在web.xml中
默认的配置是：
<init-param>
<param-name>listings</param-name>
<param-value>true</param-value>
</init-param>
把true修改为false即可。
<!-- ================== Built In Servlet Definitions ==================== -->
<!-- The default servlet for all web applications, that serves static -->
<!-- resources. It processes all requests that are not mapped to other -->
<!-- servlets with servlet mappings (defined either here or in your own -->
<!-- web.xml file. This servlet supports the following initialization -->
<!-- parameters (default values are in square brackets): -->
<!-- -->
<!-- debug Debugging detail level for messages logged -->
<!-- by this servlet. [0] -->
<!-- -->
<!-- input Input buffer size (in bytes) when reading -->
<!-- resources to be served. [2048] -->
<!-- -->
<!-- listings Should directory listings be produced if there -->
<!-- is no welcome file in this directory? [true] -->
<!-- -->