从IntentService调用AsyncTask的问题 [英] Problems in Calling AsyncTask from IntentService

问题描述

我创建 IntentService 类，并执行

的AsyncTask 但得到异常时，上preExecute（）被称为在这个code线 pDialog.show（）;

AsyncHandlerService类---

 公共类AsyncHandlerService扩展IntentService {
ProgressDialog pDialog;
HttpPost岗位;
HTT presponse响应;
上下文CTX;公共AsyncHandlerService（）{
    超级（AsyncHandlerService）;
    CTX =这一点;
}@覆盖
保护无效onHandleIntent（意向意图）{
    新LoadDeviceInfo（）执行（）;
}
类LoadDeviceInfo扩展的AsyncTask＆LT;字符串，字符串，字符串＆GT; {@覆盖
在preExecute保护无效（）{
    super.on preExecute（）;
    pDialog =新ProgressDialog（CTX）;
    pDialog.setMessage（更新设备信息...）;
    pDialog.setIndeterminate（假）;
    pDialog.setCancelable（假）;
    pDialog.show（）; //异常这里..
}保护字符串doInBackground（字符串参数... args）{
}保护无效onPostExecute（字符串FILE_URL）{
    pDialog.dismiss（）;
}
 

更新：

我打电话了 IntentService 在具有 android.intent.action.PACKAGE_REPLACED 在Android清单定义。在code ---

 公共类OnUpgradeBroadcastReceiver扩展广播接收器{
关联活动;
@覆盖
    公共无效的onReceive（最终上下文的背景下，最终的意图意图）{
         活性=背景;
         意图msgIntent =新意图（活动，AsyncHandlerService.class）;
            activity.startService（msgIntent）;
    }
}
 

错误日志：

  com.testapp.main致命错误：无法添加窗口 - 
令牌null不是一个应用
android.view.WindowManager $ BadTokenException：无法添加窗口 - 
令牌null不是一个应用
在android.view.ViewRootImpl.setView（ViewRootImpl.java:588）
在android.view.WindowManagerImpl.addView（WindowManagerImpl.java:326）
在android.view.WindowManagerImpl.addView（WindowManagerImpl.java:224）
在android.view.WindowManagerImpl $ CompatModeWrapper。
addView（WindowManagerImpl.java:149）
在android.app.Dialog.show（Dialog.java:277）
在com.testapp.main.AsyncHandlerService $ LoadDeviceInfo。
在preExecute（AsyncHandlerService.java:62）
在android.os.AsyncTask.executeOnExecutor（AsyncTask.java:586）
在android.os.AsyncTask.execute（AsyncTask.java:534）
 




解决方案

首先， IntentService 已经使用了后台线程。你不需要的其他的后台线程。做到这一点需要在后台完成的 onHandleIntent工作（）。

二，一个服务无法显示对话框 。相反，让您的应用程序的UI层知道，工作是通过消息进行事件总线上（例如， LocalBroadcastManager ，greenrobot的EventBus，广场的奥托）。如果UI层不处理该事件，您的服务可以提高一个通知或以其他方式让用户知道这是做的工作，如果是需要的。

I have created IntentService class and performing asyncTask but getting exception when onPreExecute() is called at this code line pDialog.show();

AsyncHandlerService Class ---

public class AsyncHandlerService extends IntentService{
ProgressDialog pDialog;
HttpPost post;
HttpResponse response;
Context ctx;

public AsyncHandlerService() {
    super("AsyncHandlerService");
    ctx = this;
}

@Override
protected void onHandleIntent(Intent intent) {
    new LoadDeviceInfo().execute();   
}


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

@Override
protected void onPreExecute() {
    super.onPreExecute();
    pDialog = new ProgressDialog(ctx);
    pDialog.setMessage("Updating device info...");
    pDialog.setIndeterminate(false);
    pDialog.setCancelable(false);
    pDialog.show(); //Exception here..
}

protected String doInBackground(String... args) {
}

protected void onPostExecute(String file_url) {
    pDialog.dismiss();
}

UPDATE:

I am calling the IntentService in the broadcast receiver that has the intent filter of android.intent.action.PACKAGE_REPLACED defined in android manifest. The code ---

public class OnUpgradeBroadcastReceiver extends BroadcastReceiver {
Context activity;
@Override
    public void onReceive(final Context context, final Intent intent) {
         activity = context;
         Intent msgIntent = new Intent(activity, AsyncHandlerService.class);
            activity.startService(msgIntent);
    }
}

Error Log:

com.testapp.main fatal error : Unable to add window -- 
token null is not for an application
android.view.WindowManager$BadTokenException: Unable to add window -- 
token null is not for an application
at android.view.ViewRootImpl.setView(ViewRootImpl.java:588)
at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:326)
at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:224)
at android.view.WindowManagerImpl$CompatModeWrapper.
addView(WindowManagerImpl.java:149)
at android.app.Dialog.show(Dialog.java:277)
at com.testapp.main.AsyncHandlerService$LoadDeviceInfo.
onPreExecute(AsyncHandlerService.java:62)
at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:586)
at android.os.AsyncTask.execute(AsyncTask.java:534)

解决方案

First, IntentService already uses a background thread. You do not need another background thread. Do the work that needs to be done in the background in onHandleIntent().

Second, a Service cannot display a Dialog. Instead, let the UI layer of your app know that the work was done via a message on an event bus (e.g., LocalBroadcastManager, greenrobot's EventBus, Square's Otto). If the UI layer does not handle the event, your service can raise a Notification or otherwise let the user know about the work that was done, if that is needed.

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