Activity之生命周期

1. 正常情況下的生命周期

   A->B

   AonPause-BonCreate-BonStart-BonResume(-AonStop這個是否執行取決于A是否被全部覆寫)

   B->A

   BonPause-AonStart-AonResume-BonStop-BonDestroy

   當Activity切換時，需要先将棧頂Activity置為pause，再執行新Activity的方法(此時棧頂為新的Activity)。

   是以如果有儲存資料耗時操作的話，盡量在onStop中執行，是為了不妨礙新Activity的頁面展現。而設定或者取資料等操作可以放在onResume中執行。

2. 橫豎屏切換時的生命周期

   2.1 不設定configChange

   切至橫屏：

onPause
            onSaveInstanceState[Bundle[{android:viewHierarchyState=Bundle[{android:views={=android.view.AbsSavedState[email protected], =android.view.AbsSavedState[email protected], =android.view.AbsSavedState[email protected], =android.support.v7.widget.Toolbar$SavedState@9efe2af, =android.view.AbsSavedState[email protected], =android.view.AbsSavedState[email protected], =TextView.SavedState{f06bc start= end= text=}}, android:focusedViewId=}]}]]
            onStop
            onDestroy
            onCreate:saveInstanceState[Bundle[{android:viewHierarchyState=Bundle[{android:views={=android.view.AbsSavedState[email protected], =android.view.AbsSavedState[email protected], =android.view.AbsSavedState[email protected], =android.support.v7.widget.Toolbar$SavedState@9efe2af, =android.view.AbsSavedState[email protected], =android.view.AbsSavedState[email protected], =TextView.SavedState{f06bc start= end= text=}}, android:focusedViewId=}]}]]
            onStart
            onRestoreInstanceState[Bundle[{android:viewHierarchyState=Bundle[{android:views={=android.view.AbsSavedState[email protected], =android.view.AbsSavedState[email protected], =android.view.AbsSavedState[email protected], =android.support.v7.widget.Toolbar$SavedState@9efe2af, =android.view.AbsSavedState[email protected], =android.view.AbsSavedState[email protected], =TextView.SavedState{f06bc start= end= text=}}, android:focusedViewId=}]}]]
            onResume
           

切至豎屏：

onPause
            onSaveInstanceState[Bundle[{android:viewHierarchyState=Bundle[{android:views={=android.view.AbsSavedState[email protected], =android.view.AbsSavedState[email protected], =android.view.AbsSavedState[email protected], =android.support.v7.widget.Toolbar[email protected], =android.view.AbsSavedState[email protected], =android.view.AbsSavedState[email protected], =TextView.SavedState{d31c16 start= end= text=}}, android:focusedViewId=}]}]]
            onStop
            onDestroy
            onCreate:saveInstanceState[Bundle[{android:viewHierarchyState=Bundle[{android:views={=android.view.AbsSavedState[email protected], =android.view.AbsSavedState[email protected], =android.view.AbsSavedState[email protected], =android.support.v7.widget.Toolbar[email protected], =android.view.AbsSavedState[email protected], =android.view.AbsSavedState[email protected], =TextView.SavedState{d31c16 start= end= text=}}, android:focusedViewId=}]}]]
            onStart
            onRestoreInstanceState[Bundle[{android:viewHierarchyState=Bundle[{android:views={=android.view.AbsSavedState[email protected], =android.view.AbsSavedState[email protected], =android.view.AbsSavedState[email protected], =android.support.v7.widget.Toolbar[email protected], =android.view.AbsSavedState[email protected], =android.view.AbsSavedState[email protected], =TextView.SavedState{d31c16 start= end= text=}}, android:focusedViewId=}]}]]
            onResume
           

儲存資料：

Activity.java:
            final void performSaveInstanceState(Bundle outState) {
                onSaveInstanceState(outState);  // 儲存頁面資訊
                saveManagedDialogs(outState);  // 儲存Dialog資訊
                mActivityTransitionState.saveState(outState);  // 儲存頁面跳轉資訊
                storeHasCurrentPermissionRequest(outState);
            }

            protected void onSaveInstanceState(Bundle outState) {
                outState.putBundle(WINDOW_HIERARCHY_TAG, mWindow.saveHierarchyState());  // 儲存Window資訊
                Parcelable p = mFragments.saveAllState();
                if (p != null) {
                    outState.putParcelable(FRAGMENTS_TAG, p);  // 儲存Fragment資訊
                }
                getApplication().dispatchActivitySaveInstanceState(this, outState);
            }

        PhoneWindow.java:
            public Bundle saveHierarchyState() {
                Bundle outState = new Bundle();
                if (mContentParent == null) {
                    return outState;
                }

                SparseArray<Parcelable> states = new SparseArray<Parcelable>();
                mContentParent.saveHierarchyState(states);  // 儲存頁面View資訊
                outState.putSparseParcelableArray(VIEWS_TAG, states);

                // Save the focused view ID.
                final View focusedView = mContentParent.findFocus();
                if (focusedView != null && focusedView.getId() != View.NO_ID) {
                    outState.putInt(FOCUSED_ID_TAG, focusedView.getId());
                }

                // save the panels
                SparseArray<Parcelable> panelStates = new SparseArray<Parcelable>();
                savePanelState(panelStates);
                if (panelStates.size() > ) {
                    outState.putSparseParcelableArray(PANELS_TAG, panelStates);
                }

                if (mDecorContentParent != null) {
                    SparseArray<Parcelable> actionBarStates = new SparseArray<Parcelable>();
                    mDecorContentParent.saveToolbarHierarchyState(actionBarStates);
                    outState.putSparseParcelableArray(ACTION_BAR_TAG, actionBarStates);
                }

                return outState;
            }

        View.java:
            public void saveHierarchyState(SparseArray<Parcelable> container) {
                dispatchSaveInstanceState(container);
            }

            protected void dispatchSaveInstanceState(SparseArray<Parcelable> container) {
                if (mID != NO_ID && (mViewFlags & SAVE_DISABLED_MASK) == ) {  // 設定了id且沒有disableSave
                    mPrivateFlags &= ~PFLAG_SAVE_STATE_CALLED;
                    Parcelable state = onSaveInstanceState();
                    if ((mPrivateFlags & PFLAG_SAVE_STATE_CALLED) == ) {
                        throw new IllegalStateException(
                                "Derived class did not call super.onSaveInstanceState()");
                    }
                    if (state != null) {
                        // Log.i("View", "Freezing #" + Integer.toHexString(mID)
                        // + ": " + state);
                        container.put(mID, state);
                    }
                }
            }

            protected Parcelable onSaveInstanceState() {
                mPrivateFlags |= PFLAG_SAVE_STATE_CALLED;
                if (mStartActivityRequestWho != null) {
                    BaseSavedState state = new BaseSavedState(AbsSavedState.EMPTY_STATE);
                    state.mStartActivityRequestWhoSaved = mStartActivityRequestWho; // 儲存mStartActivityRequestWho
                    return state;
                }
                return BaseSavedState.EMPTY_STATE;
            }
        ViewGroup.java:
            protected void dispatchSaveInstanceState(SparseArray<Parcelable> container) {
                super.dispatchSaveInstanceState(container);
                final int count = mChildrenCount;
                final View[] children = mChildren;
                for (int i = ; i < count; i++) {
                    View c = children[i];
                    if ((c.mViewFlags & PARENT_SAVE_DISABLED_MASK) != PARENT_SAVE_DISABLED) {
                        c.dispatchSaveInstanceState(container);  // 下發到每一個子View自己的dispatchSaveInstanceState處理
                    }
                }
            }
           

2.2 設定configChanges=”orientation|screenSize”

切至橫屏：

onConfigurationChanged[{1.0 ?mcc?mnc zh_CN ldltr sw360dp w598dp h336dp 480dpi nrml land finger -keyb/v/h -nav/h suim:1 s.16}]

切至豎屏：

onConfigurationChanged[{1.0 ?mcc?mnc zh_CN ldltr sw360dp w360dp h580dp 480dpi nrml port finger -keyb/v/h -nav/h suim:1 s.17}]