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();
    }
}