sunlabs.brazil.filter
Class ExecFilter

java.lang.Object
  sunlabs.brazil.filter.ExecFilter (view source)

All Implemented Interfaces:

Filter, Handler

public class ExecFilter
extends Object
implements Filter

Filter to Run all content through an external process filter. The content is provided as the standard input to a command, that is expected to return the new content.

The following server properties are used:

command

The command to exec. The content is supplied as stdin, and the filtered output is expected on stdout. ${...} substitutions Are done at each filter invocation.

types

A regular expression that matches the content types for the content we wish to filter

type

This property is set to the content type of the content just before command is evaluated.

newType

This property, if set, is used as the new content type. It is evaluated for ${...} at each conversion.

error

If the command failed, this property will contain the error message. If the command generated output on stderr, this property will contain the output.

The following configuration will halve the size of all jpeg and gif images, using the convert program from ImageMagic.

 prefix.types=image/(jpeg|gif)
 prefix.command= convert -sample 50% \ 
     ${map.${prefix.type}}:- ${map.${prefix.type}}:-
 map.image/gif=GIF
 map.image/jpeg=JPEG
 

Constructor Summary

ExecFilter()

Method Summary

byte[]	filter(Request request, MimeHeaders headers, byte[] content) Run content through filter.
boolean	init(Server server, String prefix) Initializes the handler.
boolean	respond(Request request) This is the request object before the content was fetched
boolean	shouldFilter(Request request, MimeHeaders headers) Only filter content types that match

Methods inherited from class java.lang.Object

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

Constructor Detail

ExecFilter

public ExecFilter()

Method Detail

init

public boolean init(Server server,
                    String prefix)

Description copied from interface: Handler

Initializes the handler.

Specified by:

init in interface Handler

Parameters:

server - The HTTP server that created this Handler. Typical Handlers will use Server.props to obtain run-time configuration information.

prefix - The handlers name. The string this Handler may prepend to all of the keys that it uses to extract configuration information from Server.props. This is set (by the Server and ChainHandler) to help avoid configuration parameter namespace collisions.

Returns:

true if this Handler initialized successfully, false otherwise. If false is returned, this Handler should not be used.

respond

public boolean respond(Request request)

This is the request object before the content was fetched

Specified by:

respond in interface Handler

Parameters:

request - The Request object that represents the HTTP request.

Returns:

true if the request was handled. A request was handled if a response was supplied to the client, typically by calling Request.sendResponse() or Request.sendError.

shouldFilter

public boolean shouldFilter(Request request,
                            MimeHeaders headers)

Only filter content types that match

Specified by:

shouldFilter in interface Filter

Parameters:

request - The in-progress HTTP request.

headers - The MIME headers generated by the wrapped Handler.

Returns:

true if this filter would like to examine and possibly rewrite the content, false otherwise.

filter

public byte[] filter(Request request,
                     MimeHeaders headers,
                     byte[] content)

Run content through filter. Process ${...}

Specified by:

filter in interface Filter

Parameters:

request - The finished HTTP request.

headers - The MIME headers generated by the Handler.

content - The output from the Handler that this Filter may rewrite.

Returns:

The rewritten content. The Filter may return the original content unchanged. The Filter may return null to indicate that the FilterHandler should stop processing the request and should not return any content to the client.