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

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_communication);

         FragmentManager fragmentMgr = getFragmentManager();
         FragmentTransaction transaction = fragmentMgr.beginTransaction();

         Fragment fragment = new CommunicationFragment();
         Bundle bundle = new Bundle();
         bundle.putCharSequence(MSG_KEY , MESSAGE);
         fragment.setArguments(bundle);

         transaction.replace(R.id.ll_communication, fragment);
         transaction.commit();
     }

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

 package com.baixd.app.framework.fragment;

 import android.app.Activity;
 import android.app.Fragment;
 import android.os.Bundle;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.TextView;
 import android.widget.Toast;

 import com.baixd.app.framework.R;

 public class CommunicationFragment extends Fragment {

     private View view;

     private TextView mTextView;

     private CharSequence msg;

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

     private OnFragmentInteractionListener mInteractionListener;

     @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;
     }

     @Override
     public void onAttach(Activity activity) {
         mInteractionListener = (OnFragmentInteractionListener) activity;
         mInteractionListener.onFragmentInteraction(RESP_MSG);
         super.onAttach(activity);
     }

     private void initView() {
         mTextView = (TextView) view.findViewById(R.id.tv_communiation_text);
         mTextView.setText(msg);
     }

     public interface OnFragmentInteractionListener {
         public void onFragmentInteraction(CharSequence c);
     }

 }

宿主Activity：CommunicationActivity.java

 package com.baixd.app.framework.fragment;

 import android.app.Fragment;
 import android.app.FragmentManager;
 import android.app.FragmentTransaction;
 import android.support.v7.app.ActionBarActivity;
 import android.os.Bundle;
 import android.view.Menu;
 import android.view.MenuItem;
 import android.widget.Toast;

 import com.baixd.app.framework.R;

 public class CommunicationActivity extends ActionBarActivity implements CommunicationFragment.OnFragmentInteractionListener{

     public static final String MSG_KEY = "msg";

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

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_communication);

         FragmentManager fragmentMgr = getFragmentManager();
         FragmentTransaction transaction = fragmentMgr.beginTransaction();

         Fragment fragment = new CommunicationFragment();

         transaction.replace(R.id.ll_communication, fragment);
         transaction.commit();
     }

     @Override
     public void onFragmentInteraction(CharSequence msg) {
         Toast.makeText(this, msg, Toast.LENGTH_SHORT).show();
     }
 }