org.clapper.curn.output
Class FileOutputHandler

java.lang.Object
  org.clapper.curn.output.FileOutputHandler

All Implemented Interfaces:

OutputHandler

Direct Known Subclasses:

FreeMarkerOutputHandler, ScriptOutputHandler

public abstract class FileOutputHandler
extends java.lang.Object
implements OutputHandler

FileOutputHandler is an abstract base class for OutputHandler subclasses that write RSS feed summaries to a file. It consolidates common logic and configuration handling for such classes, providing both consistent implementation and configuration.

Version:

$Revision: 6459 $

See Also:

OutputHandler, Curn, RSSChannel

Field Summary

static java.lang.String	CFG_ENCODING Configuration variable: encoding
static java.lang.String	CFG_SAVE_AS Where to save the output, if any
static java.lang.String	CFG_SAVE_ONLY Whether we're ONLY saving output
static java.lang.String	CFG_SAVED_BACKUPS Number of backups of saved files to keep.
static java.lang.String	CFG_SHOW_CURN_INFO Whether or not to show curn information

Constructor Summary

FileOutputHandler()
Construct a new FileOutputHandler

Method Summary

abstract void	displayChannel(RSSChannel channel, FeedInfo feedInfo) Display the list of RSSItem news items to whatever output is defined for the underlying class.
protected boolean	displayToolInfo() Determine whether or not to display curn tool-related information in the generated output.
abstract void	flush() Flush any buffered-up output.
abstract java.lang.String	getContentType() Get the content (i.e., MIME) type for output produced by this output handler.
java.io.File	getGeneratedOutput() Get the File that represents the output produced by the handler, if applicable.
java.lang.String	getName() Get the name of this output handler.
java.lang.String	getOutputEncoding() Get the output encoding.
protected java.io.File	getOutputFile() Get the output file.
boolean	hasGeneratedOutput() Determine whether this handler has produced any actual output (i.e., whether getGeneratedOutput() will return a non-null File if called).
void	init(CurnConfig config, ConfiguredOutputHandler cfgHandler) Initializes the output handler for another set of RSS channels.
abstract void	initOutputHandler(CurnConfig config, ConfiguredOutputHandler cfgHandler) Perform any subclass-specific initialization.
protected java.io.PrintWriter	openOutputFile() Open the output file, returning a PrintWriter.
protected boolean	savingOutputOnly() Determine whether the handler is saving output only, or also reporting output to curn.
void	setName(java.lang.String name) Set the name of this output handler.
protected void	setOutputEncoding(java.lang.String newEncoding) Override the encoding specified by the CFG_ENCODING configuration parameter.

Methods inherited from class java.lang.Object

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

Field Detail

CFG_ENCODING

public static final java.lang.String CFG_ENCODING

Configuration variable: encoding

See Also:

Constant Field Values

CFG_SHOW_CURN_INFO

public static final java.lang.String CFG_SHOW_CURN_INFO

Whether or not to show curn information

See Also:

Constant Field Values

CFG_SAVE_AS

public static final java.lang.String CFG_SAVE_AS

Where to save the output, if any

See Also:

Constant Field Values

CFG_SAVE_ONLY

public static final java.lang.String CFG_SAVE_ONLY

Whether we're ONLY saving output

See Also:

Constant Field Values

CFG_SAVED_BACKUPS

public static final java.lang.String CFG_SAVED_BACKUPS

Number of backups of saved files to keep.

See Also:

Constant Field Values

Constructor Detail

FileOutputHandler

public FileOutputHandler()

Construct a new FileOutputHandler

Method Detail

getName

public java.lang.String getName()

Get the name of this output handler. The name must be unique.

Specified by:

getName in interface OutputHandler

Returns:

the name

setName

public void setName(java.lang.String name)
             throws CurnException

Set the name of this output handler. Called by curn.

Specified by:

setName in interface OutputHandler

Parameters:

name - the name

Throws:

CurnException - on error

init

public final void init(CurnConfig config,
                       ConfiguredOutputHandler cfgHandler)
                throws org.clapper.util.config.ConfigurationException,
                       CurnException

Initializes the output handler for another set of RSS channels.

Specified by:

init in interface OutputHandler

Parameters:

config - the parsed curn configuration data

cfgHandler - the ConfiguredOutputHandler wrapper containing this object; the wrapper has some useful metadata, such as the object's configuration section name and extra variables.

Throws:

org.clapper.util.config.ConfigurationException - configuration error

CurnException - some other initialization error

See Also:

CurnConfig, ConfiguredOutputHandler

initOutputHandler

public abstract void initOutputHandler(CurnConfig config,
                                       ConfiguredOutputHandler cfgHandler)
                                throws org.clapper.util.config.ConfigurationException,
                                       CurnException

Perform any subclass-specific initialization. Subclasses must override this method.

Parameters:

config - the parsed curn configuration data

cfgHandler - the ConfiguredOutputHandler wrapper containing this object; the wrapper has some useful metadata, such as the object's configuration section name and extra variables.

Throws:

org.clapper.util.config.ConfigurationException - configuration error

CurnException - some other initialization error

displayChannel

public abstract void displayChannel(RSSChannel channel,
                                    FeedInfo feedInfo)
                             throws CurnException

Display the list of RSSItem news items to whatever output is defined for the underlying class. Output should be written to the PrintWriter that was passed to the init() method.

Specified by:

displayChannel in interface OutputHandler

Parameters:

channel - The parsed channel data

feedInfo - The feed.

Throws:

CurnException - unable to write output

flush

public abstract void flush()
                    throws CurnException

Flush any buffered-up output.

Specified by:

flush in interface OutputHandler

Throws:

CurnException - unable to write output

getContentType

public abstract java.lang.String getContentType()

Get the content (i.e., MIME) type for output produced by this output handler.

Specified by:

getContentType in interface OutputHandler

Returns:

the content type

See Also:

OutputHandler.hasGeneratedOutput(), OutputHandler.getGeneratedOutput()

getGeneratedOutput

public final java.io.File getGeneratedOutput()
                                      throws CurnException

Get the File that represents the output produced by the handler, if applicable. (Use of a File, rather than an InputStream, is more efficient when mailing the output, since the email API ultimately wants files and will create temporary files for InputStreams.)

Specified by:

getGeneratedOutput in interface OutputHandler

Returns:

the output file, or null if no suitable output was produced

Throws:

CurnException - an error occurred

getOutputEncoding

public java.lang.String getOutputEncoding()

Get the output encoding.

Specified by:

getOutputEncoding in interface OutputHandler

Returns:

the encoding

hasGeneratedOutput

public final boolean hasGeneratedOutput()

Determine whether this handler has produced any actual output (i.e., whether getGeneratedOutput() will return a non-null File if called).

Specified by:

hasGeneratedOutput in interface OutputHandler

Returns:

true if the handler has produced output, false if not

See Also:

getGeneratedOutput(), getContentType()

getOutputFile

protected final java.io.File getOutputFile()

Get the output file.

Returns:

the output file, or none if not created yet

openOutputFile

protected java.io.PrintWriter openOutputFile()
                                      throws CurnException

Open the output file, returning a PrintWriter. Handles whether or not to roll the saved file, etc.

Returns:

the PrintWriter

Throws:

CurnException - unable to open file

savingOutputOnly

protected final boolean savingOutputOnly()

Determine whether the handler is saving output only, or also reporting output to curn.

Returns:

true if saving output only, false if also reporting output to curn

setOutputEncoding

protected final void setOutputEncoding(java.lang.String newEncoding)

Override the encoding specified by the CFG_ENCODING configuration parameter. To have any effect, this method must be called before openOutputFile()

Parameters:

newEncoding - the new encoding, or null to use the default

See Also:

getOutputEncoding()

displayToolInfo

protected final boolean displayToolInfo()

Determine whether or not to display curn tool-related information in the generated output. Subclasses are not required to display tool-related information in the generated output, but if they do, they are strongly encouraged to do so conditionally, based on the value of this configuration item.

Returns:

true if tool-related information is to be displayed (assuming the output handler supports it), or false if tool-related information should be suppressed.