FileUtils.java

package gitj.utils;

import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.ArrayList;
import java.util.List;

import git.Repository;

public class FileUtils {

	public static String getRepoPath(File file, Repository repo) {
		String path = file.getAbsolutePath();

		path = path.replace(repo.getFolder().getAbsolutePath(), "").replace("\\", "/");

		if (path.startsWith("/")) {
			path = path.substring(1, path.length());
		}

		return path;
	}

	public static File fromRepoPath(String path, Repository repo) {
		return new File(repo.getFolder(), path);
	}

	public static File writeToTempFile(String contents) throws Exception {
		File file = File.createTempFile("tmp", ".txt");

		BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file)));
		writer.write(contents);
		writer.close();

		return file;
	}

	public static List<String> readFile(File file) throws Exception {
		List<String> lines = new ArrayList<String>();

		BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream(file)));

		String line;

		while ((line = reader.readLine()) != null) {
			lines.add(line);
		}

		reader.close();

		return lines;
	}

	/**
	 * https://stackoverflow.com/questions/453018/number-of-lines-in-a-file-in-java
	 * 
	 * 6 times faster than BufferedReader.readLine()
	 * @param filename
	 * @return
	 * @throws Exception
	 */
	public static int countLines(File file) throws Exception {
		BufferedInputStream is = new BufferedInputStream(new FileInputStream(file));
		byte[] c = new byte[1024];
		int count = 0;
		int readChars = 0;
		boolean empty = true;
		while ((readChars = is.read(c)) != -1) {
			empty = false;
			for (int i = 0; i < readChars; ++i) {
				if (c[i] == '\n') {
					++count;
				}
			}
		}
		is.close();

		return (count == 0 && !empty) ? 1 : count;
	}

}