sunlabs.brazil.handler
Class UrlMapperHandler

java.lang.Object
  sunlabs.brazil.handler.UrlMapperHandler (view source)

All Implemented Interfaces:

Handler

public class UrlMapperHandler
extends Object
implements Handler

Handler for mapping URL's or HTTP headers, or redirecting URLs based on the contents of the current HTTP request. Matches URL's (or arbitrary request properties) against a regexp pattern. If there is a match, the URL (or specified HTTP header) is rewritten or the URL is redirected.

Properties:

match

The regexp to match a url. May contain constructs of the form ${xxx}, which are replaced by the value of request.props for the key xxx

replace

The url to replace it with. This may contain both regular expression sub-patterns, such as "\1", or variables of the form ${..} which are replaced with the equivalent augmented request properties. The request properties are augmented by looking first for the special variables: "method", "url", "protocol", "query", "serverUrl", "hostname", "hostport". then in the HTTP headers, then in the request properties. The special variables "hostname" and "hostport" are derived from the http "host" header.

export

If set, use this as a properties prefix, and set request properties for each sub-expression in "match". (E.g. [export]1 [export]2 ...).

redirect

If set, the request is redirected instead of being rewritten

ignoreCase

If set, the case of the expression is ignored.

source

If set, then this string is used instead of the url as the source of the match. Variable substitution using ${xxx} is performed on source, which, if unset, defaults to "${url}". If set, ${} substitutions are taken from the special variables (see "replace", above), followed by any http request headers, followed by names in the current Request object. The source property is obtained at init time, but evaluated (for ${...}) at every request.

As an example, the configuration:
prefix.source=${user-agent}!${url}
prefix.match=Lynx.*!(.*)
prefix.replace=/text\\1
could cause all browsers with "Lynx" in their user agent header to the "text" sub-directory.

target

By default, this handler modifies the request URL. If target is specified, it names an HTTP header to be replaced instead of the URL. The "target" is ignored if "redirect" is specified, and a new header is created if the "target" header doesn't already exist.

Nested Class Summary

static class

UrlMapperHandler.MapProperties Look in a dictionary first, then the provided properties.

Constructor Summary

UrlMapperHandler()

Method Summary

boolean	init(Server server, String prefix) Initializes the handler.
boolean	respond(Request request) If this request matches the expression, rewrite it.

Methods inherited from class java.lang.Object

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

Constructor Detail

UrlMapperHandler

public UrlMapperHandler()

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)
                throws IOException

If this request matches the expression, rewrite it.

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.

Throws:

IOException - if there was an I/O error while sending the response to the client. Typically, in that case, the Server will (try to) send an error message to the client and then close the client's connection.

The IOException should not be used to silently ignore problems such as being unable to access some server-side resource (for example getting a FileNotFoundException due to not being able to open a file). In that case, the Handler's duty is to turn that IOException into a HTTP response indicating, in this case, that a file could not be found.