wt.util
Class OutputFile

java.lang.Object
  java.io.Writer
      wt.util.OutputFile

Direct Known Subclasses:

MergableWriterFile

public class OutputFile

extends Writer

OutputFile is a wrapper class for writing output to a file. It provides the ability for multiple user's of this class to request a file by name, and get a "handle" to the same file.

Depending on the WriteMode that is set, the open method will inspect the current situation, and fail or succeed. The open method will also create appropriate backup files.

The default mode is WriteMode.BACKUP, meaning a backup of an existing file will be created, with the last character of its name changed to '~'.

The following is an example of how OutputFile could be used:

    // obtain a handle to a particular output file
    OutputFile myOutputFile = OutputFile.get( "c:\temp\myFile.txt" );
 

    // if the file already exists, open() creates a backup named "c:\temp\myFile.tx~"
    if ( myOutputFile.open() ) {
       myOutputFile.println( "This is a test." );
       myOutPutFile.close();
    }
 

If the file open attempt results in a SecurityException, due to be executed in a browser client, the output writes will be redirected to System.out.

See Also:

WriteMode, PrintWriter

Field Summary

protected static Hashtable	allInstances
protected File	backup
protected String	encoding
protected String	fileName
protected boolean	keepBackup
protected String	mergeFileName
protected static boolean	readOnlyWarning
protected boolean	removeMergeFile
protected WriteMode	writeMode
protected PrintWriter	writer

Fields inherited from class java.io.Writer

lock

Constructor Summary

protected

OutputFile()

Method Summary

protected static String	backUpName(String fileName) Obtain a backup filename, based on another filename.
void	close() Close the OutputFile.
void	close(boolean success) Close the OutputFile.
protected boolean	createBackupFile(File source) Create a backup file, given a source File object.
static boolean	ensureDirectoryExists(String dir_name) Ensure a directory exists.
void	flush() Flush the stream.
static OutputFile	get(String theFileName) Obtain an instance of an OutputFile, given a filename.
static Enumeration	getAllFiles() Obtain an Enumeration of all the OutputFile objects that have been successfully requested.
String	getFileName()
String	getMergeFileName() Gets the filename that will provide input for merging.
WriteMode	getWriteMode() Obtain the WriteMode setting for this object.
PrintWriter	getWriter()
protected boolean	mergePreparation(File file) Perform necessary preparations for merging with the File.
boolean	open() Opens the OutputFile, so that print and println can be performed.
void	print(String string) Print a String.
void	println(String string) Print a String, and then finish the line.
protected boolean	restoreBackupFile(File source) Restore a backup file, given a source File object.
void	setEncoding(String encoding) Set the encoding for this file.
protected void	setFileName(String newFileName) Set the filename for the OutputFile.
void	setMergeFileName(String newMergeFileName) Set the filename that will provide input for merging.
void	setRemoveMergeFile(boolean newRemoveMergeFile) Set the switch to determine if the merge input file should be removed when done with it.
void	setWriteMode(WriteMode newWriteMode) Set the WriteMode for the OutputFile.
String	toString()
void	write(char[] cbuf, int off, int len) Write a portion of an array of characters.

Methods inherited from class java.io.Writer

write, write, write, write

Methods inherited from class java.lang.Object

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

Field Detail

allInstances

protected static final Hashtable allInstances

fileName

protected String fileName

mergeFileName

protected String mergeFileName

removeMergeFile

protected boolean removeMergeFile

writeMode

protected WriteMode writeMode

encoding

protected String encoding

writer

protected PrintWriter writer

backup

protected File backup

keepBackup

protected boolean keepBackup

readOnlyWarning

protected static final boolean readOnlyWarning

Constructor Detail

OutputFile

protected OutputFile()

Method Detail

backUpName

protected static String backUpName(String fileName)

Obtain a backup filename, based on another filename.

Parameters:

fileName - the name of the file, for which a backup filename is needed

Returns:

the String that is the backup filename

close

public void close()

Close the OutputFile. If applicable, will delete a temporary backup file.

close

public void close(boolean success)

Close the OutputFile. If applicable, will delete a temporary backup file, or restore it if passed success=false.

restoreBackupFile

protected boolean restoreBackupFile(File source)

Restore a backup file, given a source File object.

Parameters:

source - the File which needs to be restored from a backup File.

Returns:

true if it succeeds, otherwise return false

createBackupFile

protected boolean createBackupFile(File source)

Create a backup file, given a source File object.

Parameters:

source - the File which needs a backup File.

Returns:

true if it succeeds, otherwise return false

ensureDirectoryExists

public static boolean ensureDirectoryExists(String dir_name)
                                     throws FileNotFoundException,
                                            IOException

Ensure a directory exists.

Parameters:

dir_name - the name of the directory that is needed

Throws:

FileNotFoundException

IOException

flush

public void flush()

Flush the stream. If the stream has saved any characters from the various write() methods in a buffer, write them immediately to their intended destination. Then, if that destination is another character or byte stream, flush it. Thus one flush() invocation will flush all the buffers in a chain of Writers and OutputStreams.

get

public static OutputFile get(String theFileName)

Obtain an instance of an OutputFile, given a filename. Multiple requests for the same filename, will return the same instance.

Returns:

the OutputFile object for the filename

getAllFiles

public static Enumeration getAllFiles()

Obtain an Enumeration of all the OutputFile objects that have been successfully requested.

Returns:

the Enumeration of all the OutputFile objects

getFileName

public String getFileName()

getWriteMode

public WriteMode getWriteMode()

Obtain the WriteMode setting for this object.

Returns:

the WriteMode setting for this object

getWriter

public PrintWriter getWriter()

mergePreparation

protected boolean mergePreparation(File file)

Perform necessary preparations for merging with the File. This method just returns true, but exists as a means of sub-classes providing specific merge preparation behavior.

Parameters:

file - the File which will be merged.

Returns:

true if it succeeds, otherwise return false

open

public boolean open()

Opens the OutputFile, so that print and println can be performed. The WriteMode is considered to deterimine the exact actions to take.

   WriteMode.BACKUP    = Create a backup of any existing file, before re-writing it.
   WriteMode.MERGE     = Merge into an existing file.
   WriteMode.ORIGINAL  = Only open the file, if it doesn't already exist.
   WriteMode.OVERWRITE = Clobber an existing file.
 

*Assumes source mergeFile and target output file will be in the same path.

Returns:

true if it succeeds, otherwise return false

See Also:

WriteMode

print

public void print(String string)

Print a String.

println

public void println(String string)

Print a String, and then finish the line.

setEncoding

public void setEncoding(String encoding)

Set the encoding for this file. Only takes effect if file is opened after setting.

Parameters:

encoding - the encoding to use

setFileName

protected void setFileName(String newFileName)

Set the filename for the OutputFile. Only takes effect if file is opened after setting.

Parameters:

newFileName - the filename to write to.

getMergeFileName

public String getMergeFileName()

Gets the filename that will provide input for merging.

setMergeFileName

public void setMergeFileName(String newMergeFileName)

Set the filename that will provide input for merging. Only takes effect if file is opened after setting.

setRemoveMergeFile

public void setRemoveMergeFile(boolean newRemoveMergeFile)

Set the switch to determine if the merge input file should be removed when done with it. Only takes effect if file is opened after setting.

Parameters:

newRemoveMergeFile - true will remove the file, false will leave it

setWriteMode

public void setWriteMode(WriteMode newWriteMode)

Set the WriteMode for the OutputFile. Only takes effect if file is opened after setting.

Parameters:

newWriteMode - the WriteMode to use

toString

public String toString()

write

public void write(char[] cbuf,
                  int off,
                  int len)

Write a portion of an array of characters.