Activity与Fragment之间的通信

由于Fragment的生命周期完全依赖宿主Activity，所以当我们在使用Fragment时难免出现Activity和Fragment间的传值通信操作。

1、Activity向Fragment，通过声明的Fragment对象的setArguments(bundle)方法来实现Activity到Fragment的传递

 1     @Override

 2     protected void onCreate(Bundle savedInstanceState) {

 3         super.onCreate(savedInstanceState);

 4         setContentView(R.layout.activity_communication);

 5 

 6         FragmentManager fragmentMgr = getFragmentManager();

 7         FragmentTransaction transaction = fragmentMgr.beginTransaction();

 8 

 9         Fragment fragment = new CommunicationFragment();

10         Bundle bundle = new Bundle();

11         bundle.putCharSequence(MSG_KEY , MESSAGE);

12         fragment.setArguments(bundle);

13 

14         transaction.replace(R.id.ll_communication, fragment);

15         transaction.commit();

16     }

Fragment中获取Activity传递的数据，通过Bundle bundle = this.getArguments()方法获取数据

 @Override

    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        view = inflater.inflate(R.layout.fragment_communication, container, false);



        Bundle bundle = this.getArguments();

        msg = bundle.getCharSequence(CommunicationActivity.MSG_KEY);



        initView();



        Toast.makeText(getActivity(), "接收到了来自Fragment的消息：" + msg, Toast.LENGTH_SHORT).show();

        return view;

    }

2、Fragment到Activity
在Fragment需要声明一个接口，定义回调方法，如CommunicationFragment中定义了OnFragmentInteractionListener内部接口，并声明mInteractionListener这个成员变量，当调用onAttach方法时将activity转换为OnFragmentInteractionListener，并调用它的方法传递数据。而在宿主Activity中需要实现OnFragmentInteractionListener接口，并实现方法public void onFragmentInteraction(CharSequence c)，在方法中接收数据并处理

CommunicationFragment.java

 1 package com.baixd.app.framework.fragment;

 2 

 3 import android.app.Activity;

 4 import android.app.Fragment;

 5 import android.os.Bundle;

 6 import android.view.LayoutInflater;

 7 import android.view.View;

 8 import android.view.ViewGroup;

 9 import android.widget.TextView;

10 import android.widget.Toast;

11 

12 import com.baixd.app.framework.R;

13 

14 

15 public class CommunicationFragment extends Fragment {

16 

17     private View view;

18 

19     private TextView mTextView;

20 

21     private CharSequence msg;

22 

23     private static final CharSequence RESP_MSG = "成功接收消息！";

24 

25     private OnFragmentInteractionListener mInteractionListener;

26 

27     @Override

28     public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

29         view = inflater.inflate(R.layout.fragment_communication, container, false);

30 

31         Bundle bundle = this.getArguments();

32         msg = bundle.getCharSequence(CommunicationActivity.MSG_KEY);

33 

34         initView();

35 

36         Toast.makeText(getActivity(), "接收到了来自Fragment的消息：" + msg, Toast.LENGTH_SHORT).show();

37         return view;

38     }

39 

40     @Override

41     public void onAttach(Activity activity) {

42         mInteractionListener = (OnFragmentInteractionListener) activity;

43         mInteractionListener.onFragmentInteraction(RESP_MSG);

44         super.onAttach(activity);

45     }

46 

47     private void initView() {

48         mTextView = (TextView) view.findViewById(R.id.tv_communiation_text);

49         mTextView.setText(msg);

50     }

51 

52     public interface OnFragmentInteractionListener {

53         public void onFragmentInteraction(CharSequence c);

54     }

55 

56 

57 }

宿主Activity：CommunicationActivity.java

 1 package com.baixd.app.framework.fragment;

 2 

 3 import android.app.Fragment;

 4 import android.app.FragmentManager;

 5 import android.app.FragmentTransaction;

 6 import android.support.v7.app.ActionBarActivity;

 7 import android.os.Bundle;

 8 import android.view.Menu;

 9 import android.view.MenuItem;

10 import android.widget.Toast;

11 

12 import com.baixd.app.framework.R;

13 

14 public class CommunicationActivity extends ActionBarActivity implements CommunicationFragment.OnFragmentInteractionListener{

15 

16     public static final String MSG_KEY = "msg";

17 

18     public static final CharSequence MESSAGE = "向Fragment传递消息";

19 

20 

21     @Override

22     protected void onCreate(Bundle savedInstanceState) {

23         super.onCreate(savedInstanceState);

24         setContentView(R.layout.activity_communication);

25 

26         FragmentManager fragmentMgr = getFragmentManager();

27         FragmentTransaction transaction = fragmentMgr.beginTransaction();

28 

29         Fragment fragment = new CommunicationFragment();

30 

31         transaction.replace(R.id.ll_communication, fragment);

32         transaction.commit();

33     }

34 

35     @Override

36     public void onFragmentInteraction(CharSequence msg) {

37         Toast.makeText(this, msg, Toast.LENGTH_SHORT).show();

38     }

39 }