NetworkOnMainThread误差仍然存在

Question

我正在试用firebase，并希望从桶中读取一个文本文件。我可以将文件复制到本地磁盘，这样可以正常工作。现在，我想读取文本文件并将内容复制到数组中。这一次我得到了NetworkOnMainThread，尽管我启动了一个新线程来完成这项工作。至少我认为我是，我读过关于使用Asynchtask的文章，但是想知道为什么它不能像预期的那样工作。过去，获取InputstreamfromURL的代码运行良好。

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_download);
    downloadtext = (TextView) findViewById(R.id.downloadtext);
    text = new ArrayList<>();
    listViewText = (ListView) findViewById(R.id.listViewtext);
    listViewText.setAdapter(new ArrayAdapter(getApplicationContext(), android.R.layout.simple_list_item_1, text));

    Thread thread= new Thread(){
        public void run() {
            storage = FirebaseStorage.getInstance();
            storageRef = storage.getReferenceFromUrl("gs://fir-test-68815.appspot.com");
            filename = "testfile.txt";
            StorageReference file = storageRef.child(filename);

            file.getDownloadUrl().addOnSuccessListener(new OnSuccessListener<Uri>() {
                @Override
                public void onSuccess(Uri uri) {
                    Log.d(MainActivity.TAG, "URL =" + uri.toString());
                    try {
                        InputStream is = getInputStreamFromURL(uri);
                        text = getText(is);
                        textReady.post(new Runnable() {
                            @Override
                            public void run() {
                                ((ArrayAdapter)listViewText.getAdapter()).notifyDataSetChanged();
                            }
                        });
                    } catch (IOException e) {
                        e.printStackTrace();
                    }

                }
            });


        }
        private ArrayList<String> getText(InputStream is) throws IOException {
            ArrayList<String> text = new ArrayList<>();
            BufferedReader reader = null;
            reader = new BufferedReader(new InputStreamReader(is, "UTF-8"));
            String line;
            while ((line = reader.readLine()) != null) {
                text.add(line);
            }
            return text;
        }

        private InputStream getInputStreamFromURL(Uri urlToGet) throws IOException {
            InputStream is = null;
            URL downloadURL = new URL(urlToGet.toString());
            HttpURLConnection conn = (HttpURLConnection) downloadURL.openConnection();
            conn.setReadTimeout(10000 /* milliseconds */);
            conn.setConnectTimeout(15000 /* milliseconds */);
            conn.setRequestMethod("GET");
            conn.setDoInput(true);
            // Starts the query
            conn.connect();
// next two lines produce the error
            int response = conn.getResponseCode();
            is = conn.getInputStream();
            return is;
        }
    };
    thread.start();
    textReady = new Handler();

}

Answer 1

Firebase事件回调是默认情况下，在主UI线程上调用。在OnSuccessListener中也会发生这种情况。

还有使用Firebase下载文件的其他方法。但是，如果仍然希望使用getDownloadUrl()，则需要在getDownloadUrl()回调触发后在单独的线程(例如使用AsyncTask)上实现下载。