Filter配置
?在Java web开发中常会使用到功能强大的过滤器，他毕竟能给我们带来很大的方便，但是针对过滤的资源我们需要详细的了解他们在web.xml中的配置信息。这个根据几种常用的不同情况进行了总结：?
1.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>?
以上都要特别注意是否有斜杠“/”?
