byteformatter.java

MyDownloader 是一款使用 http 协议(RFC 1867)用于下载一个或多个文件到本地的简单易用的收费 Java 程序.使用托拽操作,你可以在一个页面内下载多个文件.在下载文件的过程当中

/*
 * Copyright 2005-2007 JavaAtWork All rights reserved.
 * Use is subject to license terms.
 */
package com.javaatwork.mydownloader.utils;

import java.text.DecimalFormat;

/**
 * Class for formatting bytes to a String representation (b, Kb, Mb).
 * 
 * @author Johannes Postma
 */
public class ByteFormatter {

	private static DecimalFormat formatter = new DecimalFormat("#.00");
	
	/** 
	 * Formats bytes in a String representation in b, Kb, Mb or Gb.
	 * When the format is MB or Gb the format has two decimals. 
	 * 
	 * @param bytes The bytes.
	 * @return The String representation.
	 */
	public static String format(long bytes) {		
		
		// bytes
		if (bytes < 1024) {
			return Long.toString(bytes) + " b";
		} 
		
		// kilo bytes
		else if (bytes < (1024 * 1024)) {
			double bytesSent = bytes / 1024.0;
			return Math.round(bytesSent) + " Kb";
		}
		
		// mega bytes
		else if (bytes < (1024 * 1024 * 1024)) {
			
			double bytesSent = bytes / (1024.0 * 1024.0);
			return formatter.format(bytesSent) + " Mb";
		} 
		
		// giga bytes
		else {
			double bytesSent = bytes / (1024.0 * 1024.0 * 1024.0);
			return formatter.format(bytesSent) + " Gb";
		}
	}
	
	/**
	 * Formats bytes in a String representation in Kb. 
	 * 
	 * @param bytes The bytes.
	 * @return The String representation.
	 */
	public static String formatToKiloBytes(int bytes) {
		double bytesSent = bytes / 1024.0;
		
		if (bytesSent < 1.0) {
			return "1 Kb";
		} else {
			return Long.toString(Math.round(bytesSent)) + " Kb";
		}
	}
}