java_web之使用cookie显示曾经访问过的商品

首先创建好数据库；

然后创建一个book类，在domain包里

package com.csdn.book;

public class Book {
	private String id;
	private String name;
	private String author;
	private String state;

	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 getstate() {
		return state;
	}

	public void setstate(String state) {
		this.state = state;
	}

}





//创建工具类
package com.csdn.util;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;


public class JDBCDemo {
	  public static Connection con;
    public static Connection getConnection(){
    	if(con==null){
    	try {
			Class.forName("com.mysql.jdbc.Driver");
		 con=DriverManager.getConnection("jdbc:mysql://localhost:3306/book?user=root&password=root&useUnicode=true&characterEncoding=UTF-8");
		} catch (ClassNotFoundException e) {                    
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} 
    }
         return con;
	}
	public static void dbClose1(PreparedStatement st, Connection con) {
		if (st != null) {
			try {
				st.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		if (con != null) {
			try {
				con.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
	}

	public static void dbClose(ResultSet rs, PreparedStatement st, Connection con) {
		if (rs != null) {
			try {
				rs.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		dbClose1(st, con);

	}
}





//创建dao包里的链接文件

package com.csdn.dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import com.csdn.book.Book;
import com.csdn.util.JDBCDemo;

public class BookDao {
	  
        public List<Book> getAll(){
        	Connection conn=null;
      	  PreparedStatement pt=null;
      	  ResultSet rs=null;
        	conn=JDBCDemo.getConnection();
        	
        	String sql="select * from users";
        	List<Book> list = new ArrayList<Book>();
        	try {
				pt=conn.prepareStatement(sql);
				rs=pt.executeQuery();
				while(rs.next()){
					Book book = new Book();
					book.setId(rs.getString("id"));
					book.setName(rs.getString("name"));
					book.setAuthor(rs.getString("author"));
					book.setstate(rs.getString("state"));
					list.add(book);
				}
				return list;
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				throw new RuntimeException(e);
			}/*finally{
				JDBCDemo.dbClose(rs, pt, conn);
			}*/
			
			
			
        }
        
        public Book getBook(String id){
        	//Book b=null;
        	Connection conn=null;
      	  PreparedStatement pt=null;
      	  ResultSet rs=null;
        	conn=JDBCDemo.getConnection();
        	
        	String sql = "select * from users where id=?";
        	
        	try {
				pt=conn.prepareStatement(sql);
				pt.setString(1, id);
				rs = pt.executeQuery();
				if(rs.next()){
				Book  b=new Book();
					b.setId(rs.getString("id"));
					b.setName(rs.getString("name"));
					b.setAuthor(rs.getString("author"));
					b.setstate(rs.getString("state"));
					return b;
				}
				return null;
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				throw new RuntimeException(e);
			}/*finally{
				JDBCDemo.dbClose(rs, pt, conn);
			}*/
        	
		
        }
       
}



//

package com.csdn.servlet;

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

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 com.csdn.book.Book;
import com.csdn.dao.BookDao;

public class BookServlet1 extends HttpServlet {

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

		response.setContentType("text/html;charset=UTF-8");
		PrintWriter out = response.getWriter();
		
		//显示所有书名
		out.print("本店商品有：<br />");
		//new 一个dao对象
		BookDao bkb=new BookDao();
		//调用getALL方法
		List<Book> list = bkb.getAll();
		for(Book book:list){
			out.print("<a href='/book/BookServlet2?id="+book.getId()+"'target='_blank'>"+book.getName()+"</a><br />");
		}
       out.print("您浏览过的商品是："+"<br />");
       Cookie[] cookie=request.getCookies();
       for(int i=0;cookie!=null && i<cookie.length;i++){
    	   if(cookie[i].getName().equals("books")){
    		   String[] ids=cookie[i].getValue().split(",");
    		   for(String id:ids){
    			  Book book =  bkb.getBook(id);
    			  out.print(book.getName()+"<br />");
    		   }
    	   }
       }
	}

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

	}

}




package com.csdn.servlet;

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;

import com.csdn.book.Book;
import com.csdn.dao.BookDao;

public class BookServlet2 extends HttpServlet {

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

		response.setContentType("text/html;charset=UTF-8");
		PrintWriter out = response.getWriter();
        String id = request.getParameter("id");
        System.out.println(id);
        BookDao bd= new BookDao();
        Book b=bd.getBook(id);
        System.out.println(b);
        
        out.print("书号: "+b.getId()+"<br />");
        
        out.print("书名: "+b.getName()+"<br />");
        
        out.print("作者: "+b.getAuthor()+"<br />");
        
        out.print("介绍："+b.getstate()+"<br />");
        
         String value =buildCookValue(id,request);
         
         Cookie cookie = new Cookie("books",value);
         
         cookie.setMaxAge(7*24*3600);
         cookie.setPath("/book");
         response.addCookie(cookie);
	}
	public String buildCookValue(String id,HttpServletRequest request){
		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){
			return id;
		}
		LinkedList<String> list = new LinkedList(Arrays.asList(bookhistory.split(",")));
		
		if(list.contains(id)){
			list.remove(id);
			list.addFirst(id);
		}else{
			//bookhistory=2,3,5   1  1,2,3
			//bookhistory=2,3     1  1,2,3
			if(list.size()>=3){
				list.removeLast();
				list.addFirst(id);
			}else{
				list.addFirst(id);
			}
			
		}
		StringBuffer sb = new StringBuffer();
		for(String bid: list){
			sb.append(bid+",");
		}
		
		return  sb.deleteCharAt(sb.length()-1).toString();
	}

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

	}

}