JsonFile.java

/**
 *  JsonFile
 *  Copyright 22.02.2015 by Robert Mader, @treba123
 *
 *  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 program in the file lgpl21.txt
 *  If not, see <http://www.gnu.org/licenses/>.
 */

package org.loklak.tools.storage;

import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Collection;
import java.util.Map;

import org.json.JSONException;
import org.json.JSONObject;
import org.json.JSONTokener;

/**
 * This extends JSONObject to be a file which gets loaded and written to disk
 * It also offers some key management tools
 *
 */
public class JsonFile extends JSONObject {
	
	private final File file;

	public JsonFile(File file) throws IOException{
		super();
		if(file == null) throw new IOException("File must not be null");
		
		this.file = file;
		if(file.exists()){
			JSONTokener tokener;
			tokener = new JSONTokener(new FileReader(file));
			putAll(new JSONObject(tokener));
		}
		else{
			file.createNewFile();
			commit();
		}
	}
	
	public synchronized File getFile() {
	    return this.file;
	}
	
	/**
	 * Write changes to file. It is not required that the user calls this method,
	 * however, if sub-objects of existing objects are modified, the user must handle
	 * file writings themself.
	 * @throws JSONException
	 */
	public synchronized void commit() throws JSONException {
	    File tmpFile0 = new File(this.file.getParentFile(), this.file.getName() + "." + System.currentTimeMillis());
	    File tmpFile1 = new File(tmpFile0.getParentFile(), tmpFile0.getName() + "1");
        try {
		    FileWriter writer = new FileWriter(tmpFile0);
			writer.write(this.toString(2));
			writer.close();
            this.file.renameTo(tmpFile1);
            tmpFile0.renameTo(this.file);
            tmpFile1.delete();
		} catch (IOException e) {
			throw new JSONException(e.getMessage());
		}
	}
	
	/**
	 * Return a copy of the JSON content
	 * @return JSONObject json
	 */
	public synchronized JSONObject toJSONObject(){
		JSONObject res = new JSONObject();
        res.putAll(this);
        return res;
	}

	@Override
	public synchronized JSONObject put(String key, boolean value) throws JSONException {
		super.put(key, value);
		commit();
		return this;
	}
	
	@Override
	public synchronized JSONObject put(String key, double value) throws JSONException {
		super.put(key, value);
		commit();
		return this;
	}
	
	@Override
	public synchronized JSONObject put(String key, Collection<?> value) throws JSONException {
		super.put(key, value);
		commit();
		return this;
	}
	
	@Override
	public synchronized JSONObject put(String key, int value) throws JSONException {
		super.put(key, value);
		commit();
		return this;
	}
	
	@Override
	public synchronized JSONObject put(String key, long value) throws JSONException {
		super.put(key, value);
		commit();
		return this;
	}
	
	@Override
	public synchronized JSONObject put(String key, Map<?, ?> value) throws JSONException {
		super.put(key, value);
		commit();
		return this;
	}
	
	@Override
	public synchronized JSONObject put(String key, Object value) throws JSONException {
		super.put(key, value);
		commit();
		return this;
	}

	public synchronized JSONObject put(String key, JSONObject value) throws JSONException {
		super.put(key, value);
		commit();
		return this;
	}

	@Override
	public synchronized void putAll(JSONObject other){
		super.putAll(other);
		commit();
	}
	
	@Override
	public synchronized Object remove(String key) {
		super.remove(key);
		commit();
		return this;
	}
}