以登陆为例子...............

 

public class LoginFilter implements Filter {

@Override

public void destroy() {

}

@Override

public void init(FilterConfig arg0) throws ServletException {

}

@Override

public void doFilter(ServletRequest arg0, ServletResponse arg1,FilterChain arg2)

throws IOException, ServletException {

HttpServletResponse response = (HttpServletResponse) arg1;

HttpServletRequest request=(HttpServletRequest)arg0;

HttpSession session = request.getSession(true);

String loginName = (String) session.getAttribute("loginName");//

String url=request.getRequestURI();

if(loginName==null || loginName.equals(""))

{

//判断获取的路径不为空且不是访问登录页面或执行登录操作时跳转

if(url!=null && !url.equals("") && ( url.indexOf("Login")<0 && url.indexOf("login")<0 ))

{

response.sendRedirect("login.jsp");

return ;

}

}

//已通过验证，用户访问继续

arg2.doFilter(arg0, arg1);

}

}

 

-----------------------------------------------------------------------------------------------------------

web.xml

 

<!-- 拦截 -->

<filter>

<filter-name>LoginFilter</filter-name>

<filter-class>onlyfun.filter.LoginFilter</filter-class>

</filter>

<!-- 配置多个映射，哪些请求执行过滤器 -->

<filter-mapping>

<filter-name>LoginFilter</filter-name>

<url-pattern>/WEB-INF/*</url-pattern>

</filter-mapping>

<filter-mapping>

<filter-name>LoginFilter</filter-name>

<url-pattern>*.jsp</url-pattern>

</filter-mapping>

 

 

到此为止，主要为自己做备忘，同时方便有需要的人。呵呵！