/*
* Copyright 2013 Netflix, Inc.
*
* Licensed 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 com.netflix.exhibitor.core.controlpanel;
import com.google.common.io.Closeables;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Properties;
import java.util.prefs.AbstractPreferences;
import java.util.prefs.BackingStoreException;
/**
* A wrapper around the JDK Preferences API that uses a file. IMPORTANT:
* this class does NOT support multiple processes using the file.
*/
public class FileBasedPreferences extends AbstractPreferences
{
private final File file;
private final Properties properties = new Properties();
/**
* @param file file to use as backing store
* @throws IOException errors
*/
public FileBasedPreferences(File file) throws IOException
{
super(null, "");
this.file = file;
if ( file.exists() )
{
BufferedInputStream in = new BufferedInputStream(new FileInputStream(file));
try
{
properties.load(in);
}
finally
{
Closeables.closeQuietly(in);
}
}
}
@Override
protected void putSpi(String key, String value)
{
properties.setProperty(key, value);
}
@Override
protected String getSpi(String key)
{
return properties.getProperty(key);
}
@Override
protected void removeSpi(String key)
{
properties.remove(key);
}
@Override
protected void removeNodeSpi() throws BackingStoreException
{
throw new UnsupportedOperationException();
}
@Override
protected String[] keysSpi() throws BackingStoreException
{
return new String[0];
}
@Override
protected String[] childrenNamesSpi() throws BackingStoreException
{
return new String[0];
}
@Override
protected AbstractPreferences childSpi(String name)
{
throw new UnsupportedOperationException();
}
@Override
protected void syncSpi() throws BackingStoreException
{
}
@Override
protected void flushSpi() throws BackingStoreException
{
if ( !file.getParentFile().exists() && !file.getParentFile().mkdirs() )
{
throw new BackingStoreException("Could not create parent directories for: " + file);
}
OutputStream out = null;
try
{
out = new BufferedOutputStream(new FileOutputStream(file));
properties.store(out, "# Auto-generated by " + FileBasedPreferences.class.getName());
}
catch ( IOException e )
{
throw new BackingStoreException(e);
}
finally
{
Closeables.closeQuietly(out);
}
}
}