;\" value=\"Delete\" onclick=\"deleteRecord(P_ID);\"></td>");
            out.println("</tr>");

}
    }
    if(count==0)
    {

out.println("<tr><td colspan=\"9\" align=\"center\"> </td></tr>");
            out.println("<tr><td colspan=\"9\" align=\"center\">No Record Avaliable</td></tr>");

}

out.println("<tr><td colspan=9 align=\"center\" height=\"2px\"></td></tr>");

out.println("</table>");
 out.println("</BODY>");
out.println("</HTML>");
}
}

following database i 'm using
"P_ID" NUMBER(*,0),
"LASTNAME" VARCHAR2(255 BYTE),
"FIRSTNAME" VARCHAR2(255 BYTE),
"ADDRESS" VARCHAR2(255 BYTE),
"CITY" VARCHAR2(255 BYTE)
i'm not understanding why this is not working

William Brogden

Author and all-around good cowpoke

Posts: 13078

posted 12 years ago