我是Android编程的新手，我正在尝试学习如何使用广播接收器在背景中下载图像。现在，每次运行应用程序时，应用程序都会崩溃。我一直在努力，但徒劳无功。我希望你们能帮助我。
这是代码：
public class MainActivity extends AppCompatActivity implements View.OnClickListener{
private Button go, kill;
public static ProgressBar progressBar1, progressBar2, progressBar3, progressBar4, progressBar5;
public static ImageView imageView1, imageView2, imageView3, imageView4, imageView5;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
go = (Button) findViewById(R.id.goButton);
kill = (Button) findViewById(R.id.killButton);
progressBar1 = (ProgressBar) findViewById(R.id.progressBar1);
progressBar2 = (ProgressBar) findViewById(R.id.progressBar2);
progressBar3 = (ProgressBar) findViewById(R.id.progressBar3);
progressBar4 = (ProgressBar) findViewById(R.id.progressBar4);
progressBar5 = (ProgressBar) findViewById(R.id.progressBar5);
imageView1 = (ImageView) findViewById(R.id.imageView1);
imageView2 = (ImageView) findViewById(R.id.imageView2);
imageView3 = (ImageView) findViewById(R.id.imageView3);
imageView4 = (ImageView) findViewById(R.id.imageView4);
imageView5 = (ImageView) findViewById(R.id.imageView5);
IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction(getString(R.string.downloaded));
registerReceiver(downloadReceiver, intentFilter);
go.setOnClickListener(this);
kill.setOnClickListener(this);
}
@Override
public void onClick(View v) {
switch(v.getId()){
case R.id.goButton:
Intent intent = new Intent(MainActivity.this, Interaction.class);
startService(intent);
break;
case R.id.killButton:
finish();
break;
}
}
@Override
protected void onDestroy() {
super.onDestroy();
unregisterReceiver(downloadReceiver);
}
private BroadcastReceiver downloadReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
progressBar1.setVisibility(View.GONE);
}
};
}
相互作用
public class Interaction extends Service {
final class MyThreadClass implements Runnable{
int service_id;
MyThreadClass(int service_id){
this.service_id = service_id;
}
@Override
public void run() {
// new
MainActivity.imageView1.setImageBitmap(getBitmapFromURL(getString(R.string.link1)));
MainActivity.imageView1.setVisibility(View.VISIBLE);
Intent intent1 = new Intent(getString(R.string.downloaded));
sendBroadcast(intent1);
stopSelf(service_id);
}
}
@Nullable
@Override
public IBinder onBind(Intent intent) {
return null;
}
@Override
public void onCreate() {
super.onCreate();
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
Toast.makeText(this,"Downloading Photos", Toast.LENGTH_LONG).show();
Thread thread = new Thread(new MyThreadClass(startId));
thread.start();
return START_STICKY;
}
@Override
public void onDestroy() {
super.onDestroy();
}
private Bitmap getBitmapFromURL(String src){
try {
URL url = new URL(src);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setDoInput(true);
connection.connect();
InputStream input = connection.getInputStream();
Bitmap myBitmap = BitmapFactory.decodeStream(input);
return myBitmap;
}catch (Exception e){
e.printStackTrace();
return null;
}
}
}
这是logcat：
---------崩溃的开始
10-23 10:50:15.322 2568-3873/ziad.example.com.downloadapp E/AndroidRuntime: FATAL EXCEPTION: Thread-4
Process: ziad.example.com.downloadapp, PID: 2568
android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
at android.view.ViewRootImpl.checkThread(ViewRootImpl.java:6891)
at android.view.ViewRootImpl.requestLayout(ViewRootImpl.java:1048)
at android.view.View.requestLayout(View.java:19781)
at android.view.View.requestLayout(View.java:19781)
at android.view.View.requestLayout(View.java:19781)
at android.view.View.requestLayout(View.java:19781)
at android.view.View.requestLayout(View.java:19781)
at android.view.View.requestLayout(View.java:19781)
at android.widget.RelativeLayout.requestLayout(RelativeLayout.java:360)
at android.view.View.requestLayout(View.java:19781)
at android.widget.ImageView.setImageDrawable(ImageView.java:529)
at android.widget.ImageView.setImageBitmap(ImageView.java:659)
at ziad.example.com.downloadapp.Interaction$MyThreadClass.run(Interaction.java:39)
at java.lang.Thread.run(Thread.java:761)