java使用Filter实现自动登录的方法

本文实例为大家分享了java实现自动登录的具体代码，供大家参考，具体内容如下

• 当你勾选（记住登录状态），用cookie保存用户名和密码。不勾选，cookie失效。
• 所有的页面都要经过autologinfilter.java 的过滤器，在这类中，必须要判断cookies不为null，获得所有的cookie，得到name为user的cookie，进行用户名和密码的验证，如果不为null，则将user存入session。
• 在loginservlet.java中，获得username和password参数，进行dao验证，如果不为空，放入seesion中，进行页面跳转。
• 创建cookie对象。setpath("/"),表示本应用下的所有路径都能访问此cookie。
• 对于已经正确登录的用户，再次访问其他页面必定会再次经过autologinfilter，这时，判断当前session中的user是否为null，不为null，直接通过。
• 对于**login.jsp的有关页面，不需要经过autologinfilter。
  

package com.learning.web.servlet;

import java.io.ioexception;
import javax.servlet.servletexception;
import javax.servlet.annotation.webservlet;
import javax.servlet.http.cookie;
import javax.servlet.http.httpservlet;
import javax.servlet.http.httpservletrequest;
import javax.servlet.http.httpservletresponse;

import com.learning.domain.user;
import com.learning.service.userservice;

@webservlet("/servlet/loginservlet")
public class loginservlet extends httpservlet {
 private static final long serialversionuid = 1l;
 protected void doget(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception {
   string username = request.getparameter("username");
   string password = request.getparameter("password");
   string autologin = request.getparameter("autologin");
   
   userservice userservice=new userservice();
   user user = userservice.finduser(username, password);
   //user不为null，则登录成功
   if (user!=null) {
    //创建cookie来保存用户信息
    cookie cookie=new cookie("user", user.getusername()+"&"+user.getpassword());
    cookie.setpath("/");
    //autologin不为null，则记住了登录状态
    if (autologin!=null) {
     cookie.setmaxage(1*60*60*24);//一天的有效时间
    }
    else {
     cookie.setmaxage(0);
    }
    response.addcookie(cookie);
    request.getsession().setattribute("user", user);
    request.getrequestdispatcher("/home.jsp").forward(request, response);
   }else {
    response.sendredirect(request.getcontextpath()+"/homelogin.jsp");
   }
   
 }

 protected void dopost(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception {
  doget(request, response);
 }

}

package com.learning.web.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.annotation.webfilter;
import javax.servlet.annotation.webinitparam;
import javax.servlet.http.cookie;
import javax.servlet.http.httpservletrequest;
import javax.servlet.http.httpservletresponse;
import javax.servlet.http.httpsession;
import javax.servlet.jsp.jstl.core.config;

import com.learning.domain.user;
import com.learning.service.userservice;

@webfilter(urlpatterns="/*",initparams={@webinitparam(name="autologin",value="login"),@webinitparam(name="",value="")})
public class autofilter implements filter{

 private filterconfig filterconfig;
 @override
 public void destroy() {
 }

 @override
 public void dofilter(servletrequest request, servletresponse response, filterchain chain)
   throws ioexception, servletexception {
  // 转换对象
  httpservletrequest httpservletrequest = (httpservletrequest) request;
  httpservletresponse httpservletresponse = (httpservletresponse) response;
  // 获得访问的路径
  string uri = httpservletrequest.getrequesturi();
  string contextpath = httpservletrequest.getcontextpath();
  uri = uri.substring(contextpath.length() + 1);
  // 获得初始化参数
  string login = filterconfig.getinitparameter("autologin");
  system.out.println("直接通行的路径："+login);
  // 不包含"login"的路径就要进行过滤 （xxxlogin.jsp 不需要自动登录）
  if (!uri.contains(login)) {
   httpsession session = httpservletrequest.getsession();
   user u = (user) session.getattribute("user");
   if (u != null) {
    system.out.println("session不为null");
    chain.dofilter(request, response);
   } else {

    // 处理业务逻辑
    // 1.获得cookie 得到user的信息

    string username = "";
    string password = "";
    userservice userservice = new userservice();
    cookie[] cookies = httpservletrequest.getcookies();
    for (int i = 0;cookies!=null&& i < cookies.length; i++) {  
     if ("user".equals(cookies[i].getname())) {
      string string = cookies[i].getvalue();
      string[] values = string.split("&");
      username = values[0];
      password = values[1];
      user user = userservice.finduser(username, password);
      
      // 不为空则放入session
      if (user != null) {
       system.out.println("自动登录了");
       httpservletrequest.getsession().setattribute("user", user);
      }
     }
    }
   }
  }
  // 2.放行
  chain.dofilter(request, response);
 }


 @override
 public void init(filterconfig filterconfig) throws servletexception {
  
  this.filterconfig=filterconfig;
  
 }

}

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。