在Android中将文件从内部存储复制到外部存储

Question

private void copyFile(File src, File dst) throws IOException {

    File from = new File(src.getPath());
    File to = new File(dst.getPath());
    from.renameTo(to);
}

private void copyFile(File src, File dst) throws IOException {

    FileChannel inChannel = null;
    FileChannel outChannel = null;

    try {
        inChannel = new FileInputStream(src).getChannel();
        outChannel = new FileOutputStream(dst).getChannel();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    }

    try {
        inChannel.transferTo(0, inChannel.size(), outChannel);
    } finally {
        if (inChannel != null)
            inChannel.close();
        if (outChannel != null)
            outChannel.close();
    }
}

private void copyFile(File src, File dst) throws IOException {

    FileInputStream inStream = new FileInputStream(src);

    if (!dst.exists()) {
        dst.mkdir();
    }

    if (!dst.canWrite()) {
        System.out.print("CAN'T WRITE");
        return;
    }

    FileOutputStream outStream = new FileOutputStream(dst);
    FileChannel inChannel = inStream.getChannel();
    FileChannel outChannel = outStream.getChannel();
    inChannel.transferTo(0, inChannel.size(), outChannel);
    inStream.close();
    outStream.close();
}

这些方法都不能解决我的任务。中检查了一些相关主题，我发现的唯一建议是验证

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

在androidmanifest.xml中，并且它仍然存在。

方法#1完成执行，但没有复制文件夹和文件。

因为这是我迈向Android的第一步，我觉得我错过了一些小东西。请告诉我，如何在Android中将文件从一个文件夹复制到另一个文件夹，包括文件从内部内存移动到外部内存。

Answer 1

我解决了我的问题。问题出现在目标路径中，在原始代码中：

File dst = new File(dstPath);

变量dstpath具有完整的目标路径，包括文件名，这是错误的。下面是正确的代码片段：

String dstPath = Environment.getExternalStorageDirectory() + File.separator + "myApp" + File.separator;
File dst = new File(dstPath);

exportFile(pictureFile, dst);

private File exportFile(File src, File dst) throws IOException {

    //if folder does not exist
    if (!dst.exists()) {
        if (!dst.mkdir()) {
            return null;
        }
    }

    String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
    File expFile = new File(dst.getPath() + File.separator + "IMG_" + timeStamp + ".jpg");
    FileChannel inChannel = null;
    FileChannel outChannel = null;

    try {
        inChannel = new FileInputStream(src).getChannel();
        outChannel = new FileOutputStream(expFile).getChannel();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    }

    try {
        inChannel.transferTo(0, inChannel.size(), outChannel);
    } finally {
        if (inChannel != null)
            inChannel.close();
        if (outChannel != null)
            outChannel.close();
    }

    return expFile;
}

谢谢你的提示。