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// Copyright (C) 2001-2003 Jon A. Maxwell (JAM)
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
package net.sourceforge.jnlp.util;
import java.io.*;
import java.util.*;
/**
* A properties object backed by a specified file without throwing
* exceptions. The properties are automatically loaded from the
* file when the first property is requested, but the save method
* must be called before changes are saved to the file.<p>
*
* This class does not report IO exceptions.<p>
*
* @author <a href="mailto:jmaxwell@users.sourceforge.net">Jon A. Maxwell (JAM)</a> - initial author
* @version $Revision: 1.4 $
*/
public class PropertiesFile extends Properties {
/** the file to save to */
File file;
/** the header string */
String header = "netx file";
/** lazy loaded on getProperty */
boolean loaded = false;
/**
* Create a properties object backed by the specified file.
*
* @param file the file to save and load to
*/
public PropertiesFile(File file) {
this.file = file;
}
/**
* Create a properties object backed by the specified file.
*
* @param file the file to save and load to
* @param header the file header
*/
public PropertiesFile(File file, String header) {
this.file = file;
this.header = header;
}
/**
* Returns the value of the specified key, or null if the key
* does not exist.
*/
public String getProperty(String key) {
if (!loaded)
load();
return super.getProperty(key);
}
/**
* Returns the value of the specified key, or the default value
* if the key does not exist.
*/
public String getProperty(String key, String defaultValue) {
if (!loaded)
load();
return super.getProperty(key, defaultValue);
}
/**
* Sets the value for the specified key.
*
* @return the previous value
*/
public Object setProperty(String key, String value) {
if (!loaded)
load();
return super.setProperty(key, value);
}
/**
* Returns the file backing this properties object.
*/
public File getStoreFile() {
return file;
}
/**
* Ensures that the file backing these properties has been
* loaded; call this method before calling any method defined by
* a superclass.
*/
public void load() {
loaded = true;
try {
if (!file.exists())
return;
InputStream s = new FileInputStream(file);
load(s);
} catch (IOException ex) {
// eat
}
}
/**
* Saves the properties to the file.
*/
public void store() {
if (!loaded)
return; // nothing could have changed so save unnecessary load/save
try {
OutputStream s = new FileOutputStream(file);
store(s, header);
} catch (IOException ex) {
// eat
}
}
}
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