How send the value of a dropdownlist item in servlet

Question

I want to show the book details of various type(math,phy,chem) from database to webpage. When I select a particular item from dropdowlist its corresponding book will be shown in webpage. My jsp page looks like :

<%@ page contentType="text/html; charset=utf-8" language="java" import="java.sql.*"   
    errorPage="" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org    
        /TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title>Untitled Document</title>
</head>

<body>
    <center>
        <h1>Science Book</h1><br /><br />
        <hr color="#CC9999" size="5px" /><br /><br />

        <form action="Controller">
            <select name="book">
                <option value="Math">Math</option>
                <option value="Phy">Physics</option>
                <option value="Chem">Chemistry</option>
            </select>
            <input type="submit" value="Submit"/>
        </form>
    </center>
</body>

Here Controller is the servlet name. My servlet is look like :

package com.sayan.myservlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

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

public class Controller extends HttpServlet
{
private static final long serialVersionUID = 1L;

public Controller()
{
    super();

}


protected void doGet(HttpServletRequest request, HttpServletResponse response) throws 
               ServletException, IOException 
{
    doProcess(request,response);
}


protected void doPost(HttpServletRequest request, HttpServletResponse response) throws 
               ServletException, IOException
{
    doProcess(request,response);
}


protected void doProcess(HttpServletRequest request, HttpServletResponse response) 
               throws ServletException, IOException
{
    String booktype=null;         //set drowdownlist item value
    PrintWriter out = response.getWriter();

    String drivername = "oracle.jdbc.OracleDriver";
    String url = "jdbc:oracle:thin:@172.16.0.30:1521:orcl";
    String username = "scott";
    String password = "tiger";

    Connection con = null;
    Statement st = null;
    ResultSet rs = null;

    try{
        Class.forName(drivername);
        con = DriverManager.getConnection(url,username,password);
        st = con.createStatement();

        String sql = "select name,author,publisher,price from book where 
                      type="+booktype;
        System.out.println(sql);
        rs = st.executeQuery(sql);
        out.println("<html><body><table border=5>");
        out.println("<tr><th>name</th>");
        out.println("<th>author</th>");
        out.println("<th>publisher</th>");
        out.println("<th>price</th></tr><tr>");
        while(rs.next()){
            String name = rs.getString("name");
            String author = rs.getString("author");
            String publisher = rs.getString("publisher");
            String price = rs.getString("price");

            out.println("<td>" + name + "</td>");
            out.println("<td>" + author + "</td>");
            out.println("<td>" + publisher + "</td>");
            out.println("<td>" + price + "</td>");
        }
        out.println("</tr></table></body></html");
    }catch(ClassNotFoundException cnfe){
        System.out.println("Exception caught : " + cnfe);
    }catch(SQLException se){
        System.out.println("Exception caught : " + se);
    }finally{
        try{
            con.close();
        }catch(SQLException se1){
            System.out.println("Exception caught : " + se1);
        }
    }


}

}

I want to set the dropdownlist item value in booktype String.How can I do this?. If other way is possible then please mention.

Use forwarding instead of writing the response in servlet. It is easier to accomplish the desired result. You can find more info about it on [StackOverflow Servlets wiki](http://stackoverflow.com/tags/servlets/info). — Luiggi Mendoza, Jul 18 '14 at 17:06

score 0 · Accepted Answer · answered Jul 18 '14 at 17:11

If I understand your question, then

String booktype=request.getParameter("book");

Also, you should use a PreparedStatement because your posted code is vulnerable to SQL Injection. Finally, close your Statement and ResultSet as well as your Connection or you might start leaking DB cursors.

Connection con = null;
PreparedStatement st = null;
ResultSet rs = null;
String sql = "select name,author,publisher,price from book where "
    + "type=?";

try {
  // Class.forName(drivername); // <-- not needed since JDBC Version 4
  // http://stackoverflow.com/a/8053125/2970947
  con = DriverManager.getConnection(url, username,
      password);
  st = con.prepareStatement(sql);
  st.setString(1, booktype);

  System.out.println(sql);
  rs = st.executeQuery();
  out.println("<html><body><table border=5>");
  out.println("<tr><th>name</th>");
  out.println("<th>author</th>");
  out.println("<th>publisher</th>");
  out.println("<th>price</th></tr><tr>");
  while (rs.next()) {
    String name = rs.getString("name");
    String author = rs.getString("author");
    String publisher = rs.getString("publisher");
    String price = rs.getString("price");

    out.println("<td>" + name + "</td>");
    out.println("<td>" + author + "</td>");
    out.println("<td>" + publisher + "</td>");
    out.println("<td>" + price + "</td>");
  }
  out.println("</tr></table></body></html");
} catch (ClassNotFoundException cnfe) {
  System.out.println("Exception caught : " + cnfe);
} catch (SQLException se) {
  System.out.println("Exception caught : " + se);
} finally {
  try {
    rs.close();
  } catch (SQLException se1) {
    System.out
        .println("Exception caught : " + se1);
  }
  try {
    st.close();
  } catch (SQLException se1) {
    System.out
        .println("Exception caught : " + se1);
  }
  try {
    con.close();
  } catch (SQLException se1) {
    System.out
        .println("Exception caught : " + se1);
  }
}

How send the value of a dropdownlist item in servlet

1 Answers1