异步任务 FTP 上传 Android 服务崩溃？

Question

我正在尝试通过 FTP 上传设置目录中的文件。该文件名为 "advancedsettings.xml".

代码在 Activity、 的异步任务中使用时工作正常，但是当尝试使用服务 在异步中执行完全相同的操作时任务，应用程序崩溃并出现以下错误：

01-13 16:21:08.403 21134-21151/com.name.example.xx E/AndroidRuntime﹕ FATAL EXCEPTION: AsyncTask #1 Process: com.name.example.xx, PID: 21134 java.lang.RuntimeException: An error occured while executing doInBackground() at android.os.AsyncTask.done(AsyncTask.java:300) at java.util.concurrent.FutureTask.finishCompletion(F utureTask.java:355) at java.util.concurrent.FutureTask.setException(Futur eTask.java:222) at java.util.concurrent.FutureTask.run(FutureTask.jav a:242) at android.os.AsyncTask$SerialExecutor.run(AsyncTas k.java:231) at java.util.concurrent.ThreadPoolExecutor.runWorker( ThreadPoolExecutor.java:1112) at java.util.concurrent.ThreadPoolExecutor$Worker.run (ThreadPoolExecutor.java:587) at java.lang.Thread.run(Thread.java:841) Caused by: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare() at android.os.Handler.(Handler.java:200) at android.os.Handler.(Handler.java:114) at android.widget.Toast$TN.(Toast.java:388) at android.widget.Toast.(Toast.java:114) at android.widget.Toast.makeText(Toast.java:273) at com.name.example.xx.MyService$FTPUpload.doInBackgr ound(MyService.java:58) at com.name.example.xx.MyService$FTPUpload.doInBackgr ound(MyService.java:55) at android.os.AsyncTask.call(AsyncTask.java:288) at java.util.concurrent.FutureTask.run(FutureTask.jav a:237) ************at android.os.AsyncTask$SerialExecutor.run(AsyncTas k.java:231) ************at java.util.concurrent.ThreadPoolExecutor.runWorker( ThreadPoolExecutor.java:1112) ************at java.util.concurrent.ThreadPoolExecutor$Worker.run (ThreadPoolExecutor.java:587) ************at java.lang.Thread.run(Thread.java:841) 01-13 16:21:08.473 862-862/? W/ContextImpl﹕ Calling a method in the system process without a qualified user: android.app.ContextImpl.sendBroadcast:1505 com.android.server.analytics.data.collection.appli cation.CrashAnrDetector.broadcastEvent:296 com.android.server.analytics.data.collection.appli cation.CrashAnrDetector.processDropBoxEntry:254 com.android.server.analytics.data.collection.appli cation.CrashAnrDetector.access0:60 com.android.server.analytics.data.collection.appli cation.CrashAnrDetector.onReceive:102 01-13 16:21:08.713 862-21154/? E/android.os.Debug﹕ !@Dumpstate > sdumpstate -k -t -z -d -o /data/log/dumpstate_app_error

以下是我如何从主 activity 中调用服务（单击按钮）：

Intent inetnt=new Intent(FileChooser.this, MyService.class);
        startService(inetnt);

这是服务代码：

public class MyService extends Service {

@Override
public IBinder onBind(Intent intent) {
    return null;
}

@Override
public void onCreate() {
    super.onCreate();
    Toast.makeText(MyService.this, "service start", Toast.LENGTH_LONG).show();
    new FTPUpload().execute();

}

@Override
public void onDestroy() {
    super.onDestroy();


}

@Override
public void onLowMemory() {
    super.onLowMemory();

}


@Override
public int onStartCommand(Intent intent, int flags, int startId) {

    return super.onStartCommand(intent, flags, startId);

}

public class FTPUpload extends AsyncTask<Void, Void, Void> {
    protected Void doInBackground(Void...params) {

        Toast.makeText(MyService.this, "Service FTP Upload Start", Toast.LENGTH_LONG).show();

        FTPClient con = null;

        try

        {
            con = new FTPClient();
            con.connect("host");

            // Check your USERNAME e.g myuser@mywebspace.com and check your PASSWORD to ensure they are OK.
            if (con.login("username", "password")) {
                con.enterLocalPassiveMode(); // important!
                con.setFileType(FTP.BINARY_FILE_TYPE);

                Random rand = new Random();
                String randomIntString = String.valueOf(rand.nextInt()).replaceAll("-", "");


                FileInputStream in = new FileInputStream("/storage/emulated/0/");
                //con.makeDirectory("/" + randomIntString + "/");
                con.storeFile("advancedsettings.xml", in);
                in.close();


                //PASS URL TO NEXT ACTIVITY AND LAUNCH NEXT ACTIVITY ON NOTIFICATION CLICK


            } else {


            }
        } catch (
                Exception e
                )

        { //if file does not upload successfully, write an error log.
            Toast.makeText(MyService.this, "An error occured, please report: " + e, Toast.LENGTH_LONG).show();
        }

        Toast.makeText(MyService.this, "Service FTP Upload Complete", Toast.LENGTH_LONG).show();

        return null;
    }

}

}

我可以确认我已经在应用程序标签内的 Android 清单文件中声明了该服务，如下所示：

<service android:name=".MyService"/>

有什么想法吗？非常感谢您的帮助！我很想弄清楚这个问题。

K

Answer 1

这里

Toast.makeText(MyService.this, "Service FTP Upload Start", Toast.LENGTH_LONG).show();

您正在尝试 Toast 来自 doInBackground（来自其他线程）。在开始 doInBackground 执行之前使用 onPreExecute 显示 Toast

Answer 2

请不要从 doInBackground 访问主线程，例如运行 a Toast。请改用 onPreExecute 进行此类操作。

Toast.makeText(MyService.this, 
               "Service FTP Upload Start", 
               Toast.LENGTH_LONG).show();

doInBackground should/can 无法访问 UI 线程。对于您的完整任务 Toasts 尝试 return 来自 doInBackground 的值，您将在 onPostExecute 中获得 returned 值，您可以在其中展示您的祝酒词

有关更多信息，请查看文档： Documentation

异步任务 FTP 上传 Android 服务崩溃？

Async Task FTP Upload Android Service Crashing?

java

service

android

ftp-client

android-asynctask