Java tutorial
/* * To change this license header, choose License Headers in Project Properties. * To change this template file, choose Tools | Templates * and open the template in the editor. */ import java.io.IOException; import java.io.PrintWriter; import java.sql.*; import java.lang.*; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import org.json.JSONObject; import org.json.JSONArray; import org.json.JSONException; /** * * @author Ishtiaq */ @WebServlet(name = "fetchBookDetails", urlPatterns = { "/fetchBookDetails" }) public class fetchBookDetails extends HttpServlet { /** * Processes requests for both HTTP <code>GET</code> and <code>POST</code> * methods. * * @param request servlet request * @param response servlet response * @throws ServletException if a servlet-specific error occurs * @throws IOException if an I/O error occurs */ protected void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html;charset=UTF-8"); try (PrintWriter out = response.getWriter()) { /* TODO output your page here. You may use following sample code. */ out.println("<!DOCTYPE html>"); out.println("<html>"); out.println("<head>"); out.println("<title>Servlet fetchBooks</title>"); out.println("</head>"); out.println("<body>"); out.println("<h1>Servlet fetchBooks at " + request.getContextPath() + "</h1>"); out.println("</body>"); out.println("</html>"); } } // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code."> /** * Handles the HTTP <code>GET</code> method. * * @param request servlet request * @param response servlet response * @throws ServletException if a servlet-specific error occurs * @throws IOException if an I/O error occurs */ @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { processRequest(request, response); } /** * Handles the HTTP <code>POST</code> method. * * @param request servlet request * @param response servlet response * @throws ServletException if a servlet-specific error occurs * @throws IOException if an I/O error occurs */ @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //processRequest(request, response); try { System.out.println("Inside try 1"); Class.forName("org.apache.derby.jdbc.ClientDriver").newInstance(); //setting up connection String dbURL = "jdbc:derby://localhost:1527/autolib_db_test"; Connection conn = DriverManager.getConnection(dbURL, "ishtiaq", "ishtiaq"); Statement stmt = null; ResultSet rslt = null; if (conn == null) { System.out.println("Connection Failed"); } stmt = conn.createStatement(); String bookId = request.getParameter("book"); // pass this book value from displayBookDetails function String buyBook = request.getParameter("buy"); // pass this book value from displayBookDetails function String sqlQry = ""; if (buyBook.equals("YES")) { //if a book is selected to be bought Integer bookQty = Integer.parseInt(request.getParameter("qty")); // pass this book value from displayBookDetails function sqlQry = "update books_tbl set qty = qty - " + bookQty.toString() + " where id = " + bookId + ""; //reducing quantity by bookQty which increments by 1 on every click stmt.execute(sqlQry); //executing the update query } System.out.println("SEARCH Book id " + bookId); //query to return book details by giving the ID value sqlQry = "SELECT * FROM books_tbl where id = " + bookId + ""; rslt = stmt.executeQuery(sqlQry); //creating JSON object, array object and a jason variable JSONObject jObj = new JSONObject(); JSONArray bookArr = new JSONArray(); JSONObject bookData; try { System.out.println("Inside Try"); //adding ID, name, author, price, topic, available and qty to bookData by using put while (rslt.next()) { bookData = new JSONObject(); bookData.put("id", rslt.getInt("id")); bookData.put("name", rslt.getString("bookname")); bookData.put("author", rslt.getString("author")); bookData.put("price", rslt.getInt("price")); bookData.put("topic", rslt.getString("topic")); bookData.put("available", rslt.getBoolean("available")); bookData.put("qty", rslt.getInt("qty")); bookArr.put(bookData); //putting all bookdata in book array } jObj.put("Books", bookArr); //adding book array content to string named "Books" } catch (JSONException jse) { } response.setContentType("application/json"); response.getWriter().write(jObj.toString()); //closing connection if (!stmt.isClosed()) stmt.close(); if (!rslt.isClosed()) rslt.close(); } catch (Exception e) { //return null; } } /** * Returns a short description of the servlet. * * @return a String containing servlet description */ @Override public String getServletInfo() { return "Short description"; }// </editor-fold> }