RecyclerView<第三十四篇>：条目动画之SlideIn

（1）效果图

【更新数据】

230.gif

【插入数据】

253.gif

【删除数据】

254.gif

【移动数据】

236.gif

（2）SlideInUpAnimator类代码

AnimateViewHolder.java

public interface AnimateViewHolder {

  void preAnimateAddImpl(final RecyclerView.ViewHolder holder);

  void preAnimateRemoveImpl(final RecyclerView.ViewHolder holder);

  void animateAddImpl(final RecyclerView.ViewHolder holder, ViewPropertyAnimatorListener listener);

  void animateRemoveImpl(final RecyclerView.ViewHolder holder,
                         ViewPropertyAnimatorListener listener);
}

BaseItemAnimator.java

public abstract class BaseItemAnimator extends SimpleItemAnimator {

  private static final boolean DEBUG = false;

  private ArrayList<ViewHolder> mPendingRemovals = new ArrayList<>();
  private ArrayList<ViewHolder> mPendingAdditions = new ArrayList<>();
  private ArrayList<MoveInfo> mPendingMoves = new ArrayList<>();
  private ArrayList<ChangeInfo> mPendingChanges = new ArrayList<>();

  private ArrayList<ArrayList<ViewHolder>> mAdditionsList = new ArrayList<>();
  private ArrayList<ArrayList<MoveInfo>> mMovesList = new ArrayList<>();
  private ArrayList<ArrayList<ChangeInfo>> mChangesList = new ArrayList<>();

  protected ArrayList<ViewHolder> mAddAnimations = new ArrayList<>();
  private ArrayList<ViewHolder> mMoveAnimations = new ArrayList<>();
  protected ArrayList<ViewHolder> mRemoveAnimations = new ArrayList<>();
  private ArrayList<ViewHolder> mChangeAnimations = new ArrayList<>();

  protected Interpolator mInterpolator = new DecelerateInterpolator();

  private static class MoveInfo {

    public ViewHolder holder;
    public int fromX, fromY, toX, toY;

    private MoveInfo(ViewHolder holder, int fromX, int fromY, int toX, int toY) {
      this.holder = holder;
      this.fromX = fromX;
      this.fromY = fromY;
      this.toX = toX;
      this.toY = toY;
    }
  }

  private static class ChangeInfo {

    public ViewHolder oldHolder, newHolder;
    public int fromX, fromY, toX, toY;

    private ChangeInfo(ViewHolder oldHolder, ViewHolder newHolder) {
      this.oldHolder = oldHolder;
      this.newHolder = newHolder;
    }

    private ChangeInfo(ViewHolder oldHolder, ViewHolder newHolder, int fromX, int fromY, int toX,
        int toY) {
      this(oldHolder, newHolder);
      this.fromX = fromX;
      this.fromY = fromY;
      this.toX = toX;
      this.toY = toY;
    }

    @Override public String toString() {
      return "ChangeInfo{" +
          "oldHolder=" + oldHolder +
          ", newHolder=" + newHolder +
          ", fromX=" + fromX +
          ", fromY=" + fromY +
          ", toX=" + toX +
          ", toY=" + toY +
          '}';
    }
  }

  public BaseItemAnimator() {
    super();
    setSupportsChangeAnimations(false);
  }

  public void setInterpolator(Interpolator mInterpolator) {
    this.mInterpolator = mInterpolator;
  }

  @Override public void runPendingAnimations() {
    boolean removalsPending = !mPendingRemovals.isEmpty();
    boolean movesPending = !mPendingMoves.isEmpty();
    boolean changesPending = !mPendingChanges.isEmpty();
    boolean additionsPending = !mPendingAdditions.isEmpty();
    if (!removalsPending && !movesPending && !additionsPending && !changesPending) {
      // nothing to animate
      return;
    }
    // First, remove stuff
    for (ViewHolder holder : mPendingRemovals) {
      doAnimateRemove(holder);
    }
    mPendingRemovals.clear();
    // Next, move stuff
    if (movesPending) {
      final ArrayList<MoveInfo> moves = new ArrayList<MoveInfo>();
      moves.addAll(mPendingMoves);
      mMovesList.add(moves);
      mPendingMoves.clear();
      Runnable mover = new Runnable() {
        @Override public void run() {
          boolean removed = mMovesList.remove(moves);
          if (!removed) {
            // already canceled
            return;
          }
          for (MoveInfo moveInfo : moves) {
            animateMoveImpl(moveInfo.holder, moveInfo.fromX, moveInfo.fromY, moveInfo.toX,
                moveInfo.toY);
          }
          moves.clear();
        }
      };
      if (removalsPending) {
        View view = moves.get(0).holder.itemView;
        ViewCompat.postOnAnimationDelayed(view, mover, getRemoveDuration());
      } else {
        mover.run();
      }
    }
    // Next, change stuff, to run in parallel with move animations
    if (changesPending) {
      final ArrayList<ChangeInfo> changes = new ArrayList<ChangeInfo>();
      changes.addAll(mPendingChanges);
      mChangesList.add(changes);
      mPendingChanges.clear();
      Runnable changer = new Runnable() {
        @Override public void run() {
          boolean removed = mChangesList.remove(changes);
          if (!removed) {
            // already canceled
            return;
          }
          for (ChangeInfo change : changes) {
            animateChangeImpl(change);
          }
          changes.clear();
        }
      };
      if (removalsPending) {
        ViewHolder holder = changes.get(0).oldHolder;
        ViewCompat.postOnAnimationDelayed(holder.itemView, changer, getRemoveDuration());
      } else {
        changer.run();
      }
    }
    // Next, add stuff
    if (additionsPending) {
      final ArrayList<ViewHolder> additions = new ArrayList<ViewHolder>();
      additions.addAll(mPendingAdditions);
      mAdditionsList.add(additions);
      mPendingAdditions.clear();
      Runnable adder = new Runnable() {
        public void run() {
          boolean removed = mAdditionsList.remove(additions);
          if (!removed) {
            // already canceled
            return;
          }
          for (ViewHolder holder : additions) {
            doAnimateAdd(holder);
          }
          additions.clear();
        }
      };
      if (removalsPending || movesPending || changesPending) {
        long removeDuration = removalsPending ? getRemoveDuration() : 0;
        long moveDuration = movesPending ? getMoveDuration() : 0;
        long changeDuration = changesPending ? getChangeDuration() : 0;
        long totalDelay = removeDuration + Math.max(moveDuration, changeDuration);
        View view = additions.get(0).itemView;
        ViewCompat.postOnAnimationDelayed(view, adder, totalDelay);
      } else {
        adder.run();
      }
    }
  }

  protected void preAnimateRemoveImpl(final ViewHolder holder) {
  }

  protected void preAnimateAddImpl(final ViewHolder holder) {
  }

  protected abstract void animateRemoveImpl(final ViewHolder holder);

  protected abstract void animateAddImpl(final ViewHolder holder);

  private void preAnimateRemove(final ViewHolder holder) {
    ViewHelper.clear(holder.itemView);

    if (holder instanceof AnimateViewHolder) {
      ((AnimateViewHolder) holder).preAnimateRemoveImpl(holder);
    } else {
      preAnimateRemoveImpl(holder);
    }
  }

  private void preAnimateAdd(final ViewHolder holder) {
    ViewHelper.clear(holder.itemView);

    if (holder instanceof AnimateViewHolder) {
      ((AnimateViewHolder) holder).preAnimateAddImpl(holder);
    } else {
      preAnimateAddImpl(holder);
    }
  }

  private void doAnimateRemove(final ViewHolder holder) {
    if (holder instanceof AnimateViewHolder) {
      ((AnimateViewHolder) holder).animateRemoveImpl(holder, new DefaultRemoveVpaListener(holder));
    } else {
      animateRemoveImpl(holder);
    }

    mRemoveAnimations.add(holder);
  }

  private void doAnimateAdd(final ViewHolder holder) {
    if (holder instanceof AnimateViewHolder) {
      ((AnimateViewHolder) holder).animateAddImpl(holder, new DefaultAddVpaListener(holder));
    } else {
      animateAddImpl(holder);
    }

    mAddAnimations.add(holder);
  }

  @Override public boolean animateRemove(final ViewHolder holder) {
    endAnimation(holder);
    preAnimateRemove(holder);
    mPendingRemovals.add(holder);
    return true;
  }

  protected long getRemoveDelay(final ViewHolder holder) {
    return Math.abs(holder.getOldPosition() * getRemoveDuration() / 4);
  }

  @Override public boolean animateAdd(final ViewHolder holder) {
    endAnimation(holder);
    preAnimateAdd(holder);
    mPendingAdditions.add(holder);
    return true;
  }

  protected long getAddDelay(final ViewHolder holder) {
    return Math.abs(holder.getAdapterPosition() * getAddDuration() / 4);
  }

  @Override
  public boolean animateMove(final ViewHolder holder, int fromX, int fromY, int toX, int toY) {
    final View view = holder.itemView;
    fromX += ViewCompat.getTranslationX(holder.itemView);
    fromY += ViewCompat.getTranslationY(holder.itemView);
    endAnimation(holder);
    int deltaX = toX - fromX;
    int deltaY = toY - fromY;
    if (deltaX == 0 && deltaY == 0) {
      dispatchMoveFinished(holder);
      return false;
    }
    if (deltaX != 0) {
      ViewCompat.setTranslationX(view, -deltaX);
    }
    if (deltaY != 0) {
      ViewCompat.setTranslationY(view, -deltaY);
    }
    mPendingMoves.add(new MoveInfo(holder, fromX, fromY, toX, toY));
    return true;
  }

  private void animateMoveImpl(final ViewHolder holder, int fromX, int fromY, int toX, int toY) {
    final View view = holder.itemView;
    final int deltaX = toX - fromX;
    final int deltaY = toY - fromY;
    if (deltaX != 0) {
      ViewCompat.animate(view).translationX(0);
    }
    if (deltaY != 0) {
      ViewCompat.animate(view).translationY(0);
    }
    // TODO: make EndActions end listeners instead, since end actions aren't called when
    // vpas are canceled (and can't end them. why?)
    // need listener functionality in VPACompat for this. Ick.
    mMoveAnimations.add(holder);
    final ViewPropertyAnimatorCompat animation = ViewCompat.animate(view);
    animation.setDuration(getMoveDuration()).setListener(new VpaListenerAdapter() {
      @Override public void onAnimationStart(View view) {
        dispatchMoveStarting(holder);
      }

      @Override public void onAnimationCancel(View view) {
        if (deltaX != 0) {
          ViewCompat.setTranslationX(view, 0);
        }
        if (deltaY != 0) {
          ViewCompat.setTranslationY(view, 0);
        }
      }

      @Override public void onAnimationEnd(View view) {
        animation.setListener(null);
        dispatchMoveFinished(holder);
        mMoveAnimations.remove(holder);
        dispatchFinishedWhenDone();
      }
    }).start();
  }

  @Override
  public boolean animateChange(ViewHolder oldHolder, ViewHolder newHolder, int fromX, int fromY, int toX, int toY) {
    if (oldHolder == newHolder) {
      // Don't know how to run change animations when the same view holder is re-used.
      // run a move animation to handle position changes.
      return animateMove(oldHolder, fromX, fromY, toX, toY);
    }
    final float prevTranslationX = ViewCompat.getTranslationX(oldHolder.itemView);
    final float prevTranslationY = ViewCompat.getTranslationY(oldHolder.itemView);
    final float prevAlpha = ViewCompat.getAlpha(oldHolder.itemView);
    endAnimation(oldHolder);
    int deltaX = (int) (toX - fromX - prevTranslationX);
    int deltaY = (int) (toY - fromY - prevTranslationY);
    // recover prev translation state after ending animation
    ViewCompat.setTranslationX(oldHolder.itemView, prevTranslationX);
    ViewCompat.setTranslationY(oldHolder.itemView, prevTranslationY);
    ViewCompat.setAlpha(oldHolder.itemView, prevAlpha);
    if (newHolder != null && newHolder.itemView != null) {
      // carry over translation values
      endAnimation(newHolder);
      ViewCompat.setTranslationX(newHolder.itemView, -deltaX);
      ViewCompat.setTranslationY(newHolder.itemView, -deltaY);
      ViewCompat.setAlpha(newHolder.itemView, 0);
    }
    mPendingChanges.add(new ChangeInfo(oldHolder, newHolder, fromX, fromY, toX, toY));
    return true;
  }

  private void animateChangeImpl(final ChangeInfo changeInfo) {
    final ViewHolder holder = changeInfo.oldHolder;
    final View view = holder == null ? null : holder.itemView;
    final ViewHolder newHolder = changeInfo.newHolder;
    final View newView = newHolder != null ? newHolder.itemView : null;
    if (view != null) {
      mChangeAnimations.add(changeInfo.oldHolder);
      final ViewPropertyAnimatorCompat oldViewAnim =
          ViewCompat.animate(view).setDuration(getChangeDuration());
      oldViewAnim.translationX(changeInfo.toX - changeInfo.fromX);
      oldViewAnim.translationY(changeInfo.toY - changeInfo.fromY);
      oldViewAnim.alpha(0).setListener(new VpaListenerAdapter() {
        @Override public void onAnimationStart(View view) {
          dispatchChangeStarting(changeInfo.oldHolder, true);
        }

        @Override public void onAnimationEnd(View view) {
          oldViewAnim.setListener(null);
          ViewCompat.setAlpha(view, 1);
          ViewCompat.setTranslationX(view, 0);
          ViewCompat.setTranslationY(view, 0);
          dispatchChangeFinished(changeInfo.oldHolder, true);
          mChangeAnimations.remove(changeInfo.oldHolder);
          dispatchFinishedWhenDone();
        }
      }).start();
    }
    if (newView != null) {
      mChangeAnimations.add(changeInfo.newHolder);
      final ViewPropertyAnimatorCompat newViewAnimation = ViewCompat.animate(newView);
      newViewAnimation.translationX(0).translationY(0).setDuration(getChangeDuration()).
          alpha(1).setListener(new VpaListenerAdapter() {
        @Override public void onAnimationStart(View view) {
          dispatchChangeStarting(changeInfo.newHolder, false);
        }

        @Override public void onAnimationEnd(View view) {
          newViewAnimation.setListener(null);
          ViewCompat.setAlpha(newView, 1);
          ViewCompat.setTranslationX(newView, 0);
          ViewCompat.setTranslationY(newView, 0);
          dispatchChangeFinished(changeInfo.newHolder, false);
          mChangeAnimations.remove(changeInfo.newHolder);
          dispatchFinishedWhenDone();
        }
      }).start();
    }
  }

  private void endChangeAnimation(List<ChangeInfo> infoList, ViewHolder item) {
    for (int i = infoList.size() - 1; i >= 0; i--) {
      ChangeInfo changeInfo = infoList.get(i);
      if (endChangeAnimationIfNecessary(changeInfo, item)) {
        if (changeInfo.oldHolder == null && changeInfo.newHolder == null) {
          infoList.remove(changeInfo);
        }
      }
    }
  }

  private void endChangeAnimationIfNecessary(ChangeInfo changeInfo) {
    if (changeInfo.oldHolder != null) {
      endChangeAnimationIfNecessary(changeInfo, changeInfo.oldHolder);
    }
    if (changeInfo.newHolder != null) {
      endChangeAnimationIfNecessary(changeInfo, changeInfo.newHolder);
    }
  }

  private boolean endChangeAnimationIfNecessary(ChangeInfo changeInfo, ViewHolder item) {
    boolean oldItem = false;
    if (changeInfo.newHolder == item) {
      changeInfo.newHolder = null;
    } else if (changeInfo.oldHolder == item) {
      changeInfo.oldHolder = null;
      oldItem = true;
    } else {
      return false;
    }
    ViewCompat.setAlpha(item.itemView, 1);
    ViewCompat.setTranslationX(item.itemView, 0);
    ViewCompat.setTranslationY(item.itemView, 0);
    dispatchChangeFinished(item, oldItem);
    return true;
  }

  @Override public void endAnimation(ViewHolder item) {
    final View view = item.itemView;
    // this will trigger end callback which should set properties to their target values.
    ViewCompat.animate(view).cancel();
    // TODO if some other animations are chained to end, how do we cancel them as well?
    for (int i = mPendingMoves.size() - 1; i >= 0; i--) {
      MoveInfo moveInfo = mPendingMoves.get(i);
      if (moveInfo.holder == item) {
        ViewCompat.setTranslationY(view, 0);
        ViewCompat.setTranslationX(view, 0);
        dispatchMoveFinished(item);
        mPendingMoves.remove(i);
      }
    }
    endChangeAnimation(mPendingChanges, item);
    if (mPendingRemovals.remove(item)) {
      ViewHelper.clear(item.itemView);
      dispatchRemoveFinished(item);
    }
    if (mPendingAdditions.remove(item)) {
      ViewHelper.clear(item.itemView);
      dispatchAddFinished(item);
    }

    for (int i = mChangesList.size() - 1; i >= 0; i--) {
      ArrayList<ChangeInfo> changes = mChangesList.get(i);
      endChangeAnimation(changes, item);
      if (changes.isEmpty()) {
        mChangesList.remove(i);
      }
    }
    for (int i = mMovesList.size() - 1; i >= 0; i--) {
      ArrayList<MoveInfo> moves = mMovesList.get(i);
      for (int j = moves.size() - 1; j >= 0; j--) {
        MoveInfo moveInfo = moves.get(j);
        if (moveInfo.holder == item) {
          ViewCompat.setTranslationY(view, 0);
          ViewCompat.setTranslationX(view, 0);
          dispatchMoveFinished(item);
          moves.remove(j);
          if (moves.isEmpty()) {
            mMovesList.remove(i);
          }
          break;
        }
      }
    }
    for (int i = mAdditionsList.size() - 1; i >= 0; i--) {
      ArrayList<ViewHolder> additions = mAdditionsList.get(i);
      if (additions.remove(item)) {
        ViewHelper.clear(item.itemView);
        dispatchAddFinished(item);
        if (additions.isEmpty()) {
          mAdditionsList.remove(i);
        }
      }
    }

    // animations should be ended by the cancel above.
    if (mRemoveAnimations.remove(item) && DEBUG) {
      throw new IllegalStateException(
          "after animation is cancelled, item should not be in " + "mRemoveAnimations list");
    }

    if (mAddAnimations.remove(item) && DEBUG) {
      throw new IllegalStateException(
          "after animation is cancelled, item should not be in " + "mAddAnimations list");
    }

    if (mChangeAnimations.remove(item) && DEBUG) {
      throw new IllegalStateException(
          "after animation is cancelled, item should not be in " + "mChangeAnimations list");
    }

    if (mMoveAnimations.remove(item) && DEBUG) {
      throw new IllegalStateException(
          "after animation is cancelled, item should not be in " + "mMoveAnimations list");
    }
    dispatchFinishedWhenDone();
  }

  @Override public boolean isRunning() {
    return (!mPendingAdditions.isEmpty() ||
        !mPendingChanges.isEmpty() ||
        !mPendingMoves.isEmpty() ||
        !mPendingRemovals.isEmpty() ||
        !mMoveAnimations.isEmpty() ||
        !mRemoveAnimations.isEmpty() ||
        !mAddAnimations.isEmpty() ||
        !mChangeAnimations.isEmpty() ||
        !mMovesList.isEmpty() ||
        !mAdditionsList.isEmpty() ||
        !mChangesList.isEmpty());
  }

  /**
   * Check the state of currently pending and running animations. If there are none
   * pending/running, call #dispatchAnimationsFinished() to notify any
   * listeners.
   */
  private void dispatchFinishedWhenDone() {
    if (!isRunning()) {
      dispatchAnimationsFinished();
    }
  }

  @Override public void endAnimations() {
    int count = mPendingMoves.size();
    for (int i = count - 1; i >= 0; i--) {
      MoveInfo item = mPendingMoves.get(i);
      View view = item.holder.itemView;
      ViewCompat.setTranslationY(view, 0);
      ViewCompat.setTranslationX(view, 0);
      dispatchMoveFinished(item.holder);
      mPendingMoves.remove(i);
    }
    count = mPendingRemovals.size();
    for (int i = count - 1; i >= 0; i--) {
      ViewHolder item = mPendingRemovals.get(i);
      dispatchRemoveFinished(item);
      mPendingRemovals.remove(i);
    }
    count = mPendingAdditions.size();
    for (int i = count - 1; i >= 0; i--) {
      ViewHolder item = mPendingAdditions.get(i);
      ViewHelper.clear(item.itemView);
      dispatchAddFinished(item);
      mPendingAdditions.remove(i);
    }
    count = mPendingChanges.size();
    for (int i = count - 1; i >= 0; i--) {
      endChangeAnimationIfNecessary(mPendingChanges.get(i));
    }
    mPendingChanges.clear();
    if (!isRunning()) {
      return;
    }

    int listCount = mMovesList.size();
    for (int i = listCount - 1; i >= 0; i--) {
      ArrayList<MoveInfo> moves = mMovesList.get(i);
      count = moves.size();
      for (int j = count - 1; j >= 0; j--) {
        MoveInfo moveInfo = moves.get(j);
        ViewHolder item = moveInfo.holder;
        View view = item.itemView;
        ViewCompat.setTranslationY(view, 0);
        ViewCompat.setTranslationX(view, 0);
        dispatchMoveFinished(moveInfo.holder);
        moves.remove(j);
        if (moves.isEmpty()) {
          mMovesList.remove(moves);
        }
      }
    }
    listCount = mAdditionsList.size();
    for (int i = listCount - 1; i >= 0; i--) {
      ArrayList<ViewHolder> additions = mAdditionsList.get(i);
      count = additions.size();
      for (int j = count - 1; j >= 0; j--) {
        ViewHolder item = additions.get(j);
        View view = item.itemView;
        ViewCompat.setAlpha(view, 1);
        dispatchAddFinished(item);
        //this check prevent exception when removal already happened during finishing animation
        if (j < additions.size()) {
          additions.remove(j);
        }
        if (additions.isEmpty()) {
          mAdditionsList.remove(additions);
        }
      }
    }
    listCount = mChangesList.size();
    for (int i = listCount - 1; i >= 0; i--) {
      ArrayList<ChangeInfo> changes = mChangesList.get(i);
      count = changes.size();
      for (int j = count - 1; j >= 0; j--) {
        endChangeAnimationIfNecessary(changes.get(j));
        if (changes.isEmpty()) {
          mChangesList.remove(changes);
        }
      }
    }

    cancelAll(mRemoveAnimations);
    cancelAll(mMoveAnimations);
    cancelAll(mAddAnimations);
    cancelAll(mChangeAnimations);

    dispatchAnimationsFinished();
  }

  void cancelAll(List<ViewHolder> viewHolders) {
    for (int i = viewHolders.size() - 1; i >= 0; i--) {
      ViewCompat.animate(viewHolders.get(i).itemView).cancel();
    }
  }

  private static class VpaListenerAdapter implements ViewPropertyAnimatorListener {

    @Override public void onAnimationStart(View view) {
    }

    @Override public void onAnimationEnd(View view) {
    }

    @Override public void onAnimationCancel(View view) {
    }
  }

  protected class DefaultAddVpaListener extends VpaListenerAdapter {

    ViewHolder mViewHolder;

    public DefaultAddVpaListener(final ViewHolder holder) {
      mViewHolder = holder;
    }

    @Override public void onAnimationStart(View view) {
      dispatchAddStarting(mViewHolder);
    }

    @Override public void onAnimationCancel(View view) {
      ViewHelper.clear(view);
    }

    @Override public void onAnimationEnd(View view) {
      ViewHelper.clear(view);
      dispatchAddFinished(mViewHolder);
      mAddAnimations.remove(mViewHolder);
      dispatchFinishedWhenDone();
    }
  }

  protected class DefaultRemoveVpaListener extends VpaListenerAdapter {

    ViewHolder mViewHolder;

    public DefaultRemoveVpaListener(final ViewHolder holder) {
      mViewHolder = holder;
    }

    @Override public void onAnimationStart(View view) {
      dispatchRemoveStarting(mViewHolder);
    }

    @Override public void onAnimationCancel(View view) {
      ViewHelper.clear(view);
    }

    @Override public void onAnimationEnd(View view) {
      ViewHelper.clear(view);
      dispatchRemoveFinished(mViewHolder);
      mRemoveAnimations.remove(mViewHolder);
      dispatchFinishedWhenDone();
    }
  }
}

ViewHelper.java

public final class ViewHelper {

  public static void clear(View v) {
    v.setAlpha(1);
    v.setScaleY(1);
    v.setScaleX(1);
    v.setTranslationY(0);
    v.setTranslationX(0);
    v.setRotation(0);
    v.setRotationY(0);
    v.setRotationX(0);
    v.setPivotY(v.getMeasuredHeight() / 2);
    v.setPivotX(v.getMeasuredWidth() / 2);
    ViewCompat.animate(v).setInterpolator(null).setStartDelay(0);
  }
}

SlideInUpAnimator.java

public class SlideInUpAnimator extends BaseItemAnimator {

  public SlideInUpAnimator() {

  }

  public SlideInUpAnimator(Interpolator interpolator) {
    mInterpolator = interpolator;
  }

  @Override protected void animateRemoveImpl(final RecyclerView.ViewHolder holder) {
    ViewCompat.animate(holder.itemView)
        .translationY(holder.itemView.getHeight())
        .alpha(0)
        .setDuration(getRemoveDuration())
        .setInterpolator(mInterpolator)
        .setListener(new DefaultRemoveVpaListener(holder))
        .setStartDelay(getRemoveDelay(holder))
        .start();
  }

  @Override protected void preAnimateAddImpl(RecyclerView.ViewHolder holder) {
    ViewCompat.setTranslationY(holder.itemView, holder.itemView.getHeight());
    ViewCompat.setAlpha(holder.itemView, 0);
  }

  @Override protected void animateAddImpl(final RecyclerView.ViewHolder holder) {
    ViewCompat.animate(holder.itemView)
        .translationY(0)
        .alpha(1)
        .setDuration(getAddDuration())
        .setInterpolator(mInterpolator)
        .setListener(new DefaultAddVpaListener(holder))
        .setStartDelay(getAddDelay(holder))
        .start();
  }
}

（3）刷新代码

【更新数据】

            urls.set(position, "http://img4.imgtn.bdimg.com/it/u=3209370120,2008812818&fm=26&gp=0.jpg");
            recycleViewAdapter.notifyItemChanged(position);

【插入数据】

            urls.add(position, "http://img4.imgtn.bdimg.com/it/u=3209370120,2008812818&fm=26&gp=0.jpg");
            recycleViewAdapter.notifyItemInserted(position);
            recycleViewAdapter.notifyItemRangeChanged(position, urls.size() - position);

【删除数据】

            urls.remove(position);
            recycleViewAdapter.notifyItemRemoved(position);
            recycleViewAdapter.notifyItemRangeChanged(position, urls.size() - position);

【移动数据】

            int fromPosition = position;
            int toPosition = position + 1;
            Collections.swap(urls,fromPosition,toPosition);
            recycleViewAdapter.notifyItemMoved(fromPosition, toPosition);
            recycleViewAdapter.notifyItemRangeChanged(position, toPosition - fromPosition + 1);

（4）如何使用

    SlideInUpAnimator slideInUpAnimator = new SlideInUpAnimator();
    slideInUpAnimator.setChangeDuration(300);
    slideInUpAnimator.setAddDuration(300);
    slideInUpAnimator.setRemoveDuration(3000);
    slideInUpAnimator.setMoveDuration(300);
    slideInUpAnimator.setInterpolator(new OvershootInterpolator());
    slideInUpAnimator.setSupportsChangeAnimations(true);
    recyclerview.setItemAnimator(slideInUpAnimator);
    recyclerview.setAdapter(recycleViewAdapter);

[本章完...]