android - 为什么我在访问电子表格时遇到网络主线程异常？

Question

我收到很多异常，例如 NetworkMainthread。是的，我已按照 https://developers.google.com/google-apps/spreadsheets/ 中的步骤进行操作

public class MainActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    String USERNAME = "xyz@gmail.com";
    String PASSWORD = "rrrrrrr";


    URL SPREADSHEET_FEED_URL = null;
    try {
        SPREADSHEET_FEED_URL = new URL("https://spreadsheets.google.com/feeds/spreadsheets/private/full");
        /*https://spreadsheets.google.com/feeds/spreadsheets/public/full");*/
    } catch (MalformedURLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    SpreadsheetService service = new SpreadsheetService("MySpreadsheetIntegration-v1");
    service.setProtocolVersion(SpreadsheetService.Versions.V3);
    try {
        service.setUserCredentials(USERNAME, PASSWORD);
    } catch (AuthenticationException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }


    SpreadsheetFeed feed = null;
    try {
        feed = service.getFeed(SPREADSHEET_FEED_URL,SpreadsheetFeed.class);
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (ServiceException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    List<SpreadsheetEntry> spreadsheets = feed.getEntries();
    SpreadsheetEntry spreadsheet = spreadsheets.get(0);
    System.out.println(spreadsheet.getTitle().getPlainText());
    WorksheetFeed worksheetFeed = null;
    try {
        worksheetFeed = service.getFeed(
                spreadsheet.getWorksheetFeedUrl(), WorksheetFeed.class);
    } catch (IOException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    } catch (ServiceException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    }
        List<WorksheetEntry> worksheets = worksheetFeed.getEntries();
        WorksheetEntry worksheet = worksheets.get(0);

        URL listFeedUrl = worksheet.getListFeedUrl();
        ListFeed listFeed = null;
        try {
            listFeed = service.getFeed(listFeedUrl, ListFeed.class);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (ServiceException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

       List<ListEntry> list = listFeed.getEntries();

        for (ListEntry row : list) {
            System.out.println(row.getTitle().getPlainText() + "\t" + row.getPlainTextContent());
        }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

Answer 1

NetWorkOnMaiNThread 异常发生是因为您试图在主 UI 线程中进行网络相关操作。这是不可能的。

http://developer.android.com/reference/android/os/NetworkOnMainThreadException.html

如果持续时间很短，您可以使用 asynctask。

http://developer.android.com/reference/android/os/AsyncTask.html

上面链接的引用

AsyncTasks 应该理想地用于短操作(最多几秒钟。)

您可以在 onPreExecute() 中显示进度对话框。在 doInBackground() 中执行网络相关操作。但不要从 doinBackground() 更新 ui(doInbackground() 在后台线程上运行)。在 doInBAckground() 中返回结果。 doInBackground() 的结果是 onPostExecute() 的参数。在 onPostExecute() 中关闭对话框并相应地更新用户界面。

也可以创建一个线程，做网络相关的操作。如果您创建线程，您需要注意不要从线程更新用户界面。 ui 应该在主 ui 线程上更新。

http://developer.android.com/reference/java/util/concurrent/Executor.html