Java一个简单的文件工具集

class FileUtils
{
    //文件目录下文件总数目
    public static int fileNumber(File dir)
    {
        int filenumber = 0;
        if(dir.exists())
        {
            for(File file:dir.listFiles())
            {
                if(file.isDirectory())
                {
                    filenumber = filenumber+fileNumber(file);
                }
                else
                {
                    filenumber++;
                }
            }
        }
        return filenumber;
    }
    
    //判断文件是否为图片
    public static boolean isImage(File imgFilePath)
    {
        try
        {
            FileInputStream imgfis = new FileInputStream(imgFilePath);
            byte []imgbyte = new byte[imgfis.available()];
            if((imgfis.read(imgbyte))!=-1)
            {
                if(imgbyte[0] == (byte) 'G' && imgbyte[1] == (byte) 'I' && imgbyte[2] == (byte) 'F')
                {
                    return true;
                }
                else if(imgbyte[1] == (byte) 'P' && imgbyte[2] == (byte) 'N' && imgbyte[3] == (byte) 'G')
                {
                    return true;
                }
                else if(imgbyte[6] == (byte) 'J' && imgbyte[7] == (byte) 'F' && imgbyte[8] == (byte) 'I'&& imgbyte[9] == (byte) 'F')
                {
                    return true;
                }
                else
                {
                    return false;
                }
            }
        }catch(Exception e)
        {
            System.out.println(e.toString());
            return false;
        }
        return false;
    }


    //返回该目录下所有文件的文件数组
    public static File[] listAllDirectory(File dir)
    {
        if(dir!=null&&dir.exists())
        {
            File []finalfile = new File[fileNumber(dir)];
            int markfile =0;
            int fileln=0;
            File files[] = dir.listFiles();
            for(int i=0;i<files.length;i++)
            {
                if(files[i].isDirectory())
                {
                    listAllDirectory(files[i]);
                }
                else
                {
                    finalfile[markfile++]=files[i];
                }
            }
            return finalfile;
        }
        else
        {
            return null;
        }
    }

    
    //复制文件（用文件通道）
    public static void copyFile(File oldFileAbsolutePath,File newFilePath)
    {
        File newFileAbsolutePath = new File(newFilePath,oldFileAbsolutePath.getName());
        FileInputStream fi = null;
        FileOutputStream fo = null;
        FileChannel in = null;
        FileChannel out = null;
        try {
            fi = new FileInputStream(oldFileAbsolutePath);
            fo = new FileOutputStream(newFileAbsolutePath);
            in = fi.getChannel();
            out = fo.getChannel();
            in.transferTo(0, in.size(), out);
        } catch (IOException e)
            {
                e.printStackTrace();
            }
            finally
                {
                    try
                        {
                            fi.close();
                            in.close();
                            fo.close();
                            out.close();
                        } catch (IOException e)
                            {
                                e.printStackTrace();
                            }
                }
    }
}