Archives: Servlet

Java Servlet – Logging with Log4j Example


Java Servlet – URL Rewriting Example

[code 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:<BR>");
if (items == null) {
out.println("<B>None</B>");
} else {
out.println("<UL>");
for (int i = 0; i < items.length; i++) {
out.println("<LI>" + items[i]);
}
out.println("</UL>");
}

// 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<BR>");
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 <A HREF=\"/servlet/Help/" + sessionid + "?topic=ShoppingCartViewerRewrite\">here</A>");

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" };
}
}[/code]


Java Servlet – File Upload Example

Upload.html

CommonsFileUploadServlet.java

Web.xml