java - 使用 java.nio 时抛出 IllegalArgumentException

Question

尝试通过 url 下载文件。为此，使用 java.nio 库。上面的代码适用于 sdk 24 及以上版本，但对于 android sdk 23 及以下版本会出现 IllegalArgumentException。我在尝试传输数据时收到错误。亲爱的 friend ，请您澄清一下问题所在。

    private void downloadFile(final String itemUrl) {
        new Thread(new Runnable() {
            @Override
            public void run() {

                ReadableByteChannel readableByteChannel = null;
                FileOutputStream fOutStream = null;

                String root = 
                getApplicationContext().getApplicationInfo().dataDir;
                File myDir = new File(root + "/downloadedSongs");
                if (!myDir.exists()) {
                myDir.mkdirs();
                }

                File file = new File(myDir, itemTitle);
                if (file.exists()) {
                    file.delete();
                }

                try {
                    URL url = new URL(itemUrl);
                    readableByteChannel = 
                    Channels.newChannel(url.openStream());
                    fOutStream = new FileOutputStream(file);
      fOutStream.getChannel().transferFrom(readableByteChannel, 0, Long.MAX_VALUE);

                } catch (IOException e) {
                    orderAction = Enums.OrderAction.Delete;
                } catch (IllegalArgumentException e) {
                    orderAction = Enums.OrderAction.Delete;
                    Crashlytics.logException(e);
                } finally {
                    try {
                        if (fOutStream != null) {
                            fOutStream.close();
                        }
                        if (readableByteChannel != null) {
                           readableByteChannel.close();
                        }
                    } catch (IOException ioExObj) {
                        orderAction = Enums.OrderAction.Delete;
                    }
                    closeNotification(orderAction);
                }
            }
    }).start();
}

致命异常:java.lang.IllegalArgumentException:position=0 count=9223372036854775807 at java.nio.FileChannelImpl.transferFrom(FileChannelImpl.java:370) at am.itsoft.youtomp3.services.DnlService$1.run(DnlService.java :169) 在 java.lang.Thread.run(Thread.java:818)

Answer 1

原因就在这个参数中:Long.MAX_VALUE

正确代码:

FileChannel destChannel = fOutStream.getChannel();
long blockSize;
if (Build.VERSION.SDK_INT > 23) {
  long blockSize = Long.MAX_VALUE;
} else {
  long blockSize = 8*1024;
}
long position = 0;
long loaded;
while ((loaded = destChannel.transferFrom(readableByteChannel, position, blockSize)) > 0) {
   position += loaded;
}