Android

DialogFragment你可能踩过或将要踩的坑

2022-06-03  本文已影响0人  mandypig

前言

dialogfragment是google推出用来替换dialog的一种方案,相比较dialog,dialogfragment能更好的管理dialog的展示与消失,以及在屏幕旋转时的一些状态保存问题dialogfragment都会给你处理好,看过源码其实都知道dialogfragment内部就是通过dialog来对视图进行管理。而且本质上dialogfragment就是一个fragment,任何事情感觉和fragment扯上关系都会变得没这么简单,dialogfragment也不例外,文章主要来讲下在使用dialogfragment过程中遇到的几个比较坑的问题,以及解决方法。主要可分为三个

(1)dialogfragment展示时引起的崩溃问题
(2)内存泄露问题
(3)加载含有fragment的view导致的崩溃

dialogfragment展示时引起的崩溃问题

这个问题比较简单,就是在dialogfragment要展示的时候,如果按home键返回到了桌面,这时强行调用show方法就会导致app崩溃,抛出的异常大致如下

java.lang.IllegalStateException: Can not perform this action after onSaveInstanceState

熟悉fragment应该都知道,这是一个fragment导致的崩溃,可以通过调用commitAllowingStateLoss方法来避免崩溃。出现这种崩溃场景常见的比如app首页进入后可能会弹出一些弹框广告,这些弹框如果在网络有一定延迟并且app返回到home后触发弹框,如果app没有做好处理就会导致崩溃,可以来看下dialogfragment相关的show方法

public void show(FragmentManager manager, String tag) {
        this.mDismissed = false;
        this.mShownByMe = true;
        FragmentTransaction ft = manager.beginTransaction();
        ft.add(this, tag);
        ft.commit();
    }

可以很明显的看到,并没有调用commitAllowingStateLoss,而是直接调用了commit方法。但是去翻看下dialogfragment的dismiss方法,你却会发现

void dismissInternal(boolean allowStateLoss) {
        if (!this.mDismissed) {
            this.mDismissed = true;
            this.mShownByMe = false;
            if (this.mDialog != null) {
                this.mDialog.dismiss();
            }

            this.mViewDestroyed = true;
            if (this.mBackStackId >= 0) {
                this.getFragmentManager().popBackStack(this.mBackStackId, 1);
                this.mBackStackId = -1;
            } else {
                FragmentTransaction ft = this.getFragmentManager().beginTransaction();
                ft.remove(this);
                if (allowStateLoss) {
                    ft.commitAllowingStateLoss();
                } else {
                    ft.commit();
                }
            }

        }
    }

有相关调用commitAllowingStateLoss的方法,show的时候不允许commitAllowingStateLoss但是dismiss却又允许commitAllowingStateLoss,不太理解google大佬这么做的意图。既然问题根源找到了那么问题就好解决了,主要有两个方法
(1)app代码逻辑控制,在app返回home之后如果有相关的弹框就先屏蔽掉,等app重新展示再弹框。这个方法改动比较大,可能需要对弹框逻辑进行修改,不太推荐
(2)给dialogfragment增加调用commitAllowingStateLoss的方法,目前自己采用的方法,通过修改dialograment的show方法源码即可,文末给出源码

内存泄露问题

这个应该说是使用dialogfragment遇到的比较多的一个问题,产生泄露的原因和内部使用的dialog有关以及一些三方库线程中使用到message有关,要把这个问题说明白首先看下和handler相关的message,这似乎回到了内存泄露的经典场景handler+message。但dialogfragment的内存泄露比这个要复杂一些。

android系统为了提高message的复用,使用到了一个message池来管理那些被回收的message对象,可以通过Message的obtain方法从message池中获取到message,而message最终会被放到messagequeue中等待被处理,源码如下

for (;;) {
            Message msg = queue.next(); // might block
            if (msg == null) {
                // No message indicates that the message queue is quitting.
                return;
            }

            ...

            msg.recycleUnchecked();
        }

通过next获取到message对象,最终执行完毕后通过recycleUnchecked被回收回message池中,然后继续next取出下一个要被处理的message对象,如果没有要被执行的message则next会被一直阻塞在这里。由于msg是一个局部变量,next被阻塞住会导致该局部变量无法被回收,但是最为关键的一点是,这个msg对象却被放到了message池中,可被其他的线程使用到。这就会导致一旦该msg对象被其他线程使用到就可能导致msg成员变量一直持有某些引用对象最终引发内存泄露问题。

而dialogfragment正好就踩到了这个雷上,dialogfragment内部会使用到dialog来看下dialog内部源码实现

public void setOnDismissListener(@Nullable OnDismissListener listener) {
        if (mCancelAndDismissTaken != null) {
            throw new IllegalStateException(
                    "OnDismissListener is already taken by "
                    + mCancelAndDismissTaken + " and can not be replaced.");
        }
        if (listener != null) {
            mDismissMessage = mListenersHandler.obtainMessage(DISMISS, listener);
        } else {
            mDismissMessage = null;
        }
    }

obtainMessage从message池中获取到了一个message,并且到message的obj对象被设置为了listener,listener对象实际上就是一个dialogfragment对象,而dialogfragment又和activity有着关联。
个别三方库会自己维护一个非ui线程的messagequeue,通过handleThread对消息进行处理,一旦三方库处于空闲状态,被回收的message对象就被放入了消息池当中,如果此时正好触发了上述setOnDismissListener,此时message对象就会存在两个地方引用,一个是dialog的mDismissMessage变量,另一个则是三方库的局部变量message,再来看下dialog中是如何使用mDismissMessage的

private void sendDismissMessage() {
        if (mDismissMessage != null) {
            // Obtain a new message so this dialog can be re-used
            Message.obtain(mDismissMessage).sendToTarget();
        }
    }

message内部源码
public static Message obtain(Message orig) {
        Message m = obtain();
        m.what = orig.what;
        m.arg1 = orig.arg1;
        m.arg2 = orig.arg2;
        m.obj = orig.obj;
        m.replyTo = orig.replyTo;
        m.sendingUid = orig.sendingUid;
        if (orig.data != null) {
            m.data = new Bundle(orig.data);
        }
        m.target = orig.target;
        m.callback = orig.callback;

        return m;
    }

obtain(Message orig)是直接拷贝了一份message出来,所以即使该message最后被消息队列执行完毕调用recycleUnchecked回收了也不影响dialog成员变量mDismissMessage上的结构有任何改变。知道原因后解决起来心里就有数了,处理方式如下:

private static class DialogDismissListener extends WeakReference<FixDialogFragment> implements DialogInterface.OnDismissListener {

        private DialogDismissListener(FixDialogFragment referent) {
            super(referent);
        }

        @Override
        public void onDismiss(DialogInterface dialog) {
            FixDialogFragment dialogFragment = get();
            if (dialogFragment != null) {
                dialogFragment.onDismissDialog(dialog);
            }
        }
    }

将message的what对象最终指向一个弱引用对象

mDialog.setOnDismissListener(new DialogDismissListener(this));

同理CancelListener处理过程类似。上述解决方法需要修改dialogfragment源码进行解决。文末给出完整代码

加载含有fragment的view导致的崩溃

这又是一个和fragment相关的坑。我们的dialogfragment所展示的view是通过解析xml来获取到的,一般而言这个xml中都是一些普通的view控件,但如果xml中包含了fragment节点那么问题就会稍微复杂一些。

比如如下场景,某个页面需要弹出一个dialog来展示一些银行卡信息。这些银行卡信息通过一个个item来让recyclerview进行展示,如图


{C11650A9-AA87-4292-8125-37CB2F0CE32D}_20200610225133.jpg

自己在开发中经常遇到这种通过recyclerview来展示item的场景,无论是刷新操作还是加载更多都离不开那些通用的逻辑处理,所以封装了一个fragment,给出需要展示的数据后该fragment就会自动帮你展示出来,避免了一些重复的逻辑判断工作。其实google也封装了一个类似的fragment叫ListFragment。

所以基于上述情况,我在dialogfragment需要展示的xml上使用了该fragment,导致的结果就是多次展示dialogfragment后引起了app崩溃问题。崩溃信息类似如下

 Caused by: java.lang.IllegalArgumentException: Binary XML file line #30: Duplicate id 0x7f080047

造成这个问题的主要原因就是当dialogfragment被展示时,实际上总共生成了两个fragment,而且都被添加到了同一个fragmentmanager之上,但是在remove的时候却只移除了其中一个,导致再次展示dialogfragment时出现重复添加的异常。

这两个fragment其中一个就是dialogfragment,而另一个就是xml中自己设置的fragment。dialogfragment本质上就是一个fragment,这个看类结构就明白

public class DialogFragment extends Fragment implements OnCancelListener, OnDismissListener 

dialogfragment的show源码如下

public void show(FragmentManager manager, String tag) {
        this.mDismissed = false;
        this.mShownByMe = true;
        FragmentTransaction ft = manager.beginTransaction();
        ft.add(this, tag);
        ft.commit();
    }

manager对象就是通过Activity获取到的,当dialogfragment去解析xml时如果内部有fragment,也会将该fragment添加到该fragmentmanager上,但是看下dialogfragment的dismiss源码

void dismissInternal(boolean allowStateLoss) {
        if (!this.mDismissed) {
            this.mDismissed = true;
            this.mShownByMe = false;
            if (this.mDialog != null) {
                this.mDialog.dismiss();
            }

            this.mViewDestroyed = true;
            if (this.mBackStackId >= 0) {
                this.getFragmentManager().popBackStack(this.mBackStackId, 1);
                this.mBackStackId = -1;
            } else {
                FragmentTransaction ft = this.getFragmentManager().beginTransaction();
                ft.remove(this);
                if (allowStateLoss) {
                    ft.commitAllowingStateLoss();
                } else {
                    ft.commit();
                }
            }

        }
    }

很明显,它只会remove掉dialogfragment,而xml中的fragment会被一直保留在manager之上。明白崩溃原因之后解决方法也就简单了,在dialogfragment被dismiss的时候remove掉那个xml中的fragment即可,dialogfragment提供了dismiss的监听,在内部处理逻辑

FragmentActivity context = (FragmentActivity) getContext();
        if (context != null) {
            FragmentManager manager = context.getSupportFragmentManager();
            Fragment fragment = manager.findFragmentById(XXX);
            if (fragment != null) {
                FragmentTransaction transaction = manager.beginTransaction();
                transaction.remove(fragment);
                transaction.commitAllowingStateLoss();
            }
        }

实际上当存在fragment嵌套问题时,一般内部的fragment会被添加到外部fragment的childmanager上,如果是这种情况应该不会存在上述dialogfragment崩溃的问题,可以看下fragment内部源码的处理,最终会调用到如下方法

public LayoutInflater getLayoutInflater(@Nullable Bundle savedFragmentState) {
        if (this.mHost == null) {
            throw new IllegalStateException("onGetLayoutInflater() cannot be executed until the Fragment is attached to the FragmentManager.");
        } else {
            LayoutInflater result = this.mHost.onGetLayoutInflater();
            this.getChildFragmentManager();
            LayoutInflaterCompat.setFactory2(result, this.mChildFragmentManager.getLayoutInflaterFactory());
            return result;
        }
    }

getChildFragmentManager会生成一个childmanager供内部fragment'使用,但是dialogfragment却复写了onGetLayoutInflater方法

@NonNull
    public LayoutInflater onGetLayoutInflater(@Nullable Bundle savedInstanceState) {
        if (!this.mShowsDialog) {
            return super.onGetLayoutInflater(savedInstanceState);
        } else {
            this.mDialog = this.onCreateDialog(savedInstanceState);
            if (this.mDialog != null) {
                this.setupDialog(this.mDialog, this.mStyle);
                return (LayoutInflater)this.mDialog.getContext().getSystemService("layout_inflater");
            } else {
                return (LayoutInflater)this.mHost.getContext().getSystemService("layout_inflater");
            }
        }
    }

导致最终没有调用到fragment中的生成childmanager的逻辑处理,这才是产生dialogfragment崩溃的主要原因。

结尾

文章到此就分析完了自己在开发过程中遇到的几个关于dialogfragment问题,最后给出解决后的代码,以下代码是直接在dialogfragment的基础上进行修改的,直接拷贝出dialogfragment源码修改即可。完整的源码如下,看着很多但实际上绝大部分都是dialogfragment本身的源码,具体的改动点在上述文章都已经说明不在重复讲述

/**
 * 解决内存泄露,弹框可能引起的崩溃问题
* @author stupid pig mandy
 * */
public class FixDialogFragment extends Fragment
        implements DialogInterface.OnCancelListener, DialogInterface.OnDismissListener {

    /** @hide */
    @RestrictTo(LIBRARY_GROUP)
    @IntDef({STYLE_NORMAL, STYLE_NO_TITLE, STYLE_NO_FRAME, STYLE_NO_INPUT})
    @Retention(RetentionPolicy.SOURCE)
    private @interface DialogStyle {}

    /**
     * Style for {@link #setStyle(int, int)}: a basic,
     * normal dialog.
     */
    public static final int STYLE_NORMAL = 0;

    /**
     * Style for {@link #setStyle(int, int)}: don't include
     * a title area.
     */
    public static final int STYLE_NO_TITLE = 1;

    /**
     * Style for {@link #setStyle(int, int)}: don't draw
     * any frame at all; the view hierarchy returned by {@link #onCreateView}
     * is entirely responsible for drawing the dialog.
     */
    public static final int STYLE_NO_FRAME = 2;

    /**
     * Style for {@link #setStyle(int, int)}: like
     * {@link #STYLE_NO_FRAME}, but also disables all input to the dialog.
     * The user can not touch it, and its window will not receive input focus.
     */
    public static final int STYLE_NO_INPUT = 3;

    private static final String SAVED_DIALOG_STATE_TAG = "android:savedDialogState";
    private static final String SAVED_STYLE = "android:style";
    private static final String SAVED_THEME = "android:theme";
    private static final String SAVED_CANCELABLE = "android:cancelable";
    private static final String SAVED_SHOWS_DIALOG = "android:showsDialog";
    private static final String SAVED_BACK_STACK_ID = "android:backStackId";

    int mStyle = STYLE_NORMAL;
    int mTheme = 0;
    boolean mCancelable = true;
    boolean mShowsDialog = true;
    int mBackStackId = -1;

    Dialog mDialog;
    boolean mViewDestroyed;
    boolean mDismissed;
    boolean mShownByMe;

    public FixDialogFragment() {
    }

    /**
     * Call to customize the basic appearance and behavior of the
     * fragment's dialog.  This can be used for some common dialog behaviors,
     * taking care of selecting flags, theme, and other options for you.  The
     * same effect can be achieve by manually setting Dialog and Window
     * attributes yourself.  Calling this after the fragment's Dialog is
     * created will have no effect.
     *
     * @param style Selects a standard style: may be {@link #STYLE_NORMAL},
     * {@link #STYLE_NO_TITLE}, {@link #STYLE_NO_FRAME}, or
     * {@link #STYLE_NO_INPUT}.
     * @param theme Optional custom theme.  If 0, an appropriate theme (based
     * on the style) will be selected for you.
     */
    public void setStyle(@DialogStyle int style, @StyleRes int theme) {
        mStyle = style;
        if (mStyle == STYLE_NO_FRAME || mStyle == STYLE_NO_INPUT) {
            mTheme = android.R.style.Theme_Panel;
        }
        if (theme != 0) {
            mTheme = theme;
        }
    }

    /**
     * Display the dialog, adding the fragment to the given FragmentManager.  This
     * is a convenience for explicitly creating a transaction, adding the
     * fragment to it with the given tag, and {@link FragmentTransaction#commit() committing} it.
     * This does <em>not</em> add the transaction to the fragment back stack.  When the fragment
     * is dismissed, a new transaction will be executed to remove it from
     * the activity.
     * @param manager The FragmentManager this fragment will be added to.
     * @param tag The tag for this fragment, as per
     * {@link FragmentTransaction#add(Fragment, String) FragmentTransaction.add}.
     */
    public void show(FragmentManager manager, String tag) {
        mDismissed = false;
        mShownByMe = true;
        FragmentTransaction ft = manager.beginTransaction();
        ft.add(this, tag);
        ft.commitAllowingStateLoss();
    }

    /**
     * Display the dialog, adding the fragment using an existing transaction
     * and then {@link FragmentTransaction#commit() committing} the transaction.
     * @param transaction An existing transaction in which to add the fragment.
     * @param tag The tag for this fragment, as per
     * {@link FragmentTransaction#add(Fragment, String) FragmentTransaction.add}.
     * @return Returns the identifier of the committed transaction, as per
     * {@link FragmentTransaction#commit() FragmentTransaction.commit()}.
     */
    public int show(FragmentTransaction transaction, String tag) {
        mDismissed = false;
        mShownByMe = true;
        transaction.add(this, tag);
        mViewDestroyed = false;
        mBackStackId = transaction.commit();
        return mBackStackId;
    }

    /**
     * Display the dialog, immediately adding the fragment to the given FragmentManager.  This
     * is a convenience for explicitly creating a transaction, adding the
     * fragment to it with the given tag, and calling {@link FragmentTransaction#commitNow()}.
     * This does <em>not</em> add the transaction to the fragment back stack.  When the fragment
     * is dismissed, a new transaction will be executed to remove it from
     * the activity.
     * @param manager The FragmentManager this fragment will be added to.
     * @param tag The tag for this fragment, as per
     * {@link FragmentTransaction#add(Fragment, String) FragmentTransaction.add}.
     */
    public void showNow(FragmentManager manager, String tag) {
        mDismissed = false;
        mShownByMe = true;
        FragmentTransaction ft = manager.beginTransaction();
        ft.add(this, tag);
        ft.commitNow();
    }

    /**
     * Dismiss the fragment and its dialog.  If the fragment was added to the
     * back stack, all back stack state up to and including this entry will
     * be popped.  Otherwise, a new transaction will be committed to remove
     * the fragment.
     */
    public void dismiss() {
        dismissInternal(false);
    }

    /**
     * Version of {@link #dismiss()} that uses
     * {@link FragmentTransaction#commitAllowingStateLoss()
     * FragmentTransaction.commitAllowingStateLoss()}. See linked
     * documentation for further details.
     */
    public void dismissAllowingStateLoss() {
        dismissInternal(true);
    }

    void dismissInternal(boolean allowStateLoss) {
        if (mDismissed) {
            return;
        }
        mDismissed = true;
        mShownByMe = false;
        if (mDialog != null) {
            mDialog.dismiss();
        }
        mViewDestroyed = true;
        if (mBackStackId >= 0) {
            getFragmentManager().popBackStack(mBackStackId,
                    FragmentManager.POP_BACK_STACK_INCLUSIVE);
            mBackStackId = -1;
        } else {
            FragmentTransaction ft = getFragmentManager().beginTransaction();
            ft.remove(this);
            if (allowStateLoss) {
                ft.commitAllowingStateLoss();
            } else {
                ft.commit();
            }
        }
    }

    public Dialog getDialog() {
        return mDialog;
    }

    @StyleRes
    public int getTheme() {
        return mTheme;
    }

    /**
     * Control whether the shown Dialog is cancelable.  Use this instead of
     * directly calling {@link Dialog#setCancelable(boolean)
     * Dialog.setCancelable(boolean)}, because DialogFragment needs to change
     * its behavior based on this.
     *
     * @param cancelable If true, the dialog is cancelable.  The default
     * is true.
     */
    public void setCancelable(boolean cancelable) {
        mCancelable = cancelable;
        if (mDialog != null) mDialog.setCancelable(cancelable);
    }

    /**
     * Return the current value of {@link #setCancelable(boolean)}.
     */
    public boolean isCancelable() {
        return mCancelable;
    }

    /**
     * Controls whether this fragment should be shown in a dialog.  If not
     * set, no Dialog will be created in {@link #onActivityCreated(Bundle)},
     * and the fragment's view hierarchy will thus not be added to it.  This
     * allows you to instead use it as a normal fragment (embedded inside of
     * its activity).
     *
     * <p>This is normally set for you based on whether the fragment is
     * associated with a container view ID passed to
     * {@link FragmentTransaction#add(int, Fragment) FragmentTransaction.add(int, Fragment)}.
     * If the fragment was added with a container, setShowsDialog will be
     * initialized to false; otherwise, it will be true.
     *
     * @param showsDialog If true, the fragment will be displayed in a Dialog.
     * If false, no Dialog will be created and the fragment's view hierarchy
     * left undisturbed.
     */
    public void setShowsDialog(boolean showsDialog) {
        mShowsDialog = showsDialog;
    }

    /**
     * Return the current value of {@link #setShowsDialog(boolean)}.
     */
    public boolean getShowsDialog() {
        return mShowsDialog;
    }

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
        if (!mShownByMe) {
            // If not explicitly shown through our API, take this as an
            // indication that the dialog is no longer dismissed.
            mDismissed = false;
        }
    }

    @Override
    public void onDetach() {
        super.onDetach();
        if (!mShownByMe && !mDismissed) {
            // The fragment was not shown by a direct call here, it is not
            // dismissed, and now it is being detached...  well, okay, thou
            // art now dismissed.  Have fun.
            mDismissed = true;
        }
    }

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        mShowsDialog = mContainerId == 0;

        if (savedInstanceState != null) {
            mStyle = savedInstanceState.getInt(SAVED_STYLE, STYLE_NORMAL);
            mTheme = savedInstanceState.getInt(SAVED_THEME, 0);
            mCancelable = savedInstanceState.getBoolean(SAVED_CANCELABLE, true);
            mShowsDialog = savedInstanceState.getBoolean(SAVED_SHOWS_DIALOG, mShowsDialog);
            mBackStackId = savedInstanceState.getInt(SAVED_BACK_STACK_ID, -1);
        }
    }

    @Override
    public LayoutInflater onGetLayoutInflater(Bundle savedInstanceState) {
        if (!mShowsDialog) {
            return super.onGetLayoutInflater(savedInstanceState);
        }

        mDialog = onCreateDialog(savedInstanceState);

        if (mDialog != null) {
            setupDialog(mDialog, mStyle);

            return (LayoutInflater) mDialog.getContext().getSystemService(
                    Context.LAYOUT_INFLATER_SERVICE);
        }
        return (LayoutInflater) mHost.getContext().getSystemService(
                Context.LAYOUT_INFLATER_SERVICE);
    }

    /** @hide */
    @RestrictTo(LIBRARY_GROUP)
    public void setupDialog(Dialog dialog, int style) {
        switch (style) {
            case STYLE_NO_INPUT:
                dialog.getWindow().addFlags(
                        WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE |
                                WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE);
                // fall through...
            case STYLE_NO_FRAME:
            case STYLE_NO_TITLE:
                dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
        }
    }

    /**
     * Override to build your own custom Dialog container.  This is typically
     * used to show an AlertDialog instead of a generic Dialog; when doing so,
     * {@link #onCreateView(LayoutInflater, ViewGroup, Bundle)} does not need
     * to be implemented since the AlertDialog takes care of its own content.
     *
     * <p>This method will be called after {@link #onCreate(Bundle)} and
     * before {@link #onCreateView(LayoutInflater, ViewGroup, Bundle)}.  The
     * default implementation simply instantiates and returns a {@link Dialog}
     * class.
     *
     * <p><em>Note: DialogFragment own the {@link Dialog#setOnCancelListener
     * Dialog.setOnCancelListener} and {@link Dialog#setOnDismissListener
     * Dialog.setOnDismissListener} callbacks.  You must not set them yourself.</em>
     * To find out about these events, override {@link #onCancel(DialogInterface)}
     * and {@link #onDismiss(DialogInterface)}.</p>
     *
     * @param savedInstanceState The last saved instance state of the Fragment,
     * or null if this is a freshly created Fragment.
     *
     * @return Return a new Dialog instance to be displayed by the Fragment.
     */
    @NonNull
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        return new Dialog(getActivity(), getTheme());
    }

    @Override
    public void onCancel(DialogInterface dialog) {
    }

    @Override
    public void onDismiss(DialogInterface dialog) {
        if (!mViewDestroyed) {
            // Note: we need to use allowStateLoss, because the dialog
            // dispatches this asynchronously so we can receive the call
            // after the activity is paused.  Worst case, when the user comes
            // back to the activity they see the dialog again.
            dismissInternal(true);
        }
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);

        if (!mShowsDialog) {
            return;
        }

        View view = getView();
        if (view != null) {
            if (view.getParent() != null) {
                throw new IllegalStateException(
                        "DialogFragment can not be attached to a container view");
            }
            mDialog.setContentView(view);
        }
        final Activity activity = getActivity();
        if (activity != null) {
            mDialog.setOwnerActivity(activity);
        }
        mDialog.setCancelable(mCancelable);
        mDialog.setOnCancelListener(new DialogCancelListener(this));
        mDialog.setOnDismissListener(new DialogDismissListener(this));
        if (savedInstanceState != null) {
            Bundle dialogState = savedInstanceState.getBundle(SAVED_DIALOG_STATE_TAG);
            if (dialogState != null) {
                mDialog.onRestoreInstanceState(dialogState);
            }
        }
    }

    @Override
    public void onStart() {
        super.onStart();

        if (mDialog != null) {
            mViewDestroyed = false;
            mDialog.show();
        }
    }

    @Override
    public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        if (mDialog != null) {
            Bundle dialogState = mDialog.onSaveInstanceState();
            if (dialogState != null) {
                outState.putBundle(SAVED_DIALOG_STATE_TAG, dialogState);
            }
        }
        if (mStyle != STYLE_NORMAL) {
            outState.putInt(SAVED_STYLE, mStyle);
        }
        if (mTheme != 0) {
            outState.putInt(SAVED_THEME, mTheme);
        }
        if (!mCancelable) {
            outState.putBoolean(SAVED_CANCELABLE, mCancelable);
        }
        if (!mShowsDialog) {
            outState.putBoolean(SAVED_SHOWS_DIALOG, mShowsDialog);
        }
        if (mBackStackId != -1) {
            outState.putInt(SAVED_BACK_STACK_ID, mBackStackId);
        }
    }

    @CallSuper
    protected void onDismissDialog(DialogInterface dialog) {
        onDismiss(dialog);
    }

    protected void onCancelDialog(DialogInterface dialog) {
    }

    @Override
    public void onStop() {
        super.onStop();
        if (mDialog != null) {
            mDialog.hide();
        }
    }

    /**
     * Remove dialog.
     */
    @Override
    public void onDestroyView() {
        super.onDestroyView();
        if (mDialog != null) {
            // Set removed here because this dismissal is just to hide
            // the dialog -- we don't want this to cause the fragment to
            // actually be removed.
            mViewDestroyed = true;
            mDialog.dismiss();
            mDialog = null;
        }
    }

    private static class DialogDismissListener extends WeakReference<FixDialogFragment> implements DialogInterface.OnDismissListener {

        private DialogDismissListener(FixDialogFragment referent) {
            super(referent);
        }

        @Override
        public void onDismiss(DialogInterface dialog) {
            FixDialogFragment dialogFragment = get();
            if (dialogFragment != null) {
                dialogFragment.onDismissDialog(dialog);
            }
        }
    }

    private static class DialogCancelListener extends WeakReference<FixDialogFragment> implements DialogInterface.OnCancelListener {

        private DialogCancelListener(FixDialogFragment referent) {
            super(referent);
        }

        @Override
        public void onCancel(DialogInterface dialog) {
            FixDialogFragment dialogFragment = get();
            if (dialogFragment != null) {
                dialogFragment.onCancelDialog(dialog);
            }
        }
    }
}

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