1.开始一直反应不过来一个问题：RecycleView不是自带滚动效果吗？为啥子条目还不能全部滚动，显示出来呢？
意识到：只有当RecycleView 适配器中条目数量特别多，才可以滚动。
然而自己的布局，只是一个TextView内容特别多。
2.所以网上看到看到下面的帖子里面的布局。自己修改后，完成。
https://stackoverflow.com/questions/43753083/recycleview-using-view-holder-able-to-scroll-inside
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v4.widget.NestedScrollView
android:layout_width="match_parent"
android:layout_height="wrap_content">
<android.support.v4.widget.SwipeRefreshLayout
android:id="@+id/swipe_refresh_layout"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v7.widget.RecyclerView
android:id="@+id/recycler_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:clipToPadding="false"
android:scrollbarStyle="outsideOverlay"
android:paddingBottom="28dp" />
</android.support.v4.widget.SwipeRefreshLayout>
</android.support.v4.widget.NestedScrollView>
</LinearLayout>
二、存在的问题：记得是：左右滑动加上后，就无法上下滚动了。
后来切换了，采用的
public class GallerySnapHelper extends SnapHelper { private static final float INVALID_DISTANCE = 1f; private static final float MILLISECONDS_PER_INCH = 40f; private OrientationHelper mHorizontalHelper; private RecyclerView mRecyclerView; private OnSwipeListener mListener; public OnSwipeListener getmListener() { return mListener; } public void setmListener(OnSwipeListener mListener) { this.mListener = mListener; } @Override public void attachToRecyclerView(@Nullable RecyclerView recyclerView) throws IllegalStateException { mRecyclerView = recyclerView; super.attachToRecyclerView(recyclerView); } @Override public int[] calculateDistanceToFinalSnap(@NonNull RecyclerView.LayoutManager layoutManager, @NonNull View targetView) { int[] out = new int[2]; if (layoutManager.canScrollHorizontally()) { out[0] = distanceToStart(targetView, getHorizontalHelper(layoutManager)); } else { out[0] = 0; } return out; } private int distanceToStart(View targetView, OrientationHelper helper) { return helper.getDecoratedStart(targetView) - helper.getStartAfterPadding(); } @Nullable protected LinearSmoothScroller createSnapScroller(final RecyclerView.LayoutManager layoutManager) { if (!(layoutManager instanceof RecyclerView.SmoothScroller.ScrollVectorProvider)) { return null; } return new LinearSmoothScroller(mRecyclerView.getContext()) { @Override protected void onTargetFound(View targetView, RecyclerView.State state, Action action) { int[] snapDistances = calculateDistanceToFinalSnap(mRecyclerView.getLayoutManager(), targetView); final int dx = snapDistances[0]; final int dy = snapDistances[1]; final int time = calculateTimeForDeceleration(Math.max(Math.abs(dx), Math.abs(dy))); if (time > 0) { action.update(dx, dy, time, mDecelerateInterpolator); } } @Override protected float calculateSpeedPerPixel(DisplayMetrics displayMetrics) { return MILLISECONDS_PER_INCH / displayMetrics.densityDpi; } }; } @Override public int findTargetSnapPosition(RecyclerView.LayoutManager layoutManager, int velocityX, int velocityY) { LogUtil.d(MainActivity.TAG,"---velocityX:::"+velocityX+"----velocityY:::"+velocityY); if(velocityX>0) { if (!(layoutManager instanceof RecyclerView.SmoothScroller.ScrollVectorProvider)) { LogUtil.d(MainActivity.TAG, "-!(layoutManager instanceof RecyclerView.SmoothScroller.ScrollVectorProvider)---RecyclerView.NO_POSITION--"); return RecyclerView.NO_POSITION; } final int itemCount = layoutManager.getItemCount(); if (itemCount == 0) { LogUtil.d(MainActivity.TAG, "-itemCount=0---RecyclerView.NO_POSITION--"); return RecyclerView.NO_POSITION; } final View currentView = findSnapView(layoutManager); if (currentView == null) { LogUtil.d(MainActivity.TAG, "-currentView = null---RecyclerView.NO_POSITION--"); return RecyclerView.NO_POSITION; } final int currentPosition = layoutManager.getPosition(currentView); if (currentPosition == RecyclerView.NO_POSITION) { LogUtil.d(MainActivity.TAG, "-currentPosition = RecyclerView.NO_POSITION---RecyclerView.NO_POSITION--"); return RecyclerView.NO_POSITION; } RecyclerView.SmoothScroller.ScrollVectorProvider vectorProvider = (RecyclerView.SmoothScroller.ScrollVectorProvider) layoutManager; // deltaJumps sign comes from the velocity which may not match the order of children in // the LayoutManager. To overcome this, we ask for a vector from the LayoutManager to // get the direction. PointF vectorForEnd = vectorProvider.computeScrollVectorForPosition(itemCount - 1); if (vectorForEnd == null) { LogUtil.d(MainActivity.TAG, "-vectorForEnd = null---RecyclerView.NO_POSITION--"); // cannot get a vector for the given position. return RecyclerView.NO_POSITION; } //在松手之后,列表最多只能滚多一屏的item数 int deltaThreshold = layoutManager.getWidth() / getHorizontalHelper(layoutManager).getDecoratedMeasurement(currentView); int hDeltaJump; if (layoutManager.canScrollHorizontally()) { LogUtil.d(MainActivity.TAG, "----layoutManager.canScrollHorizontally()-----" + layoutManager.canScrollHorizontally()); hDeltaJump = estimateNextPositionDiffForFling(layoutManager, getHorizontalHelper(layoutManager), velocityX, 0); if (hDeltaJump > deltaThreshold) { hDeltaJump = deltaThreshold; } if (hDeltaJump < -deltaThreshold) { hDeltaJump = -deltaThreshold; } if (vectorForEnd.x < 0) { hDeltaJump = -hDeltaJump; } } else { Log.d(TAG, "----hDeltaJump = 0--layoutManager.canScrollHorizontally()---" + layoutManager.canScrollHorizontally()); hDeltaJump = 0; } if (mListener != null) { mListener.onSwipedClear(); } if (hDeltaJump == 0) { Log.d(TAG, "----if (hDeltaJump == 0)---true--"); return RecyclerView.NO_POSITION; } int targetPos = currentPosition + hDeltaJump; if (targetPos < 0) { targetPos = 0; } if (targetPos >= itemCount) { targetPos = itemCount - 1; } Log.d(TAG, "----targetPos-----" + targetPos); return targetPos; }else { //当判断是右滑时，不处理。 Log.d(TAG, "-----“-1”-----"); return -1; } } @Override public View findSnapView(RecyclerView.LayoutManager layoutManager) { return findStartView(layoutManager, getHorizontalHelper(layoutManager)); } private View findStartView(RecyclerView.LayoutManager layoutManager, OrientationHelper helper) { if (layoutManager instanceof LinearLayoutManager) { LogUtil.d(MainActivity.TAG, "-findStartView---layoutManager instanceof LinearLayoutManager--"); int firstChildPosition = ((LinearLayoutManager) layoutManager).findFirstVisibleItemPosition(); if (firstChildPosition == RecyclerView.NO_POSITION) { LogUtil.d(MainActivity.TAG, "-findStartView---firstChildPosition == RecyclerView.NO_POSITION--"); return null; } /* 注释该段代码，否则不能正常滑动 if (((LinearLayoutManager) layoutManager).findLastCompletelyVisibleItemPosition() == layoutManager.getItemCount() - 1) { ///0 LogUtil.d(MainActivity.TAG, "-findStartView---layoutManager.getItemCount() - 1::::"+(layoutManager.getItemCount() - 1)); LogUtil.d(MainActivity.TAG, "-findStartView---((LinearLayoutManager) layoutManager).findLastCompletelyVisibleItemPosition() == layoutManager.getItemCount() - 1--"); return null; }*/ View firstChildView = layoutManager.findViewByPosition(firstChildPosition); if (helper.getDecoratedEnd(firstChildView) >= helper.getDecoratedMeasurement(firstChildView) / 2 && helper.getDecoratedEnd(firstChildView) > 0) { return firstChildView; } else { return layoutManager.findViewByPosition(firstChildPosition + 1); } } else { LogUtil.d(MainActivity.TAG, "-findStartView--!!!!!--layoutManager instanceof LinearLayoutManager--"); return null; } } private int estimateNextPositionDiffForFling(RecyclerView.LayoutManager layoutManager, OrientationHelper helper, int velocityX, int velocityY) { int[] distances = calculateScrollDistance(velocityX, velocityY); float distancePerChild = computeDistancePerChild(layoutManager, helper); if (distancePerChild <= 0) { return 0; } int distance = distances[0]; if (distance > 0) { return (int) Math.floor(distance / distancePerChild); } else { return (int) Math.ceil(distance / distancePerChild); } } private float computeDistancePerChild(RecyclerView.LayoutManager layoutManager, OrientationHelper helper) { View minPosView = null; View maxPosView = null; int minPos = Integer.MAX_VALUE; int maxPos = Integer.MIN_VALUE; int childCount = layoutManager.getChildCount(); if (childCount == 0) { return INVALID_DISTANCE; } for (int i = 0; i < childCount; i++) { View child = layoutManager.getChildAt(i); final int pos = layoutManager.getPosition(child); if (pos == RecyclerView.NO_POSITION) { continue; } if (pos < minPos) { minPos = pos; minPosView = child; } if (pos > maxPos) { maxPos = pos; maxPosView = child; } } if (minPosView == null || maxPosView == null) { return INVALID_DISTANCE; } int start = Math.min(helper.getDecoratedStart(minPosView), helper.getDecoratedStart(maxPosView)); int end = Math.max(helper.getDecoratedEnd(minPosView), helper.getDecoratedEnd(maxPosView)); int distance = end - start; if (distance == 0) { return INVALID_DISTANCE; } return 1f * distance / ((maxPos - minPos) + 1); } private OrientationHelper getHorizontalHelper(RecyclerView.LayoutManager layoutManager) { if (mHorizontalHelper == null) { mHorizontalHelper = OrientationHelper.createHorizontalHelper(layoutManager); } return mHorizontalHelper; } }
public interface OnSwipeListener<T>{ /** * 卡片还在滑动时回调 * * @param viewHolder 该滑动卡片的viewHolder * @param ratio 滑动进度的比例 * @param direction 卡片滑动的方向，CardConfig.SWIPING_LEFT 为向左滑，CardConfig.SWIPING_RIGHT 为向右滑， * CardConfig.SWIPING_NONE 为不偏左也不偏右 */ void onSwiping(RecyclerView.ViewHolder viewHolder, float ratio, int direction); /** * 卡片完全滑出时回调 * * @param viewHolder 该滑出卡片的viewHolder * @param t 该滑出卡片的数据 * @param direction 卡片滑出的方向，CardConfig.SWIPED_LEFT 为左边滑出；CardConfig.SWIPED_RIGHT 为右边滑出 */ void onSwiped(RecyclerView.ViewHolder viewHolder, T t, int direction); /** * 所有的卡片全部滑出时回调 */ void onSwipedClear(); }
Activity 界面代码
GallerySnapHelper mGallerySnapHelper = new GallerySnapHelper(); mGallerySnapHelper.setmListener(new OnSwipeListener() { @Override public void onSwiping(RecyclerView.ViewHolder viewHolder, float ratio, int direction) { } @Override public void onSwiped(RecyclerView.ViewHolder viewHolder, Object o, int direction) { } @Override public void onSwipedClear() { Log.d(TAG,"-----onSwipedClear----"); giRecyclerView.postDelayed(new Runnable() { @Override public void run() { groupIdeaHttp.getJtidea(URLCODE_GET_GROUP_IDEA,oaapi.getBASE_URL3()); giRecyclerView.getAdapter().notifyDataSetChanged(); } }, 100L); } }); mGallerySnapHelper.attachToRecyclerView(giRecyclerView); giRecyclerView.setAdapter(groupIdeaAdapter);