如何设置过滤器

Question

我想通过过滤器验证用户是否登录，用户登录了就能执行相应的操作，没有登录，就跳转到登录页面。因为我对过滤器不是很懂，哪个高手帮个忙，解决一下，感激了

Answer 1

这个随便Google下就大把案例吧 =_=

Answer 2

给个简短例子吧： <filter>
<filter-name>SessionValidFilter</filter-name>
<filter-class>web.filter.SessionValidFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>SessionValidFilter</filter-name>
<url-pattern>/jsp/*</url-pattern>
</filter-mapping>
<filter-mapping>
<filter-name>SessionValidFilter</filter-name>
<url-pattern>*.do</url-pattern>
</filter-mapping>
<filter-mapping>
<filter-name>SessionValidFilter</filter-name>
<url-pattern>/servlet/*</url-pattern>
</filter-mapping>
public class SessionValidFilter implements Filter {
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
if (!isUserLogin(request)) {
RequestDispatcher dispatcher = request
.getRequestDispatcher("/login.jsp");
dispatcher.forward(request, response); }
}
}

Answer 3

写个类，继承Filter。然后在web.xml里面添加拦截
<filter>
<filter-name>filter名</filter-name>
<filter-class>你的filter类路径</filter-class>
</filter>
<filter-mapping>
<filter-name>filter名</filter-name>
<url-pattern>你要拦截的路径，如：/*</url-pattern>
</filter-mapping>