servlets

问题 Can servlet attribute names contain a hyphen - ? Because, I tried to retrieve the attributes from the request set in the doPost in my servlet, but the result is not what I'm looking for. In my servlet I have this : String X_USER = request.getParameter("X-User"); request.setAttribute("X-User", X_USER); String YYYY_YYYY = request.getParameter("Y_CODE"); request.setAttribute("Y-Code", YYYY_YYYY); In my JSP where I want to show these attributes I do this: <li>${X-User}</li> <li>${Y-Code}</li> The

问题 For a project I'm doing, I will have files stored in Google's Cloud Storage and am building a web app to interface to those files. I would like my app to show a list of the files (or objects may be the appropriate name) stored in my bucket. I'm completely new to web development and google apis. I've been researching how to do this and have found this bit of code... Storage storage = new Storage(httpTransport, jsonFactory, credential); ObjectsList list = storage.objects().list("bucket-name")

问题 I'm trying to do something that looks small but it's failing. I'm trying to send a response message back to a jsp when login fails but not being able. As of now I can only redirect back to the jsp but cannot display a message from the servlet on it. This is the servlet part of the redirection: if (count > 0) { res.sendRedirect("adminHome.jsp"); } else { res.sendRedirect("index.jsp"); } I tried to print a message using PrintWriter and the redirect but failed because I couldn't get how to

问题 I'm trying to do something that looks small but it's failing. I'm trying to send a response message back to a jsp when login fails but not being able. As of now I can only redirect back to the jsp but cannot display a message from the servlet on it. This is the servlet part of the redirection: if (count > 0) { res.sendRedirect("adminHome.jsp"); } else { res.sendRedirect("index.jsp"); } I tried to print a message using PrintWriter and the redirect but failed because I couldn't get how to

问题 I have a scheduled job class, implements the Quartz Job class, from which I want to invoke a Servlet class that updates a flag in a DB table and then it sends emails to an appropriate emailing list. I get a java.net.ConnectException . Though the servlet is properly invoked by either entering its URL in the browser or by JavaScript in a JSP page. My Java class is the following: public class ExpirationJob implements Job { org.apache.log4j.Logger log = org.apache.log4j.Logger.getLogger(

问题 I have a scheduled job class, implements the Quartz Job class, from which I want to invoke a Servlet class that updates a flag in a DB table and then it sends emails to an appropriate emailing list. I get a java.net.ConnectException . Though the servlet is properly invoked by either entering its URL in the browser or by JavaScript in a JSP page. My Java class is the following: public class ExpirationJob implements Job { org.apache.log4j.Logger log = org.apache.log4j.Logger.getLogger(

问题 I'm getting a error when trying to connect to a mysql database. I have an DatabaseAccess.java: import java.io.*; import javax.servlet.*; import javax.servlet.http.*; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; @SuppressWarnings("serial") public class DatabaseAccess extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // Set response

问题 I am using the below method to do the described conversion. But the java.sql.Date method is deprecated. So, is their any harm in using this method? As the statements below are working fine. (Retrieving value of date as string in servlet from session and then storing the date in MySQL.) String f33_ = (String) session.getAttribute("sf33"); java.sql.Date f33 = new java.sql.Date(Integer.parseInt(f33_.substring(6, 10))- 1900, Integer.parseInt(f33_.substring(3, 5))-1,Integer.parseInt(f33_.substring

问题 The api for ServletContext#getRequestDispatcher() says: This method returns null if the ServletContext cannot return a RequestDispatcher. and Returns: a RequestDispatcher object that acts as a wrapper for the resource at the specified path, or null if the ServletContext cannot return a RequestDispatcher For what reason would the ServletContext not be able to return a RequestDispatcher? At first I figured it would be if an invalid path was passed but that doesn't return null, it results in a

问题 The api for ServletContext#getRequestDispatcher() says: This method returns null if the ServletContext cannot return a RequestDispatcher. and Returns: a RequestDispatcher object that acts as a wrapper for the resource at the specified path, or null if the ServletContext cannot return a RequestDispatcher For what reason would the ServletContext not be able to return a RequestDispatcher? At first I figured it would be if an invalid path was passed but that doesn't return null, it results in a