Servlets :: Architecture Design For Shopping Database
Apr 2, 2015
I'm working on a consulting training project to create a eCommerce online shopping application. Nothing big, just something functional and simple. That's why I want to structure it with the easiest maintainability possible. I've already ironed out the the database entities and how they'll relate to one another and even managed to establish connection to the database from my java application class. NOW I need to configure a user session on the web.xml, from what I've learned so far in my consulting, I can easily use jsp and servlets to have httpsession objects receive and send the information needed to and from the database, but the question is, how many do I need for a client's session?
Would maintainability be easier if I divide each entity's class actions to different servlets(a customer servlet, order servlet, product servlet, etc...), or can a single servlet handle an entire session without any complication?
I created a website using jsp and servlet. I made a shopping cart and got the items to display. But how can i remove the items from the cart? Next to each item is a remove button. When that is pressed the item selected needs to be removed and cart needs to refresh.
I want to display product details such as product image, name, price in a one cell of a table tag on jsp page. There should be multiple rows and 3 cells per row in the required output.i have written the following code:
This code displays all cells in only one row. I used colspan but its not working...I have attached the snapshot of above code output and required output
I am adding my shopping cart in session like bellow in servlet
HttpSession session = request.getSession(); session.setMaxInactiveInterval(60*30); // 30 minutes if (session.getAttribute("cart") == null){ session.setAttribute("cart", new ShoppingCart()); } cart = session.getAttribute("cart");
I seems if more than one person accesses it from server, if they items in the shopping cart, all the product is added to a single session. I mean if i added 4 items first and other person adds 2 items, second person sees 6 products in his cart. Where am I going wrong?
I am making a shopping cart app in JSP and servlets to bring it all together. Finally.
I have a registration servlet (c1), a registration form jsp (c2), a login jsp (c3). c1 checks if a username is in the database or not.
If the username is not there, then register the user and send them to c3. I want c3 to display a "registration successful" message if a user has just registered successfully and is coming from c1. ELSE, take the user back to c2 with a message which tells them to choose a different username or password etc.
How do I implement the logic of showing a message depending on where a user is coming from ? The servlets and jsps are ready and I only need to add this logic for a custom message. Of course, I could make a JSP for Registration Successful and one for Registration Failure. But, that seems to be unnecessary.
I am trying to design properly a simple 1to50 game (yes, the one that is so popular among mobile apps), but as a web application that allows two player games. I tried to document myself on the technologies I could use and came to the decision that some kind of Java would be suitable. I know that HTML, HTML5, CSS, JavaScript are client side languages with what I can basically design the client application that runs on a web browser. I installed Tomcat web server, configured Java Servlet API, done some research on Servlets and JSP, but I still cannot really imagine how all of this can work. Servlets form the Controller, JSP files the Model? How can I make them communicate, how can Servlets "tell" JSP files what to dynamically generate? Can JSP files communicate with JavaScript? Is JavaScript even necessary?
I thought that this question is not basically about a specific thing regarding JSP or Servlets, more about design and general concept, that is why I put this question under beginning Java.
I have just started learning Java from a local teacher, this teacher said that the Architecture Neutral refers to Hardware while Platform Independent refers to Operating System, but I found a link to a White Paper by James Gosling. The chapter 4 of this White Paper mentions about both binary code format that is independent of hardware architecture and operating system interfaces, but the main point to be noted is that he has put both under the heading Architecture Neutral. Does it mean that the original buzz word is Architecture Neutral, which includes both hardware and operating system independence?
I want to retrieve file from database which is stored with blob datatype and i am passing manually id associated with in code. Its not retrieving the file.
public class retrieve_image extends HttpServlet { /** * */ private static final long serialVersionUID = 1L; protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { ResultSet rs = null;
I am trying to make a simple login using netbeans, derby database included in netbeans and tomcat server. I made everything nice and separated: I have a model package with a class called DbConnector that has the following method:
Then i have another class, an userDAODB that has a password check method:
public boolean checkPassword(String user, String password) { try (Connection con = new DbConnector().connect(); Statement stmt = con.createStatement()) { //checks the password in the database
In the main method of this class i tested everything, it works very nice, logs me in, other methods work too, no problem what so ever.But then i go to my servlet:
public class LoginTest extends HttpServlet { public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException { String username = request.getParameter("username"); String pass = request.getParameter("pass"); UserDAODB userDAO = new UserDAODB(); boolean authe = userDAO.checkPassword(username, pass);
[code]....
So when i start the webpage and i try to click on the login button I get a NullPointerException com.model. UserDAODB. check Password (User DAODB. java:14) - so line 2 here
I have been googling a bit, i placed the derby.jar and the derbyclient.jar in the lib directory of tomcat, i tried to modify the context.xml of my application, but then it wouldn't even start anymore.
I can insert data to table by using JSP Scriptlet easily but I have a hard time with servlet.
public class UsertToDatabase() { public boolean inserUser(String name, String email, String pwd) throws SQLException { PreparedStatement pstmt = null; boolean flag = false; System.out.println("start"); openConn(); System.out.println("start_1"); if(conn == null) {
[code]....
I am positive that the above code function fine. The problem is whenever I call UserToDB() class inside the servlet, and I got this error: java.lang.ClassNotFoundException: org.postgresql.
Driver which mean that my conn (connection) is not connected to the database but I have ensure to do so by calling openConn() before start the transaction.
ResultSet rs = result.executeQuery(selectsql); int columns = rs.getRow(); while(rs.next()){
[Code].....
I can print out the result correctly, there are three rows of result from the database, but they are shown in one row on the browser, how could i show the result one row after another to let it looks pretty?
I would like to know the J2EE architectural explanation with respect to HTML5 and Adobe Flex technologies. It is just like knowing over all J2EE architectural aspects and how HTML5 and Adobe Flex technologies are used to satisfy those aspects in order act as client side components.
If I change the servlet and have "request.getRequestDispatcher("/pages/ViewCompletedWWDocs.jsp").forward(request, response);" un commented, I get exception "java.lang.IllegalStateException: Cannot forward a response that is already committed".
My query retrieves more than 5000 records from Oracle database. I want to display the records 100 per page. I know it is called pagination. Any detailed styp-by-guide or tutorial or example available?
i am newbie to servlet and m working on a project like online shopping. I have list of data items in my database and i am able to fetch and display the data from database but i want to know that how can i store these data items in ServletContext so that i can use use it frequently in other pages.
I am trying to display rows from my database from servlet by passing it to a JSP, but nothing is displayed. I checked the syntax and even the source of the page shows that it gets the data but the rows are not displayed!
