android - 尝试上传到 Dropbox : NetworkOnMainThreadException?

Question

我现在已经为此奋斗了大约 6 个小时。我遵循了 Dropbox 的“教程”(如果他们可以这样称呼，因为他们非常糟糕)，玩过 DBRoulette 示例，并做了很多事情来让我的应用程序正常工作。

我的应用程序可以毫无问题地进行身份验证。但是我无法上传任何内容，尽管完全按照教程中的内容进行操作:

这是我的一小段代码(这是为了将创建的笔记保存在手机上，然后上传到 Dropbox):

        saveBtn.setOnClickListener(new OnClickListener()
    {
        @Override
        public void onClick(View view)
        {
            try
            {
                //Create the directory if it doesn't exist. If it does exist the next two line won't do anything.
                File dropNotesDir = new File(Environment.getExternalStorageDirectory() + "/documents/AppData/Dropnotes/");
                dropNotesDir.mkdirs();
                //-----------------------------------------------------------------------------------------------
                String wholeNoteString = noteBody.getText().toString();
                //Now we create the title of the txt file. It will be the first line of the whole note. The name will get truncated to 32 characters
                //if it's too long.
                String noteTitle;
                if(wholeNoteString.indexOf("\n") >= 0) //New line character found.
                {
                    noteTitle = wholeNoteString.substring(0, wholeNoteString.indexOf("\n"));
                    if(noteTitle.length() >= 32)
                    {
                        noteTitle = wholeNoteString.substring(0, 32);
                    }
                }
                else
                {
                    if(wholeNoteString.length() >= 32)
                    {
                        noteTitle = wholeNoteString.substring(0, 32);
                    }else
                    {
                        noteTitle = wholeNoteString;
                    }
                }
                if(extras.getString("file-mode").equals("modify"))
                {
                    //We will need to delete the existing file if it does exist to save the new one.
                    File existing = new File(Environment.getExternalStorageDirectory() + "/documents/AppData/Dropnotes/" + extras.getString("noteTitle"));
                    existing.delete();
                }
                File newNote = new File(Environment.getExternalStorageDirectory() + "/documents/AppData/Dropnotes/" + noteTitle + ".txt");
                PrintWriter newNoteWriter = new PrintWriter(new FileOutputStream(newNote));
                newNoteWriter.print(noteBody.getText().toString());
                newNoteWriter.close();

                //TRYING TO UPLOAD TO DROPBOX HERE
                File fileToUpload = new File(Environment.getExternalStorageDirectory() + "/documents/AppData/Dropnotes/" + noteTitle + ".txt");
                FileInputStream file2Uis = new FileInputStream(fileToUpload);
                Entry newEntry = mDBApi.putFile("/" + noteTitle + ".txt", file2Uis, fileToUpload.length(), null, null);
                //END OF TRYING TO UPLOAD TO DROPBOX HERE

                Toast.makeText(view.getContext(), "Saved successfully", Toast.LENGTH_SHORT).show();
                finish();
            } catch (FileNotFoundException e)
            {
                Toast.makeText(view.getContext(), "File not found: " + e.getMessage(), Toast.LENGTH_SHORT).show();
                e.printStackTrace();
            } catch(Exception e)
            {
                Toast.makeText(view.getContext(), "Some bizarre exception occured: " + e.getClass().toString(), Toast.LENGTH_SHORT).show();
                e.printStackTrace();
            }
        }

    });

它给了我一个 NetworkOnMainThreadException，我不知道为什么。我正在尝试按照标题为“上传文件”的部分进行操作 here .他们的代码 fragment 让我感到困惑的是，他们甚至没有试图捕捉我抛出的异常......

有什么帮助吗？我真的需要在下周五完成这项工作。

Answer 1

在Honeycomb SDK之前，允许在主线程进行网络操作。但是，对于 Honeycomb，它不再被允许并且 NetworkOnMainThreadException如果在主/UI 线程中尝试网络操作，则抛出。

您需要在不同的线程中执行网络操作。你可以看看AsyncTask实现相同的目标。