DefaultServlet (Apache Tomcat 9.0.111 API Documentation)
Description: declaration: package: org.apache.catalina.servlets, class: DefaultServlet

# Class DefaultServlet

java.lang.Object
javax.servlet.GenericServlet
javax.servlet.http.HttpServlet
org.apache.catalina.servlets.DefaultServlet

All Implemented Interfaces:
  `Serializable, Servlet, ServletConfig`

Direct Known Subclasses:
  `WebdavServlet`

public class DefaultServlet extends HttpServlet

The default resource-serving servlet for most web applications, used to serve static resources such as HTML pages and images.

This servlet is intended to be mapped to / e.g.:

      <servlet-mapping>
          <servlet-name>default</servlet-name>
          <url-pattern>/</url-pattern>
      </servlet-mapping>

It can be mapped to sub-paths, however in all cases resources are served from the web application resource root using the full path from the root of the web application context.
e.g. given a web application structure:

    /context
      /images
        tomcat2.jpg
      /static
        /images
          tomcat.jpg

... and a servlet mapping that maps only `/static/*` to the default servlet:

      <servlet-mapping>
          <servlet-name>default</servlet-name>
          <url-pattern>/static/*</url-pattern>
      </servlet-mapping>

Then a request to `/context/static/images/tomcat.jpg` will succeed while a request to `/context/images/tomcat2.jpg` will fail.

See Also:
  - Serialized Form

- ## Nested Class Summary

  Nested Classes
  Modifier and Type
  Class
  Description
  `protected static class`
  `DefaultServlet.CompressionFormat`
  `protected static class`
  `DefaultServlet.Range`
  `protected static class`
  `DefaultServlet.SortManager`
  A class encapsulating the sorting of resources.

- ## Field Summary

  Fields
  Modifier and Type
  Field
  Description
  `protected static final int`
  `BUFFER_SIZE`
  Size of file transfer buffer in bytes.
  `protected DefaultServlet.CompressionFormat[]`
  `compressionFormats`
  List of compression formats to serve and their preference order.
  `protected String`
  `contextXsltFile`
  Allow customized directory listing per context.
  `protected int`
  `debug`
  The debugging detail level for this servlet.
  `protected String`
  `fileEncoding`
  File encoding to be used when reading static files.
  `protected static final ArrayList<DefaultServlet.Range>`
  `FULL`
  Full range marker.
  `protected String`
  `globalXsltFile`
  Allow customized directory listing per instance.
  `protected int`
  `input`
  The input buffer size to use when serving resources.
  `protected boolean`
  `listings`
  Should we generate directory listings?
  `protected String`
  `localXsltFile`
  Allow customized directory listing per directory.
  `protected static final String`
  `mimeSeparation`
  MIME multipart separation string
  `protected int`
  `output`
  The output buffer size to use when serving resources.
  `protected String`
  `readmeFile`
  Allow a readme file to be included.
  `protected boolean`
  `readOnly`
  Read only flag.
  `protected WebResourceRoot`
  `resources`
  The complete set of web application resources
  `protected int`
  `sendfileSize`
  Minimum size for sendfile usage in bytes.
  `protected boolean`
  `showServerInfo`
  Flag to determine if server information is presented.
  `protected static final StringManager`
  `sm`
  The string manager for this package.
  `protected boolean`
  `sortListings`
  Flag to determine if resources should be sorted.
  `protected DefaultServlet.SortManager`
  `sortManager`
  The sorting manager for sorting files and directories.
  `protected boolean`
  `useAcceptRanges`
  Deprecated.
  This option will be removed without replacement in Tomcat 12 onwards where it will effectively be hard coded to `true`.

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `DefaultServlet()`

- ## Method Summary

  Modifier and Type
  Method
  Description
  `protected boolean`
  `checkIfHeaders(HttpServletRequest request, HttpServletResponse response, WebResource resource)`
  Check if the conditions specified in the optional If headers are satisfied.
  `protected boolean`
  `checkIfMatch(HttpServletRequest request, HttpServletResponse response, WebResource resource)`
  Check if the if-match condition is satisfied.
  `protected boolean`
  `checkIfModifiedSince(HttpServletRequest request, HttpServletResponse response, WebResource resource)`
  Check if the if-modified-since condition is satisfied.
  `protected boolean`
  `checkIfNoneMatch(HttpServletRequest request, HttpServletResponse response, WebResource resource)`
  Check if the if-none-match condition is satisfied.
  `protected boolean`
  `checkIfRange(HttpServletRequest request, HttpServletResponse response, WebResource resource)`
  Check if the if-range condition is satisfied.
  `protected boolean`
  `checkIfUnmodifiedSince(HttpServletRequest request, HttpServletResponse response, WebResource resource)`
  Check if the if-unmodified-since condition is satisfied.
  `protected boolean`
  `checkSendfile(HttpServletRequest request, HttpServletResponse response, WebResource resource, long length, DefaultServlet.Range range)`
  Check if sendfile can be used.
  `protected void`
  `copy(InputStream is, PrintWriter writer, String encoding)`
  Copy the contents of the specified input stream to the specified output stream, and ensure that both streams are closed before returning (even in the face of an exception).
  `protected void`
  `copy(InputStream is, ServletOutputStream ostream)`
  Copy the contents of the specified input stream to the specified output stream, and ensure that both streams are closed before returning (even in the face of an exception).
  `protected void`
  `copy(WebResource resource, ServletOutputStream ostream, Iterator<DefaultServlet.Range> ranges, String contentType)`
  Copy the contents of the specified input stream to the specified output stream, and ensure that both streams are closed before returning (even in the face of an exception).
  `protected void`
  `copy(WebResource resource, ServletOutputStream ostream, DefaultServlet.Range range)`
  Copy the contents of the specified input stream to the specified output stream, and ensure that both streams are closed before returning (even in the face of an exception).
  `protected IOException`
  `copyRange(InputStream istream, ServletOutputStream ostream)`
  Copy the contents of the specified input stream to the specified output stream, and ensure that both streams are closed before returning (even in the face of an exception).
  `protected IOException`
  `copyRange(InputStream istream, ServletOutputStream ostream, long start, long end)`
  Copy the contents of the specified input stream to the specified output stream, and ensure that both streams are closed before returning (even in the face of an exception).
  `protected IOException`
  `copyRange(Reader reader, PrintWriter writer)`
  Copy the contents of the specified input stream to the specified output stream, and ensure that both streams are closed before returning (even in the face of an exception).
  `void`
  `destroy()`
  Called by the servlet container to indicate to a servlet that the servlet is being taken out of service.
  `protected String`
  `determineMethodsAllowed(HttpServletRequest req)`
  Determines the methods normally allowed for the resource.
  `protected void`
  `doDelete(HttpServletRequest req, HttpServletResponse resp)`
  Called by the server (via the `service` method) to allow a servlet to handle a DELETE request.
  `protected void`
  `doGet(HttpServletRequest request, HttpServletResponse response)`
  Called by the server (via the `service` method) to allow a servlet to handle a GET request.
  `protected void`
  `doHead(HttpServletRequest request, HttpServletResponse response)`
  Receives an HTTP HEAD request from the protected `service` method and handles the request.
  `protected void`
  `doOptions(HttpServletRequest req, HttpServletResponse resp)`
  Override default implementation to ensure that TRACE is correctly handled.
  `protected void`
  `doPost(HttpServletRequest request, HttpServletResponse response)`
  Called by the server (via the `service` method) to allow a servlet to handle a POST request.
  `protected void`
  `doPut(HttpServletRequest req, HttpServletResponse resp)`
  Called by the server (via the `service` method) to allow a servlet to handle a PUT request.
  `protected File`
  `executePartialPut(HttpServletRequest req, DefaultServlet.Range range, String path)`
  Handle a partial PUT.
  `protected Source`
  `findXsltSource(WebResource directory)`
  Return a Source for the xsl template (if possible).
  `protected String`
  `generateETag(WebResource resource)`
  Provides the entity tag (the ETag header) for the given resource.
  `protected String`
  `getPathPrefix(HttpServletRequest request)`
  Determines the appropriate path to prepend resources with when generating directory listings.
  `protected String`
  `getReadme(WebResource directory, String encoding)`
  Get the readme file as a string.
  `protected String`
  `getRelativePath(HttpServletRequest request)`
  Return the relative path associated with this servlet.
  `protected String`
  `getRelativePath(HttpServletRequest request, boolean allowEmptyPath)`
  `void`
  `init()`
  A convenience method which can be overridden so that there's no need to call `super.init(config)`.
  `protected boolean`
  `isListings()`
  `protected boolean`
  `isRangeRequestsSupported()`
  Checks if range request is supported by server
  `protected boolean`
  `isReadOnly()`
  `protected DefaultServlet.Range`
  `parseContentRange(HttpServletRequest request, HttpServletResponse response)`
  Parse the content-range header.
  `protected ArrayList<DefaultServlet.Range>`
  `parseRange(HttpServletRequest request, HttpServletResponse response, WebResource resource)`
  Parse the range header.
  `protected InputStream`
  `render(String contextPath, WebResource resource, String encoding)`
  Deprecated.
  Use `render(HttpServletRequest, String, WebResource, String)` instead
  `protected InputStream`
  `render(HttpServletRequest request, String contextPath, WebResource resource, String encoding)`
  Decide which way to render.
  `protected InputStream`
  `renderHtml(String contextPath, WebResource resource, String encoding)`
  Deprecated.
  Unused.
  `protected InputStream`
  `renderHtml(HttpServletRequest request, String contextPath, WebResource resource, String encoding)`
  Return an InputStream to an HTML representation of the contents of this directory.
  `protected String`
  `renderSize(long size)`
  Render the specified file size (in bytes).
  `protected String`
  `renderTimestamp(long timestamp)`
  Render the specified file timestamp.
  `protected InputStream`
  `renderXml(String contextPath, WebResource resource, Source xsltSource, String encoding)`
  Deprecated.
  Unused.
  `protected InputStream`
  `renderXml(HttpServletRequest request, String contextPath, WebResource resource, Source xsltSource, String encoding)`
  Return an InputStream to an XML representation of the contents this directory.
  `protected String`
  `rewriteUrl(String path)`
  URL rewriter.
  `protected void`
  `sendNotAllowed(HttpServletRequest req, HttpServletResponse resp)`
  `protected void`
  `serveResource(HttpServletRequest request, HttpServletResponse response, boolean content, String inputEncoding)`
  Serve the specified resource, optionally including the data content.
  `protected void`
  `service(HttpServletRequest req, HttpServletResponse resp)`
  Receives standard HTTP requests from the public `service` method and dispatches them to the `do`Method methods defined in this class.

  ### Methods inherited from class HttpServlet

  `doTrace, getLastModified, service`

  ### Methods inherited from class GenericServlet

  `getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, getServletName, init, log, log`

  ### Methods inherited from class Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- ## Field Details

  - ### sm

    protected static final StringManager sm
    The string manager for this package.

  - ### FULL

    protected static final ArrayList<DefaultServlet.Range> FULL
    Full range marker.

  - ### mimeSeparation

    protected static final String mimeSeparation
    MIME multipart separation string
    See Also:
      - Constant Field Values

  - ### BUFFER_SIZE

    protected static final int BUFFER_SIZE
    Size of file transfer buffer in bytes.
    See Also:
      - Constant Field Values

  - ### debug

    protected int debug
    The debugging detail level for this servlet.

  - ### input

    protected int input
    The input buffer size to use when serving resources.

  - ### listings

    protected boolean listings
    Should we generate directory listings?

  - ### readOnly

    protected boolean readOnly
    Read only flag. By default, it's set to true.

  - ### compressionFormats

    protected DefaultServlet.CompressionFormat[] compressionFormats
    List of compression formats to serve and their preference order.

  - ### output

    protected int output
    The output buffer size to use when serving resources.

  - ### localXsltFile

    protected String localXsltFile
    Allow customized directory listing per directory.

  - ### contextXsltFile

    protected String contextXsltFile
    Allow customized directory listing per context.

  - ### globalXsltFile

    protected String globalXsltFile
    Allow customized directory listing per instance.

  - ### readmeFile

    protected String readmeFile
    Allow a readme file to be included.

  - ### resources

    protected transient WebResourceRoot resources
    The complete set of web application resources

  - ### fileEncoding

    protected String fileEncoding
    File encoding to be used when reading static files. If none is specified the platform default is used.

  - ### sendfileSize

    protected int sendfileSize
    Minimum size for sendfile usage in bytes.

  - ### useAcceptRanges

    @Deprecated protected boolean useAcceptRanges
    Deprecated.
    This option will be removed without replacement in Tomcat 12 onwards where it will effectively be hard coded to `true`.
    Should the Accept-Ranges: bytes header be send with static resources?

  - ### showServerInfo

    protected boolean showServerInfo
    Flag to determine if server information is presented.

  - ### sortListings

    protected boolean sortListings
    Flag to determine if resources should be sorted.

  - ### sortManager

    protected transient DefaultServlet.SortManager sortManager
    The sorting manager for sorting files and directories.

- ## Constructor Details

  - ### DefaultServlet

    public DefaultServlet()

- ## Method Details

  - ### destroy

    public void destroy()
    Description copied from class: `javax.servlet.GenericServlet`
    Called by the servlet container to indicate to a servlet that the servlet is being taken out of service. See `Servlet.destroy()`.
    Specified by:
      `destroy` in interface `Servlet`
    Overrides:
      `destroy` in class `GenericServlet`

  - ### init

    public void init() throws ServletException
    Description copied from class: `javax.servlet.GenericServlet`
    A convenience method which can be overridden so that there's no need to call `super.init(config)`.

    Instead of overriding `GenericServlet.init(ServletConfig)`, simply override this method and it will be called by `GenericServlet.init(ServletConfig config)`. The `ServletConfig` object can still be retrieved via `GenericServlet.getServletConfig()`.

    Overrides:
      `init` in class `GenericServlet`
    Throws:
      `ServletException` - if an exception occurs that interrupts the servlet's normal operation

  - ### getRelativePath

    protected String getRelativePath(HttpServletRequest request)
    Return the relative path associated with this servlet.
    Parameters:
      `request` - The servlet request we are processing
    Returns:
      the relative path

  - ### getRelativePath

    protected String getRelativePath(HttpServletRequest request, boolean allowEmptyPath)

  - ### getPathPrefix

    protected String getPathPrefix(HttpServletRequest request)
    Determines the appropriate path to prepend resources with when generating directory listings. Depending on the behaviour of `getRelativePath(HttpServletRequest)` this will change.
    Parameters:
      `request` - the request to determine the path for
    Returns:
      the prefix to apply to all resources in the listing.

  - ### isListings

    protected boolean isListings()

  - ### isReadOnly

    protected boolean isReadOnly()

  - ### service

    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException
    Description copied from class: `javax.servlet.http.HttpServlet`
    Receives standard HTTP requests from the public `service` method and dispatches them to the `do`Method methods defined in this class. This method is an HTTP-specific version of the `Servlet.service(ServletRequest, ServletResponse)` method. There's no need to override this method.
    Overrides:
      `service` in class `HttpServlet`
    Parameters:
      `req` - the `HttpServletRequest` object that contains the request the client made of the servlet
      `resp` - the `HttpServletResponse` object that contains the response the servlet returns to the client
    Throws:
      `ServletException` - if the HTTP request cannot be handled
      `IOException` - if an input or output error occurs while the servlet is handling the HTTP request
    See Also:
      - `Servlet.service(ServletRequest, ServletResponse)`

  - ### doGet

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException
    Description copied from class: `javax.servlet.http.HttpServlet`
    Called by the server (via the `service` method) to allow a servlet to handle a GET request.

    Overriding this method to support a GET request also automatically supports an HTTP HEAD request. A HEAD request is a GET request that returns no body in the response, only the request header fields.

    When overriding this method, read the request data, write the response headers, get the response's Writer or output stream object, and finally, write the response data. It's best to include content type and encoding. When using a `PrintWriter` object to return the response, set the content type before accessing the `PrintWriter` object.

    The servlet container must write the headers before committing the response, because in HTTP the headers must be sent before the response body.

    Where possible, set the Content-Length header (with the `ServletResponse.setContentLength(int)` method), to allow the servlet container to use a persistent connection to return its response to the client, improving performance. The content length is automatically set if the entire response fits inside the response buffer.

    When using HTTP 1.1 chunked encoding (which means that the response has a Transfer-Encoding header), do not set the Content-Length header.

    The GET method should be safe, that is, without any side effects for which users are held responsible. For example, most form queries have no side effects. If a client request is intended to change stored data, the request should use some other HTTP method.

    The GET method should also be idempotent, meaning that it can be safely repeated. Sometimes making a method safe also makes it idempotent. For example, repeating queries is both safe and idempotent, but buying a product online or modifying data is neither safe nor idempotent.

    If the request is incorrectly formatted, `doGet` returns an HTTP "Bad Request" message.

    Overrides:
      `doGet` in class `HttpServlet`
    Parameters:
      `request` - an `HttpServletRequest` object that contains the request the client has made of the servlet
      `response` - an `HttpServletResponse` object that contains the response the servlet sends to the client
    Throws:
      `IOException` - if an input or output error is detected when the servlet handles the GET request
      `ServletException` - if the request for the GET could not be handled
    See Also:
      - `ServletResponse.setContentType(String)`

  - ### doHead

    protected void doHead(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException
    Description copied from class: `javax.servlet.http.HttpServlet`

    Receives an HTTP HEAD request from the protected `service` method and handles the request. The client sends a HEAD request when it wants to see only the headers of a response, such as Content-Type or Content-Length. The HTTP HEAD method counts the output bytes in the response to set the Content-Length header accurately.

    If you override this method, you can avoid computing the response body and just set the response headers directly to improve performance. Make sure that the `doHead` method you write is both safe and idempotent (that is, protects itself from being called multiple times for one HTTP HEAD request).

    If the HTTP HEAD request is incorrectly formatted, `doHead` returns an HTTP "Bad Request" message.

    Overrides:
      `doHead` in class `HttpServlet`
    Parameters:
      `request` - the request object that is passed to the servlet
      `response` - the response object that the servlet uses to return the headers to the client
    Throws:
      `IOException` - if an input or output error occurs
      `ServletException` - if the request for the HEAD could not be handled

  - ### doOptions

    protected void doOptions(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException
    Override default implementation to ensure that TRACE is correctly handled.
    Overrides:
      `doOptions` in class `HttpServlet`
    Parameters:
      `req` - the `HttpServletRequest` object that contains the request the client made of the servlet
      `resp` - the `HttpServletResponse` object that contains the response the servlet returns to the client
    Throws:
      `IOException` - if an input or output error occurs while the servlet is handling the OPTIONS request
      `ServletException` - if the request for the OPTIONS cannot be handled

  - ### determineMethodsAllowed

    protected String determineMethodsAllowed(HttpServletRequest req)
    Determines the methods normally allowed for the resource.
    Parameters:
      `req` - The Servlet request
    Returns:
      The allowed HTTP methods

  - ### sendNotAllowed

    protected void sendNotAllowed(HttpServletRequest req, HttpServletResponse resp) throws IOException
    Throws:
      `IOException`

  - ### doPost

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException
    Description copied from class: `javax.servlet.http.HttpServlet`
    Called by the server (via the `service` method) to allow a servlet to handle a POST request. The HTTP POST method allows the client to send data of unlimited length to the Web server a single time and is useful when posting information such as credit card numbers.

    When overriding this method, read the request data, write the response headers, get the response's Writer or output stream object, and finally, write the response data. It's best to include content type and encoding. When using a `PrintWriter` object to return the response, set the content type before accessing the `PrintWriter` object.

    The servlet container must write the headers before committing the response, because in HTTP the headers must be sent before the response body.

    Where possible, set the Content-Length header (with the `ServletResponse.setContentLength(int)` method), to allow the servlet container to use a persistent connection to return its response to the client, improving performance. The content length is automatically set if the entire response fits inside the response buffer.

    When using HTTP 1.1 chunked encoding (which means that the response has a Transfer-Encoding header), do not set the Content-Length header.

    This method does not need to be either safe or idempotent. Operations requested through POST can have side effects for which the user can be held accountable, for example, updating stored data or buying items online.

    If the HTTP POST request is incorrectly formatted, `doPost` returns an HTTP "Bad Request" message.

    Overrides:
      `doPost` in class `HttpServlet`
    Parameters:
      `request` - an `HttpServletRequest` object that contains the request the client has made of the servlet
      `response` - an `HttpServletResponse` object that contains the response the servlet sends to the client
    Throws:
      `IOException` - if an input or output error is detected when the servlet handles the request
      `ServletException` - if the request for the POST could not be handled
    See Also:
      - `ServletOutputStream`
      - `ServletResponse.setContentType(String)`

  - ### doPut

    protected void doPut(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException
    Description copied from class: `javax.servlet.http.HttpServlet`
    Called by the server (via the `service` method) to allow a servlet to handle a PUT request. The PUT operation allows a client to place a file on the server and is similar to sending a file by FTP.

    When overriding this method, leave intact any content headers sent with the request (including Content-Length, Content-Type, Content-Transfer-Encoding, Content-Encoding, Content-Base, Content-Language, Content-Location, Content-MD5, and Content-Range). If your method cannot handle a content header, it must issue an error message (HTTP 501 - Not Implemented) and discard the request. For more information on HTTP 1.1, see RFC 2616 .

    This method does not need to be either safe or idempotent. Operations that `doPut` performs can have side effects for which the user can be held accountable. When using this method, it may be useful to save a copy of the affected URL in temporary storage.

    If the HTTP PUT request is incorrectly formatted, `doPut` returns an HTTP "Bad Request" message.

    Overrides:
      `doPut` in class `HttpServlet`
    Parameters:
      `req` - the `HttpServletRequest` object that contains the request the client made of the servlet
      `resp` - the `HttpServletResponse` object that contains the response the servlet returns to the client
    Throws:
      `ServletException` - if the request for the PUT cannot be handled
      `IOException` - if an input or output error occurs while the servlet is handling the PUT request

  - ### executePartialPut

    protected File executePartialPut(HttpServletRequest req, DefaultServlet.Range range, String path) throws IOException
    Handle a partial PUT. New content specified in request is appended to existing content in oldRevisionContent (if present). This code does not support simultaneous partial updates to the same resource.
    Parameters:
      `req` - The Servlet request
      `range` - The range that will be written
      `path` - The path
    Returns:
      the associated file object
    Throws:
      `IOException` - an IO error occurred

  - ### doDelete

    protected void doDelete(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException
    Description copied from class: `javax.servlet.http.HttpServlet`
    Called by the server (via the `service` method) to allow a servlet to handle a DELETE request. The DELETE operation allows a client to remove a document or Web page from the server.

    This method does not need to be either safe or idempotent. Operations requested through DELETE can have side effects for which users can be held accountable. When using this method, it may be useful to save a copy of the affected URL in temporary storage.

    If the HTTP DELETE request is incorrectly formatted, `doDelete` returns an HTTP "Bad Request" message.

    Overrides:
      `doDelete` in class `HttpServlet`
    Parameters:
      `req` - the `HttpServletRequest` object that contains the request the client made of the servlet
      `resp` - the `HttpServletResponse` object that contains the response the servlet returns to the client
    Throws:
      `ServletException` - if the request for the DELETE cannot be handled
      `IOException` - if an input or output error occurs while the servlet is handling the DELETE request

  - ### checkIfHeaders

    protected boolean checkIfHeaders(HttpServletRequest request, HttpServletResponse response, WebResource resource) throws IOException
    Check if the conditions specified in the optional If headers are satisfied.
    Parameters:
      `request` - The servlet request we are processing
      `response` - The servlet response we are creating
      `resource` - The resource
    Returns:
      `true` if the resource meets all the specified conditions, and `false` if any of the conditions is not satisfied, in which case request processing is stopped
    Throws:
      `IOException` - an IO error occurred

  - ### rewriteUrl

    protected String rewriteUrl(String path)
    URL rewriter.
    Parameters:
      `path` - Path which has to be rewritten
    Returns:
      the rewritten path

  - ### serveResource

    protected void serveResource(HttpServletRequest request, HttpServletResponse response, boolean content, String inputEncoding) throws IOException, ServletException
    Serve the specified resource, optionally including the data content.
    Parameters:
      `request` - The servlet request we are processing
      `response` - The servlet response we are creating
      `content` - Should the content be included?
      `inputEncoding` - The encoding to use if it is necessary to access the source as characters rather than as bytes
    Throws:
      `IOException` - if an input/output error occurs
      `ServletException` - if a servlet-specified error occurs

  - ### parseContentRange

    protected DefaultServlet.Range parseContentRange(HttpServletRequest request, HttpServletResponse response) throws IOException
    Parse the content-range header.
    Parameters:
      `request` - The servlet request we are processing
      `response` - The servlet response we are creating
    Returns:
      the partial content-range, `null` if the content-range header was invalid or `#IGNORE` if there is no header to process
    Throws:
      `IOException` - an IO error occurred

  - ### parseRange

    protected ArrayList<DefaultServlet.Range> parseRange(HttpServletRequest request, HttpServletResponse response, WebResource resource) throws IOException
    Parse the range header.

    The caller is required to have confirmed that the requested resource exists and is a file before calling this method.

    Parameters:
      `request` - The servlet request we are processing
      `response` - The servlet response we are creating
      `resource` - The resource
    Returns:
      a list of ranges, `null` if the range header was invalid or `#FULL` if the Range header should be ignored.
    Throws:
      `IOException` - an IO error occurred

  - ### render

    @Deprecated protected InputStream render(String contextPath, WebResource resource, String encoding) throws IOException, ServletException
    Deprecated.
    Use `render(HttpServletRequest, String, WebResource, String)` instead
    Decide which way to render. HTML or XML.
    Parameters:
      `contextPath` - The path
      `resource` - The resource
      `encoding` - The encoding to use to process the readme (if any)
    Returns:
      the input stream with the rendered output
    Throws:
      `IOException` - an IO error occurred
      `ServletException` - rendering error

  - ### render

    protected InputStream render(HttpServletRequest request, String contextPath, WebResource resource, String encoding) throws IOException, ServletException
    Decide which way to render. HTML or XML.
    Parameters:
      `request` - The HttpServletRequest being served
      `contextPath` - The path
      `resource` - The resource
      `encoding` - The encoding to use to process the readme (if any)
    Returns:
      the input stream with the rendered output
    Throws:
      `IOException` - an IO error occurred
      `ServletException` - rendering error

  - ### renderXml

    @Deprecated protected InputStream renderXml(String contextPath, WebResource resource, Source xsltSource, String encoding) throws ServletException, IOException
    Deprecated.
    Unused. Will be removed in Tomcat 10
    Return an InputStream to an XML representation of the contents this directory.
    Parameters:
      `contextPath` - Context path to which our internal paths are relative
      `resource` - The associated resource
      `xsltSource` - The XSL stylesheet
      `encoding` - The encoding to use to process the readme (if any)
    Returns:
      the XML data
    Throws:
      `IOException` - an IO error occurred
      `ServletException` - rendering error

  - ### renderXml

    protected InputStream renderXml(HttpServletRequest request, String contextPath, WebResource resource, Source xsltSource, String encoding) throws IOException, ServletException
    Return an InputStream to an XML representation of the contents this directory.
    Parameters:
      `request` - The HttpServletRequest being served
      `contextPath` - Context path to which our internal paths are relative
      `resource` - The associated resource
      `xsltSource` - The XSL stylesheet
      `encoding` - The encoding to use to process the readme (if any)
    Returns:
      the XML data
    Throws:
      `IOException` - an IO error occurred
      `ServletException` - rendering error

  - ### renderHtml

    @Deprecated protected InputStream renderHtml(String contextPath, WebResource resource, String encoding) throws IOException
    Deprecated.
    Unused. Will be removed in Tomcat 10
    Return an InputStream to an HTML representation of the contents of this directory.
    Parameters:
      `contextPath` - Context path to which our internal paths are relative
      `resource` - The associated resource
      `encoding` - The encoding to use to process the readme (if any)
    Returns:
      the HTML data
    Throws:
      `IOException` - an IO error occurred

  - ### renderHtml

    protected InputStream renderHtml(HttpServletRequest request, String contextPath, WebResource resource, String encoding) throws IOException
    Return an InputStream to an HTML representation of the contents of this directory.
    Parameters:
      `request` - The HttpServletRequest being served
      `contextPath` - Context path to which our internal paths are relative
      `resource` - The associated resource
      `encoding` - The encoding to use to process the readme (if any)
    Returns:
      the HTML data
    Throws:
      `IOException` - an IO error occurred

  - ### renderSize

    protected String renderSize(long size)
    Render the specified file size (in bytes).
    Parameters:
      `size` - File size (in bytes)
    Returns:
      the formatted size

  - ### renderTimestamp

    protected String renderTimestamp(long timestamp)
    Render the specified file timestamp.
    Parameters:
      `timestamp` - File timestamp
    Returns:
      the formatted timestamp

  - ### getReadme

    protected String getReadme(WebResource directory, String encoding)
    Get the readme file as a string.
    Parameters:
      `directory` - The directory to search
      `encoding` - The readme encoding
    Returns:
      the readme for the specified directory

  - ### findXsltSource

    protected Source findXsltSource(WebResource directory) throws IOException
    Return a Source for the xsl template (if possible).
    Parameters:
      `directory` - The directory to search
    Returns:
      the source for the specified directory
    Throws:
      `IOException` - an IO error occurred

  - ### checkSendfile

    protected boolean checkSendfile(HttpServletRequest request, HttpServletResponse response, WebResource resource, long length, DefaultServlet.Range range)
    Check if sendfile can be used.
    Parameters:
      `request` - The Servlet request
      `response` - The Servlet response
      `resource` - The resource
      `length` - The length which will be written (will be used only if range is null)
      `range` - The range that will be written
    Returns:
      `true` if sendfile should be used (writing is then delegated to the endpoint)

  - ### checkIfMatch

    protected boolean checkIfMatch(HttpServletRequest request, HttpServletResponse response, WebResource resource) throws IOException
    Check if the if-match condition is satisfied.
    Parameters:
      `request` - The servlet request we are processing
      `response` - The servlet response we are creating
      `resource` - The resource
    Returns:
      `true` if the resource meets the specified condition, and `false` if the condition is not satisfied, in which case request processing is stopped
    Throws:
      `IOException` - an IO error occurred

  - ### checkIfModifiedSince

    protected boolean checkIfModifiedSince(HttpServletRequest request, HttpServletResponse response, WebResource resource)
    Check if the if-modified-since condition is satisfied.
    Parameters:
      `request` - The servlet request we are processing
      `response` - The servlet response we are creating
      `resource` - The resource
    Returns:
      `true` if the resource meets the specified condition, and `false` if the condition is not satisfied, in which case request processing is stopped

  - ### checkIfNoneMatch

    protected boolean checkIfNoneMatch(HttpServletRequest request, HttpServletResponse response, WebResource resource) throws IOException
    Check if the if-none-match condition is satisfied.
    Parameters:
      `request` - The servlet request we are processing
      `response` - The servlet response we are creating
      `resource` - The resource
    Returns:
      `true` if the resource meets the specified condition, and `false` if the condition is not satisfied, in which case request processing is stopped
    Throws:
      `IOException` - an IO error occurred

  - ### checkIfUnmodifiedSince

    protected boolean checkIfUnmodifiedSince(HttpServletRequest request, HttpServletResponse response, WebResource resource) throws IOException
    Check if the if-unmodified-since condition is satisfied.
    Parameters:
      `request` - The servlet request we are processing
      `response` - The servlet response we are creating
      `resource` - The resource
    Returns:
      `true` if the resource meets the specified condition, and `false` if the condition is not satisfied, in which case request processing is stopped
    Throws:
      `IOException` - an IO error occurred

  - ### checkIfRange

    protected boolean checkIfRange(HttpServletRequest request, HttpServletResponse response, WebResource resource) throws IOException
    Check if the if-range condition is satisfied. The calling method is required to ensure a Range header is present and that Range requests are supported for the current resource.
    Parameters:
      `request` - The servlet request we are processing
      `response` - The servlet response we are creating
      `resource` - The resource
    Returns:
      `true` if the resource meets the specified condition, and `false` if the condition is not satisfied, resulting in transfer of the new selected representation instead of a 412 (Precondition Failed) response. If the if-range condition is not valid then an appropriate status code will be set, the response will be committed and this method will return `false`
    Throws:
      `IOException` - an IO error occurred

  - ### isRangeRequestsSupported

    protected boolean isRangeRequestsSupported()
    Checks if range request is supported by server
    Returns:
      `true` server supports range requests feature.

  - ### generateETag

    protected String generateETag(WebResource resource)
    Provides the entity tag (the ETag header) for the given resource. Intended to be over-ridden by custom DefaultServlet implementations that wish to use an alternative format for the entity tag.
    Parameters:
      `resource` - The resource for which an entity tag is required.
    Returns:
      The result of calling `WebResource.getETag()` on the given resource

  - ### copy

    protected void copy(InputStream is, ServletOutputStream ostream) throws IOException
    Copy the contents of the specified input stream to the specified output stream, and ensure that both streams are closed before returning (even in the face of an exception).
    Parameters:
      `is` - The input stream to read the source resource from
      `ostream` - The output stream to write to
    Throws:
      `IOException` - if an input/output error occurs

  - ### copy

    protected void copy(InputStream is, PrintWriter writer, String encoding) throws IOException
    Copy the contents of the specified input stream to the specified output stream, and ensure that both streams are closed before returning (even in the face of an exception).
    Parameters:
      `is` - The input stream to read the source resource from
      `writer` - The writer to write to
      `encoding` - The encoding to use when reading the source input stream
    Throws:
      `IOException` - if an input/output error occurs

  - ### copy

    protected void copy(WebResource resource, ServletOutputStream ostream, DefaultServlet.Range range) throws IOException
    Copy the contents of the specified input stream to the specified output stream, and ensure that both streams are closed before returning (even in the face of an exception).
    Parameters:
      `resource` - The source resource
      `ostream` - The output stream to write to
      `range` - Range the client wanted to retrieve
    Throws:
      `IOException` - if an input/output error occurs

  - ### copy

    protected void copy(WebResource resource, ServletOutputStream ostream, Iterator<DefaultServlet.Range> ranges, String contentType) throws IOException
    Copy the contents of the specified input stream to the specified output stream, and ensure that both streams are closed before returning (even in the face of an exception).
    Parameters:
      `resource` - The source resource
      `ostream` - The output stream to write to
      `ranges` - Enumeration of the ranges the client wanted to retrieve
      `contentType` - Content type of the resource
    Throws:
      `IOException` - if an input/output error occurs

  - ### copyRange

    protected IOException copyRange(InputStream istream, ServletOutputStream ostream)
    Copy the contents of the specified input stream to the specified output stream, and ensure that both streams are closed before returning (even in the face of an exception).
    Parameters:
      `istream` - The input stream to read from
      `ostream` - The output stream to write to
    Returns:
      Exception which occurred during processing

  - ### copyRange

    protected IOException copyRange(Reader reader, PrintWriter writer)
    Copy the contents of the specified input stream to the specified output stream, and ensure that both streams are closed before returning (even in the face of an exception).
    Parameters:
      `reader` - The reader to read from
      `writer` - The writer to write to
    Returns:
      Exception which occurred during processing

  - ### copyRange

    protected IOException copyRange(InputStream istream, ServletOutputStream ostream, long start, long end)
    Copy the contents of the specified input stream to the specified output stream, and ensure that both streams are closed before returning (even in the face of an exception).
    Parameters:
      `istream` - The input stream to read from
      `ostream` - The output stream to write to
      `start` - Start of the range which will be copied
      `end` - End of the range which will be copied
    Returns:
      Exception which occurred during processing