Java Cookie记录商品浏览历史

最后显示效果如下：

存储图书信息类Book.java

package com.app2;

public class Book {
	private String id;
	private String name;
	private String price;
	private String author;
	private String description;
	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 getPrice() {
		return price;
	}
	public void setPrice(String price) {
		this.price = price;
	}
	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;
	}
	@Override
	public String toString() {
		return "Book [id=" + id + ", name=" + name + ", price=" + price + ", author=" + author + ", description="
				+ description + "]";
	}
	public Book(String id, String name, String price, String author, String description) {
		super();
		this.id = id;
		this.name = name;
		this.price = price;
		this.author = author;
		this.description = description;
	}
	public Book() {}
}

模拟数据库类，存放图书信息

package com.app2;

import java.util.HashMap;
import java.util.Map;

/*
 * 模拟数据
 */
public class BookDB {
	// key:书的id value:id对应的书
	private static Map<String, Book> books = new HashMap<String, Book>();
	static {
		books.put("1", new Book("1", "book1", "11", "luxon1", "good book 1"));
		books.put("2", new Book("2", "book2", "12", "luxon2", "good book 2"));
		books.put("3", new Book("3", "book3", "13", "luxon3", "good book 3"));
		books.put("4", new Book("4", "book4", "14", "luxon4", "good book 4"));
		books.put("5", new Book("5", "book5", "15", "luxon5", "good book 5"));
	}
	
	public static Map<String, Book> findAllBooks() {
		return books;
	}
	
	public static Book findById(String id) {
		return books.get(id);
	}
}

显示所有图书信息主页的servlet

package com.app2;

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

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

/*
 * 显示书的所有信息
 */
@WebServlet("/ShowAllBookServlet")
public class ShowAllBookServlet extends HttpServlet {

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
			response.setContentType("text/html;charset=UTF-8");
			PrintWriter out = response.getWriter();
			
			// 显示所有书籍
			out.write("<h1>书籍清单</h1>");
			Map<String, Book> books = BookDB.findAllBooks();
			for (Map.Entry<String, Book> ele : books.entrySet()) {
				out.write(ele.getValue().getName() + "  " + 
						"<a href='"+request.getContextPath()+"/ShowDetailsSerblet?id="+ele.getKey()+"' target='_blank'>详细内容</a><br/>");
			}
			
			out.write("<br/>您最近浏览的书籍历史<br/>");
			Cookie[] cs = request.getCookies();
			for (int i = 0; cs != null && i < cs.length; i++) {
				if ("bookHistory".equals(cs[i].getName())) {
					String[] ids = cs[i].getValue().split("\\-");
					for (String s : ids) {
						out.write(BookDB.findById(s).toString() + "<br/>");
					}
				}
			}
			
			System.out.println(request.getRemoteAddr());
	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doGet(request, response);
	}

}

显示图书的详细信息，设置cookie的服务servlet

package com.app2;

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

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

/*
 * 显示书的详细信息
 * 组织数据，向客户端写入cookie
 */
@WebServlet("/ShowDetailsSerblet")
public class ShowDetailsSerblet extends HttpServlet {

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		response.setContentType("text/html;UTF-8");
		PrintWriter out = response.getWriter();
		
		String id = request.getParameter("id");
		Book book = BookDB.findById(id);
		out.println(book.toString());
		
		// 往客户端写入cookie
		String bookId = makeId(id, request);
		Cookie c = new Cookie("bookHistory", bookId);
		c.setPath(request.getContextPath());
		response.addCookie(c);
	}
	
	private String makeId(String id, HttpServletRequest request) {
		// cookie为null
		Cookie[] cs = request.getCookies();
		if (cs == null) {
			return id;
		}
		
		String result = "";
		for (int i = 0; i < cs.length; i++) {
			if ("bookHistory".equals(cs[i].getName())) {
				// 浏览历史中不存在该id
				if (cs[i].getValue().indexOf(id) == -1) {
					result = id + "-" + cs[i].getValue();
					break;
				}
				else if (cs[i].getValue().indexOf(id) == 0) {
					result = cs[i].getValue();
					break;
				}
				else {
					result = id;
					String[] ids = cs[i].getValue().split("\\-");
					for (String str : ids) {
						if (!str.equals(id)) {
							result += "-" + str;
						}
					}
					break;
				}
			}
		}

		if (result.length() <= 5) {
			return result;
		}
		else {
			return result.substring(0, 5);
		}
	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doGet(request, response);
	}

}