Activity和Fragment的四种交互方式（Activity可以改变Fragment的UI,Fragment也可以改变ActivityUI）

在工作中我们经常会遇到Activity和Fragment交互。具体为什么要用Fragment，相信大家都懂的，这样可以减少Activity之间来回切换，还可以把不同模块独立化，降低耦合度。下面根据自己工作经验，详细总结一下Activity和Fragment的几种交互方式。

一、使用Bundle

这种方法只能用来传递数据，且只能是Activity向Fragmeng传递。

首先我们需要在Activity中动态添加Fragment时，用Bundle封装我们需要传递的数据

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的回调函数中通过Fragment提供的方法getArguments（）取出Bundle对象。
text = (TextView) view.findViewById(R.id.text);
Bundle bundle = getArguments();
text.setText(bundle.getString("arg"));

这种方法比较简单就不多说了

二、getActivity()、new Fragment()方式（ 这种方法比较经典，简单实用）

下面是Activity代码：

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代码：

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()方式源码下载地址.........................

三、Handler方式

传递数据是比较容易实现，但是要用到Activity和Fragment之间互相改变彼此的UI，网上关于这个问题的解决方法还是很少的，我也没遇到合适的解决方案，自己在前人的基础上研究后创造了一种方法。使Activity和Fragment共享一个Handler，然后发送消息通知彼此更新。别的也不多说了，例子代码如下，

这是Activity的代码：

<span style="font-size:14px;color:#333333;">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);
		//点击和Fragment交互，改变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
		//点击和Fragment交互，改变Fragment的UI
		Message msg = mHandler.obtainMessage();
		msg.what =0;
		mHandler.sendMessage(msg);
		HomeFragment.changeText=false;
	}
}
</span>

这是Fragment的代码：

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
		//点击和Activity交互，改变ActivityUI
		Message msg = handler.obtainMessage();
		msg.what =0;
		handler.sendMessage(msg);
	}
}

Handler方式源码下载地址....................

四、接口回调方式

接口真是个好东西，条件是两个类，一个接口，两个类之间交互。任何两个类之间交互都可以用接口回调，针对接口编程能降低两个类之间的耦合度。

下面是Activity的代码：

<span style="font-size:14px;color:#333333;">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);
		// 这样set是不行的，因为这样又重新创造了一个HomeFragment,和原来初始化的那个不是一个，回报空指针，因为HomeFragment的listener没有被set
		//所以应该这样  HomeFragment.setOnActivityChangeListener(this);
		change_fragment_bt.setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View arg0) {
				// TODO Auto-generated method stub
				//在这里执行接口方法
				onFragmentChangeListener.onFragmentChange();
			}
		});
	}

	public void onAttachFragment(Fragment fragment) {
		super.onAttachFragment(fragment);
		// 除了这种方式传递子类对象，还可以在Fragment中
		// setOnFragmentChangeListener,可以去那里面看一下，我已经注释过
		onFragmentChangeListener = (OnFragmentChangeListener) fragment;
	}

	@Override
	public void onActivityChange() {
		// TODO Auto-generated method stub
		// 在子类中实现接口的方法
		show_change_text.setText("I am UI of activity,and I have changed");
	}

}</span>

显示Fragment的代码：

<span style="font-size:14px;color:#333333;">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);
		// 这样set是不行的，因为这样又重新创造了一个MainActivity,和原来初始化的那个不是一个，回报空指针，因为activity的listener没有被set
		//所以应该这样  MainActivity.setOnFragmentChangeListener(this);
		change_activity_bt.setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View arg0) {
				// TODO Auto-generated method stub
				//在这里执行接口方法
				onActivityChangeListener.onActivityChange();
			}
		});

		return view;
	}

	public void onAttach(Activity activity) {
		super.onAttach(activity);
		// 除了这种方式传递子类对象，还可以在Activity中
				// setOnActivityChangeListener,可以去那里面看一下，我已经注释过
		onActivityChangeListener=(OnActivityChangeListener) activity;
	}

	@Override
	public void onFragmentChange() {
		// 在子类中实现接口的方法
		show_change_text.setText("I am UI of fragment,and I have changed");
	}
}
</span>

Interface方式代码下载地址.....................