Java - 檔案處理(2) - 複製檔案

在JDK1.4之前，複製檔案可以利用

(1) FileInputStream
(2) FileOutputStream
(3) read()

這三個關鍵方法來完成，程式如下:
        FileInputStream fis = null;
        FileOutputStream fos = null;
        try {
            fis  = new FileInputStream("/mnt/sdcard/xxx.apk");
            fos = new FileOutputStream("/mnt/sdcard/xxx2.apk");
            byte[] buf = new byte[1024];
            int i = 0;
            while ((i = fis.read(buf)) != -1) {
                fos.write(buf, 0, i);
            }
            if (fis != null) fis.close();
            if (fos != null) fos.close();
        }
        catch (Exception e) {
            e.printStackTrace();
        }

到了JDK1.4之後，有更具效率的新套件可以用。我們改用FileChannel的方式來實作程式:
        FileChannel fis = null;
        FileChannel fos = null;
        try {
            fis  = new FileInputStream("/mnt/sdcard/xxx.apk").getChannel();
            fos = new FileOutputStream("/mnt/sdcard/xxx2.apk").getChannel();
            fos.transferFrom(fis, 0, fis.size());
            if (fis != null) fis.close();
            if (fos != null) fos.close();
        }
        catch (Exception e) {
            e.printStackTrace();
        }