Java by API/java.rmi.server/UID
new UID()
<source lang="java">
import java.io.IOException; import java.io.PrintWriter; import java.io.UnsupportedEncodingException; import java.net.URLEncoder; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class ShoppingCartViewerRewrite extends HttpServlet {
public void doGet(HttpServletRequest req, HttpServletResponse res) throws ServletException,
IOException {
res.setContentType("text/html");
PrintWriter out = res.getWriter();
out.println("<HEAD><TITLE>Current Shopping Cart Items</TITLE></HEAD>");
out.println("<BODY>");
// Get the current session ID, or generate one if necessary
String sessionid = req.getPathInfo();
if (sessionid == null) {
sessionid = generateSessionId();
}
// Cart items are associated with the session ID
String[] items = getItemsFromCart(sessionid);
// Print the current cart items.
out.println("You currently have the following items in your cart:
");
if (items == null) {
out.println("None");
} else {
out.println("- ");
for (int i = 0; i < items.length; i++) {
out.println("
- " + items[i]); } out.println("
}
// Ask if the user wants to add more items or check out.
// Include the session ID in the action URL.
out.println("<FORM ACTION=\"/servlet/ShoppingCart/" + sessionid + "\" METHOD=POST>");
out.println("Would you like to
");
out.println("<INPUT TYPE=SUBMIT VALUE=\" Add More Items \">");
out.println("<INPUT TYPE=SUBMIT VALUE=\" Check Out \">");
out.println("</FORM>");
// Offer a help page. Include the session ID in the URL.
out.println("For help, click ");
out.println("</BODY></HTML>");
}
private static String generateSessionId() throws UnsupportedEncodingException {
String uid = new java.rmi.server.UID().toString(); // guaranteed unique
return URLEncoder.encode(uid, "UTF-8"); // encode any special chars
}
private static String[] getItemsFromCart(String sessionid) {
return new String[] { "a", "b" };
}
}
</source>
