一、session
1、基本使用
会话
在整个会话周期中任何servlet或者jsp页面都可以到会话的数据
设置数据
//将登录用户的信息存入到session中 HttpSession//获得session对象HttpSession session = req.getSession();session.setAttribute("loginUser", loginUser);
获取数据
在servlet中获取
HttpSession session = req.getSession();
session.getAttribute("loginUser");
在jsp页面获取
${sessionScope.loginUser.uname}
上面的代码实质就是下面两行代码
Users user = (Users)session.getAttribute("loginUser");
String uname = user.getUname();
2、登录的功能
每个用户必须登录以后才可以访问其他功能。
目前编写的登录没有实现这个功能。
需要添加代码来完成这个功能。
怎么完成？
登录完成后，在session存储登录用户的信息。没有登录成功，则session中没有存储登录用户信息
在所有的servlet中判断登录用户是否存在，如果存在允许访问，如果不存在，不允许访问。
a、在登录时将登录用户的信息存入session
private void login(HttpServletRequest req, HttpServletResponse resp) throws IOException {//1、获得表单中提交的数据String uname = req.getParameter("uname");String upwd = req.getParameter("upwd");Users user = new Users();user.setUname(uname);user.setUpwd(upwd);//2、调用service方法Users loginUser=us.login(user);//3、跳转if(loginUser!=null) {//将登录用户的信息存入到session中 HttpSession//获得session对象HttpSession session = req.getSession();session.setAttribute("loginUser", loginUser);resp.sendRedirect("emp.do");}else {resp.sendRedirect("login.html");}}
b、在所有要控制的servlet中添加控制代码
@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {req.setCharacterEncoding("utf-8");resp.setCharacterEncoding("utf-8");//1、获得session对象HttpSession session = req.getSession();//2、获得session中的登录用户Users loginUser = (Users) session.getAttribute("loginUser");//3、判断登录用户是否存在，来决定你是否登录成功if(loginUser!=null) {String method = req.getParameter("method");if(method==null||method.equals("")) {method="query";}switch(method) {// case "list":// list(req,resp);// break;case "query":query(req,resp);break;}}else {resp.sendRedirect("login.html");}}
c、如果用户使用完毕，需要退出登录
登录用户${sessionScope.loginUser.uname }<a href="exit.do">退出登录</a>
ExitServlet.java
package com.servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class ExitServlet extends HttpServlet {
@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {doPost(req,resp);}
@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {//销毁sessionreq.getSession().invalidate();resp.sendRedirect("login.html");}}
二、过滤器
1、问题：
上面代码实现了session控制访问的功能，但是要在每个需要控制访问的servlet中编写判断代码，工作量太大，而且不好维护。
解决方案就是使用filter过滤器
2、编写过滤器类
LoginFilter.java
实现过滤器接口Filter javax.servlet.Filter
package com.filter;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import com.entity.Users;
public class LoginFilter implements Filter {
@Overridepublic void destroy() {// TODO Auto-generated method stub
}
@Overridepublic void doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain arg2)throws IOException, ServletException {//过滤器//编写代码 //arg0 request//arg1 response//将ServletRequest的arg0转成HttpServletRequest//(HttpServletRequest) arg0 说明arg0的类型大于HttpServletRequest类型//public abstract interface javax.servlet.http.HttpServletRequest extends javax.servlet.ServletRequest HttpServletRequest req = (HttpServletRequest) arg0;//获得sessionHttpSession session = req.getSession();//获得登录用户信息Users loginUser = (Users) session.getAttribute("loginUser");if(loginUser!=null) {//放行，也就是继续运行用户请求的内容arg2.doFilter(arg0, arg1);}else {HttpServletResponse resp = (HttpServletResponse) arg1;resp.sendRedirect("login.html");}}
@Overridepublic void init(FilterConfig arg0) throws ServletException {// TODO Auto-generated method stub
}
}
3、过滤器也需要在web.xml中配置
<filter><filter-name>loginFilter</filter-name><filter-class>com.filter.LoginFilter</filter-class></filter><filter-mapping><filter-name>loginFilter</filter-name><!-- 地址栏中所有的*.do请求都会被当前filter拦截--><url-pattern>*.do</url-pattern></filter-mapping>
4、过滤器就可以将所有*.do请求过滤
实际上就是在执行目标servlet中的代码前，执行过滤器代码
在其他servlet中就不用编写session控制访问的代码
实现字符集过滤器
a、编写过滤器
package com.filter;import java.io.IOException;import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;public class EncodingFilter implements Filter {private String encoding;@Overridepublic void destroy() {// TODO Auto-generated method stub}@Overridepublic void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)throws IOException, ServletException {request.setCharacterEncoding(encoding);response.setCharacterEncoding(encoding);//上面两行代码在所有被过滤的servlet中都加上了chain.doFilter(request, response);}@Overridepublic void init(FilterConfig filterConfig) throws ServletException {// TODO Auto-generated method stubencoding = filterConfig.getInitParameter("encoding");}}
b、配置过滤器
<filter><filter-name>ef</filter-name><filter-class>com.filter.EncodingFilter</filter-class><init-param><param-name>encoding</param-name><param-value>utf-8</param-value></init-param></filter><filter-mapping><filter-name>ef</filter-name><!-- 地址栏中所有的*.do请求都会被当前filter拦截--><url-pattern>*.do</url-pattern></filter-mapping>
三、Cookie
1、自动登录
自动登录多久，设置cookie失效时间
a、登录完成时，在UsersServlet中将登录成功的用户名和密码存入cookied中
//设定cookie的失效时间String timeStr = req.getParameter("time");
//如果没有传参，则默认不保存int t = 0;if(timeStr!=null) {t = Integer.parseInt(timeStr);}//将登录户名名称和密码存到cookie中//在服务器端生成cookie//cookie只能存入字符串，想要存入的信息有多个值，需要拼接存入Cookie cookie = new Cookie("loginUser", loginUser.getUname()+":"+loginUser.getUpwd());//设定失效时间cookie.setMaxAge(t);resp.addCookie(cookie);
package com.servlet;import java.io.IOException;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.servlet.http.HttpSession;import com..entity.Users;
import com.service.UserService;
import com.service.UserServiceImpl;public class UsersServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
// req.setCharacterEncoding("utf-8");
// resp.setCharacterEncoding("utf-8");String method = req.getParameter("method");switch (method) {case "login":login(req,resp);break;default:break;}}UserService us = new UserServiceImpl();private void login(HttpServletRequest req, HttpServletResponse resp) throws IOException {//1、获得表单中提交的数据String uname = req.getParameter("uname");String upwd = req.getParameter("upwd");Users user = new Users();user.setUname(uname);user.setUpwd(upwd);//2、调用service方法Users loginUser=us.login(user);//3、跳转if(loginUser!=null) {//设定cookie的失效时间String timeStr = req.getParameter("time");int t = 0;if(timeStr!=null) {t = Integer.parseInt(timeStr);}//将登录户名名称和密码存到cookie中//在服务器端生成cookie//cookie只能存入字符串，想要存入的信息有多个值，需要拼接存入Cookie cookie = new Cookie("loginUser", loginUser.getUname()+":"+loginUser.getUpwd());cookie.setMaxAge(t);resp.addCookie(cookie);//将登录用户的信息存入到session中 HttpSession//获得session对象HttpSession session = req.getSession();//设定session的失效时间，参数为失效的秒数
// session.setMaxInactiveInterval(5);session.setAttribute("loginUser", loginUser);resp.sendRedirect("emp.do");}else {resp.sendRedirect("login.html");}}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {doGet(req,resp);}}
b、因为登录界面需要使用java代码，所以将html转成jsp
<%@ page language="java" contentType="text/html; charset=utf-8"pageEncoding="utf-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Insert title here</title>
<link rel="stylesheet" href="css/bootstrap.min.css" /><script src="http://libs.baidu.com/jquery/2.0.0/jquery.min.js"></script><script type="text/javascript" src="js/bootstrap.min.js" ></script></head><body><%//实现自动登录Cookie[] cookies = request.getCookies();for(int i=0;i<cookies.length;i++){Cookie c = cookies[i];//判断cookie中是否存在登录用户信息，如果存在，则直接登录if(c.getName().equals("loginUser")){if(c.getValue()!=null&&!c.getValue().equals("")){String[] strs = c.getValue().split(":");//在重定向的时候直接将cookie中的登录用户信息分解传入登录servletresponse.sendRedirect("users.do?method=login&uname="+strs[0]+"&upwd="+strs[1]);}}}%><div class="panel panel-info col-md-6 col-md-offset-3"><div class="panel-heading h2">登录界面</div><div class="panel-body"><form class="form-horizontal" action="users.do?method=login" method="post"><div class="form-group"><label class="col-md-2 control-label" for="uname">用户名</label><div class="col-md-10"><input type="text" name="uname" id="uname" class="form-control" ></div></div><div class="form-group"><label class="col-md-2 control-label" for="upwd">密码</label><div class="col-md-10"><input type="password" name="upwd" id="upwd" class="form-control" ></div></div><select name="time"><option value="0">不保存</option><option value="10">保存一天</option><option value="30">保存一周</option><option value="300">保存一月</option></select><button class="btn btn-success btn-block">登录</button></form></div></div></body>
</html>
将所有跳转到login.html代码转成login.jsp
在LoginFilter和ExitServlet中修改
