Android service里面啟動activity和alertdialog .

啟動activity源碼:(記得要加上Intent.FLAG_ACTIVITY_NEW_TASK)

Intent intent = new Intent();
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
intent.setClass(getApplicationContext(),FileBrowserActivity.class);
startActivity(intent);

啟動alertDialog源碼:

 AlertDialog.Builder builder = new AlertDialog.Builder(this);
 builder.setMessage("是否接受文件?")
 .setPositiveButton("是", new DialogInterface.OnClickListener() {
@Override
publicvoid onClick(DialogInterface dialog, int which) {

 }
 }).setNegativeButton("否", new OnClickListener() {
@Override
publicvoid onClick(DialogInterface dialog, int which) {
 }
 });
 AlertDialog ad = builder.create();
// ad.getWindow().setType(WindowManager.LayoutParams.TYPE_SYSTEM_DIALOG); //系統中關機對話框就是這個屬性
 ad.getWindow().setType(WindowManager.LayoutParams.TYPE_SYSTEM_ALERT);
 ad.setCanceledOnTouchOutside(false); //點擊外面區域不會讓dialog消失
 ad.show();

還要加上權限 

<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />