Question

我用它连接到互联网并检索页面源，非常简单：

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_update_library);
    String data = "";

    if(!isNetworkAvailable()){
        TextView tv = (TextView) findViewById(R.id.placeholder);
        tv.setText("No Connection!!!");
        return;
    }

    try{
        URL url = null;
        url = new URL("http://google.com");
        URLConnection conn = url.openConnection();
        BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
        String line = "";
        while((line = reader.readLine()) != null){
            data += line;
        }
        TextView tv = (TextView) findViewById(R.id.placeholder);
        tv.setText(data);
    }catch(Exception e){
        TextView tv = (TextView) findViewById(R.id.placeholder);
        tv.setText("error : "+e.toString());
    }
}

但数据不会从互联网上回来。有什么问题？

Answer 1

您需要在后台任务中放置从互联网检索数据的代码，以便在服务或AsyncTask中。

Answer 2

尝试以下代码： -

TextView tv = (TextView) findViewById(R.id.placeholder);
if(!isNetworkAvailable()){

    tv.setText("No Connection!!!");
    new ChangePasswordAsyncTask().execute();
    return;
}


private class ConnectToServer extends AsyncTask<String, String, String>
{
    private String data;

    @Override
    protected void onPreExecute()
    {
        super.onPreExecute();
    }

    @Override
    protected String doInBackground(String... params)
    {

        try
        {
            // do stuff from server
                  URL url = null;
                  url = new URL("http://google.com");
                 URLConnection conn = url.openConnection();
                  BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
                  String line = "";
                 while((line = reader.readLine()) != null){
                     data += line;
                 }
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
        return data;
    }

    @Override
    protected void onProgressUpdate(String... values)
    {
        // TODO Auto-generated method stub
        super.onProgressUpdate(values);
    }

    @Override
    protected void onPostExecute(String result)
    {
        super.onPostExecute(result);
        // String jData = "";
        try
        {
            // set UI on this method

               tv.setText(data);
        }
        catch (Exception e)
        {
            e.printStackTrace();
            // Toast.makeText(context, jMessage, Toast.LENGTH_LONG).show();
        }
    }
}

Answer 3

您是否有权使用清单访问INTERNET？

无法从android中检索互联网上的数据

3 个答案: