Android 解决NestedScrollView底部内容被遮挡显示不全

 android:fillViewport="true"

完美解决哈哈
原理

出现这个问题感觉应该是NestedScrollView的测量方法去找原因

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);

        if (!mFillViewport) {
            return;
        }

        final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
        if (heightMode == MeasureSpec.UNSPECIFIED) {
            return;
        }

        if (getChildCount() > 0) {
            View child = getChildAt(0);
            final NestedScrollView.LayoutParams lp = (LayoutParams) child.getLayoutParams();

            int childSize = child.getMeasuredHeight();
            int parentSpace = getMeasuredHeight()
                    - getPaddingTop()
                    - getPaddingBottom()
                    - lp.topMargin
                    - lp.bottomMargin;

            if (childSize < parentSpace) {
                int childWidthMeasureSpec = getChildMeasureSpec(widthMeasureSpec,
                        getPaddingLeft() + getPaddingRight() + lp.leftMargin + lp.rightMargin,
                        lp.width);
                int childHeightMeasureSpec =
                        MeasureSpec.makeMeasureSpec(parentSpace, MeasureSpec.EXACTLY);
                child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
            }
        }
    }

看到这里，mFillViewport，字面意思填充，如果是false被return出去，

   if (!mFillViewport) {
            return;
        }```

看文档说明

    /**
     * When set to true, the scroll view measure its child to make it fill the currently
     * visible area.
     */
    private boolean mFillViewport;

翻译过来
设置为true时，滚动视图将测量其子级以使其填充当前*可见区域。
默认值为false，果然没有重新测量 ，所以在xml添加设置为true就解决了