从主页键开始活动

Intent i = new Intent(this, MyActivity.class);
i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(i);

if ((getIntent().getFlags() & FLAG_ACTIVITY_LAUNCHED_FROM_HISTORY) > 0) {
   activity.startActivity(new Intent(context , MainActivity.class).addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP));    
}