Servlet Filter 过滤器 对指定页面不拦截

package niit.dxs.controller;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;

public class LoginFilter implements Filter {
private String excludedPage;
private String[] excludedPages;

@Override
public void init(FilterConfig filterConfig) throws ServletException {
excludedPage = filterConfig.getInitParameter("excludedPages");
if (excludedPage != null && excludedPage.length() > 0){
excludedPages = excludedPage.split(",");
}
}

@Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
// 获取 resquest、response、session
HttpServletRequest request = (HttpServletRequest) servletRequest;
HttpServletResponse response = (HttpServletResponse) servletResponse;
HttpSession session = request.getSession();

// 定义表示变量 并验证用户请求URL 是否包含不过滤路径
boolean flag = false;
for (String page:excludedPages) {
if (request.getServletPath().equals(page)){
flag = true;
}
}

// 验证用户登录
if (flag){
filterChain.doFilter(request,response);
}{
String userName= (String) session.getAttribute("userKey");
System.out.println("userid——————————》"+userName);
if (userName != null){
filterChain.doFilter(request,response);
}else {
request.getRequestDispatcher("index.jsp").forward(request,response);
}
}
}

@Override
public void destroy() {

}
}

<!--  过滤器   -->
<filter>
<filter-name>LoginFilter</filter-name>
<filter-class>niit.dxs.controller.LoginFilter</filter-class>
<init-param>
<param-name>excludedPages</param-name>
<param-value>/index.jsp,/register.html,/RegisterServlet,/LoginServlet</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>LoginFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>