* </tr> * <tr> * <td> cache.cachefile * <td> path to file * <td> the name of the properties file * <td> yes * </tr> * </table> * * @version 2003-09-13 * @since Ant 1.6 */ public class PropertiesfileCache implements Cache { // ----- member variables - configuration ----- /** Where to store the properties? */ private File cachefile = null; /** Object for storing the key-value-pairs. */ private Properties cache = new Properties(); // ----- member variables - internal use ----- /** Is the cache already loaded? Prevents from multiple load operations. */ private boolean cacheLoaded = false; /** Must the cache be saved? Prevents from multiple save operations. */ private boolean cacheDirty = true; // ----- Constructors ----- /** Bean-Constructor. */ public PropertiesfileCache() { } /** * Constructor. * @param cachefile set the cachefile */ public PropertiesfileCache(File cachefile) { this.cachefile = cachefile; } // ----- Cache-Configuration ----- /** * Setter. * @param file new value */ public void setCachefile(File file) { cachefile = file; } /** * Getter. * @return the cachefile */ public File getCachefile() { return cachefile; } /** * This cache is valid if the cachefile is set. * @return true if all is ok false otherwise */ public boolean isValid() { return (cachefile != null); } // ----- Data Access /** * Load the cache from underlying properties file. */ public void load() { if ((cachefile != null) && cachefile.isFile() && cachefile.canRead()) { try { BufferedInputStream bis = new BufferedInputStream( new FileInputStream(cachefile)); cache.load(bis); bis.close(); } catch (Exception e) { e.printStackTrace(); } } // after loading the cache is up to date with the file cacheLoaded = true; cacheDirty = false; } /** * Saves modification of the cache. * Cache is only saved if there is one ore more entries. * Because entries can not be deleted by this API, this Cache * implementation checks the existence of entries before creating the file * for performance optimisation. */ public void save() { if (!cacheDirty) { return; } if ((cachefile != null) && cache.propertyNames().hasMoreElements()) { try { BufferedOutputStream bos = new BufferedOutputStream( new FileOutputStream(cachefile)); cache.store(bos, null); bos.flush(); bos.close(); } catch (Exception e) { e.printStackTrace(); } } cacheDirty = false; } /** Deletes the cache and its underlying file. */ public void delete() { cache = new Properties(); cachefile.delete(); cacheLoaded = true; cacheDirty = false; } /** * Returns a value for a given key from the cache. * @param key the key * @return the stored value */ public Object get(Object key) { if (!cacheLoaded) { load(); } try { return cache.getProperty(String.valueOf(key)); } catch (ClassCastException e) { return null; } } /** * Saves a key-value-pair in the cache. * @param key the key * @param value the value */ public void put(Object key, Object value) { cache.put(String.valueOf(key), String.valueOf(value)); cacheDirty = true; } /** * Returns an iterator over the keys in the cache. * @return An iterator over the keys. */ public Iterator iterator() { Vector v = new java.util.Vector(); Enumeration en = cache.propertyNames(); while (en.hasMoreElements()) { v.add(en.nextElement()); } return v.iterator(); } // ----- additional ----- /** * Override Object.toString(). * @return information about this cache */ public String toString() { StringBuffer buf = new StringBuffer(); buf.append("<PropertiesfileCache:"); buf.append("cachefile=").append(cachefile); buf.append(";noOfEntries=").append(cache.size()); buf.append(">"); return buf.toString(); } }

	Ant example source code file (PropertiesfileCache.java) This example Ant source code file (PropertiesfileCache.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM. Java - Ant tags/keywords bufferedinputstream, bufferedoutputstream, exception, file, file, fileoutputstream, io, object, object, properties, properties, propertiesfilecache, propertiesfilecache, stringbuffer, util, vector The PropertiesfileCache.java source code /* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * */ package org.apache.tools.ant.types.selectors.modifiedselector; import java.util.Iterator; import java.util.Vector; import java.util.Enumeration; import java.util.Properties; import java.io.File; import java.io.BufferedInputStream; import java.io.FileInputStream; import java.io.BufferedOutputStream; import java.io.FileOutputStream; /** * Use java.util.Properties for storing the values. * The use of this Cache-implementation requires the use of the parameter * <param name="cache.cachefile" .../> for defining, where to store the * properties file. * * The ModifiedSelector sets the <i>cachefile to the default value * <i>cache.properties. * * Supported <param>s are: * <table> * <tr> * <th>name	values	description	required

... this post is sponsored by my books ...
#1 New Release!	FP Best Seller

 

new blog posts