判断用户登录的filter写法

package com.neuedu.lvcity.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.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


/**
 * Servlet Filter implementation class LoginFilter
 */
//@WebFilter("/LoginFilter")
public class LoginFilter implements Filter {


    /**
     * Default constructor. 
     */
    public LoginFilter() {
        // TODO Auto-generated constructor stub
    }


/**
* @see Filter#destroy()
*/
public void destroy() {
// TODO Auto-generated method stub
}


/**
* @see Filter#doFilter(ServletRequest, ServletResponse, FilterChain)
*/
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
// TODO Auto-generated method stub
// place your code here
HttpServletRequest request2=(HttpServletRequest)request;
HttpServletResponse response2=(HttpServletResponse)response;
if(request2.getSession().getAttribute("user")==null
&&request2.getRequestURI().indexOf("login.jsp")<0
){
response2.sendRedirect(request2.getContextPath()+"/login.jsp");
}else{
chain.doFilter(request, response);
}
// pass the request along the filter chain

}


/**
* @see Filter#init(FilterConfig)
*/
public void init(FilterConfig fConfig) throws ServletException {
// TODO Auto-generated method stub
}

}

filter配置

<filter>
  <filter-name>LoginFilter</filter-name>
  <filter-class>com.neuedu.lvcity.filter.LoginFilter</filter-class>
  </filter>
  <filter-mapping>
  <filter-name>LoginFilter</filter-name>
  <url-pattern>/Admin/*</url-pattern>

  </filter-mapping>

filter编码过滤

public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
// TODO Auto-generated method stub
// place your code here
request.setCharacterEncoding("utf-8");
response.setContentType("utf-8");
// pass the request along the filter chain
chain.doFilter(request, response);
}