实现用户的自动登录：
解决方案：
设置一个全站拦截的过虑器。
在此过虑器中，读取用户带过来的Cookie信息，然后从中读取用户的用户名和密码，自动帮助用户登录。
即可实现自动登录功能。
用Filter验证用户是否已经登录过。已经登录过了，我们就根据他选择的自动登录来选择让他在多久内能自动登录。
IP黑名单过滤就很简单了，只要在Filter过滤器防范一下就OK。
在init方法中，我们先把黑名单的IP加载进Set<String> set集合，
Set集合有如下特点:
Java.util.HashSet类实现了Java.util.Set接口。 1 它不允许出现重复元素； 2 不保证和政集合中元素的顺序 3 允许包含值为null的元素，但最多只能有一个null元素。 contains方法: 当且仅当 本set包含一个元素 e，并且满足(o==null ? e==null : o.equals(e))条件时,contains()方法才返回true. 因此 contains()方法 必定使用equals方法来检查是否相等. 需要注意的是: set 中是可以包含 null值的(常见的集合类都可以包含null值). 所以如果添加了null,然后判断是否包含null,将会返回true
黑名单IP过滤:
package cn.hncu.pubs; import java.io.IOException; import java.util.HashSet; import java.util.Set; 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; public class CharacterFilter implements Filter{ private String charset; //黑名单 private Set<String> set = new HashSet<String>(); @Override public void init(FilterConfig filterConfig) throws ServletException { charset = filterConfig.getInitParameter("charset"); //到数据库中把黑名单加载进来，这里简单模拟一下 set.add("192.168.31.168"); } @Override public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { request.setCharacterEncoding(charset); //以下演示黑名单过滤技术 String ip = request.getRemoteAddr();;//获得客户端的IP if(set.contains(ip)){ HttpServletResponse resp = (HttpServletResponse) response; resp.setContentType("text/html;charset=utf-8"); resp.getWriter().println("你已被列入黑名单!"); }else{//放行 chain.doFilter(request, response); } } @Override public void destroy() { } }
配置web.xml：
<filter> <filter-name>character</filter-name> <filter-class>cn.hncu.pubs.CharacterFilter</filter-class> <init-param> <param-name>charset</param-name> <param-value>utf-8</param-value> </init-param> </filter> <filter-mapping> <filter-name>character</filter-name> <url-pattern>/*</url-pattern> </filter-mapping>
这样就可以防止IP在黑名单的用户访问我们的网站了！
用户的自动登录
User值对象:
package cn.hncu.domain; /** * @author 陈浩翔 * * 2016-8-18 */ public class User { private String name; private String pwd; public User() { super(); } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getPwd() { return pwd; } public void setPwd(String pwd) { this.pwd = pwd; } }
LoginServlet.java：
package cn.hncu.servlet; import java.io.IOException; import java.io.PrintWriter; 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; import cn.hncu.domain.User; public class LoginServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doPost(request, response); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //从页面接收登录信息 String name = request.getParameter("name"); String pwd = request.getParameter("pwd"); String time = request.getParameter("time"); //System.out.println(name+","+pwd+","+time); User user = new User(); user.setName(name); user.setPwd(pwd); if(name!=null && name.trim().length()!=0 && pwd!=null){ if(name.equals(pwd)){//按理应该到后台去验证登录是否成功，这里直接以用户名和密码相同为登录成功 request.getSession().setAttribute("user", user); //登录成功，就往客户端写一个cookie,将用户名和密码存到cookie中-应该进行加密! //为了能够兼容中文，要进行编码 name = URLEncoder.encode(name, "utf-8"); pwd = URLEncoder.encode(pwd, "utf-8"); Cookie cookie = new Cookie("autoLogin", name+"#!#"+pwd); cookie.setPath(request.getContextPath());//权限：本项目中的类都可以访问该cookie //有效期 cookie.setMaxAge( 60 * Integer.parseInt(time) ); response.addCookie(cookie);//存储到客户端 }else{ request.getSession().setAttribute("error", "密码错误!"); } }else{ request.getSession().setAttribute("error", "请输入用户名!"); } response.sendRedirect(request.getContextPath()+"/index.jsp"); } }
index.jsp:
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>演示利用Filter实现自动登录</title> </head> <body> <h2>主页-演示利用Filter实现自动登录</h2> <c:if test="${!empty sessionScope.error}"> <font color="red">${sessionScope.error}</font> <c:remove var="error" scope="session"/> </c:if> <c:if test="${empty sessionScope.user}" var="boo"> <form action="<c:url value='/LoginServlet'/>" method="post"> Name:<input type="text" name="name"><br/><br/> <!-- 这里为了演示清楚，就直接用text了 --> Pwd:<input type="text" name="pwd"><br/> <fieldset> <legend>自动登录</legend> <input type="radio" name="time" value="0" checked="checked">不自动登录<br/> <input type="radio" name="time" value="1" >1分钟<br/> <input type="radio" name="time" value="60" >1小时<br/> <input type="radio" name="time" value="86400" >1天<br/> <input type="radio" name="time" value="604800" >1周<br/> <input type="radio" name="time" value="2592000" >一个月<br/> </fieldset> <input type="submit" value="登录"> </form> </c:if> <c:if test="${!boo}"> ${user.name},欢迎回来。 <a href="<c:url value='/CancelAutoLoginServlet'/>">取消自动登录</a> </c:if> </body> </html>
CancelAutoLoginServlet.java-取消自动登录：
package cn.hncu.servlet; 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 CancelAutoLoginServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doPost(request, response); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //取消自动登录，其实就是删除Cookie Cookie cookie = new Cookie("autoLogin", ""); cookie.setPath(request.getContextPath());//这个路径必须和原来的设置为一样，否则没用的 cookie.setMaxAge(0);//有效期为0即是删除 response.addCookie(cookie); response.sendRedirect(request.getContextPath()+"/index.jsp"); } }
AutoLoginFilter.java-自动登录:
package cn.hncu.filter; import java.io.IOException; import java.net.URLDecoder; 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.Cookie; import javax.servlet.http.HttpServletRequest; import cn.hncu.domain.User; public class AutoLoginFilter implements Filter { @Override public void init(FilterConfig filterConfig) throws ServletException { } @Override public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { HttpServletRequest req = (HttpServletRequest) request; if(req.getSession().getAttribute("user")==null){//还没有登录，帮你自动登录 Cookie cs[] = req.getCookies(); if(cs!=null){ for(Cookie c :cs){//找"autoLogin"这个cookie if(c.getName().equals("autoLogin")){ String str = c.getValue(); String vals[] = str.split("#!#"); String name = URLDecoder.decode(vals[0], "utf-8"); String pwd = URLDecoder.decode(vals[1], "utf-8"); //... //这里应该再去后台数据库验证是否登录能够成功,这里我就直接以两者相等来判断 if(name.equals(pwd)){//如果成功则返回一个user对象 User user = new User(); user.setName(name); user.setPwd(pwd); req.getSession().setAttribute("user", user); break; } } } } } chain.doFilter(req, response);//放行 } @Override public void destroy() { } }
web.xml:
<?xml version="1.0" encoding="UTF-8"?> <web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"> <display-name></display-name> <filter> <filter-name>character</filter-name> <filter-class>cn.hncu.pubs.CharacterFilter</filter-class> <init-param> <param-name>charset</param-name> <param-value>utf-8</param-value> </init-param> </filter> <filter> <filter-name>autoLogin</filter-name> <filter-class>cn.hncu.filter.AutoLoginFilter</filter-class> </filter> <filter-mapping> <filter-name>character</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <filter-mapping> <filter-name>autoLogin</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <servlet> <servlet-name>CancelAutoLoginServlet</servlet-name> <servlet-class>cn.hncu.servlet.CancelAutoLoginServlet</servlet-class> </servlet> <servlet> <servlet-name>LoginServlet</servlet-name> <servlet-class>cn.hncu.servlet.LoginServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>CancelAutoLoginServlet</servlet-name> <url-pattern>/CancelAutoLoginServlet</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>LoginServlet</servlet-name> <url-pattern>/LoginServlet</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> </web-app>
代码里面都有注释!
实现的功能就是自动登录和取消自动登录。
主要利用了过滤器。还有用到cookie技术。
完整项目链接:
https://github.com/chenhaoxiang/Java/tree/master/myAutoLoginWeb
myAutoLoginWeb.zip文件
