javawebday0712（ServletCookie）

• javax.servlet.http.COOKIE类用于创建一个COOKIE&＃xff0c;response接口中也定义了一个addCOOKIE方法&＃xff0c;它用于在其响应头中增加一个相应的Set-COOKIE头字段。同样&＃xff0c;request接口中也定义了一个getCOOKIEs方法&＃xff0c;它用于获取客户端提交的COOKIE。
• COOKIE类的方法&＃xff1a;
  • public COOKIE(String name,String value)
  • setValue与getValue方法&＃xff0c;设置和获取COOKIE的值
  • setMaxAge与getMaxAge方法&＃xff0c;设置COOKIE的有效期&＃xff0c;默认为整个会话过程&＃xff0c;关掉浏览器就销毁。
  • setPath与getPath方法 &＃xff0c;设置和获取访问服务器的有效路径&＃xff0c;例如&＃xff1a;/day06&＃xff0c;只会在访问服务器的day06下面的web资源的时候才会带COOKIE来。
  • setDomain与getDomain方法&＃xff0c;设置和获取服务器的有效域名&＃xff0c;例如&＃xff1a;.sina.com
  • getName方法 

• 要明白三点&＃xff1a;怎么把数据用COOKIE进行封装、怎么把COOKIE打给浏览器、怎么获取浏览器带过来的COOKIE&＃xff1f;
  • 用COOKIE的构造方法进行封装数据到COOKIE
  • 用Response的addCOOKIE()方法&＃xff0c;将COOKIE打给浏览器。
  • 用Request的getCOOKIEs()方法&＃xff0c;获取浏览器带过来的所有COOKIE。

package cn.mengmei.COOKIE;import java.io.IOException;
import java.util.Date;import javax.servlet.ServletException;
import javax.servlet.http.COOKIE;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;public class COOKIEDemo1 extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {//获取浏览器带过来的名为lastDate的COOKIECOOKIE[] COOKIEs &＃61; request.getCOOKIEs();String lastDate &＃61; "";if(COOKIEs !&＃61; null){for(COOKIE cook : COOKIEs){if(cook.getName().equals("lastDate")){lastDate &＃61; cook.getValue();}}}//将时间打印到浏览器显示response.setContentType("text/html;charset&＃61;UTF-8");response.getWriter().write("上次访问时间&＃xff1a;"&＃43;lastDate);//最新时间值String newTime &＃61; new Date(System.currentTimeMillis()).toLocaleString();//将当前时间封装到COOKIE&＃xff0c;设置有效期为30天。COOKIE COOKIE &＃61; new COOKIE("lastDate", newTime);COOKIE.setMaxAge(30*24*3600);  //设置为0&＃xff0c;可以将该COOKIE从硬盘删掉。//没有设置有效path&＃xff0c;默认是本Servlet所在目录&＃xff1a; /myday07/servlet//必须在本Servlet所在目录 /myday07/servlet 下的Servlet才能够将此COOKIE删除。//假如你在这里设置了有效目录&＃xff0c;那么在你删的时候也必须设置相同的有效目录才能够删除。//将COOKIE打给浏览器response.addCOOKIE(COOKIE);}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doGet(request, response);}
}


浏览器地址栏输入&＃xff1a;http://localhost:8080/myday07/servlet/COOKIEDemo1

第一次访问没有时间值&＃xff0c;第二次访问显示第一次访问的时间&＃xff0c;浏览器关掉再打开还能显示&＃xff1a;

上次访问时间&＃xff1a;2015-2-12 23:05:23

• 一个COOKIE只能标识一种信息&＃xff0c;它至少含有一个标识该信息的名称&＃xff08;NAME&＃xff09;和设置值&＃xff08;VALUE&＃xff09;。
• 一个WEB站点可以给一个WEB浏览器发送多个COOKIE&＃xff0c;一个WEB浏览器也可以存储多个WEB站点提供的COOKIE。
• 浏览器一般只允许存放300个COOKIE&＃xff0c;每个站点最多存放20个COOKIE&＃xff0c;每个COOKIE的大小限制为4KB。
• 如果创建了一个COOKIE&＃xff0c;并将他发送到浏览器&＃xff0c;默认情况下它是一个会话级别的COOKIE&＃xff08;即存储在浏览器的内存中&＃xff09;&＃xff0c;用户退出浏览器之后即被删除。若希望浏览器将该COOKIE存储在磁盘上&＃xff0c;则需要使用maxAge&＃xff0c;并给出一个以秒为单位的时间。将最大时效设为0则是命令浏览器删除该COOKIE。
• 注意&＃xff0c;删除COOKIE时&＃xff0c;path必须一致&＃xff0c;否则不会删除

实现过程&＃xff1a;

显示商品列表的首页Servlet&＃xff1a;

package cn.mengmei.COOKIE;import java.io.IOException;
import java.io.PrintWriter;import javax.servlet.ServletException;
import javax.servlet.http.COOKIE;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;public class MainServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("text/html;charset&＃61;UTF-8");//联合使用以下三个响应消息头&＃xff0c;控制浏览器不要缓存。response.setHeader("Expires", "-1"); response.setHeader("Cache-Control", "no-cache"); response.setHeader("Pragma", "no-cache"); PrintWriter out &＃61; response.getWriter();out.write("JSP教程 张孝祥
");out.write("HTML&＃43;CSS&＃43;JS 雷拓
");out.write("JAVA就业教程 王山海
");out.write("structs框架从入门到精通
");out.write("Windows编程 MFC


");out.write("您最近浏览过的历史记录&＃xff1a;
");COOKIE[] COOKIEs &＃61; request.getCOOKIEs();if(COOKIEs!&＃61;null){for(COOKIE cook : COOKIEs){if(cook.getName().equals("bookHistory")){String history &＃61; cook.getValue();String[] ids &＃61; history.split(",");for (String id : ids) {switch (id) {case "1":out.write("JSP教程 张孝祥
");break;case "2":out.write("HTML&＃43;CSS&＃43;JS 雷拓
");break;case "3":out.write("JAVA就业教程 王山海
");break;case "4":out.write("structs框架从入门到精通
");break;case "5":out.write("Windows编程 MFC
");break;default:break;}}}}}}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doGet(request, response);}}


详细页面&＃xff1a;

package cn.mengmei.COOKIE;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;public class DetailServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("text/html;charset&＃61;UTF-8");String id &＃61; request.getParameter("id");boolean flag &＃61; true;COOKIE[] COOKIEs &＃61; request.getCOOKIEs();if(COOKIEs!&＃61;null){for(COOKIE cook : COOKIEs){if(cook.getName().equals("bookHistory")){flag &＃61; false;String history &＃61; cook.getValue();if(!history.contains(id)){StringBuilder sb &＃61; new StringBuilder(history);sb.insert(0, id&＃43;",");history &＃61; sb.toString();System.out.println(history);cook.setValue(history);cook.setMaxAge(30*24*3600);response.addCOOKIE(cook);}else{history &＃61; history.replaceAll("["&＃43;id&＃43;"]", "");StringBuilder sb &＃61; new StringBuilder(history);sb.insert(0, id&＃43;",");history &＃61; sb.toString();history &＃61; history.replaceAll("\\W*(\\W{1})", "$1");while(history.startsWith(",")){history &＃61; history.substring(1);}while(history.endsWith(",")){history &＃61; history.substring(0, history.length()-1);}System.out.println(history);cook.setValue(history);cook.setMaxAge(30*24*3600);response.addCOOKIE(cook);}}}if(flag){COOKIE COOKIE &＃61; new COOKIE("bookHistory", id);COOKIE.setMaxAge(30*24*3600);response.addCOOKIE(COOKIE);}}else{COOKIE COOKIE &＃61; new COOKIE("bookHistory", id);COOKIE.setMaxAge(30*24*3600);response.addCOOKIE(COOKIE);}PrintWriter out &＃61; response.getWriter();switch (id) {case "1":out.write("JSP教程 张孝祥---详细信息页面。。。。。。。。。。。");break;case "2":out.write("HTML&＃43;CSS&＃43;JS 雷拓---详细信息页面。。。。。。。。。。。");break;case "3":out.write("JAVA就业教程 王山海---详细信息页面。。。。。。。。。。。");break;case "4":out.write("structs框架从入门到精通---详细信息页面。。。。。。。。。。。");break;case "5":out.write("Windows编程 MFC---详细信息页面。。。。。。。。。。。");break;default:break;}}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doGet(request, response);}}


浏览器地址栏输入&＃xff1a;http://localhost:8080/myday07/servlet/MainServlet

效果&＃xff1a;

老师讲的标准代码&＃xff1a;

package cn.mengmei.COOKIE;import java.io.IOException;
import java.io.PrintWriter;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Set;import javax.servlet.ServletException;
import javax.servlet.http.COOKIE;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;public class MainServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {//显示商品列表response.setContentType("text/html;charset&＃61;UTF-8");response.setHeader("Expires", "-1"); response.setHeader("Cache-Control", "no-cache"); response.setHeader("Pragma", "no-cache"); PrintWriter out &＃61; response.getWriter();out.write("首页图书展示&＃xff1a;
");Map map &＃61; DB.getAll();Set> set &＃61; map.entrySet();for(Map.Entry me : set){Book book &＃61; me.getValue();String name &＃61; book.getName();String id &＃61; book.getId();out.write(""&＃43;name&＃43;"
");}out.write("
");//最近浏览out.write("最近浏览&＃xff1a;
");COOKIE[] COOKIEs &＃61; request.getCOOKIEs();String bookHistory &＃61; null;for(int i&＃61;0; COOKIEs!&＃61;null && i");}}}}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doGet(request, response);}
}class DB{private static Map map &＃61; new LinkedHashMap();static{map.put("1", new Book("1","javaweb教程","张孝祥","一本好书&＃xff01;"));map.put("2", new Book("2","structs精通","黎活明","很棒&＃xff01;"));map.put("3", new Book("3","Hibernate教程","方立勋","哈哈好书&＃xff01;"));map.put("4", new Book("4","Spring讲解","刘云山","好书书书&＃xff01;"));}public static Map getAll(){return DB.map;}
}class Book{private String id;private String name;private String author;private String descrip;public Book() {super();}public Book(String id, String name, String author, String descrip) {super();this.id &＃61; id;this.name &＃61; name;this.author &＃61; author;this.descrip &＃61; descrip;}public String getId() {return id;}public void setId(String id) {this.id &＃61; id;}public String getName() {return name;}public void setName(String name) {this.name &＃61; name;}public String getAuthor() {return author;}public void setAuthor(String author) {this.author &＃61; author;}public String getDescrip() {return descrip;}public void setDescrip(String descrip) {this.descrip &＃61; descrip;}
}


package cn.mengmei.COOKIE;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;public class DetailServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {//根据id显示商品详细信息response.setContentType("text/html;charset&＃61;UTF-8");PrintWriter out &＃61; response.getWriter();out.write("商品详细&＃xff1a;
");String id &＃61; request.getParameter("id");Book book &＃61; (Book) DB.getAll().get(id);out.write("id:"&＃43;book.getId()&＃43;"
");out.write("书名:"&＃43;book.getName()&＃43;"
");out.write("作者:"&＃43;book.getAuthor()&＃43;"
");out.write("描述:"&＃43;book.getDescrip()&＃43;"
");//给浏览器端发送COOKIECOOKIE COOKIE &＃61; new COOKIE("bookHistory", makeHistory(request,id));COOKIE.setMaxAge(30*24*3600);response.addCOOKIE(COOKIE);}private String makeHistory(HttpServletRequest request, String id) {COOKIE[] COOKIEs &＃61; request.getCOOKIEs();String bookHistory &＃61; null;for(int i&＃61;0; COOKIEs!&＃61;null && i link &＃61; new LinkedList();if(bookHistory !&＃61; null){String[] ids &＃61; bookHistory.split("\\_");link.addAll(Arrays.asList(ids));if(link.contains(id)){link.remove(id);}link.addFirst(id);while(link.size() > 3){link.removeLast();}}else{link.add(id);}StringBuilder sb &＃61; new StringBuilder();for(String i : link){sb.append(i&＃43;"_");}sb.deleteCharAt(sb.length()-1);return sb.toString();}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doGet(request, response);}}