Basic CRUD operations

LOGIC SERVLET

package com.tcs.ilp.h51.servlet;

import java.io.IOException;
import java.sql.SQLException;
import java.util.ArrayList;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.apache.catalina.startup.SetAllPropertiesRule;

import com.tcs.ilp.h51.DAO.Main;
import com.tcs.ilp.h51.DAO.Main.*;
import com.tcs.ilp.h51.model.Student;

/**
 * Servlet implementation class LogicServlet
 */
public class LogicServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public LogicServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }


    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("I am in do Post method");
        //HttpSession session=request.getSession();
        ArrayList<Student> al=new ArrayList<Student>();
        String client=request.getParameter("check");
        if(client.equals("add"))
        {
            System.out.println("I am in clent");
        String id=request.getParameter("id");
        String name=request.getParameter("name");
        String college=request.getParameter("college");
        String city=request.getParameter("city");
        String mobile=request.getParameter("phone");
        try {
            al=Main.insertquery(id,name,college,city,mobile);
            request.getSession().setAttribute("reports",al);
            RequestDispatcher rd=request.getRequestDispatcher("display.jsp");
            rd.forward(request, response);

        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        }




        else if(client.equals("delete")){

        System.out.println("deleting the operation");
         String id=request.getParameter("id");

          try {

              al=Main.deletequery(id);
             RequestDispatcher rd=request.getRequestDispatcher("display1.jsp");
             rd.forward(request, response);
          }catch(Exception e){

        }

        }


        else if(client.equals("viewd")){

            System.out.println("Fetching the details");
             String id=request.getParameter("id");



            try {
            al=Main.viewquery(id);
            request.getSession().setAttribute("reports1",al);
            RequestDispatcher rd=request.getRequestDispatcher("display2.jsp");
            rd.forward(request, response);  
            }catch (Exception e){
}
}


        else if(client.equals("update"))
    {
        System.out.println("I am in update");
    String id=request.getParameter("id");
    String name=request.getParameter("name");

    try {
        al=Main.updatequery(id,name);
        request.getSession().setAttribute("reports2",al);
        RequestDispatcher rd=request.getRequestDispatcher("display3.jsp");
        rd.forward(request, response);

    } catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    }

    }}

DAOCODE package com.tcs.ilp.h51.DAO;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
//import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;

import com.tcs.ilp.h51.model.*;
public class Main {
    static String name;
    static String college;
    static String city;
    static String mobile;

    static Connection conn=null;
    static PreparedStatement stat=null;
    static ResultSet rs=null;

    public static ArrayList<Student>insertquery(String id,String name,String college,String city,String mobile) throws SQLException
    {
        ArrayList<Student> addlist=new ArrayList<Student>();


        conn=DAOFactory.createConnection();
        try
        {

            stat=conn.prepareStatement("insert into cred values(?,?,?,?,?)");
            System.out.println("query is executing");
            stat.setString(1, id);
            stat.setString(2, name);
            stat.setString(3, college);
            stat.setString(4, city);
            stat.setString(5, mobile);

            int count=stat.executeUpdate();
            if(count>0)
            {
                System.out.println("Successfully inserted");
            }
            else
            {
                System.out.println("Unsuccessful insertion");
            }

            stat=conn.prepareStatement("select * from cred");
            rs=stat.executeQuery();
            Student st=null;
            while(rs.next()){
                st=new Student();
                st.setStudentId(rs.getString(1));
                st.setStudentName(rs.getString(2));
                st.setStudentCollege(rs.getString(3));
                st.setCity(rs.getString(4));
                st.setMobile(rs.getString(5));
                addlist.add(st);
            }
            //return addlist;
        }

        catch (SQLException e) {
            e.printStackTrace();
            // TODO: handle exception
        }
        return addlist;
    }




    public static ArrayList<Student>deletequery(String id) throws SQLException
    {

        conn=DAOFactory.createConnection();
        try
        {


            stat=conn.prepareStatement("delete from cred where id=?");

            System.out.println("query is deleted");
            stat.setString(1, id);


            int count=stat.executeUpdate();
            if(count>0)
            {
                System.out.println("Successfully deleted");
            }
            else
            {
                System.out.println("Unsuccessful deletion");
            }
        }catch(Exception e){

        }
        return null;
    }   




    public static ArrayList<Student>viewquery(String id) throws SQLException
    {

        ArrayList<Student> addlist1=new ArrayList<Student>();
        conn=DAOFactory.createConnection();
        try
        {


            stat=conn.prepareStatement("select * from cred where id=?");
            System.out.println("query is executing");
            stat.setString(1, id);



            rs=stat.executeQuery();
            Student st=null;
            while(rs.next()){
                st=new Student();
                st.setStudentId(rs.getString(1));
                st.setStudentName(rs.getString(2));
                st.setStudentCollege(rs.getString(3));
                st.setCity(rs.getString(4));
                st.setMobile(rs.getString(5));
                addlist1.add(st);

            }
            //return addlist;
        }

        catch (SQLException e) {
            e.printStackTrace();
            // TODO: handle exception
        }
        return addlist1;
    }

    public static ArrayList<Student>updatequery(String id, String name) throws SQLException
    {

        ArrayList<Student> addlist2=new ArrayList<Student>();
        conn=DAOFactory.createConnection();
        try
        {


            stat=conn.prepareStatement("update cred set name=? where id=?");
            System.out.println("query is executing");
            stat.setString(1, name);
            stat.setString(2, id);



            int count=stat.executeUpdate();


            Student st=null;
            while(rs.next()){
                st=new Student();
                st.setStudentId(rs.getString(1));
                st.setStudentName(rs.getString(2));
                st.setStudentCollege(rs.getString(3));
                st.setCity(rs.getString(4));
                st.setMobile(rs.getString(5));
                addlist2.add(st);
                System.out.println("haihai");
            }

        }

        catch (SQLException e) {
            e.printStackTrace();
            // TODO: handle exception
        }
        return addlist2;
    }


}

jsp pages