android - 从异步线程更新主线程表布局

Question

我在从异步类更新表格布局时遇到问题。我的异步类正在获取 XML 数据，因此我不会阻塞主线程。我的日志显示 XML 数据正在通过，但我不知道如何使用这些数据更新我的 View 。

因此，我尝试将数据放入表格行中并将行添加到 TableLayout，但日志显示错误提示不允许 Async 类更新我的 TableLayout View 。

我的代码如下:

public class RemotePrimary extends Activity {

private static String SERVER_PATH   =   "http://test2.icerge.com/";
private static String XML_FILE1     =   "samplexml";

//private static String SERVER_PATH =   "http://tqs.mamlambo.com/";
//private static String XML_FILE1       =   "scores.jsp";

private String[] data               =   new String[10];

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    TableLayout datatable           =   (TableLayout)findViewById(R.id.TableLayout_data);

    Downloader downloader   =   new Downloader();
    downloader.execute(SERVER_PATH + XML_FILE1, datatable);

}

private class Downloader extends AsyncTask<Object, String, Boolean>{

    TableLayout table;

    @Override
    protected Boolean doInBackground(Object... params) {
        // TODO Auto-generated method stub
        String path             =   (String)params[0];
        table                   =   (TableLayout)params[1];

        XmlPullParser xmldata   =   null;
        try {
            URL serverPath      =   new URL(path);
            xmldata             =   XmlPullParserFactory.newInstance().newPullParser();
            xmldata.setInput(serverPath.openStream(), null);
            addRecord(xmldata, table);
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        return true;
    }

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

    private boolean addRecord(XmlPullParser data, TableLayout table){

        int eventType                   =   -1;
        boolean bFoundScores            =   false;


        //find some records from xml
        while(eventType != XmlResourceParser.END_DOCUMENT){
            if( eventType == XmlResourceParser.START_TAG ){
                //get the name of the tag(eg scores or score)
                String strName  =   data.getName();
                if( strName.equals("node") ){
                    bFoundScores            =   true;
                    String scoreValue       =   data.getAttributeValue(null, "Title");
                    String scoreRank        =   data.getAttributeValue(null, "Type");
                    String scoreUserName    =   data.getAttributeValue(null, "Nid");
                    Log.e("ADDING: ", scoreValue);
                    //Log.e("RETRIEVED", "collected : "+scoreValue+", "+scoreRank+", "+scoreUserName);
                    //publishProgress(scoreValue, scoreRank, scoreUserName);

                    TableRow newRow     =   new TableRow(RemotePrimary.this);
                    TextView rowText    =   new TextView(RemotePrimary.this);
                    rowText.setText(scoreValue);
                    newRow.addView(rowText);
                    table.addView(newRow);
                }
            }
            try {
                eventType   =   data.next();
            } catch (XmlPullParserException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }



        return true;
    }

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

    @Override
    protected void onPostExecute(Boolean result) {
        // TODO Auto-generated method stub
        super.onPostExecute(result);
    }

}//close Downloader class

}//关闭RemotePrimary类

我知道的有点多，但我会很感激任何帮助。

非常感谢:-)

Answer 1

您只能在 UI 线程上从 UI 进行更改。 AsyncTask 为您提供了一个通过 onPostExecute 轻松执行此操作的地方。正如它在 docs 中所说的那样, onPostExecute 始终在 UI 线程上执行。

在 doInBackground 中，完成构建要显示的结构化数据的所有艰苦工作。返回该数据，以便将其传递到 onPostExecute，然后在其中添加适当的表行。