fragment与activity之间的通信

fragment相当于一个activity，但又不能单独运行，作为一个单独的模块，调用时直接调用模块即可，对于fragment与activity之间的通信，最重要的是要注意使用包之间的统一，以免发生错误。

下面来看一下例子： 

定义xml布局时要注意的一个问题是fragment布局必须设置id，否则会有解析fragment报错（具体原因不知道）

<span style="font-size:14px;"><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="fragment.list.ListMainActivity">

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/fragment_btn"
        android:text="显示对话框"/>

    <fragment
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/fragment_list_layout"
        android:layout_below="@id/fragment_btn"
        android:name="fragment.list.ListMainFragment"></fragment>
</RelativeLayout></span>

下面是定义的fragment的一个子类listFragment：

<span style="font-size:14px;">public class ListMainFragment extends ListFragment {
    private String[] str = {"北京","上海","成都"};
    private  listAdapter mAdapter;
    private OnFragmentDialogListener mListener;    //声明回调接口
    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        mAdapter = new listAdapter(getActivity());
        setListAdapter(mAdapter);
        mAdapter.setlist(str);

    }

    @Override
    public void onListItemClick(ListView l, View v, int position, long id) {
        super.onListItemClick(l, v, position, id);
        String msg = (String) mAdapter.getItem(position);
        Toast.makeText(getActivity(),msg,Toast.LENGTH_SHORT).show();

        onButtonPressed(msg);


    }</span>

<span style="font-size:14px;">
</span>

<span style="font-size:14px;">
</span>

<span style="font-size:14px;"><span style="white-space:pre">	</span>//下面是参照官方方法通过回调实现参数传递
    public void onButtonPressed(String msg) {
        Logs.e("--------"+msg);
        if (mListener != null) {
            mListener.onFragmentDialog(msg);
        }
    }

</span>

<span style="font-size:14px;"><span style="white-space:pre">	</span>//绑定activity
    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        Logs.e("aaaaaaaaaaaaaa");
        if (activity instanceof OnFragmentDialogListener) {
            mListener = (OnFragmentDialogListener) activity;
        } else {
            throw new RuntimeException(activity.toString()
                    + " must implement OnFragmentInteractionListener");
        }
    }

</span>

<span style="font-size:14px;"><span style="white-space:pre">	</span>//我调用的包<span style="font-family:Arial, Helvetica, sans-serif;">import android.app.ListFragment   ，因此当调用下面参数为context时不能运行，此错误弄了很久才弄出来，很不容易发现，若是引用包时是</span><span style="font-family: Arial, Helvetica, sans-serif;">import</span><span style="font-family: Arial, Helvetica, sans-serif;"> </span><span style="font-family: Arial, Helvetica, sans-serif;">android.support.v4.app.ListFragment</span><span style="font-family: Arial, Helvetica, sans-serif;">;那么就可以调用下面方法了，此方法为6.0后方法</span><span style="font-family: Arial, Helvetica, sans-serif;">
</span>
//    @Override
//    public void onAttach(Context context) {         
//        super.onAttach(context);
//        Logs.e("aaaaaaaaaaaaaa");
//        if (context instanceof OnFragmentDialogListener) {
//            mListener = (OnFragmentDialogListener) context;
//        } else {
//            throw new RuntimeException(context.toString()
//                    + " must implement OnFragmentInteractionListener");
//        }
//    }

    @Override
    public void onDetach() {
        super.onDetach();
        mListener = null;
    }

    public interface OnFragmentDialogListener {         //定义回调接口
        // TODO: Update argument type and name
        void onFragmentDialog(String msg);
    }</span>

<span style="font-size:14px;">}</span>

定义DialogFragment：注意包的调用import android.app.DialogFragment;

还可以采用自定义view在oncreatView中创造即可，下面我采用的是系统方式

<span style="font-size:14px;">public class AlertDialogFragment extends DialogFragment {
    private String mArgs;

    public static AlertDialogFragment newInstance(String msg) {

        Bundle args = new Bundle();
        args.putCharSequence("msg", msg);
        AlertDialogFragment fragment = new AlertDialogFragment();
        fragment.setArguments(args);

        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null) {
            mArgs = getArguments().getCharSequence("msg").toString();
        }

    }

    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        AlertDialog.Builder dialog = new AlertDialog.Builder(getActivity());
        dialog.setPositiveButton("确定", new DialogInterface.OnClickListener() {

            @Override
            public void onClick(DialogInterface dialog, int which) {

            }
        }).setIcon(R.mipmap.ic_launcher).setMessage("欢迎来到" + mArgs);    //不知怎么图标未显示，若是知道原因希望能够分享一下

        Logs.e("11111111111111111111"+mArgs);
        return dialog.create();
    }</span>

activity中包导入:import android.app.Activity;

<span style="font-size:14px;">public class ListMainActivity extends Activity implements ListMainFragment.OnFragmentDialogListener {    //实现接口
    private Button mDialogBtn;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_list_main_layout);
        mDialogBtn = (Button) findViewById(R.id.fragment_btn);

        mDialogBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                getFragmentManager().beginTransaction().add(AlertDialogFragment.newInstance(""),null).commit();
            }
        });
    }

</span>

<span style="font-size:14px;"><span style="white-space:pre">	</span>//接口方法
    @Override
    public void onFragmentDialog(String msg) {
        getFragmentManager().beginTransaction().add(AlertDialogFragment.newInstance(msg),null).commit();  //动态设置fragment
    }</span>

实现效果如下：