Unit06： 状态管理-cookie

　　　　Unit06： 状态管理-cookie　　　　

web

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();
        }
    }
 
}

FindCostServlet.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();
        }
    }
 
}

IndexServlet.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);
    }
 
}

LoginServlet.java

<?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>

web.xml