软帝学院教你使用cookie法,查看最近看过的书

软帝学院教你使用cookie法,查看最近看过的书

 

public class Book implements Serializable {

private String id;

private String name;

private String price;

private String auth;

private String publish;

private String description;

 

public Book() {

}

 

public Book(String id, String name, String price, String auth,

String publish, String description) {

super();

this.id = id;

this.name = name;

this.price = price;

this.auth = auth;

this.publish = publish;

this.description = description;

}

 

public String getDescription() {

return description;

}

 

public void setDescription(String description) {

this.description = 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 getAuth() {

return auth;

}

public void setAuth(String auth) {

this.auth = auth;

}

public String getPublish() {

return publish;

}

public void setPublish(String publish) {

this.publish = publish;

}

 

}

public void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

response.setContentType("text/html;charset=utf-8");

//1.获取要看的书的id,查询数据库找出书,输出书的详细信息

String id = request.getParameter("id");

Book book = BookDao.getBook(id);

if(book==null){

response.getWriter().write("找不到这本书!");

return;

}else{

response.getWriter().write("<h1>书名:"+book.getName()+"</h1>");

response.getWriter().write("<h3>作者:"+book.getAuth()+"</h3>");

response.getWriter().write("<h3>售价:"+book.getPrice()+"</h3>");

response.getWriter().write("<h3>出版社:"+book.getPublish()+"</h3>");

response.getWriter().write("<h3>描述信息:"+book.getDescription()+"</h3>");

}

 

//2.发送cookie保存最后看过的书

// --- 1 --> 1

// 1 --2,1 --> 2,1

// 2,1--3,2,1 --> 3,2,1

// 3,2,1 -- 4,3,2 --> 4,3,2

// 4,3,2 --3,4,2 --> 3,4,2

String ids = "";

 

Cookie [] cs = request.getCookies();

Cookie findC = null;

if(cs!=null){

for(Cookie c : cs){

if("last".equals(c.getName())){

findC = c;

}

}

}

 

if(findC == null){

//说明之前没有看过书的记录

ids += book.getId();

}else{

//说明之前有历史看过的书的记录,需要根据历史记录算一个新的记录出来

String [] olds = findC.getValue().split(",");

StringBuffer buffer = new StringBuffer();

buffer.append(book.getId()+",");

for(int i = 0;i<olds.length && buffer.toString().split(",").length<3 ;i++){

String old = olds[i];

if(!old.equals(book.getId())){

buffer.append(old+",");

}

}

ids = buffer.substring(0, buffer.length()-1);

}

 

Cookie lastC = new Cookie("last",ids);

lastC.setMaxAge(3600*24*30);

lastC.setPath(request.getContextPath());

response.addCookie(lastC);

}