Servlet之Cookie与Session

 

 

import java.io.IOException;
import java.io.PrintWriter;

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


public class SetCookie extends HttpServlet {

    /**
     * Constructor of the object.
     */
    public SetCookie() {
        super();
    }

    /**
     * Destruction of the servlet.
     */
    public void destroy() {
        super.destroy(); // Just puts "destroy" string in log

        // Put your code here

    }

    /**
     * The doGet method of the servlet.
     *
     * This method is called when a form has its tag value method equals to get.
     *
     * @param request the request send by the client to the server
     * @param response the response send by the server to the client
     * @throws ServletException if an error occurred
     * @throws IOException if an error occurred
     */
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {


        for(int i=0; i<3; i++){
            //缺省的maxAge为-1，表示cookie仅用于当前浏览器

            Cookie cook = new Cookie("Session-Cookie-"+i,"Cookie-Value-S"+i);
            response.addCookie(cook);
            cook = new Cookie("Persistent-Cookie-"+i,"Cookie-Value-P"+i);
            //cookie在一个小时内有效，无论用户是否退出浏览器

            cook.setMaxAge(3600);
            response.addCookie(cook);
        }
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        String title = "Setting Cookies..";


        out.println(""</SPAN><SPAN style="COLOR: #0000cc">+</SPAN>title<SPAN style="COLOR: #0000cc">+</SPAN><SPAN style="COLOR: #ff00ff">""+""+title+"
");

    }

    /**
     * The doPost method of the servlet.
     *
     * This method is called when a form has its tag value method equals to post.
     *
     * @param request the request send by the client to the server
     * @param response the response send by the server to the client
     * @throws ServletException if an error occurred
     * @throws IOException if an error occurred
     */
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        doGet(request,response);
    }

    /**
     * Returns information about the servlet, such as
     * author, version, and copyright.
     *
     * @return String information about this servlet
     */
    public String getServletInfo() {
        return "This is my default servlet created by Eclipse";
    }

    /**
     * Initialization of the servlet.
     *
     * @throws ServletException if an error occurs
     */
    public void init() throws ServletException {
        // Put your code here

    }

}

 

 

import java.io.IOException;
import java.io.PrintWriter;

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


public class ShowSession extends HttpServlet {

    /**
     * Constructor of the object.
     */
    public ShowSession() {
        super();
    }

    /**
     * Destruction of the servlet.
     */
    public void destroy() {
        super.destroy(); // Just puts "destroy" string in log

        // Put your code here

    }

    /**
     * The doGet method of the servlet.
     *
     * This method is called when a form has its tag value method equals to get.
     *
     * @param request the request send by the client to the server
     * @param response the response send by the server to the client
     * @throws ServletException if an error occurred
     * @throws IOException if an error occurred
     */
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        //Provides a way to identify a user across more than one page request

        //or visit to a Web site and to store information about that user.

        HttpSession session = request.getSession(true);
        Integer accessCount = (Integer)session.getAttribute("accessCount");
        String heading;
        if(accessCount == null){
            accessCount = new Integer(0);
            heading = "Welcome, the firt time see you..";
        }else{
            heading ="Welcome Back..";
            accessCount = new Integer(accessCount.intValue() + 1);

        }

        session.setAttribute("accessCount", accessCount);
        out.println("");
        out.println("");
        out.println(" A Servlet");
        out.println(" ");
        out.println(" " +heading +"");
        out.println(session.getId()+"--"+ session.getLastAccessedTime()+"--"+session.getAttribute("accessCount"));
        out.println(" ");
        out.println("");
        out.flush();
        out.close();
    }

    /**
     * The doPost method of the servlet.
     *
     * This method is called when a form has its tag value method equals to post.
     *
     * @param request the request send by the client to the server
     * @param response the response send by the server to the client
     * @throws ServletException if an error occurred
     * @throws IOException if an error occurred
     */
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        doGet(request,response);
    }



    /**
     * Initialization of the servlet.
     *
     * @throws ServletException if an error occurs
     */
    public void init() throws ServletException {
        // Put your code here

    }

}