Android onNewIntent调用时机

onNewIntent调用时机

[Android Activity官网]https://developer.android.com/reference/android/app/Activity.html

onNewIntent

void onNewIntent (Intent intent)

This is called for activities that set launchMode to "singleTop" in their package, or if a client used the FLAG_ACTIVITY_SINGLE_TOP flag when calling startActivity(Intent).
In either case, when the activity is re-launched while at the top of the activity stack instead of a new instance of the activity being started, onNewIntent() will be called on the existing instance with the Intent that was used to re-launch it.
An activity will always be paused before receiving a new intent, so you can count on onResume() being called after this method.
Note that getIntent() still returns the original Intent. You can use setIntent(Intent) to update it to this new Intent.

个人解读

当通过intent启动activiy时，它处于栈顶，并且已有一个实例存在，这时就不会调用onCreate->onStart->onResume, 而是调用 onNewIntent->onRestart->onStart->onResume
activity有4种启动模式，当activity的launchMode为默认standard时，重新启动会生成新的实例。所以不会调用onNewIntent, 但其他三种模式都会调用onNewIntent： singleTop是本身已处于栈顶， 重新启动会调用；singleTask是重新启动会销毁上层所有activity，之后会处于栈顶，也会被调用；singleInstance类似。
官方提示，在 onNewIntent 中应调用 setIntent()来更新intent，否则后面的 getIntent会得到旧的 intent
所以正确的代码编写是：

 public void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   setContentView(R.layout.main);
   initViewWithData();
 }

 protected void onNewIntent(Intent intent) {
   super.onNewIntent(intent);
   // Note that getIntent() still returns the original Intent. You can use setIntent(Intent) to update it to this new Intent.
   setIntent(intent);
   initViewWithData();
 }

 private void processExtraData(){
   Intent intent = getIntent();
   // ...
 }