Android界面：ScrollView+ViewPager不显

一、前言

界面构成是CoordinatorLayout + AppBarLayout（TabLaout） + ScrollView，其中ScrollView包含ViewPager，ViewPager中包含Fragment（ListView）的复杂布局。

参考：Android ScrollView嵌套ViewPager不显示和出现空白部分 解决方法

二、使用

使用的是第二种方法，自定义ViewPager

public class ViewPagerForScrollView extends ViewPager{
    private int current;
    private int height = 0;
    /**
     * 保存position与对于的View
     */
    private HashMap<Integer, View> mChildrenViews = new LinkedHashMap<Integer, View>();

    private boolean scrollble = true;

    public ViewPagerForScrollView(Context context) {
        super(context);
    }

    public ViewPagerForScrollView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent event) {
        // Never allow swiping to switch between pages
        return false;
    }

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

        if (mChildrenViews.size() > current) {
            View child = mChildrenViews.get(current);
            child.measure(widthMeasureSpec, MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
            height = child.getMeasuredHeight();
        }

        heightMeasureSpec = MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY);

        super.onMeasure(widthMeasureSpec, heightMeasureSpec);

    }

    public void resetHeight(int current) {
        this.current = current;
        if (mChildrenViews.size() > current) {
                LinearLayout.LayoutParams layoutParams = (LinearLayout.LayoutParams) getLayoutParams();
                if (layoutParams == null) {
                    layoutParams = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, height);
                } else {
                    layoutParams.height = height;
                }
                setLayoutParams(layoutParams);
            }
    }
    /**
     * 保存position与对于的View
     */
    public void setObjectForPosition(View view, int position)
    {
        mChildrenViews.put(position, view);
    }


    @Override
    public boolean onTouchEvent(MotionEvent ev) {
        if (!scrollble) {
            return true;
        }
        return super.onTouchEvent(ev);
    }


    public boolean isScrollble() {
        return scrollble;
    }

    public void setScrollble(boolean scrollble) {
        this.scrollble = scrollble;
    }
}

布局

        <ScrollView
            android:id="@+id/sv_home"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:scrollbars="none"
            app:layout_behavior="@string/appbar_scrolling_view_behavior">

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:orientation="vertical">

                <ViewPagerForScrollView 
                    android:id="@+id/home_list_content"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content" />
            </LinearLayout>

        </ScrollView>

Fragment中

    @SuppressLint("ValidFragment")
    public HomTestFragment(ExpandViewPager viewPager){
        this.viewPager = viewPager;            
    }

在onCreateView中设置位置

 viewPager.setObjectForPosition(rootView, 0);

Activity中设置界面切换监听

        viewPagerHome.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
                viewPagerHome.resetHeight(position);
            }

            @Override
            public void onPageSelected(int position) {

            }

            @Override
            public void onPageScrollStateChanged(int state) {

            }
        });

三、总结

比起参考的解决方法，修改后 ViewPager 可以滚动。另外，控件不显示问题是要重新计算高度，滑动冲突则需分配触摸事件。