package qingxia.tang.entity;
public class Book {
private String id;
private String bookName;
private double bookPrice;
private String author;
public Book(String id, String bookName, double bookPrice, String author) {
super();
this.id = id;
this.bookName = bookName;
this.bookPrice = bookPrice;
this.author = author;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getBookName() {
return bookName;
}
public void setBookName(String bookName) {
this.bookName = bookName;
}
public double getBookPrice() {
return bookPrice;
}
public void setBookPrice(double bookPrice) {
this.bookPrice = bookPrice;
}
public String getAuthor() {
return author;
}
public void setAuthor(String author) {
this.author = author;
}
@Override
public String toString() {
return "Book [id=" + id + ", bookName=" + bookName + ", bookPrice=" + bookPrice + ", author=" + author + "]";
}
}
package qingxia.tang.util;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import qingxia.tang.entity.Book;
public class DbUtils {
private static Map<String,Book> books =new HashMap<String,Book>();
static {
books.put("1", new Book("1","西游记",20,"吴承恩"));
books.put("2", new Book("2","红楼梦",30,"曹雪婷"));
books.put("3", new Book("3","水浒传",25,"施耐庵"));
books.put("4", new Book("4","三国演义",10,"罗贯中"));
}
public static Map<String,Book> getAllBook(){
return books;
}
public static Book getBookById(String id){
return books.get(id);
}
}
package tang;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
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;
import qingxia.tang.entity.Book;
import qingxia.tang.util.DbUtils;
/**
* Servlet implementation class ShowBookDetail
*/
@WebServlet("/ShowBookDetail")
public class ShowBookDetail extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public ShowBookDetail() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//显示所有书籍
response.setContentType("text/html;charset=UTF-8");
PrintWriter pw=response.getWriter();
pw.write("图书馆有如下书籍：</br>");
Map<String, Book> allBook = DbUtils.getAllBook();
for(Entry<String, Book> book:allBook.entrySet()){
pw.write("<a href='"+request.getContextPath()+"/BookDetail?id="+book.getKey()+"' target='_blank'>"+book.getValue().getBookName()+"</a></br>");
}
pw.write("已浏览如下书籍：</br>");
Cookie[] cookies = request.getCookies();
for (int i = 0;cookies!=null && i < cookies.length; i++) {
if(cookies[i].getName().equals("bookDetailHistory")){
//获取以-拼接的字符串
String value = cookies[i].getValue();
//以-分裂字符串，得到字符串数组
String[] split = value.split("-");
for (int j = 0; j < split.length; j++) {
pw.write(DbUtils.getBookById(split[j]).getBookName()+"</br>");
}
}
}
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
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书详情的显示
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package tang;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;
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;
import qingxia.tang.entity.Book;
import qingxia.tang.util.DbUtils;
/**
* Servlet implementation class BookDetail
*/
@WebServlet("/BookDetail")
public class BookDetail extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public BookDetail() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter pw=response.getWriter();
String id=request.getParameter("id");
Book bookById = DbUtils.getBookById(id);
pw.write(bookById.toString());
Cookie cookie = new Cookie("bookDetailHistory",oganizeId(id,request));
//设置cookie的路径
cookie.setPath("/");
//设置cookie存活时间
cookie.setMaxAge(Integer.MAX_VALUE);
//将cookie提交到浏览器客户端
response.addCookie(cookie);
}
/**
* 将书的key值用-隔开存入到cookie当中
* @param id
* @param request
* @return
*/
private String oganizeId(String id, HttpServletRequest request) {
Cookie[] cookies = request.getCookies();
if(cookies==null){
//说明第一次访问，无cookies值
return id;
}
//浏览器中有cookie值
Cookie historyBook=null;
for (int i = 0; i < cookies.length; i++) {
//判断cookie中是否保存了bookDetailHistory
//如果cookie值中包含bookDetailHistory
if("bookDetailHistory".equals(cookies[i].getName())){
//将key值是bookDetailHistory的value值取到
historyBook=cookies[i];
}
}
//如果cookie中无bookDetailHistory值
if(historyBook==null){
return id;
}
//cookie值中有bookDetailHistory值
//获取cookie值是bookDetailHistory的value值
String value = historyBook.getValue();
System.out.println("value"+value);
//将bookDetailHistory的value值以-分隔开
String[] split = value.split("-");
//将取到的字符串数组转化成list
LinkedList<String> list=new LinkedList<String>(Arrays.asList(split));
System.out.println("list.size()"+list.size()+" id:"+id);
//如果list中的元素小于3
if(list.size()<3){
//list中的元素包含某一本书，将包含的书移除掉
if(list.contains(id)){
list.remove(id);
}
//如果list中的元素等于大于3
}else{
//list中的元素包含某一本书，将包含的书移除掉
if(list.contains(id)){
list.remove(id);
//list中的元素中无与id相同的书，则将最后一本书删除，即只能显示三本书
}else{
list.removeLast();
}
}
//将书添加到首栏中
list.addFirst(id);
StringBuffer sb=new StringBuffer();
for (int i = 0;i<list.size();i++) {
//即第一次循环不需要拼接-
if(i>0){
sb.append("-");
}
//先拼接再添加值，保证最后一位不会出现-
sb.append(list.get(i));
}
return sb.toString();
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
显示效果：
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