文件字节大小显示成M,G和K

//字节大小，K,M,G  
public static final long KB = 1024;  
public static final long MB = KB * 1024;  
public static final long GB = MB * 1024;  
  
/** 
 * 文件字节大小显示成M,G和K  
 * @param size 
 * @return 
 */  
public static String displayFileSize(long size) {  
    if (size >= GB) {  
        return String.format("%.1f GB", (float) size / GB);  
    } else if (size >= MB) {  
        float value = (float) size / MB;  
        return String.format(value > 100 ? "%.0f MB" : "%.1f MB", value);  
    } else if (size >= KB) {  
        float value = (float) size / KB;  
        return String.format(value > 100 ? "%.0f KB" : "%.1f KB", value);  
    } else {  
        return String.format("%d B", size);  
    }  
}