防止未登录访问 可用过滤器Filter实现

package com.zh.util;

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.zh.bean.admin.Admin;

public class SessionFilter implements Filter{

@Override
public void destroy() {

}

@Override
public void doFilter(ServletRequest arg0, ServletResponse arg1,
FilterChain arg2) throws IOException, ServletException {
System.out.println("do!!");
HttpServletRequest request = (HttpServletRequest)arg0;
HttpServletResponse response = (HttpServletResponse)arg1;

String url = request.getRequestURI();
System.out.println(url);
boolean b1=!url.equals("/cpShop/admin/login.jsp");

boolean b2=url.substring(url.length()-3).equals(".do");
boolean b3=!url.substring(url.length()-13).equals("loginAdmin.do");
boolean b4=!url.substring(url.length()-4).equals(".jsp");

HttpSession session = request.getSession();
Admin admin = (Admin) session.getAttribute("admin");
System.out.println(admin+"  ");
if(b1&&b2&&b3&&b4){
if(admin == null){
System.out.println("8888888888");
response.sendRedirect("/cpShop/admin/login.jsp");
}else{
arg2.doFilter(request, response);
return;
}
}else{
arg2.doFilter(request, response);
return;
}

}

@Override
public void init(FilterConfig arg0) throws ServletException {
System.out.println("start!!");
}

}

<filter>
<description>过滤器</description>
<filter-name>adminFilter</filter-name>
<filter-class>com.zh.util.SessionFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>adminFilter</filter-name>
<url-pattern>/admin/*</url-pattern>
</filter-mapping>