NTriplesReader.java

package org.jcommons.file.rdf;

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.nio.charset.Charset;
import java.util.zip.GZIPInputStream;
import java.util.zip.ZipInputStream;

public class NTriplesReader {
	private InputStream fin;
	private BufferedReader stringReader;
	private String currentLine;
	private TripleReader tripleReader;

	public NTriplesReader(String path) {
		if (path.toLowerCase().startsWith("/users")) {
			if (!loadHDFSFile(path))
				System.err.println("Error found!");
		} else if (path.toLowerCase().endsWith(".gz")) {
			if (!loadGZipFile(path))
				System.err.println("An error is found in loading " + path);
		} else if (path.toLowerCase().endsWith(".zip")) {
			if (!loadZipFile(path))
				System.err.println("An error is found in loading " + path);
		} else if (path.toLowerCase().endsWith(".bz2")) {
			if (!loadBZ2File(path))
				System.err.println("An error is found in loading " + path);
		} else {
			if (loadGZipFile(path + ".gz"))
				System.out.println("GZipped file is found, using it instaed.");
			else if (loadZipFile(path + ".zip"))
				System.out.println("Zipped file is found, using it instaed.");
			else if (loadBZ2File(path + ".bz2"))
				System.out.println("BZipped file is found, using it instaed.");
			else if (!loadTextFile(path))
				System.err.println(path + " was not found!");
		}
	}

	private boolean loadHDFSFile(String path) {
//		Configuration conf = new Configuration();
//		conf.set("fs.defaultFS", me.zhishi.tools.Path.hdfs_fsName);
//		try {
//			FileSystem fs = FileSystem.get(URI.create(path), conf);
//			fin = fs.open(new Path(path));
//			stringReader = new BufferedReader(new InputStreamReader(fin));
//			System.out.println("Loading " + path);
//			return true;
//		} catch (IOException e) {
//			System.out.println(e);
//			return false;
//		}
		return false;
	}

	private boolean loadGZipFile(String path) {
		try {
			fin = new GZIPInputStream(new FileInputStream(path));
			stringReader = new BufferedReader(new InputStreamReader(fin,
					Charset.forName("UTF-8")));
			System.out.println("Loading " + path);
			return true;
		} catch (IOException e) {
			return false;
		}
	}

	private boolean loadZipFile(String path) {
		try {
			fin = new ZipInputStream(new FileInputStream(path));
			((ZipInputStream) fin).getNextEntry();
			stringReader = new BufferedReader(new InputStreamReader(fin,
					Charset.forName("UTF-8")));
			System.out.println("Loading " + path);
			return true;
		} catch (FileNotFoundException e) {
			return false;
		} catch (IOException e) {
			System.err.println(path + " has no entries!");
			return false;
		}
	}

	private boolean loadBZ2File(String path) {
//		try {
//			InputStream fileIS = new FileInputStream(path);
//			fileIS.read();
//			fileIS.read();
//			fin = new CBZip2InputStream(fileIS);
//			stringReader = new BufferedReader(new InputStreamReader(fin,
//					Charset.forName("UTF-8")));
//			System.out.println("Loading " + path);
//			return true;
//		} catch (IOException e) {
//			return false;
//		}
		return false;
	}

	private boolean loadTextFile(String path) {
		try {
			fin = new FileInputStream(path);
			stringReader = new BufferedReader(new InputStreamReader(fin,
					Charset.forName("UTF-8")));
			System.out.println("Loading " + path);
			return true;
		} catch (FileNotFoundException e) {
			return false;
		}
	}

	public NTriplesReader(ZipInputStream fin) {
		this.fin = fin;
		try {
			fin.getNextEntry();
		} catch (IOException e) {
			System.err.println("No entries!");
		}
		stringReader = new BufferedReader(new InputStreamReader(fin,
				Charset.forName("UTF-8")));
	}

	public NTriplesReader(InputStream fin) {
		this.fin = fin;
		stringReader = new BufferedReader(new InputStreamReader(fin,
				Charset.forName("UTF-8")));
	}

	/**
	 * Call this method to move to the next line.
	 * 
	 * @return
	 */
	public String readNextLine() {
		try {
			do {
				currentLine = stringReader.readLine();
			} while (currentLine != null && !currentLine.startsWith("<"));
			if (currentLine != null) {
				tripleReader = new TripleReader(currentLine);
			}
			return currentLine;
		} catch (NullPointerException e) {
			System.out.println(currentLine);
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		return null;
	}

	public String getCurrentLine() {
		return currentLine;
	}

	public TripleReader getTripleReader() {
		return tripleReader;
	}

	public void close() {
		try {
			stringReader.close();
			fin.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}