谷歌建议我们使用DialogFragment而不是使用Fragments API创建一个简单的对话框,但是使用一个孤立的DialogFragment来创建一个简单的Yes-No确认消息框是荒谬的。在这种情况下,最佳实践是什么?


当前回答

我可以建议简化一下@ashishduh的回答吗:

public class AlertDialogFragment extends DialogFragment {
public static final String ARG_TITLE = "AlertDialog.Title";
public static final String ARG_MESSAGE = "AlertDialog.Message";

public static void showAlert(String title, String message, Fragment targetFragment) {
    DialogFragment dialog = new AlertDialogFragment();
    Bundle args = new Bundle();
    args.putString(ARG_TITLE, title);
    args.putString(ARG_MESSAGE, message);
    dialog.setArguments(args);
    dialog.setTargetFragment(targetFragment, 0);
    dialog.show(targetFragment.getFragmentManager(), "tag");
}

public AlertDialogFragment() {}

@NonNull
@Override
public AlertDialog onCreateDialog(Bundle savedInstanceState)
{
    Bundle args = getArguments();
    String title = args.getString(ARG_TITLE, "");
    String message = args.getString(ARG_MESSAGE, "");

    return new AlertDialog.Builder(getActivity())
            .setTitle(title)
            .setMessage(message)
            .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener()
            {
                @Override
                public void onClick(DialogInterface dialog, int which)
                {
                    getTargetFragment().onActivityResult(getTargetRequestCode(), Activity.RESULT_OK, null);
                }
            })
            .create();
}

它消除了(类的)用户熟悉组件内部结构的需要,并使使用变得非常简单:

AlertDialogFragment.showAlert(title, message, this);

附注:在我的情况下,我需要一个简单的警告对话框,所以这就是我所创建的。您可以将该方法应用于Yes/No或您需要的任何其他类型。

其他回答

我建议使用DialogFragment。

当然,用它创建一个“Yes/No”对话框是相当复杂的,因为它应该是相当简单的任务,但用dialog创建一个类似的对话框也是令人惊讶地复杂。

(活动的生命周期使它变得复杂-你必须让Activity管理对话框的生命周期-没有办法传递自定义参数,例如自定义消息给Activity。如果使用API级别低于8)

这样做的好处是,你通常可以很容易地在DialogFragment之上构建自己的抽象。

DialogFragment具有对话框和片段的功能。基本上所有的生命周期事件都是由DialogFragment自动管理的,比如屏幕配置的改变等。

通用AlertDialogFragment与生成器模式

In my project, I already used AlertDialog.Builder already a lot before I found out that it's problematic. However, I did not want to change that much code anywhere in my app. Additionally, I actually am a fan of passing OnClickListeners as anonymous classes where they are needed (that is, when using setPositiveButton(), setNegativeButton() etc.) instead of having to implement thousands of callback methods to communicate between a dialog fragment and the holder fragment, which can, in my opinion, lead to very confusing and complex code. Especially, if you have multiple different dialogs in one fragment and then need to distinguish in the callback implementations between which dialog currently being shown.

因此,我结合了不同的方法来创建一个通用的AlertDialogFragment助手类,它可以像AlertDialog一样使用:


解决方案

(请注意,我在我的代码中使用Java 8 lambda表达式,所以如果你还没有使用lambda表达式,你可能必须更改部分代码。)

/**
 * Helper class for dialog fragments to show a {@link AlertDialog}. It can be used almost exactly
 * like a {@link AlertDialog.Builder}
 * <p />
 * Creation Date: 22.03.16
 *
 * @author felix, http://flx-apps.com/
 */
public class AlertDialogFragment extends DialogFragment {
    protected FragmentActivity activity;
    protected Bundle args;
    protected String tag = AlertDialogFragment.class.getSimpleName();

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        activity = getActivity();
        args = getArguments();
    }

    @NonNull
    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        Dialog dialog = setDialogDefaults(new AlertDialog.Builder(getActivity())).create();

        if (args.containsKey("gravity")) {
            dialog.getWindow().getAttributes().gravity = args.getInt("gravity");
        }

        dialog.setOnShowListener(d -> {
            if (dialog != null && dialog.findViewById((android.R.id.message)) != null) {
                ((TextView) dialog.findViewById(android.R.id.message)).setMovementMethod(LinkMovementMethod.getInstance());
            }
        });
        return dialog;
    }

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        return super.onCreateView(inflater, container, savedInstanceState);
    }

    @Override
    public void onDismiss(DialogInterface dialog) {
        super.onDismiss(dialog);

        if (args.containsKey("onDismissListener")) {
            Parcelable onDismissListener = args.getParcelable("onDismissListener");
            if (onDismissListener != null && onDismissListener instanceof ParcelableOnDismissListener) {
                ((ParcelableOnDismissListener) onDismissListener).onDismiss(this);
            }
        }
    }

    /**
     * Sets default dialog properties by arguments which were set using {@link #builder(FragmentActivity)}
     */
    protected AlertDialog.Builder setDialogDefaults(AlertDialog.Builder builder) {
        args = getArguments();
        activity = getActivity();

        if (args.containsKey("title")) {
            builder.setTitle(args.getCharSequence("title"));
        }

        if (args.containsKey("message")) {
            CharSequence message = args.getCharSequence("message");
            builder.setMessage(message);
        }

        if (args.containsKey("viewId")) {
            builder.setView(getActivity().getLayoutInflater().inflate(args.getInt("viewId"), null));
        }

        if (args.containsKey("positiveButtonText")) {
            builder.setPositiveButton(args.getCharSequence("positiveButtonText"), (dialog, which) -> {
                onButtonClicked("positiveButtonListener", which);
            });
        }

        if (args.containsKey("negativeButtonText")) {
            builder.setNegativeButton(args.getCharSequence("negativeButtonText"), (dialog, which) -> {
                onButtonClicked("negativeButtonListener", which);
            });
        }

        if (args.containsKey("neutralButtonText")) {
            builder.setNeutralButton(args.getCharSequence("neutralButtonText"), (dialog, which) -> {
                onButtonClicked("neutralButtonListener", which);
            });
        }

        if (args.containsKey("items")) {
            builder.setItems(args.getStringArray("items"), (dialog, which) -> {
                onButtonClicked("itemClickListener", which);
            });
        }

        // @formatter:off
        // FIXME this a pretty hacky workaround: we don't want to show the dialog if onClickListener of one of the dialog's button click listener were lost
        //       the problem is, that there is no (known) solution for parceling a OnClickListener in the long term (only for state changes like orientation change,
        //       but not if the Activity was completely lost)
        if (
                (args.getParcelable("positiveButtonListener") != null && !(args.getParcelable("positiveButtonListener") instanceof ParcelableOnClickListener)) ||
                (args.getParcelable("negativeButtonListener") != null && !(args.getParcelable("negativeButtonListener") instanceof ParcelableOnClickListener)) ||
                (args.getParcelable("neutralButtonListener") != null && !(args.getParcelable("neutralButtonListener") instanceof ParcelableOnClickListener)) ||
                (args.getParcelable("itemClickListener") != null && !(args.getParcelable("itemClickListener") instanceof ParcelableOnClickListener))
        ) {
            new DebugMessage("Forgot onClickListener. Needs to be dismissed.")
                    .logLevel(DebugMessage.LogLevel.VERBOSE)
                    .show();
            try {
                dismissAllowingStateLoss();
            } catch (NullPointerException | IllegalStateException ignored) {}
        }
        // @formatter:on

        return builder;
    }

    public interface OnDismissListener {
        void onDismiss(AlertDialogFragment dialogFragment);
    }

    public interface OnClickListener {
        void onClick(AlertDialogFragment dialogFragment, int which);
    }

    protected void onButtonClicked(String buttonKey, int which) {
        ParcelableOnClickListener parcelableOnClickListener = getArguments().getParcelable(buttonKey);
        if (parcelableOnClickListener != null) {
            parcelableOnClickListener.onClick(this, which);
        }
    }

    // region Convenience Builder Pattern class almost similar to AlertDialog.Builder
    // =============================================================================================

    public AlertDialogFragment builder(FragmentActivity activity) {
        this.activity = activity;
        this.args = new Bundle();
        return this;
    }

    public AlertDialogFragment addArguments(Bundle bundle) {
        args.putAll(bundle);
        return this;
    }

    public AlertDialogFragment setTitle(int titleStringId) {
        return setTitle(activity.getString(titleStringId));
    }

    public AlertDialogFragment setTitle(CharSequence title) {
        args.putCharSequence("title", title);
        return this;
    }

    public AlertDialogFragment setMessage(int messageStringId) {
        return setMessage(activity.getString(messageStringId));
    }

    public AlertDialogFragment setMessage(CharSequence message) {
        args.putCharSequence("message", message);
        return this;
    }

    public AlertDialogFragment setPositiveButton(int textStringId, OnClickListener onClickListener) {
        return setPositiveButton(activity.getString(textStringId), onClickListener);
    }

    public AlertDialogFragment setPositiveButton(CharSequence text, AlertDialogFragment.OnClickListener onClickListener) {
        args.putCharSequence("positiveButtonText", text);
        args.putParcelable("positiveButtonListener", createParcelableOnClickListener(onClickListener));
        return this;
    }

    public AlertDialogFragment setNegativeButton(int textStringId, AlertDialogFragment.OnClickListener onClickListener) {
        return setNegativeButton(activity.getString(textStringId), onClickListener);
    }

    public AlertDialogFragment setNegativeButton(CharSequence text, AlertDialogFragment.OnClickListener onClickListener) {
        args.putCharSequence("negativeButtonText", text);
        args.putParcelable("negativeButtonListener", createParcelableOnClickListener(onClickListener));
        return this;
    }

    public AlertDialogFragment setNeutralButton(int textStringId, AlertDialogFragment.OnClickListener onClickListener) {
        return setNeutralButton(activity.getString(textStringId), onClickListener);
    }

    public AlertDialogFragment setNeutralButton(CharSequence text, AlertDialogFragment.OnClickListener onClickListener) {
        args.putCharSequence("neutralButtonText", text);
        args.putParcelable("neutralButtonListener", createParcelableOnClickListener(onClickListener));
        return this;
    }

    public AlertDialogFragment setOnDismissListener(OnDismissListener onDismissListener) {
        if (onDismissListener == null) {
            return this;
        }

        Parcelable p = new ParcelableOnDismissListener() {
            @Override
            public void onDismiss(AlertDialogFragment dialogFragment) {
                onDismissListener.onDismiss(dialogFragment);
            }
        };
        args.putParcelable("onDismissListener", p);
        return this;
    }

    public AlertDialogFragment setItems(String[] items, AlertDialogFragment.OnClickListener onClickListener) {
        args.putStringArray("items", items);
        args.putParcelable("itemClickListener", createParcelableOnClickListener(onClickListener));
        return this;
    }

    public AlertDialogFragment setView(int viewId) {
        args.putInt("viewId", viewId);
        return this;
    }

    public AlertDialogFragment setGravity(int gravity) {
        args.putInt("gravity", gravity);
        return this;
    }

    public AlertDialogFragment setTag(String tag) {
        this.tag = tag;
        return this;
    }

    public AlertDialogFragment create() {
        setArguments(args);
        return AlertDialogFragment.this;
    }

    public AlertDialogFragment show() {
        create();
        try {
            super.show(activity.getSupportFragmentManager(), tag);
        }
        catch (IllegalStateException e1) {

            /**
             * this whole part is used in order to attempt to show the dialog if an
             * {@link IllegalStateException} was thrown (it's kinda comparable to
             * {@link FragmentTransaction#commitAllowingStateLoss()} 
             * So you can remove all those dirty hacks if you are sure that you are always
             * properly showing dialogs in the right moments
             */

            new DebugMessage("got IllegalStateException attempting to show dialog. trying to hack around.")
                    .logLevel(DebugMessage.LogLevel.WARN)
                    .exception(e1)
                    .show();

            try {
                Field mShownByMe = DialogFragment.class.getDeclaredField("mShownByMe");
                mShownByMe.setAccessible(true);
                mShownByMe.set(this, true);
                Field mDismissed = DialogFragment.class.getDeclaredField("mDismissed");
                mDismissed.setAccessible(true);
                mDismissed.set(this, false);
            }
            catch (Exception e2) {
                new DebugMessage("error while showing dialog")
                        .exception(e2)
                        .logLevel(DebugMessage.LogLevel.ERROR)
                        .show();
            }
            FragmentTransaction transaction = activity.getSupportFragmentManager().beginTransaction();
            transaction.add(this, tag);
            transaction.commitAllowingStateLoss(); // FIXME hacky and unpredictable workaround
        }
        return AlertDialogFragment.this;
    }

    @Override
    public int show(FragmentTransaction transaction, String tag) {
        throw new NoSuchMethodError("Please use AlertDialogFragment.show()!");
    }

    @Override
    public void show(FragmentManager manager, String tag) {
        throw new NoSuchMethodError("Please use AlertDialogFragment.show()!");
    }

    protected ParcelableOnClickListener createParcelableOnClickListener(AlertDialogFragment.OnClickListener onClickListener) {
        if (onClickListener == null) {
            return null;
        }

        return new ParcelableOnClickListener() {
            @Override
            public void onClick(AlertDialogFragment dialogFragment, int which) {
                onClickListener.onClick(dialogFragment, which);
            }
        };
    }

    /**
     * Parcelable OnClickListener (can be remembered on screen rotation)
     */
    public abstract static class ParcelableOnClickListener extends ResultReceiver implements AlertDialogFragment.OnClickListener {
        public static final Creator<ResultReceiver> CREATOR = ResultReceiver.CREATOR;

        ParcelableOnClickListener() {
            super(null);
        }

        @Override
        public abstract void onClick(AlertDialogFragment dialogFragment, int which);
    }

    /**
     * Parcelable OnDismissListener (can be remembered on screen rotation)
     */
    public abstract static class ParcelableOnDismissListener extends ResultReceiver implements AlertDialogFragment.OnDismissListener {
        public static final Creator<ResultReceiver> CREATOR = ResultReceiver.CREATOR;

        ParcelableOnDismissListener() {
            super(null);
        }

        @Override
        public abstract void onDismiss(AlertDialogFragment dialogFragment);
    }


    // =============================================================================================
    // endregion
}

使用

// showing a normal alert dialog with state loss on configuration changes (like device rotation)
new AlertDialog.Builder(getActivity())
        .setTitle("Are you sure? (1)")
        .setMessage("Do you really want to do this?")
        .setPositiveButton("Yes", (dialog, which) -> Toast.makeText(getContext(), "Yes clicked", Toast.LENGTH_SHORT).show())
        .setNegativeButton("Cancel", null)
        .show();

// showing a dialog fragment using the helper class with no state loss on configuration changes
new AlertDialogFragment.builder(getActivity())
        .setTitle("Are you sure? (2)")
        .setMessage("Do you really want to do this?")
        .setPositiveButton("Yes", (dialog, which) -> Toast.makeText(getContext(), "Yes clicked", Toast.LENGTH_SHORT).show())
        .setNegativeButton("Cancel", null)
        .show();

我在这里发表这篇文章不仅是为了分享我的解决方案,也是因为我想征求你们的意见:这种方法在某种程度上是合法的还是有问题的?

是的,使用DialogFragment和onCreateDialog,你可以简单地使用AlertDialog构建器创建一个简单的AlertDialog与Yes/No确认按钮。根本没有多少代码。

关于处理事件在你的片段会有各种方法,但我只是在我的片段定义了一个消息处理程序,通过它的构造函数传递到DialogFragment,然后将消息传递回我的片段的处理程序适当的各种点击事件。有很多方法,但下面的方法对我来说是有效的。

在对话框中保存一个消息并在构造函数中实例化它:

private Message okMessage;
...
okMessage = handler.obtainMessage(MY_MSG_WHAT, MY_MSG_OK);

在你的对话框中实现onClickListener,然后适当地调用处理程序:

public void onClick(.....
    if (which == DialogInterface.BUTTON_POSITIVE) {
        final Message toSend = Message.obtain(okMessage);
        toSend.sendToTarget();
    }
 }

Edit

由于Message是可打包的,你可以在onSaveInstanceState中保存它并恢复它

outState.putParcelable("okMessage", okMessage);

然后在onCreate中

if (savedInstanceState != null) {
    okMessage = savedInstanceState.getParcelable("okMessage");
}

你可以创建一般的DialogFragment子类,如YesNoDialog和OkDialog,并传入标题和消息,如果你在应用程序中使用对话框很多。

public class YesNoDialog extends DialogFragment
{
    public static final String ARG_TITLE = "YesNoDialog.Title";
    public static final String ARG_MESSAGE = "YesNoDialog.Message";

    public YesNoDialog()
    {

    }

    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState)
    {
        Bundle args = getArguments();
        String title = args.getString(ARG_TITLE);
        String message = args.getString(ARG_MESSAGE);

        return new AlertDialog.Builder(getActivity())
            .setTitle(title)
            .setMessage(message)
            .setPositiveButton(android.R.string.yes, new DialogInterface.OnClickListener()
            {
                @Override
                public void onClick(DialogInterface dialog, int which)
                {
                    getTargetFragment().onActivityResult(getTargetRequestCode(), Activity.RESULT_OK, null);
                }
            })
            .setNegativeButton(android.R.string.no, new DialogInterface.OnClickListener()
            {
                @Override
                public void onClick(DialogInterface dialog, int which)
                {
                    getTargetFragment().onActivityResult(getTargetRequestCode(), Activity.RESULT_CANCELED, null);
                }
            })
            .create();
    }
}

然后使用以下命令调用它:

    DialogFragment dialog = new YesNoDialog();
    Bundle args = new Bundle();
    args.putString(YesNoDialog.ARG_TITLE, title);
    args.putString(YesNoDialog.ARG_MESSAGE, message);
    dialog.setArguments(args);
    dialog.setTargetFragment(this, YES_NO_CALL);
    dialog.show(getFragmentManager(), "tag");

并在onActivityResult中处理结果。