DialogFragment文档

概览

一个显示对话框的Fragment，浮在这个Activity的上方。包含一个基于Fragment状态适当显示的Dialog对象。可以通过DialogFragment的API控制这个对话框的显示、隐藏、销毁，不需要直接调用Dialog的。
重写FragmentDialog类实现onCreateView()给对话框提供内容，或者重写onCreateDialog()创建一个完全自定义的对话框，例如拥有自己内容的AlertDialog。

生命周期

DialogFragment在保持Fragment生命周期的驱动下可以做很多不同的事，代替Dialog。注意Dialog通常是自治的实体–他们是自己的窗口，接收自己的输入事件，自己决定何时销毁(当接收到返回键或其他按键事件)。
DialogFragment需要确定Fragment和Dialog发生的状态保持一致。做到这一点，要监听Dialog的销毁事件，当事件发生时要移除自己的状态。这意味着要使用show(FragmentManager, String)或者show(FragmentTransaction, String)为你的UI添加DialogFragment实例，以便注意Dialog销毁时移除它们。

Basic Dialog

DialogFragment的简单用法是作为Fragment图层的简单浮动容器。下面是一个简单的实现：

public static class MyDialogFragment extends DialogFragment {
    int mNum;

    /**
     * Create a new instance of MyDialogFragment, providing "num"
     * as an argument.
     */
    static MyDialogFragment newInstance(int num) {
        MyDialogFragment f = new MyDialogFragment();

        // Supply num input as an argument.
        Bundle args = new Bundle();
        args.putInt("num", num);
        f.setArguments(args);

        return f;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mNum = getArguments().getInt("num");

        // Pick a style based on the num.
        int style = DialogFragment.STYLE_NORMAL, theme = 0;
        switch ((mNum-1)%6) {
            case 1: style = DialogFragment.STYLE_NO_TITLE; break;
            case 2: style = DialogFragment.STYLE_NO_FRAME; break;
            case 3: style = DialogFragment.STYLE_NO_INPUT; break;
            case 4: style = DialogFragment.STYLE_NORMAL; break;
            case 5: style = DialogFragment.STYLE_NORMAL; break;
            case 6: style = DialogFragment.STYLE_NO_TITLE; break;
            case 7: style = DialogFragment.STYLE_NO_FRAME; break;
            case 8: style = DialogFragment.STYLE_NORMAL; break;
        }
        switch ((mNum-1)%6) {
            case 4: theme = android.R.style.Theme_Holo; break;
            case 5: theme = android.R.style.Theme_Holo_Light_Dialog; break;
            case 6: theme = android.R.style.Theme_Holo_Light; break;
            case 7: theme = android.R.style.Theme_Holo_Light_Panel; break;
            case 8: theme = android.R.style.Theme_Holo_Light; break;
        }
        setStyle(style, theme);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.fragment_dialog, container, false);
        View tv = v.findViewById(R.id.text);
        ((TextView)tv).setText("Dialog #" + mNum + ": using style "
                + getNameForNum(mNum));

        // Watch for button clicks.
        Button button = (Button)v.findViewById(R.id.show);
        button.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
                // When button is clicked, call up to owning activity.
                ((FragmentDialog)getActivity()).showDialog();
            }
        });

        return v;
    }
}

在Activity中显示：

void showDialog() {
    mStackLevel++;

    // DialogFragment.show() will take care of adding the fragment
    // in a transaction.  We also want to remove any currently showing
    // dialog, so make our own transaction and take care of that here.
    FragmentTransaction ft = getFragmentManager().beginTransaction();
    Fragment prev = getFragmentManager().findFragmentByTag("dialog");
    if (prev != null) {
        ft.remove(prev);
    }
    ft.addToBackStack(null);

    // Create and show the dialog.
    DialogFragment newFragment = MyDialogFragment.newInstance(mStackLevel);
    newFragment.show(ft, "dialog");
}

移除正在显示的Dialog，通过argument创建一个新的DialogFragment，并在堆栈中以新状态显示出来。当事务提交之后，DialogFragment和Dialog会被摧毁，如果有前一个的话会直接显示出来。注意既然这样，当Dialog从DialogFramgent销毁时应该小心的提交事务。

AlertDialog

除了实现onCreateView(LayoutInflater, ViewGroup, Bundle)在Dialog中生成图层之外，也可以通过onCreateDialog(Bundle)创建自定义Dialog对象。
创建一个AlertDialog是很有用的，它允许你向用户显示由Fragment管理的标准通知。简单实现如下：

 public static class MyAlertDialogFragment extends DialogFragment {

    public static MyAlertDialogFragment newInstance(int title) {
        MyAlertDialogFragment frag = new MyAlertDialogFragment();
        Bundle args = new Bundle();
        args.putInt("title", title);
        frag.setArguments(args);
        return frag;
    }

    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        int title = getArguments().getInt("title");

        return new AlertDialog.Builder(getActivity())
                .setIcon(R.drawable.alert_dialog_icon)
                .setTitle(title)
                .setPositiveButton(R.string.alert_dialog_ok,
                    new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int whichButton) {
                            ((FragmentAlertDialog)getActivity()).doPositiveClick();
                        }
                    }
                )
                .setNegativeButton(R.string.alert_dialog_cancel,
                    new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int whichButton) {
                            ((FragmentAlertDialog)getActivity()).doNegativeClick();
                        }
                    }
                )
                .create();
    }
}

Activity创建这个Fragment应该有下面的方法来显示和从Fragment接收结果：

void showDialog() {
    DialogFragment newFragment = MyAlertDialogFragment.newInstance(
            R.string.alert_dialog_two_buttons_title);
    newFragment.show(getFragmentManager(), "dialog");
}

public void doPositiveClick() {
    // Do stuff here.
    Log.i("FragmentAlertDialog", "Positive click!");
}

public void doNegativeClick() {
    // Do stuff here.
    Log.i("FragmentAlertDialog", "Negative click!");
}

注意既然Fragment没有放在返回栈中，只是作为一个无限期运行的Fragment被添加。因为Dialog通常是模态的，这仍将作为一个返回栈操作，从dialog获取用户输入直到销毁。当Dialog销毁，DialogFragment会自动在FragmentManager中移除它。

对话框和植入框的选择

如果你有一个Fragment在某些情况下作为Dialog显示，某些情况下嵌入大的UI是很有用的，这种情况通常会根据你如何使用Fragment去选择，但是可以通过setShowsDialog(boolean)自定义。

例如，这是一个简单的对话框Fragment:

public static class MyDialogFragment extends DialogFragment {
    static MyDialogFragment newInstance() {
        return new MyDialogFragment();
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.hello_world, container, false);
        View tv = v.findViewById(R.id.text);
        ((TextView)tv).setText("This is an instance of MyDialogFragment");
        return v;
    }
}

这个Fragment的的一个实例，可以创建和显示对话框

void showDialog() {
    // Create the fragment and show it as a dialog.
    DialogFragment newFragment = MyDialogFragment.newInstance();
    newFragment.show(getFragmentManager(), "dialog");
}

也可以作为图层的内容添加：

FragmentTransaction ft = getFragmentManager().beginTransaction();
DialogFragment newFragment = MyDialogFragment.newInstance();
ft.add(R.id.embedded, newFragment);
ft.commit();