jimm.twice.util
Class Persistence

java.lang.Object
  jimm.twice.util.Persistence

public class Persistence

extends java.lang.Object

This class is used to implement persistence. It uses the file system, creating a file for every key. The contents of the file are lines of text data. Within each line, values are separated by the SEPARATOR string. A few important simplifying assumptions:

• No attempt is made to escape the SEPARATOR string within the data.
• The key values are mutated when used as file names. Ever character that does not match [-_\.a-zA-Z0-9] is turned into an underscore.

This persistence mechanism is outside of the hierarchy of ICE classes because this particular persistence mechanism is very simplistic and should be replaced with something more robust (like a database) in real implementations.

Author:

Jim Menard, jimm@io.com

Field Summary

protected java.lang.String	dirPath
protected static java.lang.String	SEPARATOR

Constructor Summary

Persistence(java.lang.String storageDirPath)

Method Summary

java.io.BufferedReader	getBufferedReader(java.lang.String key) Returns a collection containing lists of strings.
java.io.FileInputStream	getFileInputStream(java.lang.String key)
java.io.FileOutputStream	getFileOutputStream(java.lang.String key)
java.io.PrintWriter	getPrintWriter(java.lang.String key) Stores the lists contained within the values collection as lines within a file.
boolean	hasKey(java.lang.String key) Returns true if a permanent storage file already exists for the specified key.
java.util.Set	keySet() Returns a set containing all of the keys.
protected java.lang.String	makeSafe(java.lang.String key) Key values are mutated when used as file names.
void	remove(java.lang.String key) Removes the permanent storage associated with the specified key.

Methods inherited from class java.lang.Object

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

Field Detail

SEPARATOR

protected static final java.lang.String SEPARATOR

See Also:

Constant Field Values

dirPath

protected java.lang.String dirPath

Constructor Detail

Persistence

public Persistence(java.lang.String storageDirPath)

Method Detail

hasKey

public boolean hasKey(java.lang.String key)

Returns true if a permanent storage file already exists for the specified key.

remove

public void remove(java.lang.String key)

Removes the permanent storage associated with the specified key. No harm done if there is no storage already.

keySet

public java.util.Set keySet()

Returns a set containing all of the keys. Returns an empty set if there are none.

getBufferedReader

public java.io.BufferedReader getBufferedReader(java.lang.String key)

Returns a collection containing lists of strings. Returns null if there is no file corresponding to the specified key.

getFileInputStream

public java.io.FileInputStream getFileInputStream(java.lang.String key)

getPrintWriter

public java.io.PrintWriter getPrintWriter(java.lang.String key)

Stores the lists contained within the values collection as lines within a file.

getFileOutputStream

public java.io.FileOutputStream getFileOutputStream(java.lang.String key)

makeSafe

protected java.lang.String makeSafe(java.lang.String key)

Key values are mutated when used as file names. Ever character that does not match [-_\.a-zA-Z0-9] is turned into an underscore.