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“/”?