Apache Tomcat 7 (7.0.100) - Default Servlet Reference
Author: Tim Funk

| # Apache Tomcat 7 Version 7.0.100, Feb 11 2020 |

Links Docs Home FAQ User Comments User Guide 1) Introduction 2) Setup 3) First webapp 4) Deployer 5) Manager 6) Host Manager 7) Realms and AAA 8) Security Manager 9) JNDI Resources 10) JDBC DataSources 11) Classloading 12) JSPs 13) SSL/TLS 14) SSI 15) CGI 16) Proxy Support 17) MBeans Descriptors 18) Default Servlet 19) Clustering 20) Load Balancer 21) Connectors 22) Monitoring and Management 23) Logging 24) APR/Native 25) Virtual Hosting 26) Advanced IO 27) Additional Components 28) Mavenized 29) Security Considerations 30) Windows Service 31) Windows Authentication 32) Tomcat's JDBC Pool 33) WebSocket Reference Release Notes Configuration Tomcat Javadocs Servlet Javadocs JSP 2.2 Javadocs EL 2.2 Javadocs WebSocket 1.1 Javadocs Common Annotations 1.1 Javadocs JK 1.2 Documentation Apache Tomcat Development Building Changelog Status Developers Architecture Functional Specs. Tribes | # Default Servlet Reference
Table of Contents
What is the DefaultServlet Where is it declared? What can I change? How do I customize directory listings? How do I secure directory listings?
What is the DefaultServlet
The default servlet is the servlet which serves static resources as well as serves the directory listings (if directory listings are enabled).
Where is it declared?
> It is declared globally in $CATALINA_BASE/conf/web.xml. By default here is it's declaration:
>         <servlet>
>             <servlet-name>default</servlet-name>
>             <servlet-class>
>               org.apache.catalina.servlets.DefaultServlet
>             </servlet-class>
>             <init-param>
>                 <param-name>debug</param-name>
>                 <param-value>0</param-value>
>             </init-param>
>             <init-param>
>                 <param-name>listings</param-name>
>                 <param-value>false</param-value>
>             </init-param>
>             <load-on-startup>1</load-on-startup>
>         </servlet>

>     ...

>         <servlet-mapping>
>             <servlet-name>default</servlet-name>
>             <url-pattern>/</url-pattern>
>         </servlet-mapping>
So by default, the default servlet is loaded at webapp startup and directory listings are disabled and debugging is turned off.
What can I change?
> The DefaultServlet allows the following initParamters:
> Property | Description
> --- | ---
> `debug` | Debugging level. It is not very useful unless you are a tomcat developer. As of this writing, useful values are 0, 1, 11, 1000. [0]
> `listings` | If no welcome file is present, can a directory listing be shown? value may be true or false [false] Welcome files are part of the servlet api. WARNING: Listings of directories containing many entries are expensive. Multiple requests for large directory listings can consume significant proportions of server resources.
> `readmeFile` | If a directory listing is presented, a readme file may also be presented with the listing. This file is inserted as is so it may contain HTML.
> `globalXsltFile` | If you wish to customize your directory listing, you can use an XSL transformation. This value is a relative file name (to either $CATALINA_BASE/conf/ or $CATALINA_HOME/conf/) which will be used for all directory listings. This can be overridden per context and/or per directory. See contextXsltFile and localXsltFile below. The format of the xml is shown below.
> `contextXsltFile` | You may also customize your directory listing by context by configuring `contextXsltFile`. This must be a context relative path (e.g.: `/path/to/context.xslt`) to a file with a `.xsl` or `.xslt` extension. This overrides `globalXsltFile`. If this value is present but a file does not exist, then `globalXsltFile` will be used. If `globalXsltFile` does not exist, then the default directory listing will be shown.
> `localXsltFile` | You may also customize your directory listing by directory by configuring `localXsltFile`. This must be a file in the directory where the listing will take place to with a `.xsl` or `.xslt` extension. This overrides `globalXsltFile` and `contextXsltFile`. If this value is present but a file does not exist, then `contextXsltFile` will be used. If `contextXsltFile` does not exist, then `globalXsltFile` will be used. If `globalXsltFile` does not exist, then the default directory listing will be shown.
> `input` | Input buffer size (in bytes) when reading resources to be served. [2048]
> `output` | Output buffer size (in bytes) when writing resources to be served. [2048]
> `readonly` | Is this context "read only", so HTTP commands like PUT and DELETE are rejected? [true]
> `fileEncoding` | File encoding to be used when reading static resources. [platform default]
> `sendfileSize` | If the connector used supports sendfile, this represents the minimal file size in KB for which sendfile will be used. Use a negative value to always disable sendfile. [48]
> `useAcceptRanges` | If true, the Accept-Ranges header will be set when appropriate for the response. [true]
> `showServerInfo` | Should server information be presented in the response sent to clients when directory listing is enabled. [true]
How do I customize directory listings?
> You can override DefaultServlet with you own implementation and use that in your web.xml declaration. If you can understand what was just said, we will assume you can read the code to DefaultServlet servlet and make the appropriate adjustments. (If not, then that method isn't for you) You can use either `localXsltFile` or `globalXsltFile` and DefaultServlet will create an xml document and run it through an xsl transformation based on the values provided in `localXsltFile` and `globalXsltFile`. `localXsltFile` is first checked, followed by `globalXsltFile`, then default behaviors takes place. Format:
>         <listing>
>          <entries>
>           <entry type='file|dir' urlPath='aPath' size='###' date='gmt date'>
>             fileName1
>           </entry>
>           <entry type='file|dir' urlPath='aPath' size='###' date='gmt date'>
>             fileName2
>           </entry>
>           ...
>          </entries>
>          <readme></readme>
>         </listing>
> size will be missing if `type='dir'` Readme is a CDATA entry The following is a sample xsl file which mimics the default tomcat behavior:
>     <?xml version="1.0" encoding="UTF-8"?>

>     <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
>       version="3.0">

>       <xsl:output method="html" html-version="5.0"
>         encoding="UTF-8" indent="no"
>         doctype-system="about:legacy-compat"/>

>       <xsl:template match="listing">
>        <html>
>         <head>
>           <title>
>             Sample Directory Listing For
>             <xsl:value-of select="@directory"/>
>           </title>
>           <style>
>             h1 {color : white;background-color : #0086b2;}
>             h3 {color : white;background-color : #0086b2;}
>             body {font-family : sans-serif,Arial,Tahoma;
>                  color : black;background-color : white;}
>             b {color : white;background-color : #0086b2;}
>             a {color : black;} HR{color : #0086b2;}
>             table td { padding: 5px; }
>           </style>
>         </head>
>         <body>
>           <h1>Sample Directory Listing For
>                 <xsl:value-of select="@directory"/>
>           </h1>
>           <hr style="height: 1px;" />
>           <table style="width: 100%;">
>             <tr>
>               <th style="text-align: left;">Filename</th>
>               <th style="text-align: center;">Size</th>
>               <th style="text-align: right;">Last Modified</th>
>             </tr>
>             <xsl:apply-templates select="entries"/>
>             </table>
>           <xsl:apply-templates select="readme"/>
>           <hr style="height: 1px;" />
>           <h3>Apache Tomcat/7.0</h3>
>         </body>
>        </html>
>       </xsl:template>

>       <xsl:template match="entries">
>         <xsl:apply-templates select="entry"/>
>       </xsl:template>

>       <xsl:template match="readme">
>         <hr style="height: 1px;" />
>         <pre><xsl:apply-templates/></pre>
>       </xsl:template>

>       <xsl:template match="entry">
>         <tr>
>           <td style="text-align: left;">
>             <xsl:variable name="urlPath" select="@urlPath"/>
>             <a href="{$urlPath}">
>               <pre><xsl:apply-templates/></pre>
>             </a>
>           </td>
>           <td style="text-align: right;">
>             <pre><xsl:value-of select="@size"/></pre>
>           </td>
>           <td style="text-align: right;">
>             <pre><xsl:value-of select="@date"/></pre>
>           </td>
>         </tr>
>       </xsl:template>

>     </xsl:stylesheet>
How do I secure directory listings?
Use web.xml in each individual webapp. See the security section of the Servlet specification.
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