关于Actionbar重写的假设

/*
* Copyright (C) 2010 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the “License”);
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an “AS IS” BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

package com.android.internal.app;

import android.animation.ValueAnimator;
import android.view.ViewParent;
import com.android.internal.view.ActionBarPolicy;
import com.android.internal.view.menu.MenuBuilder;
import com.android.internal.view.menu.MenuPopupHelper;
import com.android.internal.view.menu.SubMenuBuilder;
import com.android.internal.widget.ActionBarContainer;
import com.android.internal.widget.ActionBarContextView;
import com.android.internal.widget.ActionBarOverlayLayout;
import com.android.internal.widget.ActionBarView;
import com.android.internal.widget.ScrollingTabContainerView;

import android.animation.Animator;
import android.animation.Animator.AnimatorListener;
import android.animation.AnimatorListenerAdapter;
import android.animation.AnimatorSet;
import android.animation.ObjectAnimator;
import android.app.ActionBar;
import android.app.Activity;
import android.app.Dialog;
import android.app.FragmentTransaction;
import android.content.Context;
import android.content.res.Configuration;
import android.content.res.Resources;
import android.graphics.drawable.Drawable;
import android.os.Handler;
import android.util.Log;
import android.util.TypedValue;
import android.view.ActionMode;
import android.view.ContextThemeWrapper;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.view.Window;
import android.view.accessibility.AccessibilityEvent;
import android.view.animation.AnimationUtils;
import android.widget.SpinnerAdapter;

import java.lang.ref.WeakReference;
import java.util.ArrayList;

/**
* ActionBarImpl is the ActionBar implementation used
* by devices of all screen sizes. If it detects a compatible decor,
* it will split contextual modes across both the ActionBarView at
* the top of the screen and a horizontal LinearLayout at the bottom
* which is normally hidden.
*/
public class ActionBarImpl extends ActionBar {
private static final String TAG = “ActionBarImpl”;

private Context mContext;
private Context mThemedContext;
private Activity mActivity;
private Dialog mDialog;

private ActionBarOverlayLayout mOverlayLayout;
private ActionBarContainer mContainerView;
private ActionBarView mActionView;
private ActionBarContextView mContextView;
private ActionBarContainer mSplitView;
private View mContentView;
private ScrollingTabContainerView mTabScrollView;

private ArrayList mTabs = new ArrayList();

private TabImpl mSelectedTab;
private int mSavedTabPosition = INVALID_POSITION;

private boolean mDisplayHomeAsUpSet;

ActionModeImpl mActionMode;
ActionMode mDeferredDestroyActionMode;
ActionMode.Callback mDeferredModeDestroyCallback;

private boolean mLastMenuVisibility;
private ArrayList mMenuVisibilityListeners =
        new ArrayList();

private static final int CONTEXT_DISPLAY_NORMAL = 0;
private static final int CONTEXT_DISPLAY_SPLIT = 1;

private static final int INVALID_POSITION = -1;

private int mContextDisplayMode;
private boolean mHasEmbeddedTabs;

final Handler mHandler = new Handler();
Runnable mTabSelector;

private int mCurWindowVisibility = View.VISIBLE;

private boolean mContentAnimations = true;
private boolean mHiddenByApp;
private boolean mHiddenBySystem;
private boolean mShowingForMode;

private boolean mNowShowing = true;

private Animator mCurrentShowAnim;
private boolean mShowHideAnimationEnabled;

final AnimatorListener mHideListener = new AnimatorListenerAdapter() {
    @Override
    public void onAnimationEnd(Animator animation) {
        if (mContentAnimations && mContentView != null) {
            mContentView.setTranslationY(0);
            mContainerView.setTranslationY(0);
        }
        if (mSplitView != null && mContextDisplayMode == CONTEXT_DISPLAY_SPLIT) {
            mSplitView.setVisibility(View.GONE);
        }
        mContainerView.setVisibility(View.GONE);
        mContainerView.setTransitioning(false);
        mCurrentShowAnim = null;
        completeDeferredDestroyActionMode();
        if (mOverlayLayout != null) {
            mOverlayLayout.requestFitSystemWindows();
        }
    }
};

final AnimatorListener mShowListener = new AnimatorListenerAdapter() {
    @Override
    public void onAnimationEnd(Animator animation) {
        mCurrentShowAnim = null;
        mContainerView.requestLayout();
    }
};

final ValueAnimator.AnimatorUpdateListener mUpdateListener =
        new ValueAnimator.AnimatorUpdateListener() {
    @Override
    public void onAnimationUpdate(ValueAnimator animation) {
        final ViewParent parent = mContainerView.getParent();
        ((View) parent).invalidate();
    }
};

public ActionBarImpl(Activity activity) {
    mActivity = activity;
    Window window = activity.getWindow();
    View decor = window.getDecorView();
    boolean overlayMode = mActivity.getWindow().hasFeature(Window.FEATURE_ACTION_BAR_OVERLAY);
    init(decor);
    if (!overlayMode) {
        mContentView = decor.findViewById(android.R.id.content);
    }
}

public ActionBarImpl(Dialog dialog) {
    mDialog = dialog;
    init(dialog.getWindow().getDecorView());
}

/**
 * Only for edit mode.
 * @hide
 */
public ActionBarImpl(View layout) {
    assert layout.isInEditMode();
    init(layout);
}

private void init(View decor) {
    mContext = decor.getContext();
    mOverlayLayout = (ActionBarOverlayLayout) decor.findViewById(
            com.android.internal.R.id.action_bar_overlay_layout);
    if (mOverlayLayout != null) {
        mOverlayLayout.setActionBar(this);
    }
    mActionView = (ActionBarView) decor.findViewById(com.android.internal.R.id.action_bar);
    mContextView = (ActionBarContextView) decor.findViewById(
            com.android.internal.R.id.action_context_bar);
    mContainerView = (ActionBarContainer) decor.findViewById(
            com.android.internal.R.id.action_bar_container);
    mSplitView = (ActionBarContainer) decor.findViewById(
            com.android.internal.R.id.split_action_bar);

    if (mActionView == null || mContextView == null || mContainerView == null) {
        throw new IllegalStateException(getClass().getSimpleName() + " can only be used " +
                "with a compatible window decor layout");
    }

    mActionView.setContextView(mContextView);
    mContextDisplayMode = mActionView.isSplitActionBar() ?
            CONTEXT_DISPLAY_SPLIT : CONTEXT_DISPLAY_NORMAL;

    // This was initially read from the action bar style
    final int current = mActionView.getDisplayOptions();
    final boolean homeAsUp = (current & DISPLAY_HOME_AS_UP) != 0;
    if (homeAsUp) {
        mDisplayHomeAsUpSet = true;
    }

    ActionBarPolicy abp = ActionBarPolicy.get(mContext);
    setHomeButtonEnabled(abp.enableHomeButtonByDefault() || homeAsUp);
    setHasEmbeddedTabs(abp.hasEmbeddedTabs());
}

public void onConfigurationChanged(Configuration newConfig) {
    setHasEmbeddedTabs(ActionBarPolicy.get(mContext).hasEmbeddedTabs());
}

private void setHasEmbeddedTabs(boolean hasEmbeddedTabs) {
    mHasEmbeddedTabs = hasEmbeddedTabs;
    // Switch tab layout configuration if needed
    if (!mHasEmbeddedTabs) {
        mActionView.setEmbeddedTabView(null);
        mContainerView.setTabContainer(mTabScrollView);
    } else {
        mContainerView.setTabContainer(null);
        mActionView.setEmbeddedTabView(mTabScrollView);
    }
    final boolean isInTabMode = getNavigationMode() == NAVIGATION_MODE_TABS;
    if (mTabScrollView != null) {
        if (isInTabMode) {
            mTabScrollView.setVisibility(View.VISIBLE);
            if (mOverlayLayout != null) {
                mOverlayLayout.requestFitSystemWindows();
            }
        } else {
            mTabScrollView.setVisibility(View.GONE);
        }
    }
    mActionView.setCollapsable(!mHasEmbeddedTabs && isInTabMode);
}

public boolean hasNonEmbeddedTabs() {
    return !mHasEmbeddedTabs && getNavigationMode() == NAVIGATION_MODE_TABS;
}

private void ensureTabsExist() {
    if (mTabScrollView != null) {
        return;
    }

    ScrollingTabContainerView tabScroller = new ScrollingTabContainerView(mContext);

    if (mHasEmbeddedTabs) {
        tabScroller.setVisibility(View.VISIBLE);
        mActionView.setEmbeddedTabView(tabScroller);
    } else {
        if (getNavigationMode() == NAVIGATION_MODE_TABS) {
            tabScroller.setVisibility(View.VISIBLE);
            if (mOverlayLayout != null) {
                mOverlayLayout.requestFitSystemWindows();
            }
        } else {
            tabScroller.setVisibility(View.GONE);
        }
        mContainerView.setTabContainer(tabScroller);
    }
    mTabScrollView = tabScroller;
}

void completeDeferredDestroyActionMode() {
    if (mDeferredModeDestroyCallback != null) {
        mDeferredModeDestroyCallback.onDestroyActionMode(mDeferredDestroyActionMode);
        mDeferredDestroyActionMode = null;
        mDeferredModeDestroyCallback = null;
    }
}

public void setWindowVisibility(int visibility) {
    mCurWindowVisibility = visibility;
}

/**
 * Enables or disables animation between show/hide states.
 * If animation is disabled using this method, animations in progress
 * will be finished.
 *
 * @param enabled true to animate, false to not animate.
 */
public void setShowHideAnimationEnabled(boolean enabled) {
    mShowHideAnimationEnabled = enabled;
    if (!enabled && mCurrentShowAnim != null) {
        mCurrentShowAnim.end();
    }
}

public void addOnMenuVisibilityListener(OnMenuVisibilityListener listener) {
    mMenuVisibilityListeners.add(listener);
}

public void removeOnMenuVisibilityListener(OnMenuVisibilityListener listener) {
    mMenuVisibilityListeners.remove(listener);
}

public void dispatchMenuVisibilityChanged(boolean isVisible) {
    if (isVisible == mLastMenuVisibility) {
        return;
    }
    mLastMenuVisibility = isVisible;

    final int count = mMenuVisibilityListeners.size();
    for (int i = 0; i < count; i++) {
        mMenuVisibilityListeners.get(i).onMenuVisibilityChanged(isVisible);
    }
}

@Override
public void setCustomView(int resId) {
    setCustomView(LayoutInflater.from(getThemedContext()).inflate(resId, mActionView, false));
}

@Override
public void setDisplayUseLogoEnabled(boolean useLogo) {
    setDisplayOptions(useLogo ? DISPLAY_USE_LOGO : 0, DISPLAY_USE_LOGO);
}

@Override
public void setDisplayShowHomeEnabled(boolean showHome) {
    setDisplayOptions(showHome ? DISPLAY_SHOW_HOME : 0, DISPLAY_SHOW_HOME);
}

@Override
public void setDisplayHomeAsUpEnabled(boolean showHomeAsUp) {
    setDisplayOptions(showHomeAsUp ? DISPLAY_HOME_AS_UP : 0, DISPLAY_HOME_AS_UP);
}

@Override
public void setDisplayShowTitleEnabled(boolean showTitle) {
    setDisplayOptions(showTitle ? DISPLAY_SHOW_TITLE : 0, DISPLAY_SHOW_TITLE);
}

@Override
public void setDisplayShowCustomEnabled(boolean showCustom) {
    setDisplayOptions(showCustom ? DISPLAY_SHOW_CUSTOM : 0, DISPLAY_SHOW_CUSTOM);
}

@Override
public void setHomeButtonEnabled(boolean enable) {
    mActionView.setHomeButtonEnabled(enable);
}

@Override
public void setTitle(int resId) {
    setTitle(mContext.getString(resId));
}

@Override
public void setSubtitle(int resId) {
    setSubtitle(mContext.getString(resId));
}

public void setSelectedNavigationItem(int position) {
    switch (mActionView.getNavigationMode()) {
    case NAVIGATION_MODE_TABS:
        selectTab(mTabs.get(position));
        break;
    case NAVIGATION_MODE_LIST:
        mActionView.setDropdownSelectedPosition(position);
        break;
    default:
        throw new IllegalStateException(
                "setSelectedNavigationIndex not valid for current navigation mode");
    }
}

public void removeAllTabs() {
    cleanupTabs();
}

private void cleanupTabs() {
    if (mSelectedTab != null) {
        selectTab(null);
    }
    mTabs.clear();
    if (mTabScrollView != null) {
        mTabScrollView.removeAllTabs();
    }
    mSavedTabPosition = INVALID_POSITION;
}

public void setTitle(CharSequence title) {
    mActionView.setTitle(title);
}

public void setSubtitle(CharSequence subtitle) {
    mActionView.setSubtitle(subtitle);
}

public void setDisplayOptions(int options) {
    if ((options & DISPLAY_HOME_AS_UP) != 0) {
        mDisplayHomeAsUpSet = true;
    }
    mActionView.setDisplayOptions(options);
}

public void setDisplayOptions(int options, int mask) {
    final int current = mActionView.getDisplayOptions(); 
    if ((mask & DISPLAY_HOME_AS_UP) != 0) {
        mDisplayHomeAsUpSet = true;
    }
    mActionView.setDisplayOptions((options & mask) | (current & ~mask));
}

public void setBackgroundDrawable(Drawable d) {
    mContainerView.setPrimaryBackground(d);
}

public void setStackedBackgroundDrawable(Drawable d) {
    mContainerView.setStackedBackground(d);
}

public void setSplitBackgroundDrawable(Drawable d) {
    if (mSplitView != null) {
        mSplitView.setSplitBackground(d);
    }
}

public View getCustomView() {
    return mActionView.getCustomNavigationView();
}

public CharSequence getTitle() {
    return mActionView.getTitle();
}

public CharSequence getSubtitle() {
    return mActionView.getSubtitle();
}

public int getNavigationMode() {
    return mActionView.getNavigationMode();
}

public int getDisplayOptions() {
    return mActionView.getDisplayOptions();
}

public ActionMode startActionMode(ActionMode.Callback callback) {
    if (mActionMode != null) {
        mActionMode.finish();
    }

    mContextView.killMode();
    ActionModeImpl mode = new ActionModeImpl(callback);
    if (mode.dispatchOnCreate()) {
        mode.invalidate();
        mContextView.initForMode(mode);
        animateToMode(true);
        if (mSplitView != null && mContextDisplayMode == CONTEXT_DISPLAY_SPLIT) {
            // TODO animate this
            if (mSplitView.getVisibility() != View.VISIBLE) {
                mSplitView.setVisibility(View.VISIBLE);
                if (mOverlayLayout != null) {
                    mOverlayLayout.requestFitSystemWindows();
                }
            }
        }
        mContextView.sendAccessibilityEvent(AccessibilityEvent.TYPE_WINDOW_STATE_CHANGED);
        mActionMode = mode;
        return mode;
    }
    return null;
}

private void configureTab(Tab tab, int position) {
    final TabImpl tabi = (TabImpl) tab;
    final ActionBar.TabListener callback = tabi.getCallback();

    if (callback == null) {
        throw new IllegalStateException("Action Bar Tab must have a Callback");
    }

    tabi.setPosition(position);
    mTabs.add(position, tabi);

    final int count = mTabs.size();
    for (int i = position + 1; i < count; i++) {
        mTabs.get(i).setPosition(i);
    }
}

@Override
public void addTab(Tab tab) {
    addTab(tab, mTabs.isEmpty());
}

@Override
public void addTab(Tab tab, int position) {
    addTab(tab, position, mTabs.isEmpty());
}

@Override
public void addTab(Tab tab, boolean setSelected) {
    ensureTabsExist();
    mTabScrollView.addTab(tab, setSelected);
    configureTab(tab, mTabs.size());
    if (setSelected) {
        selectTab(tab);
    }
}

@Override
public void addTab(Tab tab, int position, boolean setSelected) {
    ensureTabsExist();
    mTabScrollView.addTab(tab, position, setSelected);
    configureTab(tab, position);
    if (setSelected) {
        selectTab(tab);
    }
}

@Override
public Tab newTab() {
    return new TabImpl();
}

@Override
public void removeTab(Tab tab) {
    removeTabAt(tab.getPosition());
}

@Override
public void removeTabAt(int position) {
    if (mTabScrollView == null) {
        // No tabs around to remove
        return;
    }

    int selectedTabPosition = mSelectedTab != null
            ? mSelectedTab.getPosition() : mSavedTabPosition;
    mTabScrollView.removeTabAt(position);
    TabImpl removedTab = mTabs.remove(position);
    if (removedTab != null) {
        removedTab.setPosition(-1);
    }

    final int newTabCount = mTabs.size();
    for (int i = position; i < newTabCount; i++) {
        mTabs.get(i).setPosition(i);
    }

    if (selectedTabPosition == position) {
        selectTab(mTabs.isEmpty() ? null : mTabs.get(Math.max(0, position - 1)));
    }
}

@Override
public void selectTab(Tab tab) {
    if (getNavigationMode() != NAVIGATION_MODE_TABS) {
        mSavedTabPosition = tab != null ? tab.getPosition() : INVALID_POSITION;
        return;
    }

    final FragmentTransaction trans = mActionView.isInEditMode() ? null :
            mActivity.getFragmentManager().beginTransaction().disallowAddToBackStack();

    if (mSelectedTab == tab) {
        if (mSelectedTab != null) {
            mSelectedTab.getCallback().onTabReselected(mSelectedTab, trans);
            mTabScrollView.animateToTab(tab.getPosition());
        }
    } else {
        mTabScrollView.setTabSelected(tab != null ? tab.getPosition() : Tab.INVALID_POSITION);
        if (mSelectedTab != null) {
            mSelectedTab.getCallback().onTabUnselected(mSelectedTab, trans);
        }
        mSelectedTab = (TabImpl) tab;
        if (mSelectedTab != null) {
            mSelectedTab.getCallback().onTabSelected(mSelectedTab, trans);
        }
    }

    if (trans != null && !trans.isEmpty()) {
        trans.commit();
    }
}

@Override
public Tab getSelectedTab() {
    return mSelectedTab;
}

@Override
public int getHeight() {
    return mContainerView.getHeight();
}

public void enableContentAnimations(boolean enabled) {
    mContentAnimations = enabled;
}

@Override
public void show() {
    if (mHiddenByApp) {
        mHiddenByApp = false;
        updateVisibility(false);
    }
}

private void showForActionMode() {
    if (!mShowingForMode) {
        mShowingForMode = true;
        if (mOverlayLayout != null) {
            mOverlayLayout.setShowingForActionMode(true);
        }
        updateVisibility(false);
    }
}

public void showForSystem() {
    if (mHiddenBySystem) {
        mHiddenBySystem = false;
        updateVisibility(true);
    }
}

@Override
public void hide() {
    if (!mHiddenByApp) {
        mHiddenByApp = true;
        updateVisibility(false);
    }
}

private void hideForActionMode() {
    if (mShowingForMode) {
        mShowingForMode = false;
        if (mOverlayLayout != null) {
            mOverlayLayout.setShowingForActionMode(false);
        }
        updateVisibility(false);
    }
}

public void hideForSystem() {
    if (!mHiddenBySystem) {
        mHiddenBySystem = true;
        updateVisibility(true);
    }
}

private static boolean checkShowingFlags(boolean hiddenByApp, boolean hiddenBySystem,
        boolean showingForMode) {
    if (showingForMode) {
        return true;
    } else if (hiddenByApp || hiddenBySystem) {
        return false;
    } else {
        return true;
    }
}

private void updateVisibility(boolean fromSystem) {
    // Based on the current state, should we be hidden or shown?
    final boolean shown = checkShowingFlags(mHiddenByApp, mHiddenBySystem,
            mShowingForMode);

    if (shown) {
        if (!mNowShowing) {
            mNowShowing = true;
            doShow(fromSystem);
        }
    } else {
        if (mNowShowing) {
            mNowShowing = false;
            doHide(fromSystem);
        }
    }
}

public void doShow(boolean fromSystem) {
    if (mCurrentShowAnim != null) {
        mCurrentShowAnim.end();
    }
    mContainerView.setVisibility(View.VISIBLE);

    if (mCurWindowVisibility == View.VISIBLE && (mShowHideAnimationEnabled
            || fromSystem)) {
        mContainerView.setTranslationY(0); // because we're about to ask its window loc
        float startingY = -mContainerView.getHeight();
        if (fromSystem) {
            int topLeft[] = {0, 0};
            mContainerView.getLocationInWindow(topLeft);
            startingY -= topLeft[1];
        }
        mContainerView.setTranslationY(startingY);
        AnimatorSet anim = new AnimatorSet();
        ObjectAnimator a = ObjectAnimator.ofFloat(mContainerView, View.TRANSLATION_Y, 0);
        a.addUpdateListener(mUpdateListener);
        AnimatorSet.Builder b = anim.play(a);
        if (mContentAnimations && mContentView != null) {
            b.with(ObjectAnimator.ofFloat(mContentView, View.TRANSLATION_Y,
                    startingY, 0));
        }
        if (mSplitView != null && mContextDisplayMode == CONTEXT_DISPLAY_SPLIT) {
            mSplitView.setTranslationY(mSplitView.getHeight());
            mSplitView.setVisibility(View.VISIBLE);
            b.with(ObjectAnimator.ofFloat(mSplitView, View.TRANSLATION_Y, 0));
        }
        anim.setInterpolator(AnimationUtils.loadInterpolator(mContext,
                com.android.internal.R.interpolator.decelerate_cubic));
        anim.setDuration(250);
        // If this is being shown from the system, add a small delay.
        // This is because we will also be animating in the status bar,
        // and these two elements can't be done in lock-step.  So we give
        // a little time for the status bar to start its animation before
        // the action bar animates.  (This corresponds to the corresponding
        // case when hiding, where the status bar has a small delay before
        // starting.)
        anim.addListener(mShowListener);
        mCurrentShowAnim = anim;
        anim.start();
    } else {
        mContainerView.setAlpha(1);
        mContainerView.setTranslationY(0);
        if (mContentAnimations && mContentView != null) {
            mContentView.setTranslationY(0);
        }
        if (mSplitView != null && mContextDisplayMode == CONTEXT_DISPLAY_SPLIT) {
            mSplitView.setAlpha(1);
            mSplitView.setTranslationY(0);
            mSplitView.setVisibility(View.VISIBLE);
        }
        mShowListener.onAnimationEnd(null);
    }
    if (mOverlayLayout != null) {
        mOverlayLayout.requestFitSystemWindows();
    }
}

public void doHide(boolean fromSystem) {
    if (mCurrentShowAnim != null) {
        mCurrentShowAnim.end();
    }

    if (mCurWindowVisibility == View.VISIBLE && (mShowHideAnimationEnabled
            || fromSystem)) {
        mContainerView.setAlpha(1);
        mContainerView.setTransitioning(true);
        AnimatorSet anim = new AnimatorSet();
        float endingY = -mContainerView.getHeight();
        if (fromSystem) {
            int topLeft[] = {0, 0};
            mContainerView.getLocationInWindow(topLeft);
            endingY -= topLeft[1];
        }
        ObjectAnimator a = ObjectAnimator.ofFloat(mContainerView, View.TRANSLATION_Y, endingY);
        a.addUpdateListener(mUpdateListener);
        AnimatorSet.Builder b = anim.play(a);
        if (mContentAnimations && mContentView != null) {
            b.with(ObjectAnimator.ofFloat(mContentView, View.TRANSLATION_Y,
                    0, endingY));
        }
        if (mSplitView != null && mSplitView.getVisibility() == View.VISIBLE) {
            mSplitView.setAlpha(1);
            b.with(ObjectAnimator.ofFloat(mSplitView, View.TRANSLATION_Y,
                    mSplitView.getHeight()));
        }
        anim.setInterpolator(AnimationUtils.loadInterpolator(mContext,
                com.android.internal.R.interpolator.accelerate_cubic));
        anim.setDuration(250);
        anim.addListener(mHideListener);
        mCurrentShowAnim = anim;
        anim.start();
    } else {
        mHideListener.onAnimationEnd(null);
    }
}

public boolean isShowing() {
    return mNowShowing;
}

public boolean isSystemShowing() {
    return !mHiddenBySystem;
}

void animateToMode(boolean toActionMode) {
    if (toActionMode) {
        showForActionMode();
    } else {
        hideForActionMode();
    }

    mActionView.animateToVisibility(toActionMode ? View.GONE : View.VISIBLE);
    mContextView.animateToVisibility(toActionMode ? View.VISIBLE : View.GONE);
    if (mTabScrollView != null && !mActionView.hasEmbeddedTabs() && mActionView.isCollapsed()) {
        mTabScrollView.animateToVisibility(toActionMode ? View.GONE : View.VISIBLE);
    }
}

public Context getThemedContext() {
    if (mThemedContext == null) {
        TypedValue outValue = new TypedValue();
        Resources.Theme currentTheme = mContext.getTheme();
        currentTheme.resolveAttribute(com.android.internal.R.attr.actionBarWidgetTheme,
                outValue, true);
        final int targetThemeRes = outValue.resourceId;

        if (targetThemeRes != 0 && mContext.getThemeResId() != targetThemeRes) {
            mThemedContext = new ContextThemeWrapper(mContext, targetThemeRes);
        } else {
            mThemedContext = mContext;
        }
    }
    return mThemedContext;
}

@Override
public boolean isTitleTruncated() {
    return mActionView != null && mActionView.isTitleTruncated();
}

@Override
public void setHomeAsUpIndicator(Drawable indicator) {
    mActionView.setHomeAsUpIndicator(indicator);
}

@Override
public void setHomeAsUpIndicator(int resId) {
    mActionView.setHomeAsUpIndicator(resId);
}

@Override
public void setHomeActionContentDescription(CharSequence description) {
    mActionView.setHomeActionContentDescription(description);
}

@Override
public void setHomeActionContentDescription(int resId) {
    mActionView.setHomeActionContentDescription(resId);
}

/**
 * @hide 
 */
public class ActionModeImpl extends ActionMode implements MenuBuilder.Callback {
    private ActionMode.Callback mCallback;
    private MenuBuilder mMenu;
    private WeakReference mCustomView;

    public ActionModeImpl(ActionMode.Callback callback) {
        mCallback = callback;
        mMenu = new MenuBuilder(getThemedContext())
                .setDefaultShowAsAction(MenuItem.SHOW_AS_ACTION_IF_ROOM);
        mMenu.setCallback(this);
    }

    @Override
    public MenuInflater getMenuInflater() {
        return new MenuInflater(getThemedContext());
    }

    @Override
    public Menu getMenu() {
        return mMenu;
    }

    @Override
    public void finish() {
        if (mActionMode != this) {
            // Not the active action mode - no-op
            return;
        }

        // If this change in state is going to cause the action bar
        // to be hidden, defer the onDestroy callback until the animation
        // is finished and associated relayout is about to happen. This lets
        // apps better anticipate visibility and layout behavior.
        if (!checkShowingFlags(mHiddenByApp, mHiddenBySystem, false)) {
            // With the current state but the action bar hidden, our
            // overall showing state is going to be false.
            mDeferredDestroyActionMode = this;
            mDeferredModeDestroyCallback = mCallback;
        } else {
            mCallback.onDestroyActionMode(this);
        }
        mCallback = null;
        animateToMode(false);

        // Clear out the context mode views after the animation finishes
        mContextView.closeMode();
        mActionView.sendAccessibilityEvent(AccessibilityEvent.TYPE_WINDOW_STATE_CHANGED);

        mActionMode = null;
    }

    @Override
    public void invalidate() {
        mMenu.stopDispatchingItemsChanged();
        try {
            mCallback.onPrepareActionMode(this, mMenu);
        } finally {
            mMenu.startDispatchingItemsChanged();
        }
    }

    public boolean dispatchOnCreate() {
        mMenu.stopDispatchingItemsChanged();
        try {
            return mCallback.onCreateActionMode(this, mMenu);
        } finally {
            mMenu.startDispatchingItemsChanged();
        }
    }

    @Override
    public void setCustomView(View view) {
        mContextView.setCustomView(view);
        mCustomView = new WeakReference(view);
    }

    @Override
    public void setSubtitle(CharSequence subtitle) {
        mContextView.setSubtitle(subtitle);
    }

    @Override
    public void setTitle(CharSequence title) {
        mContextView.setTitle(title);
    }

    @Override
    public void setTitle(int resId) {
        setTitle(mContext.getResources().getString(resId));
    }

    @Override
    public void setSubtitle(int resId) {
        setSubtitle(mContext.getResources().getString(resId));
    }

    @Override
    public CharSequence getTitle() {
        return mContextView.getTitle();
    }

    @Override
    public CharSequence getSubtitle() {
        return mContextView.getSubtitle();
    }

    @Override
    public void setTitleOptionalHint(boolean titleOptional) {
        super.setTitleOptionalHint(titleOptional);
        mContextView.setTitleOptional(titleOptional);
    }

    @Override
    public boolean isTitleOptional() {
        return mContextView.isTitleOptional();
    }

    @Override
    public View getCustomView() {
        return mCustomView != null ? mCustomView.get() : null;
    }

    public boolean onMenuItemSelected(MenuBuilder menu, MenuItem item) {
        if (mCallback != null) {
            return mCallback.onActionItemClicked(this, item);
        } else {
            return false;
        }
    }

    public void onCloseMenu(MenuBuilder menu, boolean allMenusAreClosing) {
    }

    public boolean onSubMenuSelected(SubMenuBuilder subMenu) {
        if (mCallback == null) {
            return false;
        }

        if (!subMenu.hasVisibleItems()) {
            return true;
        }

        new MenuPopupHelper(getThemedContext(), subMenu).show();
        return true;
    }

    public void onCloseSubMenu(SubMenuBuilder menu) {
    }

    public void onMenuModeChange(MenuBuilder menu) {
        if (mCallback == null) {
            return;
        }
        invalidate();
        mContextView.showOverflowMenu();
    }
}

/**
 * @hide
 */
public class TabImpl extends ActionBar.Tab {
    private ActionBar.TabListener mCallback;
    private Object mTag;
    private Drawable mIcon;
    private CharSequence mText;
    private CharSequence mContentDesc;
    private int mPosition = -1;
    private View mCustomView;

    @Override
    public Object getTag() {
        return mTag;
    }

    @Override
    public Tab setTag(Object tag) {
        mTag = tag;
        return this;
    }

    public ActionBar.TabListener getCallback() {
        return mCallback;
    }

    @Override
    public Tab setTabListener(ActionBar.TabListener callback) {
        mCallback = callback;
        return this;
    }

    @Override
    public View getCustomView() {
        return mCustomView;
    }

    @Override
    public Tab setCustomView(View view) {
        mCustomView = view;
        if (mPosition >= 0) {
            mTabScrollView.updateTab(mPosition);
        }
        return this;
    }

    @Override
    public Tab setCustomView(int layoutResId) {
        return setCustomView(LayoutInflater.from(getThemedContext())
                .inflate(layoutResId, null));
    }

    @Override
    public Drawable getIcon() {
        return mIcon;
    }

    @Override
    public int getPosition() {
        return mPosition;
    }

    public void setPosition(int position) {
        mPosition = position;
    }

    @Override
    public CharSequence getText() {
        return mText;
    }

    @Override
    public Tab setIcon(Drawable icon) {
        mIcon = icon;
        if (mPosition >= 0) {
            mTabScrollView.updateTab(mPosition);
        }
        return this;
    }

    @Override
    public Tab setIcon(int resId) {
        return setIcon(mContext.getResources().getDrawable(resId));
    }

    @Override
    public Tab setText(CharSequence text) {
        mText = text;
        if (mPosition >= 0) {
            mTabScrollView.updateTab(mPosition);
        }
        return this;
    }

    @Override
    public Tab setText(int resId) {
        return setText(mContext.getResources().getText(resId));
    }

    @Override
    public void select() {
        selectTab(this);
    }

    @Override
    public Tab setContentDescription(int resId) {
        return setContentDescription(mContext.getResources().getText(resId));
    }

    @Override
    public Tab setContentDescription(CharSequence contentDesc) {
        mContentDesc = contentDesc;
        if (mPosition >= 0) {
            mTabScrollView.updateTab(mPosition);
        }
        return this;
    }

    @Override
    public CharSequence getContentDescription() {
        return mContentDesc;
    }
}

@Override
public void setCustomView(View view) {
    mActionView.setCustomNavigationView(view);
}

@Override
public void setCustomView(View view, LayoutParams layoutParams) {
    view.setLayoutParams(layoutParams);
    mActionView.setCustomNavigationView(view);
}

@Override
public void setListNavigationCallbacks(SpinnerAdapter adapter, OnNavigationListener callback) {
    mActionView.setDropdownAdapter(adapter);
    mActionView.setCallback(callback);
}

@Override
public int getSelectedNavigationIndex() {
    switch (mActionView.getNavigationMode()) {
        case NAVIGATION_MODE_TABS:
            return mSelectedTab != null ? mSelectedTab.getPosition() : -1;
        case NAVIGATION_MODE_LIST:
            return mActionView.getDropdownSelectedPosition();
        default:
            return -1;
    }
}

@Override
public int getNavigationItemCount() {
    switch (mActionView.getNavigationMode()) {
        case NAVIGATION_MODE_TABS:
            return mTabs.size();
        case NAVIGATION_MODE_LIST:
            SpinnerAdapter adapter = mActionView.getDropdownAdapter();
            return adapter != null ? adapter.getCount() : 0;
        default:
            return 0;
    }
}

@Override
public int getTabCount() {
    return mTabs.size();
}

@Override
public void setNavigationMode(int mode) {
    final int oldMode = mActionView.getNavigationMode();
    switch (oldMode) {
        case NAVIGATION_MODE_TABS:
            mSavedTabPosition = getSelectedNavigationIndex();
            selectTab(null);
            mTabScrollView.setVisibility(View.GONE);
            break;
    }
    if (oldMode != mode && !mHasEmbeddedTabs) {
        if (mOverlayLayout != null) {
            mOverlayLayout.requestFitSystemWindows();
        }
    }
    mActionView.setNavigationMode(mode);
    switch (mode) {
        case NAVIGATION_MODE_TABS:
            ensureTabsExist();
            mTabScrollView.setVisibility(View.VISIBLE);
            if (mSavedTabPosition != INVALID_POSITION) {
                setSelectedNavigationItem(mSavedTabPosition);
                mSavedTabPosition = INVALID_POSITION;
            }
            break;
    }
    mActionView.setCollapsable(mode == NAVIGATION_MODE_TABS && !mHasEmbeddedTabs);
}

@Override
public Tab getTabAt(int index) {
    return mTabs.get(index);
}


@Override
public void setIcon(int resId) {
    mActionView.setIcon(resId);
}

@Override
public void setIcon(Drawable icon) {
    mActionView.setIcon(icon);
}

public boolean hasIcon() {
    return mActionView.hasIcon();
}

@Override
public void setLogo(int resId) {
    mActionView.setLogo(resId);
}

@Override
public void setLogo(Drawable logo) {
    mActionView.setLogo(logo);
}

public boolean hasLogo() {
    return mActionView.hasLogo();
}

public void setDefaultDisplayHomeAsUpEnabled(boolean enable) {
    if (!mDisplayHomeAsUpSet) {
        setDisplayHomeAsUpEnabled(enable);
    }
}

}

mContentView和mActionView
![取这两个属性中的一个，给这个属性设置监听，可以试一下)

这边还要注意一个点 就是在界面显示的之后才能反射，不然反射到的值可能为空