web 同一账号多地方登陆，前者被踢掉并提示

业务需求

admin这个账号在A电脑登陆，同时又有一个人在B电脑登陆admin这个账号，那么A电脑上面的admin就不能操作而被强制下线并对A电脑操作的人员进行账号安全提示。同一台电脑不同浏览器可以随意登陆同一个账号，并且不受影响。

实现思路

当用户登陆的时候，小王登录把账号的session和ip存到application里面。小李再次登录账号，先看看这个账号有没有在application里面，如果有把里面的删除掉，把现在的添加进去。当小王进行请求的时候来个过滤器，获取一下现在的session和ip是否与application里面的进行判断，不一样的话证明有人再次登录了，那么就要跳转到登录页面了。就是这个意思了，自行理解吧。

代码

过滤器

 <filter>
		<filter-name>LoginLimitFilter</filter-name>
				<!--Loginfilter类所在位置-->
		<filter-class>com.gosoft.wsms.common.filter.Loginfilter</filter-class>
    </filter>
	<filter-mapping>
		<filter-name>LoginLimitFilter</filter-name>
		<!--拦截所有请求了，你可以自行设置-->
		<url-pattern>/*</url-pattern>
	</filter-mapping>  

Loginfilter类
jre自己找吧

import java.io.IOException;
import java.io.PrintWriter;
import java.math.BigDecimal;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.Map;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletContext;
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.gosoft.wsms.common.utils.RequestUtil;
import com.gosoft.wsms.common.utils.WebConstants;

public class Loginfilter implements Filter {

	@Override
	public void destroy() {
		// TODO Auto-generated method stub

	}

	@Override
	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain filterChain) throws IOException, ServletException {
		HttpServletRequest servletRequest = (HttpServletRequest) request;
		HttpServletResponse servletResponse = (HttpServletResponse) response;
		HttpSession session = servletRequest.getSession();
		ServletContext application = session.getServletContext();
		Map<Object, String> userSessionMap = (Map<Object, String>) application.getAttribute("userSessionMap");
		String firstUserAcc = (String) session.getAttribute("userAcc");
	    if (firstUserAcc != null) {//
			String currentId = null;
			for (Object entry : userSessionMap.keySet()) {
				if (firstUserAcc.equals(entry)) {
					currentId = userSessionMap.get(firstUserAcc);
				}
			}
			String sessionId =currentId.substring(0,currentId.indexOf(","));
			String loginIp =currentId.substring(currentId.indexOf(",")+1);
			String lastLoginIp=Loginfilter.getIpAddr(servletRequest);
		    String currentSessionId=session.getId();
			if (null != userSessionMap) {
		    	if(!loginIp.equals(lastLoginIp)){
				if (!sessionId.equals(currentSessionId)) {
                   if (servletRequest.getHeader("x-requested-with") != null
							&& servletRequest.getHeader("x-requested-with").equalsIgnoreCase("XMLHttpRequest")) {
						servletResponse.setContentType("application/json; charset="+ WebConstants.ENCODING);
						servletResponse.setHeader("Cache-Control", "no-cache"); // 取消浏览器缓存
						servletResponse.setHeader("responseState", "output");// 在响应头设置session状态
    					PrintWriter out = servletResponse.getWriter();
						if (RequestUtil.isMobile(servletRequest)) {
							out.print("{\"error_type\":\"error_403\"}");
						} else {
							out.print("{error_type:'error_403'}");
						}
						out.flush();
						out.close();
					} else if (servletRequest.getParameter("requestHeader") != null
							&& servletRequest.getParameter("requestHeader").equalsIgnoreCase("XMLHttpRequest")) {
						servletResponse.setContentType("application/json; charset="+ WebConstants.ENCODING);
						servletResponse.setHeader("Cache-Control", "no-cache"); // 取消浏览器缓存
						servletResponse.setHeader("responseState", "output");// 在响应头设置session状态
						PrintWriter out = servletResponse.getWriter();
						if (RequestUtil.isMobile(servletRequest)) {
							out.print("{\"error_type\":\"error_403\"}");
						} else {
							out.print("{error_type:'error_403'}");
						}
						out.flush();
						out.close();
					} else {
						if (RequestUtil.isMobile(servletRequest)) {
							servletRequest.getRequestDispatcher(
									"/error/kick.jsp").forward(servletRequest,
									servletResponse);
						} else {
							session.invalidate();
							servletRequest.getRequestDispatcher(
									"/error/kick.jsp").forward(servletRequest,
									servletResponse);
						}
					}

				} else {
					 filterChain.doFilter(servletRequest, servletResponse);
				}

			} else {
			//继续下一个过滤器或者继续请求
				filterChain.doFilter(servletRequest, servletResponse);
			}
		    }else{
		    	filterChain.doFilter(servletRequest, servletResponse);
		    }
		    
		} else {
            filterChain.doFilter(servletRequest, servletResponse);

		}
	}

	private String split(String currentId, String string) {
	      return null;
	}

	@Override
	public void init(FilterConfig arg0) throws ServletException {
	}
	//获取ip
	  public static String getIpAddr(HttpServletRequest request){
	        String ipAddress = request.getHeader("x-forwarded-for");
	        if(ipAddress == null || ipAddress.length() == 0 || "unknown".equalsIgnoreCase(ipAddress)) {
	            ipAddress = request.getRemoteAddr();
	            if(ipAddress.equals("127.0.0.1") || ipAddress.equals("0:0:0:0:0:0:0:1")){
	                //根据网卡取本机配置的IP
	                InetAddress inet=null;
	                try {
	                    inet = InetAddress.getLocalHost();
	                } catch (UnknownHostException e) {
	                    e.printStackTrace();
	                }
	                ipAddress= inet.getHostAddress();
	            }
	        }
	        return ipAddress;
	    }

}

登录等时候存储session和ip这里没有完整代码

回去账号
Object userAcc=user.get("USER_ACC");
				session.setAttribute("userAcc", userAcc);
				String ipAddress = request.getHeader("x-forwarded-for");
			        if(ipAddress == null || ipAddress.length() == 0 ) {
			            ipAddress = request.getRemoteAddr();
			            if(ipAddress.equals("127.0.0.1") || ipAddress.equals("0:0:0:0:0:0:0:1")){
			                //根据网卡取本机配置的IP
			                InetAddress inet=null;
			                try {
			                    inet = InetAddress.getLocalHost();
			                } catch (UnknownHostException e) {
			                    e.printStackTrace();
			                }
			                ipAddress= inet.getHostAddress();
			            }
			        }
			       
				Map<Object,String> userSessionMap=null;
				ServletContext application=session.getServletContext();
				 //取出key-value对判断
                userSessionMap=(Map)application.getAttribute("userSessionMap");
				 if(null==userSessionMap){
					 userSessionMap=new HashMap<Object,String>();
					 application.setAttribute("userSessionMap", userSessionMap);
				 }
				 //取出相同userAcc下sessionUserAcc判断是否登陆过
			     String sessionUserAcc=userSessionMap.get(userAcc);
				 String sessionIp=session.getId()+","+ipAddress;
				 if(sessionUserAcc==null){
					 userSessionMap.put(userAcc, sessionIp);
				 }else{
					 userSessionMap.remove(sessionUserAcc);
					 userSessionMap.put(userAcc,sessionIp);
				 }