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 }