是的,我认为就目前而言,您应该认为我是一个彻头彻尾的菜鸟,我有点不知所措。
我试图从几个部分教程中拼凑出我对此的理解,每个教程都涉及我想做的不同方面。
总而言之,我想做的就是从 URL 中读取文本以显示在 TextView 中,我的理解是自 3.0 更新以来我需要一个 AsyncTask 来执行此操作。
任何关于我出错的地方的帮助都会很棒,因为我不明白是什么导致了错误以及如何修复。
我确实知道 doInBackground 的 try 和 catch 中包含的代码在 3.0 更新之前可以自行运行。这是否也需要修改以与 Async 一起使用,但我不知道。
我还认为,一旦解决了这个问题,其他问题可能会出现,如果有人发现一些明显的问题,如果您能指出,我将不胜感激。
String Event;
TextView eventText;
TextView titleText;
String HTML;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.newevent);
titleText = (TextView) findViewById(R.id.Title);
eventText = (TextView) findViewById(R.id.Event);
new eventupdate().execute();
}
public class eventupdate extends AsyncTask<String, Void, Void> {
@Override
protected Void doInBackground(String... url) {
try {
Thread.sleep(4000);
HttpClient httpClient = new DefaultHttpClient();
HttpContext localContext = new BasicHttpContext();
HttpGet httpGet = new HttpGet(
"http://masterzangetsu.eu/Apps/rocksoctest"); // URL!
HttpResponse response = httpClient.execute(httpGet,
localContext);
String result = "";
BufferedReader reader = new BufferedReader(
new InputStreamReader(response.getEntity().getContent()));
String line = null;
while ((line = reader.readLine()) != null) {
result += line + "\n";
HTML = result;
}
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
eventText.setText("" + HTML);
// TODO Auto-generated method stub
return null;
}
}
LogCat 错误是:
W/dalvikvm(394): threadid=9: thread exiting with uncaught exception (group=0x40015560)
E/AndroidRuntime(394): FATAL EXCEPTION: AsyncTask #1
E/AndroidRuntime(394): java.lang.RuntimeException: An error occured while executing doInBackground()
E/AndroidRuntime(394): at android.os.AsyncTask$3.done(AsyncTask.java:200)
E/AndroidRuntime(394): at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:274)
E/AndroidRuntime(394): at java.util.concurrent.FutureTask.setException(FutureTask.java:125)
E/AndroidRuntime(394): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:308)
E/AndroidRuntime(394): at java.util.concurrent.FutureTask.run(FutureTask.java:138)
E/AndroidRuntime(394): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1088)
E/AndroidRuntime(394): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:581)
E/AndroidRuntime(394): at java.lang.Thread.run(Thread.java:1019)
E/AndroidRuntime(394): Caused by: android.view.ViewRoot$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
E/AndroidRuntime(394): at android.view.ViewRoot.checkThread(ViewRoot.java:2932)
E/AndroidRuntime(394): at android.view.ViewRoot.requestLayout(ViewRoot.java:629)
E/AndroidRuntime(394): at android.view.View.requestLayout(View.java:8267)
E/AndroidRuntime(394): at android.view.View.requestLayout(View.java:8267)
E/AndroidRuntime(394): at android.view.View.requestLayout(View.java:8267)
E/AndroidRuntime(394): at android.view.View.requestLayout(View.java:8267)
E/AndroidRuntime(394): at android.widget.ScrollView.requestLayout(ScrollView.java:1291)
E/AndroidRuntime(394): at android.view.View.requestLayout(View.java:8267)
E/AndroidRuntime(394): at android.widget.RelativeLayout.requestLayout(RelativeLayout.java:257)
E/AndroidRuntime(394): at android.view.View.requestLayout(View.java:8267)
E/AndroidRuntime(394): at android.widget.TextView.checkForRelayout(TextView.java:5521)
E/AndroidRuntime(394): at android.widget.TextView.setText(TextView.java:2724)
E/AndroidRuntime(394): at android.widget.TextView.setText(TextView.java:2592)
E/AndroidRuntime(394): at android.widget.TextView.setText(TextView.java:2567)
E/AndroidRuntime(394): at com.MasterZangetsu.kentrocksoc.nextEvent$eventupdate.doInBackground(nextEvent.java:81)
E/AndroidRuntime(394): at com.MasterZangetsu.kentrocksoc.nextEvent$eventupdate.doInBackground(nextEvent.java:1)
E/AndroidRuntime(394): at android.os.AsyncTask$2.call(AsyncTask.java:185)
E/AndroidRuntime(394): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:306)
最佳答案
这行在这里
eventText.setText("" + HTML);
导致了您的问题。您不能从 doInBackground()
更新 UI
。它必须在其他方法之一中完成或发送回主 Activity
方法。在这里你可以在 onPostExecute()
Read through the AyncTask Docs
有多种方法可以完成此操作,但您可以更改 AsyncTask
以将结果返回到 onPostExecute()
public class eventupdate extends AsyncTask<String, Void, String> // change last param
然后在doInBackground()
中添加onPostExecute()
方法并修改return
语句
public class eventupdate extends AsyncTask<String, Void, String>
@Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
eventText.setText("" + result);
}
@Override
protected String doInBackground(String... url) {
// do your work
return HTML;
关于java - Android,使用异步任务从 url 中获取文本,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/15835357/