android - 异步任务 "Only the original thread that created a view hierarchy can touch its views."

Question

我尝试跨 AsyncTaks 修改 Spinner 内容，但我不能，Logcat 写为“09-19 16:36:11.189: ERROR/ERROR THE(6078): 只有创建 View 层次结构的原始线程可以触摸它的 View 。”。

public class GetGroups extends AsyncTask<Void, Void, Void> {

    @Override
    protected Void doInBackground(Void... params) {
        Spinner combo = (Spinner) findViewById(R.id.group_combo);

        setGroups(combo);

        return null;
    }

    @Override
    protected void onPostExecute(Void unused)
    {
        super.onPostExecute(unused);


        Spinner combo = (Spinner) findViewById(R.id.severity_combo);

        combo.setSelection(1);

        //updateGroups();
        //if (!isFinishing())
        //{
            /*Spinner combo = (Spinner) findViewById(R.id.group_combo);
            ProgressBar pg = (ProgressBar) findViewById(R.id.loading_group);

            pg.setVisibility(ProgressBar.GONE);
            combo.setVisibility(Spinner.VISIBLE);

            combo.setSelection(0);*/
        //}
    }
}
}

函数setGroups是:

 public void setGroups(Spinner combo) {

    try {
        DefaultHttpClient httpClient = new DefaultHttpClient();

        HttpPost httpPost = new HttpPost(this.object.url);

        List<NameValuePair> parameters = new ArrayList<NameValuePair>(2);
        parameters.add(new BasicNameValuePair("user", this.object.user));
        parameters.add(new BasicNameValuePair("pass", this.object.password));
        parameters.add(new BasicNameValuePair("op", "get"));
        parameters.add(new BasicNameValuePair("op2", "groups"));
        parameters.add(new BasicNameValuePair("other_mode", "url_encode_separator_|"));
        parameters.add(new BasicNameValuePair("return_type", "csv"));
        parameters.add(new BasicNameValuePair("other", ";"));

        UrlEncodedFormEntity entity = new UrlEncodedFormEntity(parameters);

        httpPost.setEntity(entity);

        HttpResponse response = httpClient.execute(httpPost);
        HttpEntity entityResponse = response.getEntity();

        String return_api = this.object.convertStreamToString(entityResponse.getContent());

        String[] lines = return_api.split("\n");

        ArrayList<String> array = new ArrayList<String>();

        for (int i= 0; i < lines.length; i++) {
            String[] groups = lines[i].split(";", 21);

            this.pandoraGroups.put(new Integer(groups[0]), groups[1]);

            array.add(groups[1]);
        }

        ArrayAdapter<String> spinnerArrayAdapter = new ArrayAdapter<String>(this,
            android.R.layout.simple_spinner_item,
            array);
        combo.setAdapter(spinnerArrayAdapter);
    }
    catch (Exception e) {
        Log.e("ERROR THE ", e.getMessage());

        return;
    }
}

怎么了？谢谢。

Answer 1

正如 Peter 所提到的，您无法使用 doInBackground() 访问 View 。但是，您可以在 onPostExecute() 中执行此操作。据我所知，这就是您应该处理 doInBackground() 返回结果的地方。

我遇到了这个问题，并通过将 View 修改代码移动到 onPostExecute() 来修复它。

致那些刚开始接触 Android 开发的人:
- doInBackground():与您的 View /fragment/Activity 运行的主线程/原始线程不同的另一个线程(在后台)发生的任何内部情况(这是 AsyncTask< 的重点 ==> 你不能触摸 View !
- onPostExecute():现在后台工作已经完成，这里它回到了主/线程线程 ==> 你现在可以触摸 View 了!