Cookie应用

CookieDemo1

import java.io.IOException;
import java.io.PrintWriter;
import java.util.LinkedHashMap;
import java.util.Map;

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

import sun.security.action.PutAllAction;

import com.sun.faces.config.beans.LifecycleBean;

public class CookieDemo1 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        
        //1.输出网站所有商品
        out.print("本站的所有商品：<br/>");
        //模拟一个数据库输出
        Map<String, Book> map = Db.getAll();
        //增强for循环迭代map
        for(Map.Entry<String,Book> entry:map.entrySet()){
            Book book = entry.getValue();
            out.print("<a href='/test01/servlet/CookieDemo2?id="+book.getId()+"' target='_blank'>"+book.getName()+"</a><br/>");
        }
        
        //2.显示用户曾经看过的商品
        out.print("<br/>你曾经看过的商品：<br/>");
        Cookie[] cookies = request.getCookies();
        for(int i = 0;cookies!=null && i<cookies.length;i++){
            if(cookies[i].getName().equals("bookHistory")){
                String[] ids = cookies[i].getValue().split("\\,");
                //增强for循环
                for(String id:ids){
                    Book book =map.get(id);
                    out.print(book.getName()+"<br/>");
                }
            }
        }
    }

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

    }
}
class Db{
    private static Map<String, Book> map = new LinkedHashMap<String,Book>();
    static{
        map.put("1", new Book("1", "水浒传", "施耐庵", "good"));
        map.put("2", new Book("2", "西游记", "吴承恩", "good"));
        map.put("3", new Book("3", "三国演义", "罗贯中", "good"));
        map.put("4", new Book("4", "红楼梦", "曹雪芹", "good"));
    }
    public  static Map<String, Book> getAll(){
        return map;
    }
}
class Book{
    private String id;
    private String name;
    private String author;
    private String description;
    
    public Book(String id, String name, String author, String description) {
        super();
        this.id = id;
        this.name = name;
        this.author = author;
        this.description = description;
    }

    public Book() {
        super();
        // TODO Auto-generated constructor stub
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAuthor() {
        return author;
    }

    public void setAuthor(String author) {
        this.author = author;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }
    
    
}

CookieDemo2

import java.awt.image.RescaleOp;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.LinkedList;

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

//显示商品详细信息
public class CookieDemo2 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // 中文乱码
        response.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();

        // 显示商品详细信息，先得到商品id
        String id = request.getParameter("id");
        Book book = Db.getAll().get(id);

        out.print(book.getId() + "<br/>");
        out.print(book.getName() + "<br/>");
        out.print(book.getAuthor() + "<br/>");
        out.print(book.getDescription() + "<br/>");

        // 构建Cookie,回写给浏览器
        String cookieValue = bulidCookieValue(id, request);
        Cookie cookie = new Cookie("bookHistory", cookieValue);
        cookie.setMaxAge(1 * 30 * 24 * 60 * 60);
        cookie.setPath("/test01");
        response.addCookie(cookie);
    }

    private String bulidCookieValue(String id, HttpServletRequest request) {
        
        //bookHistory = null   1    1
        //bookHistory = 2,5,1  1    1,2,5
        //bookHistory = 2,5,4  1    1,2,5
        //bookHistory = 2,5    1    1,2,5
                
        String bookHistory = null;
        Cookie[] cookies = request.getCookies();
        for(int i = 0;cookies!=null && i<cookies.length;i++){
            if(cookies[i].getName().equals("bookHistory")){
                bookHistory=cookies[i].getValue();
            }
        }
        
        if(bookHistory==null){
            //bookHistory = null    1    1
            return id;
        }
        
        LinkedList list = new LinkedList(Arrays.asList(bookHistory.split("\\,")));
        if(list.contains(id)){
            //bookHistory = 2,5,1  1    1,2,5
            list.remove(id);
            list.addFirst(id);
        }else{
            if(list.size()>=3){
                //bookHistory = 2,5,4  1    1,2,5
                //bookHistory = 2,5    1    1,2,5
                list.removeLast();
                list.addFirst(id);
            }else{
                list.addFirst(id);
            }
        }
        
        StringBuffer sb = new StringBuffer();
        for(int i=0;i<list.size();i++){
            sb.append(list.get(i)+",");
        }
        
        return sb.deleteCharAt(sb.length()-1).toString();
    }

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

    }

}