Activity和Fragment的四種交互方式（Activity可以改變Fragment的UI,Fragment也可以改變ActivityUI） · Android 實戰

轉載請標明原地址：[http://blog.csdn.net/gaolei1201/article/details/44037831?](http://blog.csdn.net/gaolei1201/article/details/44037831) 在工作中我們經常會遇到Activity和Fragment交互。具體為什么要用Fragment，相信大家都懂的，這樣可以減少Activity之間來回切換，還可以把不同模塊獨立化，降低耦合度。下面根據自己工作經驗，詳細總結一下Activity和Fragment的幾種交互方式。 ## 一、使用Bundle 這種方法只能用來傳遞數據，且只能是Activity向Fragmeng傳遞。首先我們需要在Activity中動態添加Fragment時，用Bundle封裝我們需要傳遞的數據 ~~~ HomeFragment arg = new HomeFragment(); Bundle bundle = new Bundle(); bundle.putString("arg", edit.getText().toString()); arg.setArguments(bundle); FragmentManager fm = getFragmentManager(); FragmentTransaction ft = fm.beginTransaction(); ft.replace(R.id.layout_fragment, arg); ft.commit(); 然后在Fragment的回調函數中通過Fragment提供的方法getArguments（）取出Bundle對象。 text = (TextView) view.findViewById(R.id.text); Bundle bundle = getArguments(); text.setText(bundle.getString("arg")); ~~~ 這種方法比較簡單就不多說了 ## 二、getActivity()、new Fragment()方式（?這種方法比較經典，簡單實用）下面是Activity代碼： ~~~ public class MainActivity extends FragmentActivity { private TextView show_change_text; private Button change_fragment_bt; private HomeFragment homeFragment; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); homeFragment=new HomeFragment(); getSupportFragmentManager().beginTransaction() .replace(R.id.fragment_content,homeFragment ).commit(); change_fragment_bt = (Button) findViewById(R.id.change_fragment_bt); show_change_text = (TextView) findViewById(R.id.show_change_text); change_fragment_bt.setOnClickListener(new OnClickListener() { @Override public void onClick(View arg0) { // TODO Auto-generated method stub homeFragment.changeText(); } }); } public void changeText(){ show_change_text.setText("I am UI of activity,and I have changed"); } public void onAttachFragment(Fragment fragment) { super.onAttachFragment(fragment); } } ~~~ 下面是Fragment代碼： ~~~ public class HomeFragment extends Fragment { private TextView show_change_text; private Button change_activity_bt; public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { super.onCreateView(inflater, container, savedInstanceState); View view = inflater.inflate(R.layout.home_fragment, null); change_activity_bt = (Button) view .findViewById(R.id.change_activity_bt); show_change_text = (TextView) view.findViewById(R.id.show_change_text); change_activity_bt.setOnClickListener(new OnClickListener() { @Override public void onClick(View arg0) { // TODO Auto-generated method stub ((MainActivity) getActivity()).changeText(); } }); return view; } public void changeText(){ show_change_text.setText("I am UI of fragment,and I have changed"); } public void onAttach(Activity activity) { super.onAttach(activity); } } ~~~ [? getActivity()、new Fragment()方式源碼下載地址.........................](http://download.csdn.net/detail/gaolei1201/8994197) ## 三、Handler方式傳遞數據是比較容易實現，但是要用到Activity和Fragment之間互相改變彼此的UI，網上關于這個問題的解決方法還是很少的，我也沒遇到合適的解決方案，自己在前人的基礎上研究后創造了一種方法。使Activity和Fragment共享一個Handler，然后發送消息通知彼此更新。別的也不多說了，例子代碼如下，這是Activity的代碼： ~~~ public class MainActivity extends FragmentActivity implements OnClickListener { private Handler mHandler; private long lastPressBack; private boolean isFirstPressBack = true; private Button change_fragment_bt; private TextView show_change_text; private HomeFragment homeFragment; Handler handler = new Handler() { @Override public void handleMessage(Message msg) { switch (msg.what) { case 0: show_change_text.setText("I am UI of activity,and I have changed"); break; } } }; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); change_fragment_bt=(Button)findViewById(R.id.change_fragment_bt); show_change_text=(TextView)findViewById(R.id.show_change_text); change_fragment_bt.setOnClickListener(this); getSupportFragmentManager().beginTransaction() .replace(R.id.fragment_content, new HomeFragment()) .commit(); } public void onAttachFragment(Fragment fragment) { super.onAttachFragment(fragment); homeFragment=(HomeFragment) fragment; homeFragment.setHandler(handler) ; } public boolean onKeyDown(int keyCode, KeyEvent event) { super.onKeyDown(keyCode, event); //點擊和Fragment交互，改變Fragment的UI if (keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0) { if(HomeFragment.changeText){ Message msg = mHandler.obtainMessage(); msg.what =0; mHandler.sendMessage(msg); HomeFragment.changeText=false; return false; } if (!isFirstPressBack) { if (System.currentTimeMillis() - lastPressBack > 2 * 1000) { lastPressBack = System.currentTimeMillis(); } else { finish(); } } lastPressBack = System.currentTimeMillis(); Toast.makeText(this,getString(R.string.exit_app),Toast.LENGTH_SHORT).show(); isFirstPressBack = false; return false; } return false; } public void setHandler(Handler handler) { mHandler = handler; } @Override public void onClick(View arg0) { // TODO Auto-generated method stub //點擊和Fragment交互，改變Fragment的UI Message msg = mHandler.obtainMessage(); msg.what =0; mHandler.sendMessage(msg); HomeFragment.changeText=false; } } ~~~ 這是Fragment的代碼： ~~~ public class HomeFragment extends Fragment implements OnClickListener{ private TextView show_change_text; private Button change_activity_bt; private MainActivity mActivity; public static boolean changeText=true; Handler handler = new Handler() { @Override public void handleMessage(Message msg) { switch (msg.what) { case 0: show_change_text.setText("I am UI of fragment,and I have changed"); break; } } }; public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { super.onCreateView(inflater, container, savedInstanceState); View view = inflater.inflate(R.layout.home_fragment, null); show_change_text=(TextView)view.findViewById(R.id.show_change_text); change_activity_bt=(Button)view.findViewById(R.id.change_activity_bt); change_activity_bt.setOnClickListener(this); return view; } public void onAttach(Activity activity) { super.onAttach(activity); mActivity = (MainActivity) activity; mActivity.setHandler(handler); } public void setHandler(Handler handler) { this.handler = handler; } public void onDestroy(){ super.onDestroy(); changeText=true; } @Override public void onClick(View arg0) { // TODO Auto-generated method stub //點擊和Activity交互，改變ActivityUI Message msg = handler.obtainMessage(); msg.what =0; handler.sendMessage(msg); } } ~~~ ?[Handler方式源碼下載地址....................](http://download.csdn.net/detail/gaolei1201/8929807) ## 四、接口回調方式接口真是個好東西，條件是兩個類，一個接口，兩個類之間交互。任何兩個類之間交互都可以用接口回調，針對接口編程能降低兩個類之間的耦合度。下面是Activity的代碼： ~~~ public class MainActivity extends FragmentActivity implements OnActivityChangeListener{ private TextView show_change_text; private Button change_fragment_bt; public static OnFragmentChangeListener onFragmentChangeListener; public static void setOnFragmentChangeListener( OnFragmentChangeListener onFragmentChangeListener) { MainActivity.onFragmentChangeListener = onFragmentChangeListener; } @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); getSupportFragmentManager().beginTransaction() .replace(R.id.fragment_content, new HomeFragment()).commit(); change_fragment_bt = (Button) findViewById(R.id.change_fragment_bt); show_change_text = (TextView) findViewById(R.id.show_change_text); // new HomeFragment().setOnActivityChangeListener(this); // 這樣set是不行的，因為這樣又重新創造了一個HomeFragment,和原來初始化的那個不是一個，回報空指針，因為HomeFragment的listener沒有被set //所以應該這樣 HomeFragment.setOnActivityChangeListener(this); change_fragment_bt.setOnClickListener(new OnClickListener() { @Override public void onClick(View arg0) { // TODO Auto-generated method stub //在這里執行接口方法 onFragmentChangeListener.onFragmentChange(); } }); } public void onAttachFragment(Fragment fragment) { super.onAttachFragment(fragment); // 除了這種方式傳遞子類對象，還可以在Fragment中 // setOnFragmentChangeListener,可以去那里面看一下，我已經注釋過 onFragmentChangeListener = (OnFragmentChangeListener) fragment; } @Override public void onActivityChange() { // TODO Auto-generated method stub // 在子類中實現接口的方法 show_change_text.setText("I am UI of activity,and I have changed"); } } ~~~ 顯示Fragment的代碼： ~~~ public class HomeFragment extends Fragment implements OnFragmentChangeListener { private TextView show_change_text; private Button change_activity_bt; public static OnActivityChangeListener onActivityChangeListener; public void setOnActivityChangeListener(OnActivityChangeListener onActivityChangeListener){ HomeFragment.onActivityChangeListener=onActivityChangeListener; } public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { super.onCreateView(inflater, container, savedInstanceState); View view = inflater.inflate(R.layout.home_fragment, null); change_activity_bt = (Button) view .findViewById(R.id.change_activity_bt); show_change_text = (TextView) view.findViewById(R.id.show_change_text); // new MainActivity().setOnFragmentChangeListener(this); // 這樣set是不行的，因為這樣又重新創造了一個MainActivity,和原來初始化的那個不是一個，回報空指針，因為activity的listener沒有被set //所以應該這樣 MainActivity.setOnFragmentChangeListener(this); change_activity_bt.setOnClickListener(new OnClickListener() { @Override public void onClick(View arg0) { // TODO Auto-generated method stub //在這里執行接口方法 onActivityChangeListener.onActivityChange(); } }); return view; } public void onAttach(Activity activity) { super.onAttach(activity); // 除了這種方式傳遞子類對象，還可以在Activity中 // setOnActivityChangeListener,可以去那里面看一下，我已經注釋過 onActivityChangeListener=(OnActivityChangeListener) activity; } @Override public void onFragmentChange() { // 在子類中實現接口的方法 show_change_text.setText("I am UI of fragment,and I have changed"); } } ~~~ [ Interface方式代碼下載地址.....................](http://download.csdn.net/detail/gaolei1201/8929815)