CSVFileSpliter.java

package org.molgenis.lifelinesresearchportal.plugins.loader.ThreadReaders;

import java.io.BufferedReader;
import java.io.FileReader;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.molgenis.util.SimpleTuple;

public class CSVFileSpliter
{

	private final BufferedReader br;
	private final int maxNumRows;
	private int splitKeyIndex;
	private final String[] headers;

	private List<String[]> leftOver = new ArrayList<String[]>();
	private boolean hasMore = true;

	public CSVFileSpliter(String fileName, int maxNumRows, int splitKeyIndex) throws Exception
	{
		this.br = new BufferedReader(new FileReader(fileName));
		this.maxNumRows = maxNumRows;
		this.splitKeyIndex = splitKeyIndex;

		this.headers = br.readLine().replace("\"", "").split("\\,");
	}

	public CSVFileSpliter(String fileName, int maxNumRows, String splitFieldName) throws Exception
	{
		this(fileName, maxNumRows, -1);
		for (int i = 0; i < headers.length; ++i)
		{
			if (headers[i].toLowerCase().equals(splitFieldName.toLowerCase()))
			{
				splitKeyIndex = i;
				break;
			}
		}
		if (splitKeyIndex == -1)
		{
			throw new IllegalArgumentException(String.format("Couldn't find fieldName '%s' in file '%s'",
					splitFieldName, fileName));
		}
	}

	public synchronized List<String[]> getLines() throws Exception
	{
		List<String[]> result = new ArrayList<String[]>(maxNumRows);

		if (!leftOver.isEmpty()) result.addAll(leftOver);

		while (br.ready())
		{
			String line = br.readLine();
			String[] parts = line.split("\\,");

			result.add(parts);

			if (result.size() > maxNumRows)
			{
				break;
			}
		}
		if (!br.ready())
		{
			hasMore = false;
		}

		if (hasMore)
		{
			String lastSplitKey = result.get(result.size() - 1)[splitKeyIndex];
			for (int i = result.size(); i >= 0; --i)
			{
				if (!result.get(i - 1)[splitKeyIndex].equals(lastSplitKey))
				{
					leftOver = result.subList(i, result.size());
					result = result.subList(0, i);

					break;
				}
			}
		}
		return result;
	}

	public synchronized List<SimpleTuple> getTuples() throws Exception
	{
		List<String[]> lines = getLines();
		List<SimpleTuple> simpleTuples = new ArrayList<SimpleTuple>(lines.size());
		for (String[] line : lines)
		{
			Map<String, Object> valueMap = new HashMap<String, Object>(headers.length);
			for (int i = 0; i < line.length; ++i)
			{
				valueMap.put(headers[i], line[i]);
			}
			simpleTuples.add(new SimpleTuple(valueMap));
		}
		return simpleTuples;
	}

	public synchronized boolean hasMore()
	{
		return hasMore;
	}

	public void close() throws Exception
	{
		br.close();
	}

	public String[] getHeaders()
	{
		return headers;
	}
}