Filter配置总结
1。如果要映射过滤应用程序中所有资源：

<filter>
<filter-name>loggerfilter</filter-name>
<filter-class>myfilter.LoggerFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>loggerfilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>

2.过滤指定的类型文件资源

<filter>
<filter-name>loggerfilter</filter-name>
<filter-class>myfilter.LoggerFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>loggerfilter</filter-name>
<url-pattern>*.html</url-pattern>
</filter-mapping>

其中<url-pattern>*.html</url-pattern>要过滤jsp那么就改
*.html为*.jsp,但是注意没有“/”斜杠

如果要同时过滤多种类型资源：

<filter>
<filter-name>loggerfilter</filter-name>
<filter-class>myfilter.LoggerFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>loggerfilter</filter-name>
<url-pattern>*.html</url-pattern>
</filter-mapping>

<filter-mapping>
<filter-name>loggerfilter</filter-name>
<url-pattern>*.jsp</url-pattern>
</filter-mapping>

3.过滤指定的目录

<filter>
<filter-name>loggerfilter</filter-name>
<filter-class>myfilter.LoggerFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>loggerfilter</filter-name>
<url-pattern>/folder_name/*</url-pattern>
</filter-mapping>

4.过滤指定的servlet

<filter>
<filter-name>loggerfilter</filter-name>
<filter-class>myfilter.LoggerFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>loggerfilter</filter-name>
<servlet-name>loggerservlet</servlet-name>
</filter-mapping>

<servlet>
<servlet-name>loggerservlet</servlet-name>
<servlet-class>myfilter.LoggerServlet</servlet-class>
</servlet>

5.过滤指定文件

<filter>
<filter-name>loggerfilter</filter-name>
<filter-class>myfilter.LoggerFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>loggerfilter</filter-name>
<url-pattern>/simplefilter.html</url-pattern>
</filter-mapping>

以上都要注意是否有斜杠“/”