SERVLETJSP Unit06： 状态管理-cookie

一.开发思路

1.需求

• 和需求人员沟通需求,明确需求

2.设计(图文)

• 先将功能拆分成若干请求
• 每个请求画出程序执行的过程图
  

  根据操作推导出本功能所包含的请求

3.开发

• 逐个请求逐个组件开发

二.资费查询

三.问题

1.如何格式化jsp上显示的时间?

• fmt.tld
• formatDate

2.路径相关问题

• 在jsp上引用样式文件和图片为什么没写../
• 为什么要将jsp放在WEB-INF下
• 为什么要将静态资源放在webapp下
  

3.编码问题

• 为什么jsp上有2处声明了编码
• pageEncoding是给服务器翻译jsp时用的
• meta中的编码是给浏览器加载HTML时用的

四.增加资费

---

FindCostServlet.java

package web;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 FindCostServlet extends HttpServlet {    //相当于MainServlet.findCost()    @Override    protected void service(        HttpServletRequest req,         HttpServletResponse res) throws ServletException, IOException {        Cookie[] cs = req.getCookies();        if(cs != null) {            res.setContentType(                "text/html;charset=utf-8");            PrintWriter out = res.getWriter();            for(Cookie c : cs) {                out.println(                    c.getName()+":"+c.getValue());            }            out.close();        }    }}

IndexServlet.java

package web;import java.io.IOException;import java.io.PrintWriter;import java.net.URLDecoder;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 IndexServlet extends HttpServlet {    //相当于MainServlet.toIndex()    @Override    protected void service(        HttpServletRequest req,         HttpServletResponse res) throws ServletException, IOException {        //浏览器再次访问此服务器时,会自动传入        //之前保存的cookie,现在获取此cookie.        Cookie[] cs = req.getCookies();        //将cookie中的数据显示到页面上        if(cs != null) {            res.setContentType(                "text/html;charset=utf-8");            PrintWriter out = res.getWriter();            for(Cookie c : cs) {                String value =                     URLDecoder.decode(                        c.getValue(),"utf-8");                out.println(                    c.getName()+":"+value);            }            out.close();        }    }}

LoginServlet.java

package web;import java.io.IOException;import java.net.URLEncoder;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 LoginServlet extends HttpServlet {    //相当于MainServlet.login()    @Override    protected void service(        HttpServletRequest req,         HttpServletResponse res) throws ServletException, IOException {        //接收传入的参数        String code = req.getParameter("code");        //存入cookie,给其他功能使用        //1.一个cookie对象中只能存一个数据        //2.所存的数据必须是字符串        //3.可以创建更多个cookie以保存更多的数据        Cookie c1 = new Cookie("code",code);        //设置cookie的生存时间        c1.setMaxAge(600000);        //将cookie存入response,在服务器响应时,        //会自动把cookie发送给浏览器.        res.addCookie(c1);        //向cookie中存中文        Cookie c2 = new Cookie("city",            URLEncoder.encode("北京", "utf-8"));        res.addCookie(c2);        //设置cookie的有效路径        Cookie c3 = new Cookie("name","Tarena");        c3.setPath("/jsp3");        res.addCookie(c3);    }}

web.xml

<?xml version="1.0" encoding="UTF-8"?><web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5">  <display-name>jsp3</display-name>  <welcome-file-list>    <welcome-file>index.html</welcome-file>    <welcome-file>index.htm</welcome-file>    <welcome-file>index.jsp</welcome-file>    <welcome-file>default.html</welcome-file>    <welcome-file>default.htm</welcome-file>    <welcome-file>default.jsp</welcome-file>  </welcome-file-list>  <servlet>      <servlet-name>login</servlet-name>      <servlet-class>web.LoginServlet</servlet-class>  </servlet>  <servlet-mapping>      <servlet-name>login</servlet-name>      <url-pattern>/main/login</url-pattern>  </servlet-mapping>  <servlet>      <servlet-name>index</servlet-name>      <servlet-class>web.IndexServlet</servlet-class>  </servlet>  <servlet-mapping>      <servlet-name>index</servlet-name>      <url-pattern>/main/index</url-pattern>  </servlet-mapping>  <servlet>      <servlet-name>findCost</servlet-name>      <servlet-class>web.FindCostServlet</servlet-class>  </servlet>  <servlet-mapping>      <servlet-name>findCost</servlet-name>      <url-pattern>/cost/find</url-pattern>  </servlet-mapping></web-app>