再谈Fragment（二）

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Fragment的生命周期

关键方法

onAttach()

onCreateView()

启动Fragment-->屏幕锁屏-->屏幕解锁-->切换到其他的Fragment

-->回到桌面-->回到应用-->退出Fragment

启动Fragment

onAttach()-->onCreate()-->onCreateView()-->onActivityCreated()-->onStart()-->onResume()

屏幕锁屏

onPause()-->onStop()

屏幕解锁

onStart()-->onResume()

切换到其他Fragment

第一个：onPause()-->onStop()-->onDestroyView()-->onDestroy()-->onDetach()

第二个：onAttach()-->onCreate()-->onCreateView()-->onActivityCreated()-->onStart()-->onResume()

Fragment与Activity通信

Fragment可调用getActivity()方法获取它所在的Activity

Activity可调用FragmentManager的findFragmentById()或findFragmentByTag()方法获取Fragment

Activity-->Fragment：在Activity中创建Bundle数据包，并调用Fragment的setArguments(Bundle bundle)方法

Fragment-->Activity：需要在Fragment中定义一个内部回调接口，再让包含该Fragment的Acitivity实现该回调接口。这样Fragment可调用该回调方法将数据传递给Acitivity

main4.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:id="@+id/layout"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical" >    <EditText        android:id="@+id/editText"        android:layout_width="match_parent"        android:layout_height="wrap_content" />    <Button        android:id="@+id/send"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="发送" /></LinearLayout>

MyFragment5.java

public class MyFragment5 extends Fragment {private String code = "Thank you, Activity!";public MyListener listener;public interface MyListener {public void thank(String code);}@Overridepublic void onAttach(Activity activity) {listener = (MyListener) activity;super.onAttach(activity);}@Overridepublic View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {View view = inflater.inflate(R.layout.fragment2, container, false);TextView tv = (TextView) view.findViewById(R.id.text);String text = (String) getArguments().get("name");tv.setText(text);Toast.makeText(getActivity(), "已成功接收到" + text, Toast.LENGTH_SHORT).show();Toast.makeText(getActivity(), "向Activity发送" + code, Toast.LENGTH_SHORT).show();listener.thank(code);return view;}}

MainActivity4.java

public class MainActivity4 extends Activity implements MyListener {private EditText editText;private Button send;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.main4);editText = (EditText) findViewById(R.id.editText);send = (Button) findViewById(R.id.send);send.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {String text = editText.getText().toString();MyFragment5 fragment5 = new MyFragment5();Bundle bundle = new Bundle();bundle.putString("name", text);fragment5.setArguments(bundle);FragmentManager fragmentManager = getFragmentManager();FragmentTransaction beginTransaction = fragmentManager.beginTransaction();beginTransaction.add(R.id.layout, fragment5, "fragment5");beginTransaction.commit();Toast.makeText(MainActivity4.this, "向Fragment发送数据" + text, Toast.LENGTH_SHORT).show();}});}@Overridepublic void thank(String code) {Toast.makeText(MainActivity4.this, "已成功接收到" + code + ", 客气了", Toast.LENGTH_SHORT).show();}}

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