stream.io.JSONWriter Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of streams-core Show documentation
The newest version!
/*
 *  streams library
 *
 *  Copyright (C) 2011-2014 by Christian Bockermann, Hendrik Blom
 * 
 *  streams is a library, API and runtime environment for processing high
 *  volume data streams. It is composed of three submodules "stream-api",
 *  "stream-core" and "stream-runtime".
 *
 *  The streams library (and its submodules) is free software: you can 
 *  redistribute it and/or modify it under the terms of the 
 *  GNU Affero General Public License as published by the Free Software 
 *  Foundation, either version 3 of the License, or (at your option) any 
 *  later version.
 *
 *  The stream.ai library (and its submodules) 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 Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with this program.  If not, see http://www.gnu.org/licenses/.
 */
package stream.io;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintStream;

import net.minidev.json.JSONObject;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import stream.Data;
import stream.data.DataFactory;

/**
 * 
 * This is a simple JSON writer that will write all data items into JSON strings
 * (one line for each item).
 * 
 * 
 * @author Christian Bockermann <[email protected]>
 * 
 */
public class JSONWriter extends AbstractWriter {

	static Logger log = LoggerFactory.getLogger(JSONWriter.class);

	PrintStream p;

	public JSONWriter() {
		super();
	}

	public JSONWriter(File file) throws IOException {
		this(new FileOutputStream(file));
	}

	public JSONWriter(OutputStream out) throws IOException {
		p = new PrintStream(out);
	}

	/**
	 * @see stream.io.CsvWriter#write(stream.Data)
	 */
	@Override
	public void write(Data datum) {
		Data item = DataFactory.create();
		for (String key : this.selectedKeys(datum)) {
			if (datum.containsKey(key))
				item.put(key, datum.get(key));
		}
        if (p != null) {
		    p.println(JSONObject.toJSONString(item));
        } else {
            log.error("JSONWriter has not been set right: PrintStream is null.");
        }
	}
}