1.继承servlet的Filter,在web.xml中配置
<filter>
<filter-name>FirstFilter</filter-name>
<filter-class>com.weisen.ebuy.filter.FirstFilter</filter-class>
</filter>
<filter>
<filter-name>SecFilter</filter-name>
<filter-class>com.weisen.ebuy.filter.SecFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>FirstFilter</filter-name>
<url-pattern>/index.jsp</url-pattern>
</filter-mapping>
<filter-mapping>
<filter-name>SecFilter</filter-name>
<url-pattern>/index.jsp</url-pattern>
</filter-mapping>
2.重定向:resp.sendRedirect();地址栏变化
转发:req.getRequestDisPatcher("index.jsp").forward(req,resp);地址栏无变化