再谈Fragment（二）

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);
}

@Override
public void onAttach(Activity activity) {
listener = (MyListener) activity;
super.onAttach(activity);
}

@Override
public 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;

@Override
protected 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() {

@Override
public 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();
}
});

}

@Override
public void thank(String code) {
Toast.makeText(MainActivity4.this, "已成功接收到" + code + ", 客气了",
Toast.LENGTH_SHORT).show();
}

}