Servlet cookie 賦值與取值及頁面之前傳值處理方法,下面先是講一下關於如何獲取與給cookies設置值，然後再利用一個實例詳細值了servlet cookie實例操作。
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();
}
}
cookie 獲取
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();
}
}
根據上面的實例我們來看看servlet cookie的頁面之間傳遞
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);
}
}
<?xml version="1.0" encoding="ISO-8859-1"?><!DOCTYPE web-app
PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.2//EN"
"http://java.sun.com/j2ee/dtds/web-app_2_2.dtd"><web-app>
<servlet><servlet-name>MyServletName</servlet-name>
<servlet-class>MyServlet</servlet-class>
<init-param>
<param-name>
go
</param-name>
<param-value>
weather
</param-value>
</init-param>
</servlet>
<servlet-mapping><servlet-name>MyServletName</servlet-name>
<url-pattern>/index.html</url-pattern>
</servlet-mapping>
</web-app>
