java Filter過濾器

web.xml的配置

<init-para>裏存放：過濾器初始化時要調用的值

<diapatcher>裏存放：請求方式

<url-pattern>過濾條件

 sessionKey = filterConfig.getInitParameter("checkSessionKey"); 

<filter>
    <display-name>UserFilter</display-name>
    <filter-name>UserFilter</filter-name>
    <filter-class>com.cn.servlet.UserFilter</filter-class>
    <init-param>
    	<param-name>checkSessionKey</param-name>
    	<param-value>ss</param-value>
    </init-param>
  </filter>
  <filter-mapping>
    <filter-name>UserFilter</filter-name>
    <url-pattern>/*</url-pattern>
    <dispatcher>REQUEST</dispatcher>
  </filter-mapping>