二、Dialog的消失

1、dismiss

private final Runnable mDismissAction = this::dismissDialog;public void dismiss() {if (Looper.myLooper() == mHandler.getLooper()) {dismissDialog();} else {mHandler.post(mDismissAction);} } 復制代碼

保證UI操作都在主線程執行，而且引用了Java8新特性寫法this::dismissDialog，最后都會調用dismissDialog()

2、dismissDialog

void dismissDialog() {if (mDecor == null || !mShowing) {return;}if (mWindow.isDestroyed()) {Log.e(TAG, "Tried to dismissDialog() but the Dialog's window was already destroyed!");return;}try {//這里移除DecorViewmWindowManager.removeViewImmediate(mDecor);} finally {if (mActionMode != null) {mActionMode.finish();}mDecor = null;mWindow.closeAllPanels();onStop();mShowing = false;sendDismissMessage();} } 復制代碼

從show中知道，我們將DecorView加入到WindowManager中去，所以這里移除的是DecorView

3、WindowManagerImpl.removeViewImmediate

public void removeViewImmediate(View view) {//委托給mGlobal來進行實現mGlobal.removeView(view, true); } 復制代碼

同樣的交給WindowManagerGlobal去處理

4、WindowManagerGlobal.removeView

public void removeView(View view, boolean immediate) {if (view == null) {throw new IllegalArgumentException("view must not be null");}synchronized (mLock) {//待remove view的索引int index = findViewLocked(view, true);//mRoots保存著每一個viewRootImpl對象View curView = mRoots.get(index).getView();//真正對view進行了remove操作removeViewLocked(index, immediate);if (curView == view) {return;}throw new IllegalStateException("Calling with view " + view+ " but the ViewAncestor is attached to " + curView);} } 復制代碼

找到對應要移除的View后進行View邏輯處理工作

5、WindowManagerGlobal.removeViewLocked

private void removeViewLocked(int index, boolean immediate) {ViewRootImpl root = mRoots.get(index);View view = root.getView();if (view != null) {InputMethodManager imm = InputMethodManager.getInstance();if (imm != null) {imm.windowDismissed(mViews.get(index).getWindowToken());}}//重點在ViewRootImpl中的die方法中boolean deferred = root.die(immediate);if (view != null) {view.assignParent(null);if (deferred) {mDyingViews.add(view);}} } 復制代碼

找到對應的ViewRootImpl，進行移除并釋放工作

6、ViewRootImpl.die

boolean die(boolean immediate) {if (immediate && !mIsInTraversal) {//繼續跟蹤doDie();return false;}if (!mIsDrawing) {destroyHardwareRenderer();} else {Log.e(TAG, "Attempting to destroy the window while drawing!\n" +" window=" + this + ", title=" + mWindowAttributes.getTitle());}mHandler.sendEmptyMessage(MSG_DIE);return true; } 復制代碼

7、ViewRootImpl.doDie

void doDie() {checkThread();if (LOCAL_LOGV) Log.v(TAG, "DIE in " + this + " of " + mSurface);synchronized (this) {if (mRemoved) {return;}mRemoved = true;if (mAdded) {//這里是真正移除Dialog的ViewdispatchDetachedFromWindow();}if (mAdded && !mFirst) {//硬件渲染destroydestroyHardwareRenderer();if (mView != null) {int viewVisibility = mView.getVisibility();boolean viewVisibilityChanged = mViewVisibility != viewVisibility;if (mWindowAttributesChanged || viewVisibilityChanged) {// If layout params have been changed, first give them// to the window manager to make sure it has the correct// animation info.try {if ((relayoutWindow(mWindowAttributes, viewVisibility, false)& WindowManagerGlobal.RELAYOUT_RES_FIRST_TIME) != 0) {mWindowSession.finishDrawing(mWindow);}} catch (RemoteException e) {}}//Surface的釋放mSurface.release();}}mAdded = false;}//移除之前存儲的變量WindowManagerGlobal.getInstance().doRemoveView(this); } 復制代碼

保證線程安全后，做移除和釋放工作

8、WindowManagerGlobal.doRemoveView

一般程序最后的工作都是釋放工作，移除之前存儲的變量

void doRemoveView(ViewRootImpl root) {synchronized (mLock) {final int index = mRoots.indexOf(root);if (index >= 0) {//釋放工作mRoots.remove(index);mParams.remove(index);final View view = mViews.remove(index);mDyingViews.remove(view);}}if (HardwareRenderer.sTrimForeground && HardwareRenderer.isAvailable()) {doTrimForeground();} } 復制代碼

9、ViewRootImpl.dispatchDetachedFromWindow

void dispatchDetachedFromWindow() {if (mView != null && mView.mAttachInfo != null) {mAttachInfo.mTreeObserver.dispatchOnWindowAttachedChange(false);//此方法會回調onDetachedFromWindow方法，會做資源的回收mView.dispatchDetachedFromWindow();}mAccessibilityInteractionConnectionManager.ensureNoConnection();mAccessibilityManager.removeAccessibilityStateChangeListener(mAccessibilityInteractionConnectionManager);mAccessibilityManager.removeHighTextContrastStateChangeListener(mHighContrastTextManager);removeSendWindowContentChangedCallback();destroyHardwareRenderer();setAccessibilityFocus(null, null);mView.assignParent(null);mView = null;mAttachInfo.mRootView = null;mSurface.release();if (mInputQueueCallback != null && mInputQueue != null) {mInputQueueCallback.onInputQueueDestroyed(mInputQueue);mInputQueue.dispose();mInputQueueCallback = null;mInputQueue = null;}if (mInputEventReceiver != null) {mInputEventReceiver.dispose();mInputEventReceiver = null;}try {//這里調用了mWindowSession的remove方法，在WindowManagerService層通過IPC機制完成真正的window刪除mWindowSession.remove(mWindow);} catch (RemoteException e) {}// Dispose the input channel after removing the window so the Window Manager// doesn't interpret the input channel being closed as an abnormal termination.if (mInputChannel != null) {mInputChannel.dispose();mInputChannel = null;}mDisplayManager.unregisterDisplayListener(mDisplayListener);unscheduleTraversals(); } 復制代碼

到最后會和添加View的時候完成閉環，還是通過WindowSession的IPC機制去調用的，最后在WindowManagerService層通過IPC機制去實現的 ##總結 1.Dialog的dismiss和show形成閉環，調用的過程是相似的，只不過多了資源的釋放環節

DialogFragment

DialogFragment本身繼承自Fragment

public class DialogFragment extends Fragmentimplements DialogInterface.OnCancelListener, DialogInterface.OnDismissListener 復制代碼

在平時中，我們需要自定義WeDialogFragment，而且在正式開發中踩過的坑：

• 需要對參數進行onSaveInstanceState操作，這類操作主要是防止異步吊起DialogFragment報nullPoint的Bug
• 需要重寫show()，對show做一層彈出時候的保護，這類操作主要是防止異步吊起DialogFragment報onSaveInstanceState的Bug

public class WeDialogFragment extends DialogFragment {@Overridepublic void onSaveInstanceState(Bundle outState) {super.onSaveInstanceState(outState);Bundle bundle = new Bundle();bundle.putString(BUNDLE_TITLE, title);}@Overridepublic void onCreate(@Nullable Bundle savedInstanceState) {super.onCreate(savedInstanceState);setStyle(DialogFragment.STYLE_NO_TITLE, R.style.WeDialog);if (savedInstanceState != null) {title = savedInstanceState.getString(BUNDLE_TITLE);}}@Overridepublic Dialog onCreateDialog(Bundle savedInstanceState) {Dialog dialog = super.onCreateDialog(savedInstanceState);dialog.setCanceledOnTouchOutside(true);dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);dialog.getWindow().setWindowAnimations(R.style.DialogAnimation);dialog.getWindow().setBackgroundDrawableResource(android.R.color.transparent);return dialog;}@Nullable@Overridepublic View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container,@Nullable Bundle savedInstanceState) {return inflater.inflate(R.layout.view_fragment_dialog, container, false);}@Overridepublic void show(FragmentManager manager, String tag) {if (!manager.isStateSaved()) {super.show(manager, tag);}} } 復制代碼

然后在Activity中彈出DialogFragment

WeDialogFragment weDialogFragment = new WeDialogFragment(); weDialogFragment.show(activity.getSupportFragmentManager(),"weDialogFragment"); 復制代碼

一、DialogFragment的顯示

1、DialogFragment.show

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

show的方法其實就是對Fragment的處理，將Fragment添加到Fragment棧中

二、DialogFragment的隱藏

####1、DialogFragment.dismiss

public void dismiss() {dismissInternal(false); }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();}} } 復制代碼

dismiss的方法也是對Fragment的處理，將Fragment移除到Fragment棧中

三、Dialog的創建

1、DialogFragment.onCreateDialog

@NonNull public Dialog onCreateDialog(Bundle savedInstanceState) {return new Dialog(getActivity(), getTheme()); } 復制代碼

和創建普通的Dialog沒什么區別，我們重寫該方法，可以自定義彈出AlertDialog等其他自定義Dialog

四、Dialog的視圖

1、DialogFragment.onActivityCreated

@Override public void onActivityCreated(Bundle savedInstanceState) {super.onActivityCreated(savedInstanceState);if (!mShowsDialog) {return;}//拿到的就是onCreateView返回值的view對象，具體可以在Fragment源碼找到View view = getView();if (view != null) {if (view.getParent() != null) {throw new IllegalStateException("DialogFragment can not be attached to a container view");}//真正設置viewmDialog.setContentView(view);}final Activity activity = getActivity();if (activity != null) {mDialog.setOwnerActivity(activity);}mDialog.setCancelable(mCancelable);mDialog.setOnCancelListener(this);mDialog.setOnDismissListener(this);if (savedInstanceState != null) {Bundle dialogState = savedInstanceState.getBundle(SAVED_DIALOG_STATE_TAG);if (dialogState != null) {mDialog.onRestoreInstanceState(dialogState);}} } 復制代碼

在Activity創建的時候，Fragment的周期會回調onActivityCreated，從而對Dialog設置視圖

五、Dialog的顯示隱藏

Dialog顯示隱藏就簡單了，隨著Fragment的生命周期顯示和隱藏，直接看代碼就行了

@Override public void onStart() {super.onStart();if (mDialog != null) {mViewDestroyed = false;mDialog.show();} }@Override public void onStop() {super.onStop();if (mDialog != null) {mDialog.hide();} } 復制代碼

總結

DialogFragment = Fragment + Dialog，DialogFragment本身繼承Fragment，Fragment只是用來依附在Activity上，可以監聽Activity的生命周期，從而去通知Dialog做對應的操作，而Dialog才是我們正在顯示在屏幕上的彈窗，而非一個Fragment。這里的Dialog真正顯示出來的View是從**onCreateView()中獲取view后，在源碼中調用dialog的setContentView()**顯示出來的

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