Class SubstPropsHandler

java.lang.Object

sunlabs.brazil.properties.SubstPropsHandler

All Implemented Interfaces:

Handler

public class SubstPropsHandler
extends Object
implements Handler

Handler that performs value conversions on ${...} substitutions. For any property whose name matches the supplied regular expression, The source value is "converted" based on a token in the regular expression.

This Handler is a generalization of the convert attribute of the get tag of the SetTemplate. Unlike the implementation in the SetTemplate that implements a small, fixed set of conversions of property values in the context of get, this handler allows plug-able conversion filters, and performs the conversions any time ${...} substitutions are resolved, not just in the context of the get tag.

This requires the addition of new syntax in ${...} substitutions to specify the both the conversion (or filter) to apply, and the value to apply it to. This new syntax is configurable using the match, key, and token attributes, but defaults to: ${filter(value)} where filter represents the conversion filter, and value represents the property name whose contents is filtered.

Any class that implements the Convert interface can be loaded and called to perform filtering. Filters that implement all the options of the <get ... convert=xxx> conversion options are included.

See the examples, below for the details.

match

A regular expression that matches a property name that is a candidate for filtering. This expression should have at least 2 sets of ()'s in order to gather values for "key" and "token" below. The default value is ^([a-z]+)\([^)]+\)$

key

The regular expression substitution string used to represent the actual property name to filter. The default is \\2

token

The regular expression substitution string used to represent the filter name or "token". The default is \\1

Using the defaults for "match", "key", and "token", a property named "foo" would be represented as ${xxx(foo)} where "xxx" is the name of the conversion filter.

tokens

A witespace separated list of filter names or "token"s that map the conversion filters to conversion classes. For each token (e.g. foo), there should be a property of the form "foo.class" which specifies the name of the class that implements the filter, (and implements the Convert interface described below). Any additional properties (e.g. x, y, z) needed to initialize a filter should be present in the properties file as "foo.x, foo.y...".

[token].code

The name to match the "token" in the property name. The default is "[token]".

This class contains sample implementations of the convert interface. See below for their functions.

Version:

1.5

Author:

Stephen Uhler

See Also:

• Properties

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	SubstPropsHandler.Convert	Class that maps strings to strings.
static class	SubstPropsHandler.Html	HTML escape a value.
static class	SubstPropsHandler.LowerCase	Convert a value to lowercase.
static class	SubstPropsHandler.Resub	Do a regexp substitution on a value.
class	SubstPropsHandler.SubstProps	This class implements a properties object that knows how to extract the "name" and "filter" from a properly constructed name, and to invoke the filter on the value of the encoded name.
static class	SubstPropsHandler.Url	URL encode a String.

Constructor Summary

Constructors

Constructor	Description
SubstPropsHandler()

Method Summary

Modifier and Type	Method	Description
boolean	init(Server server, String prefix)	Initializes the handler.
boolean	respond(Request request)	Responds to an HTTP request.
String	toString()

Methods inherited from class Object

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

Constructor Details

SubstPropsHandler

public SubstPropsHandler()

Method Details

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

Description copied from interface: Handler

Responds to an HTTP request.

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.

toString

public String toString()

Overrides:

toString in class Object