我有一个 RecyclerView ，大约有20个项目。渲染和阻止de UI需要很长时间。
我使用 ConstraintLayout 来定位每行中的项目。它们并不复杂，如截图所示 - Link to animated gif。
我还有一个 ViewPager 用于主导航（参见下栏）。在每个页面片段上还有一个ViewPager。在这个内部的ViewPager中，您可以找到RecyclerView（在NestedScrollView中）。
此外，我在NestedScrollView上有一个滚动侦听器，对标题进行视差效果。
我注意到如果我删除了一些项目并且只有3个项目的RecyclerView，它会变得更快。所以它似乎与RecyclerView的行有些问题。
我还做了一个测试，用一个固定高度的FrameLayout替换每行的ConstraintLayout - 性能相同
我还使用 Iconics （用于字体图标）和书法（用于自定义排版） - 这会影响性能吗？
当我在更改到第一页后立即滚动并且UI被阻止时，请注意该圈子。另请注意，ViewPager在转到第二页时会滑动，但从第二页到第一页时，它会阻止动画并立即显示列表。
行项目（history_item.xml）：
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
android:id="@+id/container"
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="76dp"
android:clickable="true">
<TextView
android:id="@+id/date"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintHorizontal_chainStyle="spread"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
android:textSize="11sp"
android:textAllCaps="true"
android:textColor="@color/black"
android:text="12 JUN"
android:layout_marginTop="@dimen/margin_xs"
android:layout_marginLeft="@dimen/margin_small"/>
<com.mikepenz.iconics.view.IconicsTextView
android:id="@+id/icon"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintTop_toBottomOf="@id/date"
app:layout_constraintLeft_toLeftOf="@id/date"
app:layout_constraintRight_toLeftOf="@+id/kms"
android:layout_marginRight="5dp"
android:layout_marginTop="5dp"
android:text="{evz_workout_running}"
android:textColor="@color/colorPrimary"
android:textSize="22sp"
android:gravity="left" />
<TextView
android:id="@+id/kms"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintLeft_toRightOf="@id/icon"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintRight_toLeftOf="@+id/icon_time"
app:layout_constraintHorizontal_chainStyle="spread"
android:layout_marginTop="@dimen/margin_xs"
android:textSize="34sp"
android:textColor="@color/black"
android:textAppearance="@style/textStyleBlack"
android:text="325,4"
android:translationY="-12dp" />
<TextView
android:id="@+id/kms_label"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintTop_toTopOf="@id/kms"
app:layout_constraintRight_toRightOf="@id/kms"
android:layout_marginTop="32dp"
android:textSize="9sp"
android:textColor="@color/black"
android:text="KMS"
android:textAppearance="@style/textStyleBold"/>
<com.mikepenz.iconics.view.IconicsTextView
android:id="@+id/icon_time"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintLeft_toRightOf="@id/kms"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintRight_toLeftOf="@+id/icon_speed"
android:layout_marginTop="@dimen/margin_xs"
android:layout_marginLeft="@dimen/margin_medium"
android:layout_marginRight="@dimen/margin_medium"
app:layout_constraintHorizontal_chainStyle="spread"
android:text="{evz_config_duration}"
android:textColor="@color/gray"
android:textSize="26sp" />
<TextView
android:id="@+id/time"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintTop_toBottomOf="@id/icon_time"
app:layout_constraintLeft_toLeftOf="@id/icon_time"
app:layout_constraintRight_toRightOf="@id/icon_time"
android:layout_marginTop="5dp"
android:textSize="10sp"
android:textColor="@color/black"
android:textAppearance="@style/textStyleBold"
android:text="00:00:07"/>
<com.mikepenz.iconics.view.IconicsTextView
android:id="@+id/icon_speed"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintTop_toTopOf="@id/icon_time"
app:layout_constraintLeft_toRightOf="@id/icon_time"
app:layout_constraintRight_toLeftOf="@+id/icon_points"
app:layout_constraintHorizontal_chainStyle="spread"
android:paddingTop="2sp"
android:paddingBottom="2sp"
android:text="{evz_rate}"
android:textColor="@color/gray"
android:textSize="22sp" />
<TextView
android:id="@+id/speed"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintTop_toBottomOf="@id/icon_speed"
app:layout_constraintLeft_toLeftOf="@id/icon_speed"
app:layout_constraintRight_toRightOf="@id/icon_speed"
android:layout_marginTop="5dp"
android:textSize="10sp"
android:textColor="@color/black"
android:textAppearance="@style/textStyleBold"
android:text="00'00''"/>
<com.mikepenz.iconics.view.IconicsTextView
android:id="@+id/icon_points"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintTop_toTopOf="@id/icon_time"
app:layout_constraintLeft_toRightOf="@id/icon_speed"
app:layout_constraintRight_toRightOf="parent"
android:layout_marginRight="@dimen/margin_small"
android:paddingTop="2dp"
android:paddingBottom="2dp"
android:text="{evz_star}"
android:textColor="@color/gray"
android:textSize="22sp"/>
<TextView
android:id="@+id/points"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintTop_toBottomOf="@id/icon_points"
app:layout_constraintLeft_toLeftOf="@id/icon_points"
app:layout_constraintRight_toRightOf="@id/icon_points"
android:layout_marginTop="5dp"
android:textSize="10sp"
android:textColor="@color/black"
android:textAppearance="@style/textStyleBold"
android:text="3500"/>
<Button
android:id="@+id/undo_button"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
android:layout_margin="0dp"
android:layout_gravity="end|center_vertical"
android:background="@color/red"
android:textColor="@color/white"
style="@style/Base.Widget.AppCompat.Button.Borderless"
android:textAppearance="@style/textStyleBold"
android:textAllCaps="true"
android:text="Anular"
android:textSize="18sp"
android:visibility="gone"
/>
</android.support.constraint.ConstraintLayout>
具有RecyclerView（pager_fragment.xml）的片段：
<?xml version="1.0" encoding="utf-8"?>
<merge
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<android.support.v4.widget.NestedScrollView
android:id="@+id/sub_scroll"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fillViewport="true">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:paddingTop="210dp">
<pt.sportzone.everyzone.ui.DynamicViewPager
android:id="@+id/sub_pager"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</LinearLayout>
</android.support.v4.widget.NestedScrollView>
<android.support.constraint.ConstraintLayout
android:id="@+id/sub_header"
android:layout_width="match_parent"
android:layout_height="wrap_content">
...
</android.support.constraint.ConstraintLayout>
</merge>
Fragment类（PagerFragment.java）：
public class PagerFragment extends Fragment implements IPagerFragment, ViewPager.OnPageChangeListener, View.OnClickListener {
...
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setHasOptionsMenu(true);
}
@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
// Get elements from Layout
mPager = (DynamicViewPager) view.findViewById(R.id.sub_pager);
if (mButton1 != null && mButton2 != null && mButton3 != null) {
...
if (mHeader != null) {
// Listen to when tree is ready so we can setup parallax
mHeader.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
@Override
public void onGlobalLayout() {
mHeader.getViewTreeObserver().removeOnGlobalLayoutListener(this);
setupParallax();
}
});
}
}
if (mPager != null) mPager.setCurrentItem(0);
activate();
}
@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
super.setUserVisibleHint(isVisibleToUser);
if (!isVisibleToUser) activated = false;
active = isVisibleToUser;
}
protected void activate() {
if (active && getView() != null && getActivity() != null && !activated) {
activated = true;
}
}
@Override
public void onPageSelected(int position) {
if (mPager == null) return;
//Log.d(EZ.TAG, "Page Selected: " + position);
FragmentPagerAdapter adapter = (FragmentPagerAdapter) mPager.getAdapter();
targetPosition = position;
IPagerFragment fragmentAppear = (IPagerFragment) adapter.getItem(targetPosition);
IPagerFragment fragmentDisappear = (IPagerFragment) adapter.getItem(currentPosition);
fragmentDisappear.willDisappear(targetPosition);
fragmentAppear.willAppear(currentPosition);
mButton1.setSelected(false);
mButton2.setSelected(false);
mButton3.setSelected(false);
switch (position) {
case 0:
mButton1.setSelected(true);
break;
case 1:
mButton2.setSelected(true);
break;
case 2:
mButton3.setSelected(true);
break;
}
}
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
if (mPager == null) return;
//Log.d(EZ.TAG, position + " - " + positionOffset + " - " + positionOffsetPixels);
FragmentPagerAdapter adapter = (FragmentPagerAdapter) mPager.getAdapter();
//currentPosition = position;
if (position == targetPosition && positionOffsetPixels == 0) {
IPagerFragment fragmentAppear = (IPagerFragment) adapter.getItem(targetPosition);
IPagerFragment fragmentDisappear = (IPagerFragment) adapter.getItem(currentPosition);
currentPosition = targetPosition;
fragmentDisappear.didDisappear();
fragmentAppear.didAppear();
}
}
@Override
public void onPageScrollStateChanged(int state) {
}
public void setupParallax() {
// Listen for scroll events
if (scrollChangedListener == null) {
// Get initial data
initialWidth = mBackground.getWidth();
initialHeight = mBackground.getHeight();
initialRatio = initialHeight / initialWidth;
curveInitialHeight = mCurve.getHeight();
if (mScroll != null && collapseHeader) {
mScroll.setOnScrollChangeListener(new NestedScrollView.OnScrollChangeListener() {
@Override
public void onScrollChange(NestedScrollView v, int scrollX, int scrollY, int oldScrollX, int oldScrollY) {
doParallax(v, scrollX, scrollY, oldScrollX, oldScrollY);
}
});
}
UI.flattenConstraintRatio(mBackground);
UI.flattenConstraintRatio(mBackgroundSpacer);
UI.flattenConstraintRatio(mCurve);
mCurve.setScaleType(ImageView.ScaleType.FIT_XY);
// Run first parallax iteration
doParallax(mScroll, 0, 0, 0, 0);
}
}
public void doParallax(NestedScrollView v, int scrollX, int scrollY, int oldScrollX, int oldScrollY) {
// No height, something's wrong, just go away
if (initialHeight == 0) return;
// Get the percentage of scroll till hitting the max scroll target (initial Height)
float percent = (float)scrollY / curveInitialHeight;
float percentLeft = 1 - percent;
if (percent < 0) percent = 0;
if (percent > 1) percent = 1;
float percentFast = Math.min(percent * 1.4f, 1);
float percentLeftFast = 1 - percentFast;
// Adjust the profile background image
int headerHeight = Math.max((int)initialHeight - (int)(percent * curveInitialHeight), (int)initialHeight - (int)curveInitialHeight); // 24 -> status bar, 53 -> action bar
UI.setConstraintHeight(mBackground, headerHeight);
int curveHeight = Math.max((int)(percentLeft * curveInitialHeight), 0);
UI.setConstraintHeight(mCurve, curveHeight);
if (mButton1 != null) {
mButton1.getButtonLabel().setAlpha(percentLeft);
mButton2.getButtonLabel().setAlpha(percentLeft);
mButton3.getButtonLabel().setAlpha(percentLeft);
}
// Adjust Elements alpha
//mBackground.getDrawable().setAlpha((int)(percentLeftFast * 255));
//mGradient.setAlpha(percentLeft);
}
适配器（HistoryAdapter.java）：
public class HistoryAdapter extends RecyclerView.Adapter<HistoryAdapter.ViewHolder> {
private static final int PENDING_REMOVAL_TIMEOUT = 3000; // 3sec
private Fragment fragment;
List<Music> items;
List<Music> itemsPendingRemoval;
boolean undoOn;
private Handler handler = new Handler(); // hanlder for running delayed runnables
HashMap<Music, Runnable> pendingRunnables = new HashMap<>(); // map of items to pending runnables, so we can cancel a removal if need be
public static class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
Music track;
public TextView mDate;
public IconicsTextView mIcon;
public TextView mKms;
public IconicsTextView mIconTime;
public TextView mTime;
public IconicsTextView mIconSpeed;
public TextView mSpeed;
public IconicsTextView mIconPoints;
public TextView mPoints;
public ConstraintLayout mContainer;
public Button mUndo;
OnHistoryItemClickedListener mListener;
public ViewHolder(Fragment fragment, View holder) {
super(holder);
// Force interface implementation
if (fragment instanceof OnHistoryItemClickedListener) {
mListener = (OnHistoryItemClickedListener) fragment;
} else {
throw new RuntimeException(fragment.toString()
+ " must implement OnHistoryItemClickedListener");
}
mContainer = (ConstraintLayout) holder.findViewById(R.id.container);
mDate = (TextView) holder.findViewById(R.id.date);
mIcon = (IconicsTextView) holder.findViewById(R.id.icon);
mKms = (TextView) holder.findViewById(R.id.kms);
mIconTime = (IconicsTextView) holder.findViewById(R.id.icon_time);
mTime = (TextView) holder.findViewById(R.id.time);
mIconSpeed = (IconicsTextView) holder.findViewById(R.id.icon_speed);
mSpeed = (TextView) holder.findViewById(R.id.speed);
mIconPoints = (IconicsTextView) holder.findViewById(R.id.icon_points);
mPoints = (TextView) holder.findViewById(R.id.points);
mUndo = (Button) holder.findViewById(R.id.undo_button);
mContainer.setOnClickListener(this);
}
@Override
public void onClick(View v) {
if (v == mContainer) {
mListener.onHistoryItemClicked(this.getLayoutPosition(), track);
}
}
}
public interface OnHistoryItemClickedListener {
void onHistoryItemClicked(int position, Music music);
void onHistoryItemRemoved(int position, Music music);
}
public HistoryAdapter(Fragment fragment, List<Music> items) {
this.fragment = fragment;
this.items = items;
this.itemsPendingRemoval = new ArrayList<>();
}
@Override
public HistoryAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
LayoutInflater inflater = (LayoutInflater) fragment.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View track = inflater.inflate(R.layout.history_item, parent, false);
return new HistoryAdapter.ViewHolder(fragment, track);
}
@Override
public void onBindViewHolder(HistoryAdapter.ViewHolder holder, int position) {
final Music item = items.get(position);
if (itemsPendingRemoval.contains(item)) {
// we need to show the "undo" state of the row
holder.itemView.setBackgroundColor(Color.RED);
//holder.titleTextView.setVisibility(View.GONE);
holder.mUndo.setVisibility(View.VISIBLE);
holder.mUndo.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// user wants to undo the removal, let's cancel the pending task
Runnable pendingRemovalRunnable = pendingRunnables.get(item);
pendingRunnables.remove(item);
if (pendingRemovalRunnable != null) handler.removeCallbacks(pendingRemovalRunnable);
itemsPendingRemoval.remove(item);
// this will rebind the row in "normal" state
notifyItemChanged(items.indexOf(item));
}
});
} else {
// we need to show the "normal" state
holder.itemView.setBackgroundColor(Color.WHITE);
//holder.titleTextView.setVisibility(View.VISIBLE);
//holder.titleTextView.setText(item);
holder.mUndo.setVisibility(View.GONE);
holder.mUndo.setOnClickListener(null);
}
holder.track = item;
if (position == getItemCount() - 1) {
holder.mContainer.setBackground(ContextCompat.getDrawable(fragment.getContext(), R.drawable.row_with_arrow_no_border));
} else {
holder.mContainer.setBackground(ContextCompat.getDrawable(fragment.getContext(), R.drawable.row_with_arrow));
}
}
...
我向适配器添加项目（对于测试我使用postDelayed runnable来模拟加载时间）
private void dataLoaded() {
Handler handler = new Handler();
handler.postDelayed(new Runnable() {
@Override
public void run() {
// specify an adapter (see also next example)
if (getView() != null) {
mAdapter = new HistoryAdapter(MainActivityHistoryFragment.this, data.getTracks());
mAdapter.setUndoOn(true);
mHistory.setAdapter(mAdapter);
}
}
}, 500);
}
答案 0 :(得分：1)
每次加载数据时都不应该创建新的适配器。这可能是导致延误的原因。而是尝试添加一种方法来交换/重置现有适配器上的数据，调用notifyDataSetChanged()。有关详细信息，请参阅this example。