【Android】Activity与Fragment的生命周期的关系
一、问题描述:
假设有两个Activity(1和2),每个Activity拥有一个Fragment,并分别有一个Button,点击Button1可以start Activity2,然后点击Button2可以finish掉自己(即Activity2),然后返回到Activity1。根据这个简单模型描述一下Activity和Fragment的生命周期之间的依赖关系?
二、生命周期知识
Activity和Fragment的生命周期图谱可以参考我的另外一篇博客:【Android】Fragment的生命周期详解,他们的关系大致如下图:
三、代码验证
MainActivity和SecondActivity的布局是这样的,里面各添加了一个Fragment:
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| /** * MainActivity布局xml文件 */
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent">
<Button android:id="@+id/button" android:text="开启第二个Activity" android:layout_gravity="center" android:layout_width="wrap_content" android:layout_height="wrap_content"></Button>
<LinearLayout android:id="@+id/linearlayout" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" android:background="#339999"> </LinearLayout>
</LinearLayout>
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public class MainActivity extends Activity { private static final String LOG_TAG = "MainActivity"; private Button mButton;
@Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); Log.w(LOG_TAG, "==============onCreate()");
FragmentManager fragmentManager = getFragmentManager(); FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
FirstFragment firstFragment = new FirstFragment(); fragmentTransaction.add(R.id.linearlayout, firstFragment); fragmentTransaction.commit();
mButton = (Button) findViewById(R.id.button); mButton.setOnClickListener(new View.OnClickListener() {
@Override public void onClick(View v) { Log.w(LOG_TAG, "------------------mButton onClick-------------------"); startActivity(new Intent(MainActivity.this, SecondActivity.class)); } }); }
@Override protected void onStart() { super.onStart(); Log.w(LOG_TAG, "==============onStart()"); }
@Override protected void onRestart() { super.onRestart(); Log.w(LOG_TAG, "==============onRestart()"); }
@Override protected void onResume() { super.onResume(); Log.w(LOG_TAG, "==============onResume()"); }
@Override protected void onPause() { super.onPause(); Log.w(LOG_TAG, "==============onPause()"); }
@Override protected void onStop() { super.onStop(); Log.w(LOG_TAG, "==============onStop()"); }
@Override protected void onDestroy() { super.onDestroy(); Log.w(LOG_TAG, "==============onDestroy()"); } }
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public class FirstFragment extends Fragment { private static final String LOG_TAG = "FirstFragment"; private static final String ARG_PARAM1 = "param1"; private static final String ARG_PARAM2 = "param2";
private String mParam1; private String mParam2;
public FirstFragment() { }
@Override public void onAttach(Activity activity) { super.onAttach(activity); Log.w(LOG_TAG, "onAttach..."); }
@Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); Log.w(LOG_TAG, "onCreate..."); if (getArguments() != null) { mParam1 = getArguments().getString(ARG_PARAM1); mParam2 = getArguments().getString(ARG_PARAM2); } }
@Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { Log.w(LOG_TAG, "onCreateView..."); return inflater.inflate(R.layout.fragment_first, container, false); }
@Override public void onActivityCreated(Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); Log.w(LOG_TAG, "onActivityCreated..."); }
@Override public void onStart() { super.onStart(); Log.w(LOG_TAG, "onStart..."); }
@Override public void onResume() { super.onResume(); Log.w(LOG_TAG, "onResume..."); }
@Override public void onPause() { super.onPause(); Log.w(LOG_TAG, "onPause..."); }
@Override public void onStop() { super.onStop(); Log.w(LOG_TAG, "onStop..."); }
@Override public void onDestroyView() { super.onDestroyView(); Log.w(LOG_TAG, "onDestroyView..."); }
@Override public void onDestroy() { super.onDestroy(); Log.w(LOG_TAG, "onDestroy..."); }
@Override public void onDetach() { super.onDetach(); Log.w(LOG_TAG, "onDetach..."); }
}
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四、运行结果
1、第一次打开以后:
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| com.example.kuguan.anlearning W/MainActivity﹕ ==============onCreate() com.example.kuguan.anlearning W/FirstFragment﹕ onAttach... com.example.kuguan.anlearning W/FirstFragment﹕ onCreate... com.example.kuguan.anlearning W/FirstFragment﹕ onCreateView... com.example.kuguan.anlearning W/FirstFragment﹕ onActivityCreated... com.example.kuguan.anlearning W/MainActivity﹕ ==============onStart() com.example.kuguan.anlearning W/FirstFragment﹕ onStart... com.example.kuguan.anlearning W/MainActivity﹕ ==============onResume() com.example.kuguan.anlearning W/FirstFragment﹕ onResume...
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2、点击MainActivity中的按钮“打开第二个Activity”以后:
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| com.example.kuguan.anlearning W/MainActivity﹕ ----------------mButton onClick----------------- com.example.kuguan.anlearning W/FirstFragment﹕ onPause... com.example.kuguan.anlearning W/MainActivity﹕ ==============onPause() com.example.kuguan.anlearning W/SecondFragment﹕ onAttach... com.example.kuguan.anlearning W/SecondFragment﹕ onCreate... com.example.kuguan.anlearning W/SecondFragment﹕ onCreateView... com.example.kuguan.anlearning W/SecondFragment﹕ onActivityCreated... com.example.kuguan.anlearning W/SecondActivity﹕ ==============onStart() com.example.kuguan.anlearning W/SecondFragment﹕ onStart... com.example.kuguan.anlearning W/SecondActivity﹕ ==============onResume() com.example.kuguan.anlearning W/SecondFragment﹕ onResume... com.example.kuguan.anlearning W/FirstFragment﹕ onStop... com.example.kuguan.anlearning W/MainActivity﹕ ==============onStop()
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3、点击SecondActivity的按钮“finish”之后:
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| com.example.kuguan.anlearning W/SecondActivity﹕ -----------------mButton onClick------------------ com.example.kuguan.anlearning W/SecondFragment﹕ onPause... com.example.kuguan.anlearning W/SecondActivity﹕ ==============onPause() com.example.kuguan.anlearning W/MainActivity﹕ ==============onRestart() com.example.kuguan.anlearning W/MainActivity﹕ ==============onStart() com.example.kuguan.anlearning W/FirstFragment﹕ onStart... com.example.kuguan.anlearning W/MainActivity﹕ ==============onResume() com.example.kuguan.anlearning W/FirstFragment﹕ onResume... com.example.kuguan.anlearning W/SecondFragment﹕ onStop... com.example.kuguan.anlearning W/SecondActivity﹕ ==============onStop() com.example.kuguan.anlearning W/SecondFragment﹕ onDestroyView... com.example.kuguan.anlearning W/SecondFragment﹕ onDestroy... com.example.kuguan.anlearning W/SecondFragment﹕ onDetach... com.example.kuguan.anlearning W/SecondActivity﹕ ==============onDestroy()
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4、点击back键使MainActivity退到后台:
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| com.example.kuguan.anlearning W/FirstFragment﹕ onPause... com.example.kuguan.anlearning W/MainActivity﹕ ==============onPause() com.example.kuguan.anlearning W/FirstFragment﹕ onStop... com.example.kuguan.anlearning W/MainActivity﹕ ==============onStop() com.example.kuguan.anlearning W/FirstFragment﹕ onDestroyView... com.example.kuguan.anlearning W/FirstFragment﹕ onDestroy... com.example.kuguan.anlearning W/FirstFragment﹕ onDetach... com.example.kuguan.anlearning W/MainActivity﹕ ==============onDestroy()
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5、在MianActivity显示的时候,按HOME键:
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| com.example.kuguan.anlearning W/FirstFragment﹕ onPause... com.example.kuguan.anlearning W/MainActivity﹕ ==============onPause() com.example.kuguan.anlearning W/FirstFragment﹕ onStop... com.example.kuguan.anlearning W/MainActivity﹕ ==============onStop()
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6、然后再点击Icon打开:
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| com.example.kuguan.anlearning W/MainActivity﹕ ==============onRestart() com.example.kuguan.anlearning W/MainActivity﹕ ==============onStart() com.example.kuguan.anlearning W/FirstFragment﹕ onStart... com.example.kuguan.anlearning W/MainActivity﹕ ==============onResume() com.example.kuguan.anlearning W/FirstFragment﹕ onResume...
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【参考资料】:
1、Fragment和Activity