Java Tutorial/Servlet/Cookie
Версия от 17:44, 31 мая 2010; (обсуждение)
Содержание
Add Cookie Servlet
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class AddCookieServlet extends HttpServlet {
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String data = request.getParameter("data");
Cookie cookie = new Cookie("MyCookie", data);
response.addCookie(cookie);
response.setContentType("text/html");
PrintWriter pw = response.getWriter();
pw.println("<B>MyCookie has been set to");
pw.println(data);
pw.close();
}
}
Get Cookies Servlet
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class GetCookiesServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
Cookie[] cookies = request.getCookies();
response.setContentType("text/html");
PrintWriter pw = response.getWriter();
pw.println("<B>");
for (int i = 0; i < cookies.length; i++) {
String name = cookies[i].getName();
String value = cookies[i].getValue();
pw.println("name = " + name + "; value = " + value);
}
pw.close();
}
}
Get/Set Cookie
import java.util.*;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class MyServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws IOException, ServletException
{
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<HTML>");
out.println("<HEAD>");
out.println("<TITLE>");
out.println("A Web Page");
out.println("</TITLE>");
out.println("</HEAD>");
out.println("<BODY");
Cookie[] cookies = request.getCookies();
boolean foundCookie = false;
for(int i = 0; i < cookies.length; i++) {
Cookie cookie1 = cookies[i];
if (cookie1.getName().equals("color")) {
out.println("bgcolor = " + cookie1.getValue());
foundCookie = true;
}
}
if (!foundCookie) {
Cookie cookie1 = new Cookie("color", "cyan");
cookie1.setMaxAge(24*60*60);
response.addCookie(cookie1);
}
out.println(">");
out.println("<H1>Setting and Reading Cookies</H1>");
out.println("This page will set its background color using a cookie when reloaded.");
out.println("</BODY>");
out.println("</HTML>");
}
}
List Servlet Cookie Information
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class Cookies extends HttpServlet {
public void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException,
IOException {
resp.setContentType("text/html");
req.getSession();
PrintWriter out = resp.getWriter();
Cookie cookies[] = req.getCookies();
out.println("<html>");
out.println("<head>");
out.println("<title>Servlet Cookie Information</title>");
out.println("</head>");
out.println("<body>");
if ((cookies == null) || (cookies.length == 0)) {
out.println("<center><h1>No Cookies found</h1>");
} else {
out.println("<center><h1>Cookies found</h1>");
for (int i = 0; i < cookies.length; i++) {
Cookie c = cookies[i];
out.println(c.getName() + "::" + c.getValue() + "::"
+ c.getComment() + "::" + c.getMaxAge() + "<BR/>");
}
out.println("</table></center>");
}
out.println("</body>");
out.println("</html>");
out.flush();
}
}
Parse a Cookie: header into individual tokens according to RFC 2109.
/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
*
* Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.
*
* The contents of this file are subject to the terms of either the GNU
* General Public License Version 2 only ("GPL") or the Common Development
* and Distribution License("CDDL") (collectively, the "License"). You
* may not use this file except in compliance with the License. You can obtain
* a copy of the License at https://glassfish.dev.java.net/public/CDDL+GPL.html
* or glassfish/bootstrap/legal/LICENSE.txt. See the License for the specific
* language governing permissions and limitations under the License.
*
* When distributing the software, include this License Header Notice in each
* file and include the License file at glassfish/bootstrap/legal/LICENSE.txt.
* Sun designates this particular file as subject to the "Classpath" exception
* as provided by Sun in the GPL Version 2 section of the License file that
* accompanied this code. If applicable, add the following below the License
* Header, with the fields enclosed by brackets [] replaced by your own
* identifying information: "Portions Copyrighted [year]
* [name of copyright owner]"
*
* Contributor(s):
*
* If you wish your version of this file to be governed by only the CDDL or
* only the GPL Version 2, indicate your decision by adding "[Contributor]
* elects to include this software in this distribution under the [CDDL or GPL
* Version 2] license." If you don"t indicate a single choice of license, a
* recipient has the option to distribute your version of this file under
* either the CDDL, the GPL Version 2 or to extend the choice of license to
* its licensees as provided above. However, if you add GPL Version 2 code
* and therefore, elected the GPL Version 2 license, then the option applies
* only if the new code is made subject to such option by the copyright
* holder.
*/
/*
* Copyright 2004-2005 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
import java.lang.System;
import java.lang.String;
import java.lang.IndexOutOfBoundsException;
import java.lang.ArrayIndexOutOfBoundsException;
/**
* Parse a Cookie: header into individual tokens according to RFC 2109.
*/
public class CookieTokenizer
{
/**
* Upper bound on the number of cookie tokens to accept. The limit is
* based on the 4 different attributes (4.3.4) and the 20 cookie minimum
* (6.3) given in RFC 2109 multiplied by 2 to accomodate the 2 tokens in
* each name=value pair ("JSESSIONID=1234" is 2 tokens).
*/
private static final int MAX_COOKIE_TOKENS = 4 * 20 * 2;
/**
* Array of cookie tokens. Even indices contain name tokens while odd
* indices contain value tokens (or null).
*/
private String tokens[] = new String[MAX_COOKIE_TOKENS];
/**
* Number of cookie tokens currently in the tokens[] array.
*/
private int numTokens = 0;
/**
* Parse a name=value pair from the Cookie: header.
*
* @param cookies The Cookie: header to parse
* @param beginIndex The index in cookies to begin parsing from, inclusive
*/
private int parseNameValue(String cookies, int beginIndex) {
int length = cookies.length();
int index = beginIndex;
while (index < length) {
switch (cookies.charAt(index)) {
case ";":
case ",":
// Found end of name token without value
tokens[numTokens] = cookies.substring(beginIndex, index).trim();
if (tokens[numTokens].length() > 0) {
numTokens++;
tokens[numTokens] = null;
numTokens++;
}
return index + 1;
case "=":
// Found end of name token with value
tokens[numTokens] = cookies.substring(beginIndex, index).trim();
numTokens++;
return parseValue(cookies, index + 1);
case """:
// Skip past quoted span
do index++; while (cookies.charAt(index) != """);
break;
}
index++;
}
if (index > beginIndex) {
// Found end of name token without value
tokens[numTokens] = cookies.substring(beginIndex, index).trim();
if (tokens[numTokens].length() > 0) {
numTokens++;
tokens[numTokens] = null;
numTokens++;
}
}
return index;
}
/**
* Parse the name=value tokens from a Cookie: header.
*
* @param cookies The Cookie: header to parse
*/
public int tokenize(String cookies) {
numTokens = 0;
if (cookies != null) {
try {
// Advance through cookies, parsing name=value pairs
int length = cookies.length();
int index = 0;
while (index < length)
index = parseNameValue(cookies, index);
}
catch (ArrayIndexOutOfBoundsException e) {
// Filled up the tokens[] array
}
catch (IndexOutOfBoundsException e) {
// Walked off the end of the cookies header
}
}
return numTokens;
}
/**
* Return the number of cookie tokens parsed from the Cookie: header.
*/
public int getNumTokens() {
return numTokens;
}
/**
* Returns a given cookie token from the Cookie: header.
*
* @param index The index of the cookie token to return
*/
public String tokenAt(int index) {
return tokens[index];
}
/**
* Parse the value token from a name=value pair.
*
* @param cookies The Cookie: header to parse
* @param beginIndex The index in cookies to begin parsing from, inclusive
*/
private int parseValue(String cookies, int beginIndex) {
int length = cookies.length();
int index = beginIndex;
while (index < length) {
switch (cookies.charAt(index)) {
case ";":
case ",":
// Found end of value token
tokens[numTokens] = cookies.substring(beginIndex, index).trim();
numTokens++;
return index + 1;
case """:
// Skip past quoted span
do index++; while (cookies.charAt(index) != """);
break;
}
index++;
}
// Found end of value token
tokens[numTokens] = cookies.substring(beginIndex, index).trim();
numTokens++;
return index;
}
}
Servlet Cookie Reader
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
public class MyServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, java.io.IOException {
Cookie cookie = null;
//Get an array of Cookies associated with this domain
Cookie[] cookies = request.getCookies();
boolean hasCookies = false;
if (cookies != null)
hasCookies = true;
// display the name/value of each cookie
response.setContentType("text/html");
java.io.PrintWriter out = response.getWriter();
out.println("<html>");
out.println("<head>");
out.println("<title>Cookie information</title>");
out.println("</head>");
out.println("<body>");
if (hasCookies){
out.println("<h2> The name and value of each found cookie</h2>");
for (int i = 0; i < cookies.length; i++){
cookie = cookies[i];
out.println("Name of cookie #"+(i + 1)+": "+cookie.getName()+"<br>");
out.println("Value of cookie #"+(i + 1)+": "+cookie.getValue()+"<br><br>");
}
} else {
out.println("<h2> This request did not include any cookies</h2>");
}
out.println("</body>");
out.println("</html>");
out.close();
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, java.io.IOException {
doGet(request,response);
}
}
Servlet Cookie Setter
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
public class MyServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, java.io.IOException {
Cookie cookie = null;
//Get an array of Cookies associated with this domain
Cookie[] cookies = request.getCookies();
boolean newCookie = false;
//Get the "mycookie" Cookie if it exists
if (cookies != null){
for (int i = 0; i < cookies.length; i++){
if (cookies[i].getName().equals("mycookie")){
cookie = cookies[i];
}
}//end for
}//end if
if (cookie == null){
newCookie=true;
//Get the cookie"s Max-Age from a context-param element
//If the "cookie-age" param is not set properly
//then set the cookie to a default of -1, "never expires"
int maxAge;
try{
maxAge = new Integer(getServletContext().getInitParameter("cookie-age")).intValue();
} catch (Exception e) {
maxAge = -1;
}
//Create the Cookie object
cookie = new Cookie("mycookie",""+getNextCookieValue());
cookie.setPath(request.getContextPath());
cookie.setMaxAge(maxAge);
response.addCookie(cookie);
}//end if
// get some info about the cookie
response.setContentType("text/html");
java.io.PrintWriter out = response.getWriter();
out.println("<html>");
out.println("<head>");
out.println("<title>Cookie info</title>");
out.println("</head>");
out.println("<body>");
out.println("<h2> Information about the cookie named \"mycookie\"</h2>");
out.println("Cookie value: "+cookie.getValue()+"<br>");
if (newCookie){
out.println("Cookie Max-Age: "+cookie.getMaxAge()+"<br>");
out.println("Cookie Path: "+cookie.getPath()+"<br>");
}
out.println("</body>");
out.println("</html>");
out.close();
}
private long getNextCookieValue(){
/*This produces a cookie value to show how to create Cookie objects. If
this method was heavily used in a production environment it may
produce too many objects; synchronization of a single Date object
might be better, based on performance testing. At any rate a
production environment would produce a unique cookie value in a
different manner such as from a unique database ID. */
//returns the number of milleseconds since Jan 1, 1970
return new java.util.Date().getTime();
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, java.io.IOException {
doGet(request,response);
}
}
