RecyclerView不显示阴影的方法
安卓6.0以后不管是RecylerView或者Listview或者ViePpager以及Scrollviw滚动到底部和顶部都会出现阴影,有时你会感觉挺烦的,只需要在xml中添加两行代码就能去除掉阴影
android:fadingEdge="none"
android:overScrollMode="never"
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解决RecyclerView和Scrollviw的冲突
如何让Scrollviw里面显示显示RecyclerView
xml需要用一个view包含recylerview
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
//务必添加此属性
android:descendantFocusability="blocksDescendants">
<android.support.v7.widget.RecyclerView
android:id="@+id/recyler_view"
android:fadingEdge="none"
android:overScrollMode="never"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</RelativeLayout>
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代码中需要添加如下属性
mRecyclerView.setLayoutManager(new FullyLinearLayoutManager(mContext));
mRecyclerView.setNestedScrollingEnabled(false);
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FullyLinearLayoutManager是线性布局的manager,recylerview还需要FullyGridLayoutManager,ExStaggeredGridLayoutManager根据需要选择不同的管理器
1.FullyLinearLayoutManager的代码如下
public class FullyLinearLayoutManager extends LinearLayoutManager {
private static final String TAG = FullyLinearLayoutManager.class.getSimpleName();
public FullyLinearLayoutManager(Context context) {
super(context);
}
public FullyLinearLayoutManager(Context context, int orientation, boolean reverseLayout) {
super(context, orientation, reverseLayout);
}
private int[] mMeasuredDimension = new int[2];
@Override
public void onMeasure(RecyclerView.Recycler recycler, RecyclerView.State state,
int widthSpec, int heightSpec) {
final int widthMode = View.MeasureSpec.getMode(widthSpec);
final int heightMode = View.MeasureSpec.getMode(heightSpec);
final int widthSize = View.MeasureSpec.getSize(widthSpec);
final int heightSize = View.MeasureSpec.getSize(heightSpec);
int width = 0;
int height = 0;
for (int i = 0; i < getItemCount(); i++) {
measureScrapChild(recycler, i,
View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
mMeasuredDimension);
if (getOrientation() == HORIZONTAL) {
width = width + mMeasuredDimension[0];
if (i == 0) {
height = mMeasuredDimension[1];
}
} else {
height = height + mMeasuredDimension[1];
if (i == 0) {
width = mMeasuredDimension[0];
}
}
}
switch (widthMode) {
case View.MeasureSpec.EXACTLY:
width = widthSize;
case View.MeasureSpec.AT_MOST:
case View.MeasureSpec.UNSPECIFIED:
}
switch (heightMode) {
case View.MeasureSpec.EXACTLY:
height = heightSize;
case View.MeasureSpec.AT_MOST:
case View.MeasureSpec.UNSPECIFIED:
}
setMeasuredDimension(width, height);
}
private void measureScrapChild(RecyclerView.Recycler recycler, int position, int widthSpec,
int heightSpec, int[] measuredDimension) {
try {
View view = recycler.getViewForPosition(0);//fix 动态添加时报IndexOutOfBoundsException
if (view != null) {
RecyclerView.LayoutParams p = (RecyclerView.LayoutParams) view.getLayoutParams();
int childWidthSpec = ViewGroup.getChildMeasureSpec(widthSpec,
getPaddingLeft() + getPaddingRight(), p.width);
int childHeightSpec = ViewGroup.getChildMeasureSpec(heightSpec,
getPaddingTop() + getPaddingBottom(), p.height);
view.measure(childWidthSpec, childHeightSpec);
measuredDimension[0] = view.getMeasuredWidth() + p.leftMargin + p.rightMargin;
measuredDimension[1] = view.getMeasuredHeight() + p.bottomMargin + p.topMargin;
recycler.recycleView(view);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
}
}
}
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2.FullyGridLayoutManager的代码如下
public class FullyGridLayoutManager extends GridLayoutManager {
public FullyGridLayoutManager(Context context, int spanCount) {
super(context, spanCount);
}
public FullyGridLayoutManager(Context context, int spanCount, int orientation, boolean reverseLayout) {
super(context, spanCount, orientation, reverseLayout);
}
private int[] mMeasuredDimension = new int[2];
@Override
public void onMeasure(RecyclerView.Recycler recycler, RecyclerView.State state, int widthSpec, int heightSpec) {
final int widthMode = View.MeasureSpec.getMode(widthSpec);
final int heightMode = View.MeasureSpec.getMode(heightSpec);
final int widthSize = View.MeasureSpec.getSize(widthSpec);
final int heightSize = View.MeasureSpec.getSize(heightSpec);
int width = 0;
int height = 0;
int count = getItemCount();
int span = getSpanCount();
for (int i = 0; i < count; i++) {
measureScrapChild(recycler, i,
View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
mMeasuredDimension);
if (getOrientation() == HORIZONTAL) {
if (i % span == 0) {
width = width + mMeasuredDimension[0];
}
if (i == 0) {
height = mMeasuredDimension[1];
}
} else {
if (i % span == 0) {
height = height + mMeasuredDimension[1];
}
if (i == 0) {
width = mMeasuredDimension[0];
}
}
}
switch (widthMode) {
case View.MeasureSpec.EXACTLY:
width = widthSize;
case View.MeasureSpec.AT_MOST:
case View.MeasureSpec.UNSPECIFIED:
}
switch (heightMode) {
case View.MeasureSpec.EXACTLY:
height = heightSize;
case View.MeasureSpec.AT_MOST:
case View.MeasureSpec.UNSPECIFIED:
}
setMeasuredDimension(width, height);
}
private void measureScrapChild(RecyclerView.Recycler recycler, int position, int widthSpec,
int heightSpec, int[] measuredDimension) {
if (position < getItemCount()) {
try {
View view = recycler.getViewForPosition(0);//fix 动态添加时报IndexOutOfBoundsException
if (view != null) {
RecyclerView.LayoutParams p = (RecyclerView.LayoutParams) view.getLayoutParams();
int childWidthSpec = ViewGroup.getChildMeasureSpec(widthSpec,
getPaddingLeft() + getPaddingRight(), p.width);
int childHeightSpec = ViewGroup.getChildMeasureSpec(heightSpec,
getPaddingTop() + getPaddingBottom(), p.height);
view.measure(childWidthSpec, childHeightSpec);
measuredDimension[0] = view.getMeasuredWidth() + p.leftMargin + p.rightMargin;
measuredDimension[1] = view.getMeasuredHeight() + p.bottomMargin + p.topMargin;
recycler.recycleView(view);
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
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3.ExStaggeredGridLayoutManager的代码如下
public class ExStaggeredGridLayoutManager extends StaggeredGridLayoutManager {
public ExStaggeredGridLayoutManager(int spanCount, int orientation) {
super(spanCount, orientation);
}
// 尺寸的数组,[0]是宽,[1]是高
private int[] measuredDimension = new int[2];
// 用来比较同行/列那个item罪宽/高
private int[] dimension;
@Override
public void onMeasure(RecyclerView.Recycler recycler, RecyclerView.State state, int widthSpec, int heightSpec) {
// 宽的mode+size
final int widthMode = View.MeasureSpec.getMode(widthSpec);
final int widthSize = View.MeasureSpec.getSize(widthSpec);
// 高的mode + size
final int heightMode = View.MeasureSpec.getMode(heightSpec);
final int heightSize = View.MeasureSpec.getSize(heightSpec);
// 自身宽高的初始值
int width = 0;
int height = 0;
// item的数目
int count = getItemCount();
// item的列数
int span = getSpanCount();
// 根据行数或列数来创建数组
dimension = new int[span];
for (int i = 0; i < count; i++) {
measureScrapChild(recycler, i,
View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED), measuredDimension);
// 如果是竖直的列表,计算item的高,否则计算宽度
//Log.d("LISTENER", "position " + i + " height = " + measuredDimension[1]);
if (getOrientation() == VERTICAL) {
dimension[findMinIndex(dimension)] += measuredDimension[1];
} else {
dimension[findMinIndex(dimension)] += measuredDimension[0];
}
}
if (getOrientation() == VERTICAL) {
height = findMax(dimension);
} else {
width = findMax(dimension);
}
switch (widthMode) {
// 当控件宽是match_parent时,宽度就是父控件的宽度
case View.MeasureSpec.EXACTLY:
width = widthSize;
break;
case View.MeasureSpec.AT_MOST:
break;
case View.MeasureSpec.UNSPECIFIED:
break;
}
switch (heightMode) {
// 当控件高是match_parent时,高度就是父控件的高度
case View.MeasureSpec.EXACTLY:
height = heightSize;
break;
case View.MeasureSpec.AT_MOST:
break;
case View.MeasureSpec.UNSPECIFIED:
break;
}
// 设置测量尺寸
setMeasuredDimension(width, height);
}
private void measureScrapChild(RecyclerView.Recycler recycler, int position, int widthSpec,
int heightSpec, int[] measuredDimension) {
// 挨个遍历所有item
if (position < getItemCount()) {
try {
View view = recycler.getViewForPosition(position);//fix 动态添加时报IndexOutOfBoundsException
if (view != null) {
RecyclerView.LayoutParams lp = (RecyclerView.LayoutParams) view.getLayoutParams();
int childWidthSpec = ViewGroup.getChildMeasureSpec(widthSpec, getPaddingLeft() + getPaddingRight(), lp.width);
int childHeightSpec = ViewGroup.getChildMeasureSpec(heightSpec, getPaddingTop() + getPaddingBottom(), lp.height);
// 子view进行测量,然后可以通过getMeasuredWidth()获得测量的宽,高类似
view.measure(childWidthSpec, childHeightSpec);
// 将item的宽高放入数组中
measuredDimension[0] = view.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;
measuredDimension[1] = view.getMeasuredHeight() + lp.topMargin + lp.bottomMargin;
recycler.recycleView(view);
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
private int findMax(int[] array) {
int max = array[0];
for (int value : array) {
if (value > max) {
max = value;
}
}
return max;
}
/**
* 得到最数组中最小元素的下标
*
* @param array
* @return
*/
private int findMinIndex(int[] array) {
int index = 0;
int min = array[0];
for (int i = 0; i < array.length; i++) {
if (array[i] < min) {
min = array[i];
index = i;
}
}
return index;
}
}
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RecylerView滚动到底部
好多开发只知道一下的方法
第一种方法:
mRecycleView.smoothScrollBy(distance,duration);
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第二种方法:
mRecycleView.smoothScrollOffset(offset);
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第三种方法:
mRecycleView.smoothToPosition(index);
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第四种方法:
mRecycleView.scrollToPosition(index);
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等等,以上是能达到效果的,但是如果item过长的话,用上面的方法就无法达到效果,我盟可以尝试一下的方法
//messageListView.computeVerticalScrollRange()整个控件的高度
messageListView.scrollBy(0, messageListView.computeVerticalScrollRange());
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判断是否滚动到底部的方法
1.第一种
RecyclerView.canScrollVertically(1)的值表示是否能向上滚动,false表示已经滚动到底部
RecyclerView.canScrollVertically(-1)的值表示是否能向下滚动,false表示已经滚动到顶部
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2.第二种
public static boolean isSlideToBottom(RecyclerView recyclerView) {
if (recyclerView == null) return false;
if (recyclerView.computeVerticalScrollExtent() + recyclerView.computeVerticalScrollOffset()
>= recyclerView.computeVerticalScrollRange())
return true;
return false;
}
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这样就很清晰明了,computeVerticalScrollExtent()是当前屏幕显示的区域高度,computeVerticalScrollOffset() 是当前屏幕之前滑过的距离,而computeVerticalScrollRange()是整个View控件的高度。
这些基础的属性好多人并不知道,使用好上面的这些属性,能让你对recylerview做许多的操作。
RecylerView添加头和尾
这里就直接上代码了
public class HeaderAndFooterWrapper extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private static final int BASE_ITEM_TYPE_HEADER = 0x10;
private static final int BASE_ITEM_TYPE_FOOTER = 0x20;
private SparseArrayCompat<View> mHeaderViews = new SparseArrayCompat<>();
private SparseArrayCompat<View> mFootViews = new SparseArrayCompat<>();
private RecyclerView.Adapter mInnerAdapter;
public HeaderAndFooterWrapper(RecyclerView.Adapter adapter) {
mInnerAdapter = adapter;
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
if (mHeaderViews.get(viewType) != null) {
ViewHolder holder = ViewHolder.createViewHolder(parent.getContext(), mHeaderViews.get(viewType));
return holder;
} else if (mFootViews.get(viewType) != null) {
ViewHolder holder = ViewHolder.createViewHolder(parent.getContext(), mFootViews.get(viewType));
return holder;
}
return mInnerAdapter.onCreateViewHolder(parent, viewType);
}
@Override
public int getItemViewType(int position) {
if (isHeaderViewPos(position)) {
return mHeaderViews.keyAt(position);
} else if (isFooterViewPos(position)) {
return mFootViews.keyAt(position - getHeadersCount() - getRealItemCount());
}
return mInnerAdapter.getItemViewType(position - getHeadersCount());
}
private int getRealItemCount() {
return mInnerAdapter.getItemCount();
}
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
if (isHeaderViewPos(position)) {
return;
}
if (isFooterViewPos(position)) {
return;
}
mInnerAdapter.onBindViewHolder(holder, position - getHeadersCount());
}
@Override
public int getItemCount() {
return getHeadersCount() + getFootersCount() + getRealItemCount();
}
@Override
public void onAttachedToRecyclerView(RecyclerView recyclerView) {
mInnerAdapter.onAttachedToRecyclerView(recyclerView);
RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
if (layoutManager instanceof GridLayoutManager) {
final GridLayoutManager gridLayoutManager = (GridLayoutManager) layoutManager;
final GridLayoutManager.SpanSizeLookup spanSizeLookup = gridLayoutManager.getSpanSizeLookup();
gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
@Override
public int getSpanSize(int position) {
int viewType = getItemViewType(position);
if (mHeaderViews.get(viewType) != null) {
return gridLayoutManager.getSpanCount();
} else if (mFootViews.get(viewType) != null) {
return gridLayoutManager.getSpanCount();
}
if (spanSizeLookup != null)
return spanSizeLookup.getSpanSize(position);
return 1;
}
});
gridLayoutManager.setSpanCount(gridLayoutManager.getSpanCount());
}
}
@Override
public void onViewAttachedToWindow(RecyclerView.ViewHolder holder) {
mInnerAdapter.onViewAttachedToWindow(holder);
int position = holder.getLayoutPosition();
if (isHeaderViewPos(position) || isFooterViewPos(position)) {
ViewGroup.LayoutParams lp = holder.itemView.getLayoutParams();
if (lp != null
&& lp instanceof StaggeredGridLayoutManager.LayoutParams) {
StaggeredGridLayoutManager.LayoutParams p =
(StaggeredGridLayoutManager.LayoutParams) lp;
p.setFullSpan(true);
}
}
}
private boolean isHeaderViewPos(int position) {
return position < getHeadersCount();
}
private boolean isFooterViewPos(int position) {
return position >= getHeadersCount() + getRealItemCount();
}
public void addHeaderView(View view) {
mHeaderViews.put(mHeaderViews.size() + BASE_ITEM_TYPE_HEADER, view);
}
public void addFootView(View view) {
mFootViews.put(mFootViews.size() + BASE_ITEM_TYPE_FOOTER, view);
}
public int getHeadersCount() {
return mHeaderViews.size();
}
public int getFootersCount() {
return mFootViews.size();
}
}
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使用方法
HeaderAndFooterWrapper footerWrapper = new HeaderAndFooterWrapper(你自己的dadapter);
footerWrapper.addFootView(footview);
footerWrapper.addHeaderView(Headerview);
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要屏蔽notifyItemChanged方法产生的动画,可使用以下方法:
((SimpleItemAnimator)mUserListView.getItemAnimator()).setSupportsChangeAnimations(false);
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