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
转载请附上原文博客链接：
http://blog.csdn.net/qq_26525215
时间： 2024-08-05 04:11:43