話不多說,先上圖片
圖1 圖2
圖3
ScrollerView嵌套RecyclerView
圖1:相關推薦下面recyclerView高度設置爲wrap_content時,無法顯示。
圖2:recyclerView中最底下的item顯示不全,想必大家也發現了是dividerItemDecoration分割線的原因,其實說是分割線的原因只是表面的,本質上還是MyLinearLayoutManager裏面的 onMeasure()的問題。
圖1:recyclerView高度設置爲wrap_content時,無法顯示。
原因:使用的是系統的LinLayoutManager。
我們要自己實現LinearLayoutManager,爲什麼呢,我們實現這個是幹嘛呢?
其實我們實現的MyLinearLayoutManager就是測量計算recyclerView中數據的寬高,也就是重寫我們下面的onMeasure
給我們的recyclerView設置自定義的LMyLinearLayoutManager就可以解決圖一的問題了。,其實這個效果就是圖三的效果
public class MyLinearLayoutManager extends LinearLayoutManager {
private static final String TAG = MyLinearLayoutManager.class.getSimpleName();
public MyLinearLayoutManager(Context context) {
super(context);
}
public MyLinearLayoutManager(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);
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 {
}
}
}
圖2:recyclerView中最底下的item顯示不全,想必大家也發現了是dividerItemDecoration分割線的原因,其實說是分割線的原因只是表面的,本質上還是MyLinearLayoutManager裏面的 onMeasure()的問題。
有些人就說了這個不是很明顯就看出來了嗎,這個是我爲了讓大家看清效果臨時改的分割線,之前使用的分割線是和底色一樣的顏色,貌似有點逗比,結果就只能看見底下item顯示不全的現象,最後我才發現是分割線的原因,所以我們要把分割線給他去掉,當然有些人就說了我就是想加分割線呢,其實就是在MyLinearLayoutManager裏面的 onMeasure方法裏面把分割線的佈局寬高給他算進去就可以,
//添加分割線就會出現recyclerView顯示不全的問題
/* hor_dividerItemDecoration = new DividerItemDecoration(BookDetailActivity.this, DividerItemDecoration.VERTICAL_LIST);
refer_recyclerView.addItemDecoration(hor_dividerItemDecoration);*/
因爲在之前的onMesure裏面沒有計算分割線的高度,那麼在界面中分割線會佔空間,就會把item擠下去,就會導致item顯示不全,所以解決方法就是在onMeasure裏面給計算上分割線的高度即可,就是圖三的效果啦