📄 showitems.java
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package coreservlets;import java.io.*;import javax.servlet.*;import javax.servlet.http.*;import java.util.*;/** Servlet that displays a list of items being ordered. * Accumulates them in an ArrayList with no attempt at * detecting repeated items. Used to demonstrate basic * session tracking. Updated to Java 5. * <p> * From <a href="http://courses.coreservlets.com/Course-Materials/">the * coreservlets.com tutorials on servlets, JSP, Struts, JSF, Ajax, GWT, and Java</a>. */@SuppressWarnings("unchecked")public class ShowItems extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { HttpSession session = request.getSession(); if (session.getAttribute("login") == null) { response.setContentType("text/html"); PrintWriter out = response.getWriter(); out.println("<html>"); out.println("<head>"); out.println("<title>User is not logged in</title>"); out.println("</head>"); out.println("<body>"); out.println("<br><p align=\"center\">Please log in <a href=\"./login.html\">here</a> first</p>"); out.println("</body>"); out.println("</html>"); out.close(); return; } List<String> previousItems = (List<String>) session.getAttribute("previousItems"); if (previousItems == null) { previousItems = new ArrayList<String>(); session.setAttribute("previousItems", previousItems); } String newItem = request.getParameter("newItem"); if ((newItem != null) && (!newItem.trim().equals(""))) { previousItems.add(newItem); } response.setContentType("text/html"); PrintWriter out = response.getWriter(); String title = "Items Purchased"; String docType = "<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.0 " + "Transitional//EN\">\n"; out.println(docType + "<HTML>\n" + "<HEAD><TITLE>" + title + "</TITLE></HEAD>\n" + "<BODY BGCOLOR=\"#FDF5E6\">\n" + "<H1>" + title + "</H1>"); if (previousItems.size() == 0) { out.println("<I>No items</I>"); } else { out.println("<UL>"); for (String item : previousItems) { out.println(" <LI>" + item); } out.println("</UL>"); } out.println("</BODY></HTML>"); }}⌨️ 快捷键说明
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