com.aoindustries.servlet.http

Class LastModifiedServlet

java.lang.Object

javax.servlet.GenericServlet

javax.servlet.http.HttpServlet

com.aoindustries.servlet.http.LastModifiedServlet

All Implemented Interfaces:

Serializable, Servlet, ServletConfig

public class LastModifiedServlet
extends HttpServlet

Sets the modified time to that of the file itself and all dependencies. Currently only *.css supported.

When mapped to handle *.css files, parses the underlying file from the file system and automatically adds lastModified=#### URL parameters. This allows the replacement of files to be immediately visible to browsers while still efficiently caching when nothing changed.

The current CSS parser is extremely simple and may not catch all URLs. Specifically, it only looks for URLs on a line-by-line basis and does not support blackslash (\) escapes.

All files must be in the UTF-8 encoding.

See Also:

This requires the cache be active, Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	LastModifiedServlet.AddLastModifiedWhen

Field Summary

Fields

Modifier and Type	Field and Description
static String	LAST_MODIFIED_HEADER_NAME The header that may be used to disable automatic lastModified parameters.
static String	LAST_MODIFIED_PARAMETER_NAME The name of the last modified parameter that is optionally added.

Constructor Summary

Constructors

Constructor and Description
LastModifiedServlet()

Method Summary

Modifier and Type	Method and Description
static String	addLastModified(ServletContext servletContext, HttpServletRequest request, String servletPath, String url, LastModifiedServlet.AddLastModifiedWhen when) Adds a last modified time (to the nearest second) to a URL if the resource is directly available as a local resource.
protected void	doGet(HttpServletRequest request, HttpServletResponse response)
static String	encodeLastModified(long lastModified) Encodes a last modified value.
protected long	getLastModified(HttpServletRequest request)
static long	getLastModified(ServletContext servletContext, HttpServletRequest request, String path) Automatically determines extension from path.
static long	getLastModified(ServletContext servletContext, HttpServletRequest request, String path, String extension) Gets a last modified time given a context-relative path starting with a slash (/).

Methods inherited from class javax.servlet.http.HttpServlet

doDelete, doHead, doOptions, doPost, doPut, doTrace, service, service

Methods inherited from class javax.servlet.GenericServlet

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

Methods inherited from class java.lang.Object

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

Field Detail

LAST_MODIFIED_PARAMETER_NAME

public static final String LAST_MODIFIED_PARAMETER_NAME

The name of the last modified parameter that is optionally added. The value is URL-safe and does not need to be passed through URLEncoder.

See Also:

Constant Field Values

LAST_MODIFIED_HEADER_NAME

public static final String LAST_MODIFIED_HEADER_NAME

The header that may be used to disable automatic lastModified parameters.

See Also:

Constant Field Values

Constructor Detail

LastModifiedServlet

public LastModifiedServlet()

Method Detail

encodeLastModified

public static String encodeLastModified(long lastModified)

Encodes a last modified value. The value is URL-safe and does not need to be passed through URLEncoder.

getLastModified

public static long getLastModified(ServletContext servletContext,
                                   HttpServletRequest request,
                                   String path,
                                   String extension)

Gets a last modified time given a context-relative path starting with a slash (/).

Any file ending in ".css" (case-insensitive) will be parsed and will have a modified time that is equal to the greatest of itself or any referenced URL.

Returns:

the modified time or 0 when unknown.

getLastModified

public static long getLastModified(ServletContext servletContext,
                                   HttpServletRequest request,
                                   String path)

Automatically determines extension from path.

See Also:

#getLastModified(javax.servlet.ServletContext, java.lang.String, java.lang.String)

addLastModified

public static String addLastModified(ServletContext servletContext,
                                     HttpServletRequest request,
                                     String servletPath,
                                     String url,
                                     LastModifiedServlet.AddLastModifiedWhen when)
                              throws MalformedURLException

Adds a last modified time (to the nearest second) to a URL if the resource is directly available as a local resource. Only applies to relative URLs (./, ../) or URLs that begin with a slash (/).

This implementation assume anchors (#) are always after the last question mark (?).

Throws:

MalformedURLException

getLastModified

protected long getLastModified(HttpServletRequest request)

Overrides:

getLastModified in class HttpServlet

doGet

protected void doGet(HttpServletRequest request,
                     HttpServletResponse response)
              throws ServletException,
                     IOException

Overrides:

doGet in class HttpServlet

Throws:

ServletException

IOException