1

我有一个用 http 查询条目填充我的 SQLite DB 的函数：

try {
        stringEntity = new StringEntity(SQL);
        httpPost.setEntity(stringEntity);
        httpResponse = httpClient.execute(httpPost);
        httpEntity = httpResponse.getEntity();
        bos = new ByteArrayOutputStream();
        httpEntity.writeTo(bos);

        data = bos.toString();

        reader = new BufferedReader(
                  new StringReader(data));

        try {
            //SAVE DATA IN MY DB || WORKS
        } catch(IOException e) {
          e.printStackTrace();
        }

    } catch (IOException e3) {
        // TODO Auto-generated catch block
        e3.printStackTrace();
    }

我尝试做的是在程序开始之前在我的活动上设置文本视图的文本（在我发布的代码中的第一个“try { ..”之前）。但文本不会改变，因为我的活动太忙而无法获取数据（我想。我没有其他解释..）

有什么建议么？

谢谢，prexx

UPDATE '' 从 AsyncTask 获取数据 ''

 txtAction.setText("Loading...");

    AsyncTask<String, String, String> test = new cAsyncTask();

    try {
        data = test.execute(URL).get();

        reader = new BufferedReader(
                  new StringReader(data));

        while ((line = reader.readLine()) != null) {
            //SAVE DATA IN DB || WORKS
            }
        }

    } catch(IOException e) {
      e.printStackTrace();
    } catch (InterruptedException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (ExecutionException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

我的异步任务：

class cAsyncTask extends AsyncTask<String, String, String> {

protected String doInBackground(String... urls) {
    int count = urls.length;
    String data = "";
    DefaultHttpClient httpClient = new DefaultHttpClient();
    HttpPost httpPost;
    StringEntity stringEntity;
    HttpResponse httpResponse;
    HttpEntity httpEntity;
    ByteArrayOutputStream bos;
    String line;
    BufferedReader reader;
    for (int i = 0; i < count; i++) {
        httpPost = new HttpPost(urls[i].toString());
        try {
            stringEntity = new StringEntity(SQL);
            httpPost.setEntity(stringEntity);
            httpResponse = httpClient.execute(httpPost);
            httpEntity = httpResponse.getEntity();
            bos = new ByteArrayOutputStream();
            httpEntity.writeTo(bos);

            data = bos.toString();

        } catch (IOException e3) {
            // TODO Auto-generated catch block
            e3.printStackTrace();
        }
    }
    return data;
}

protected void onProgressUpdate(String... progress) {

}

protected void onPostExecute(String result) {
    String test = result;
}
4

3 回答 3

4

将代码的繁忙部分放入一个单独的线程中。

查看AsyncTask实用程序

AsyncTask.execute()之后打电话textview.setText("foo")，你会没事的:)

问候

更新代码示例：

 txtAction.setText("Loading...");
 AsyncTask<String, String, String> test = new cAsyncTask();
 test.execute("http://...");

class cAsyncTask extends AsyncTask<String, String, String> {

protected String doInBackground(String... urls) {
    int count = urls.length;
    String data = "";
    DefaultHttpClient httpClient = new DefaultHttpClient();
    HttpPost httpPost;
    StringEntity stringEntity;
    HttpResponse httpResponse;
    HttpEntity httpEntity;
    ByteArrayOutputStream bos;
    String line;
    BufferedReader reader;
    for (int i = 0; i < count; i++) {
        httpPost = new HttpPost(urls[i].toString());
        try {
            stringEntity = new StringEntity(SQL);
            httpPost.setEntity(stringEntity);
            httpResponse = httpClient.execute(httpPost);
            httpEntity = httpResponse.getEntity();
            bos = new ByteArrayOutputStream();
            httpEntity.writeTo(bos);

            data = bos.toString();

        } catch (IOException e3) {
            // TODO Auto-generated catch block
            e3.printStackTrace();
        }
    }
     reader = new BufferedReader(
                  new StringReader(data));
       String line = "";
        while ((line = reader.readLine()) != null) {
            //SAVE DATA IN DB || WORKS
     }
    return data;
}


protected void onPostExecute(String result) {
    String test = result;
   textView.setText("Done!");
}

}

关键是将所有繁忙的代码放入doInBackGround将在单独的线程中运行的方法中。所有 UI 修改必须在同一个 UI 线程中，这可以在onPostExecute将在同一个 UI 线程中执行的方法中完成

于 2011-06-13T15:12:40.993 回答
0

您可以尝试在 TextView 上调用 invalidate()。但是对于繁重的数据加载方法，使用异步任务是最佳实践。这不会中断用户操作 UI 控件。

于 2011-06-13T15:19:11.767 回答
0

它与“太忙”无关，而是只有在方法返回时才会设置文本。并且随着您的网络，这将被延迟。

顺便提一句。在 UI 线程上的 Honeycomb 网络上将引发异常并终止您的应用程序。

于 2011-06-13T15:37:38.413 回答