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javaWeb 使用cookie显示商品浏览记录

2016-10-15 10:26 549 查看
package de.bvb.cookie;

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

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

/**
* 显示商品列表和已经浏览过的商品
*
* @author joker
*
*/
public class CookieDemo11 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();
// 显示商品列表
out.write("商品列表: <br/>");
for (Entry<String, Book> b : Db.getBooks().entrySet()) {
out.write("<a target='_blank' href='/web/CookieDemo12?id="
+ b.getKey() + "'>" + b.getValue().getName() + "</a><br/>");
}

// 显示浏览过的商品
out.write(" <br/> <br/>浏览过的商品: <br/>");
Cookie[] cookies = request.getCookies();
for (int i = 0; cookies != null && i < cookies.length; i++) {
if (cookies[i].getName().equals("history")) {
String[] ids = cookies[i].getValue().split("\\,");
for (String s : ids) {
out.write(Db.getBooks().get(s).getName() + "<br/>");
}
}
}
}

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

doGet(request, response);
}
}

class Db {
private static LinkedHashMap<String, Book> books = new LinkedHashMap<String, Book>();
static {
books.put("1", new Book("1", "javaWeb", "javaweb"));
books.put("2", new Book("2", "android", "android"));
books.put("3", new Book("3", "spring", "spring"));
books.put("4", new Book("4", "strus", "strus"));
books.put("5", new Book("5", "ios", "ios"));
}

public static Map<String, Book> getBooks() {
return books;
}
}

class Book {
private String id;
private String name;
private String description;

public Book(String id, String name, String description) {
super();
this.id = id;
this.name = name;
this.description = description;
}

public Book() {
super();
}

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 getDescription() {
return description;
}

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

}


package de.bvb.cookie;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.Date;
import java.util.LinkedList;
import java.util.Map.Entry;

import javax.enterprise.inject.ResolutionException;
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 javax.swing.text.DateFormatter;

/**
* 显示商品详情
*
* @author joker
*
*/
public class CookieDemo12 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();

// 显示商品详情
out.write("商品详情: <br/>");
String id = request.getParameter("id");
for (Entry<String, Book> b : Db.getBooks().entrySet()) {
if (id.equals(b.getKey())) {
out.write(b.getValue().getId() + "<br/>");
out.write(b.getValue().getName() + "<br/>");
out.write(b.getValue().getDescription() + "<br/>");
}
}

// 回写cookie,保存最后浏览的商品id
String history = buildIds(id, request);
Cookie cookie = new Cookie("history", history);
cookie.setMaxAge(1 * 30 * 24 * 60 * 60);
cookie.setPath("/web");
response.addCookie(cookie);
}

private String buildIds(String id, HttpServletRequest request) {
String history = null;
Cookie[] cookies = request.getCookies();
for (int i = 0; cookies != null && i < cookies.length; i++) {
if (cookies[i].getName().equals("history")) {
history = cookies[i].getValue();
}
}
if (history == null) {
return id;
}
LinkedList<String> ids = new LinkedList<String>(Arrays.asList(history
.split("\\,")));
if (ids.contains(id)) {
ids.remove(id);
} else {
if (ids.size() >= 3) { // 最多显示3条浏览历史
ids.removeLast();
}
}
ids.addFirst(id);
StringBuffer sb = new StringBuffer();
for (String s : ids) {
sb.append(s).append(",");
}
return sb.deleteCharAt(sb.length() - 1).toString();
}

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

doGet(request, response);
}

}
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