Request display : Do Get Do Post « Servlets « Java

Request display

import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class RequestDisplay extends HttpServlet {

  public void doGet(HttpServletRequest request, HttpServletResponse response)
      throws ServletException, {

    ContextObject obj = (ContextObject) request
    //display the attribute's Map keys
    response.setContentType("text/html"); out = response.getWriter();
        .println("<html><head><title>Request Attribute</title></head><body>");
    out.println("<h2>Request attribute values</h2>");
    if (obj != null)

  } //end doGet



class ContextObject {

  private Map map;

  public ContextObject() {

    map = Collections.synchronizedMap(new HashMap());

  public void put(Object key, Object value) {

    if (key == null || value == null)
      throw new IllegalArgumentException(
          "Invalid parameters passed to ContextObject.put");

    map.put(key, value);

  public Map getMap() {

    return map;


  public String getValues() {

    StringBuffer buf = new StringBuffer("");
    Set set = map.keySet();

    synchronized (map) {

      Iterator i = set.iterator();
      while (i.hasNext())
        buf.append((String) + "<br>");

    return buf.toString();


  public String toString() {

    return getClass().getName() + "[ " + map + " ]";



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