如何将 BackgroundWorker 的结果设置为 TextView

Posted 2023-05-07

【中文标题】如何将 BackgroundWorker 的结果设置为 TextView

【英文标题】：how to set result of BackgroundWorker to TextView

【发布时间】：2017-06-28 21:44:48

【问题描述】：

我对 android 非常陌生，无法将数据库中的结果输入屏幕上的TextView。目前，我的应用程序在单击按钮后返回一条消息。我在屏幕上有两个TextView 元素txtViewBegin 和txtViewEind。从mysql（通过php）我得到一个像22-02-2014 24-05-2017 这样的字符串，我将其拆分为Strings (.split(" ")) 的数组。

我可以使用后台工作人员的setTextView（onPostExecute 吗？）

或者我应该在我的MainActivity 中这样做吗？在这方面仍然是菜鸟。对不起。

这是我的BackgroundWorker：

public class BackgroundWorker extends AsyncTask<String,Void,String> 
Context context;
AlertDialog alertDialog;
BackgroundWorker(Context ctx)
    context = ctx;



@Override
protected String doInBackground(String... params) 
    String type = params[0];
    String login_url= "http://*************/****.php";
    if(type.equals("Draai"))
        try 
            URL url = new URL(login_url);
            HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
            httpURLConnection.setRequestMethod("POST");
            httpURLConnection.setDoOutput(false);
            httpURLConnection.setDoInput(true);
            //OutputStream outputStream = httpURLConnection.getOutputStream();
            //BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(outputStream,"UTF-8"));
            //String post_data = URLEncoder.encode("user_name""UTF-8")// HIER KUN JE VARIABELEN INGEVEN DIE WORDEN GEIMPLEMENTEERD IN HET PHP DOCUMENT
            //bufferedWriter.write();
            //bufferedWriter.flush();
            // bufferedWriter.close();
            //outputStream.close();
            InputStream inputStream = httpURLConnection.getInputStream();
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream, "iso-8859-1"));
            String result ="";
            String line="";
            while ((line=bufferedReader.readLine()) != null)
                result += line;
            
            String[] separated = result.split(" ");
            bufferedReader.close();
            inputStream.close();
            httpURLConnection.disconnect();
            return result;

         catch (MalformedURLException e) 
            e.printStackTrace();
         catch (IOException e) 
            e.printStackTrace();
         catch (Exception e)
            e.printStackTrace();
        
    
    return null;


@Override
protected void onPreExecute() 
        alertDialog = new AlertDialog.Builder(context).create();
        alertDialog.setTitle("TijdsDuur");


@Override
protected void onPostExecute(String result) 
    alertDialog.setMessage(result);
    alertDialog.show();


@Override
protected void onProgressUpdate(Void... values) 
    super.onProgressUpdate(values);

还有我的MainActivity:

public class MainActivity extends AppCompatActivity 
TextView ViewBegin, ViewEind;

@Override
protected void onCreate(Bundle savedInstanceState) 
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    ViewBegin = (TextView) findViewById(R.id.txtViewBegin);
    ViewEind = (TextView) findViewById(R.id.txtViewEind);


public void onDraai(View view)
    String type = "Draai";

    BackgroundWorker backgroundWorker = new BackgroundWorker(this);
    backgroundWorker.execute(type);

【参考方案1】：

1.) 在您的BackgroundWorker 中为回调创建一个interface

public interface DataCallBack
     void onDataReceived(String s);

2.) 在 Activity 中实现该回调接口

public class MainActivity extends AppCompatActivity implements BackgroundWorker.DataCallBack 

3.) 任务完成后，通知您的活动并显示数据

你的MainActivity 看起来像

public class MainActivity extends AppCompatActivity implements BackgroundWorker.DataCallBack 
TextView ViewBegin, ViewEind;

  // .....code

    @Override
    void onDataReceived(String s)
         if(s!=null)
            String[] separated = result.split(" ");
            ViewBegin.setText(separated[0]);  
            ViewEind.setText(separated[1]);  
             
    

  // .....code

你的 BackgroundWorker 类看起来像

public class BackgroundWorker extends AsyncTask<String,Void,String> 
    Context context;
    AlertDialog alertDialog;
    DataCallBack callback;

    BackgroundWorker(Context ctx)
        context = ctx;

        // initialize the callback reference
        callback = (DataCallBack) cxt;
    

    public interface DataCallBack
         void onDataReceived(String s);
    

    // .....code

    @Override
    protected void onPostExecute(String result) 
        callback.onDataReceived(result);
        // ^^^ send data to Activity

        alertDialog.setMessage(result);
        alertDialog.show();
    

    // .....code