org.eclipse.jetty.servlets

Class AsyncGzipFilter

java.lang.Object

org.eclipse.jetty.servlets.UserAgentFilter

org.eclipse.jetty.servlets.AsyncGzipFilter

All Implemented Interfaces:

Filter, GzipFactory

public class AsyncGzipFilter
extends UserAgentFilter
implements GzipFactory

Async GZIP Filter This filter is a gzip filter using jetty internal mechanism to apply gzip compression to output that is compatible with async IO and does not need to wrap the response nor output stream. The filter will gzip the content of a response if:

• The filter is mapped to a matching path
• accept-encoding header is set to either gzip, deflate or a combination of those
• The response status code is >=200 and <300
• The content length is unknown or more than the minGzipSize initParameter or the minGzipSize is 0(default)
• If a list of mimeTypes is set by the mimeTypes init parameter, then the Content-Type is in the list.
• If no mimeType list is set, then the content-type is not in the list defined by excludedMimeTypes
• No content-encoding is specified by the resource

Compressing the content can greatly improve the network bandwidth usage, but at a cost of memory and CPU cycles. If this filter is mapped for static content, then use of efficient direct NIO may be prevented, thus use of the gzip mechanism of the DefaultServlet is advised instead.

This filter extends UserAgentFilter and if the the initParameter excludedAgents is set to a comma separated list of user agents, then these agents will be excluded from gzip content.

Init Parameters:

bufferSize

The output buffer size. Defaults to 8192. Be careful as values <= 0 will lead to an IllegalArgumentException. See: GZIPOutputStream.GZIPOutputStream(java.io.OutputStream, int) and: DeflaterOutputStream.DeflaterOutputStream(java.io.OutputStream, Deflater, int)

minGzipSize

Content will only be compressed if content length is either unknown or greater than minGzipSize.

deflateCompressionLevel

The compression level used for deflate compression. (0-9). See: Deflater.Deflater(int, boolean)

deflateNoWrap

The noWrap setting for deflate compression. Defaults to true. (true/false) See: Deflater.Deflater(int, boolean)

methods

Comma separated list of HTTP methods to compress. If not set, only GET requests are compressed.

mimeTypes

Comma separated list of mime types to compress. If it is not set, then the excludedMimeTypes list is used.

excludedMimeTypes

Comma separated list of mime types to never compress. If not set, then the default is the commonly known image, video, audio and compressed types.

excludedAgents

Comma separated list of user agents to exclude from compression. Does a String.contains(CharSequence) to check if the excluded agent occurs in the user-agent header. If it does -> no compression

excludeAgentPatterns

Same as excludedAgents, but accepts regex patterns for more complex matching.

excludePaths

Comma separated list of paths to exclude from compression. Does a String.startsWith(String) comparison to check if the path matches. If it does match -> no compression. To match subpaths use excludePathPatterns instead.

excludePathPatterns

Same as excludePath, but accepts regex patterns for more complex matching.

vary

Set to the value of the Vary header sent with responses that could be compressed. By default it is set to 'Vary: Accept-Encoding, User-Agent' since IE6 is excluded by default from the excludedAgents. If user-agents are not to be excluded, then this can be set to 'Vary: Accept-Encoding'. Note also that shared caches may cache copies of a resource that is varied by User-Agent - one per variation of the User-Agent, unless the cache does some normalization of the UA string.

checkGzExists

If set to true, the filter check if a static resource with ".gz" appended exists. If so then the normal processing is done so that the default servlet can send the pre existing gz content.

Field Summary

Fields

Modifier and Type	Field and Description
protected static ThreadLocal<byte[]>	_buffer
protected int	_bufferSize
protected boolean	_checkGzExists
protected ServletContext	_context
protected int	_deflateCompressionLevel
protected boolean	_deflateNoWrap
protected ThreadLocal<Deflater>	_deflater
protected Set<Pattern>	_excludedAgentPatterns
protected Set<String>	_excludedAgents
protected Set<Pattern>	_excludedPathPatterns
protected Set<String>	_excludedPaths
protected boolean	_excludeMimeTypes
protected Set<String>	_methods
protected Set<String>	_mimeTypes
protected int	_minGzipSize
protected HttpField	_vary
static int	DEFAULT_MIN_GZIP_SIZE
static String	DEFLATE
static String	ETAG
static String	ETAG_GZIP
static String	GZIP

Constructor Summary

Constructors

Constructor and Description
AsyncGzipFilter()

Method Summary

Methods

Modifier and Type	Method and Description
void	destroy()
void	doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
int	getBufferSize()
Deflater	getDeflater(Request request, long content_length)
HttpField	getVaryField()
void	init(FilterConfig filterConfig)
boolean	isExcludedMimeType(String mimetype)
void	recycle(Deflater deflater)

Methods inherited from class org.eclipse.jetty.servlets.UserAgentFilter

getUserAgent, getUserAgent

Methods inherited from class java.lang.Object

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

Field Detail

GZIP

public static final String GZIP

See Also:

Constant Field Values

DEFLATE

public static final String DEFLATE

See Also:

Constant Field Values

ETAG_GZIP

public static final String ETAG_GZIP

See Also:

Constant Field Values

ETAG

public static final String ETAG

See Also:

Constant Field Values

DEFAULT_MIN_GZIP_SIZE

public static final int DEFAULT_MIN_GZIP_SIZE

See Also:

Constant Field Values

_context

protected ServletContext _context

_mimeTypes

protected final Set<String> _mimeTypes

_excludeMimeTypes

protected boolean _excludeMimeTypes

_bufferSize

protected int _bufferSize

_minGzipSize

protected int _minGzipSize

_deflateCompressionLevel

protected int _deflateCompressionLevel

_deflateNoWrap

protected boolean _deflateNoWrap

_checkGzExists

protected boolean _checkGzExists

_deflater

protected final ThreadLocal<Deflater> _deflater

_buffer

protected static final ThreadLocal<byte[]> _buffer

_methods

protected final Set<String> _methods

_excludedAgents

protected Set<String> _excludedAgents

_excludedAgentPatterns

protected Set<Pattern> _excludedAgentPatterns

_excludedPaths

protected Set<String> _excludedPaths

_excludedPathPatterns

protected Set<Pattern> _excludedPathPatterns

_vary

protected HttpField _vary

Constructor Detail

AsyncGzipFilter

public AsyncGzipFilter()

Method Detail

init

public void init(FilterConfig filterConfig)
          throws ServletException

Specified by:

init in interface Filter

Overrides:

init in class UserAgentFilter

Throws:

ServletException

See Also:

UserAgentFilter.init(javax.servlet.FilterConfig)

destroy

public void destroy()

Specified by:

destroy in interface Filter

Overrides:

destroy in class UserAgentFilter

See Also:

UserAgentFilter.destroy()

doFilter

public void doFilter(ServletRequest req,
            ServletResponse res,
            FilterChain chain)
              throws IOException,
                     ServletException

Specified by:

doFilter in interface Filter

Overrides:

doFilter in class UserAgentFilter

Throws:

IOException

ServletException

See Also:

UserAgentFilter.doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse, javax.servlet.FilterChain)

getVaryField

public HttpField getVaryField()

Specified by:

getVaryField in interface GzipFactory

getDeflater

public Deflater getDeflater(Request request,
                   long content_length)

Specified by:

getDeflater in interface GzipFactory

recycle

public void recycle(Deflater deflater)

Specified by:

recycle in interface GzipFactory

isExcludedMimeType

public boolean isExcludedMimeType(String mimetype)

Specified by:

isExcludedMimeType in interface GzipFactory

getBufferSize

public int getBufferSize()

Specified by:

getBufferSize in interface GzipFactory