我有一个类似的(但更复杂的场景)。我有一个对话框，其中包含一个ViewPager。 其中一个子页面很短，具有静态高度。 另一个子页面应该总是尽可能高。 另一个子页面包含一个ScrollView，如果ScrollView内容不需要对话框可用的全部高度，那么该页面(以及整个对话框)应该WRAP_CONTENT。

现有的答案都不完全适用于这个特定的场景。坚持住，这是一段颠簸的旅程。

void setupView() {
    final ViewPager.SimpleOnPageChangeListener pageChangeListener = new ViewPager.SimpleOnPageChangeListener() {
        @Override
        public void onPageSelected(int position) {
            currentPagePosition = position;

            // Update the viewPager height for the current view

            /*
            Borrowed from https://github.com/rnevet/WCViewPager/blob/master/wcviewpager/src/main/java/nevet/me/wcviewpager/WrapContentViewPager.java
            Gather the height of the "decor" views, since this height isn't included
            when measuring each page's view height.
             */
            int decorHeight = 0;
            for (int i = 0; i < viewPager.getChildCount(); i++) {
                View child = viewPager.getChildAt(i);
                ViewPager.LayoutParams lp = (ViewPager.LayoutParams) child.getLayoutParams();
                if (lp != null && lp.isDecor) {
                    int vgrav = lp.gravity & Gravity.VERTICAL_GRAVITY_MASK;
                    boolean consumeVertical = vgrav == Gravity.TOP || vgrav == Gravity.BOTTOM;
                    if (consumeVertical) {
                        decorHeight += child.getMeasuredHeight();
                    }
                }
            }

            int newHeight = decorHeight;

            switch (position) {
                case PAGE_WITH_SHORT_AND_STATIC_CONTENT:
                    newHeight += measureViewHeight(thePageView1);
                    break;
                case PAGE_TO_FILL_PARENT:
                    newHeight = ViewGroup.LayoutParams.MATCH_PARENT;
                    break;
                case PAGE_TO_WRAP_CONTENT:
//                  newHeight = ViewGroup.LayoutParams.WRAP_CONTENT; // Works same as MATCH_PARENT because...reasons...
//                  newHeight += measureViewHeight(thePageView2); // Doesn't allow scrolling when sideways and height is clipped

                    /*
                    Only option that allows the ScrollView content to scroll fully.
                    Just doing this might be way too tall, especially on tablets.
                    (Will shrink it down below)
                     */
                    newHeight = ViewGroup.LayoutParams.MATCH_PARENT;
                    break;
            }

            // Update the height
            ViewGroup.LayoutParams layoutParams = viewPager.getLayoutParams();
            layoutParams.height = newHeight;
            viewPager.setLayoutParams(layoutParams);

            if (position == PAGE_TO_WRAP_CONTENT) {
                // This page should wrap content

                // Measure height of the scrollview child
                View scrollViewChild = ...; // (generally this is a LinearLayout)
                int scrollViewChildHeight = scrollViewChild.getHeight(); // full height (even portion which can't be shown)
                // ^ doesn't need measureViewHeight() because... reasons...

                if (viewPager.getHeight() > scrollViewChildHeight) { // View pager too tall?
                    // Wrap view pager height down to child height
                    newHeight = scrollViewChildHeight + decorHeight;

                    ViewGroup.LayoutParams layoutParams2 = viewPager.getLayoutParams();
                    layoutParams2.height = newHeight;
                    viewPager.setLayoutParams(layoutParams2);
                }
            }

            // Bonus goodies :)
            // Show or hide the keyboard as appropriate. (Some pages have EditTexts, some don't)
            switch (position) {
                // This case takes a little bit more aggressive code than usual

                if (position needs keyboard shown){
                    showKeyboardForEditText();
                } else if {
                    hideKeyboard();
                }
            }
        }
    };

    viewPager.addOnPageChangeListener(pageChangeListener);

    viewPager.getViewTreeObserver().addOnGlobalLayoutListener(
            new ViewTreeObserver.OnGlobalLayoutListener() {
                @Override
                public void onGlobalLayout() {
                    // http://stackoverflow.com/a/4406090/4176104
                    // Do things which require the views to have their height populated here
                    pageChangeListener.onPageSelected(currentPagePosition); // fix the height of the first page

                    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
                        viewPager.getViewTreeObserver().removeOnGlobalLayoutListener(this);
                    } else {
                        viewPager.getViewTreeObserver().removeGlobalOnLayoutListener(this);
                    }

                }
            }
    );
}


...

private void showKeyboardForEditText() {
    // Make the keyboard appear.
    getDialog().getWindow().clearFlags(WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE | WindowManager.LayoutParams.FLAG_ALT_FOCUSABLE_IM);
    getDialog().getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_VISIBLE | WindowManager.LayoutParams.SOFT_INPUT_ADJUST_PAN);

    inputViewToFocus.requestFocus();

    // http://stackoverflow.com/a/5617130/4176104
    InputMethodManager inputMethodManager =
            (InputMethodManager) getActivity().getSystemService(Context.INPUT_METHOD_SERVICE);
    inputMethodManager.toggleSoftInputFromWindow(
            inputViewToFocus.getApplicationWindowToken(),
            InputMethodManager.SHOW_IMPLICIT, 0);
}

...

/**
 * Hide the keyboard - http://stackoverflow.com/a/8785471
 */
private void hideKeyboard() {
    InputMethodManager inputManager = (InputMethodManager) getActivity().getSystemService(Context.INPUT_METHOD_SERVICE);

    inputManager.hideSoftInputFromWindow(inputBibleBookStart.getWindowToken(), InputMethodManager.HIDE_NOT_ALWAYS);
}

...

//https://github.com/rnevet/WCViewPager/blob/master/wcviewpager/src/main/java/nevet/me/wcviewpager/WrapContentViewPager.java
private int measureViewHeight(View view) {
    view.measure(ViewGroup.getChildMeasureSpec(-1, -1, view.getLayoutParams().width), View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED));
    return view.getMeasuredHeight();
}

非常感谢@Raanan提供的代码来测量视图和测量装饰高度。我在他的库中遇到了一些问题——动画结结巴，我认为当对话框的高度足够短时，我的ScrollView无法滚动。

在我的例子中，当应用大小时，我需要一个带有wrap_content的viewpager来显示当前选择的元素和动画。下面您可以看到我的实现。有人能派上用场吗?

package one.xcorp.widget

import android.animation.ValueAnimator
import android.content.Context
import android.util.AttributeSet
import android.view.View
import android.view.ViewGroup.LayoutParams.MATCH_PARENT
import android.view.ViewGroup.LayoutParams.WRAP_CONTENT
import one.xcorp.widget.R
import kotlin.properties.Delegates.observable

class ViewPager : android.support.v4.view.ViewPager {

    var enableAnimation by observable(false) { _, _, enable ->
        if (enable) {
            addOnPageChangeListener(onPageChangeListener)
        } else {
            removeOnPageChangeListener(onPageChangeListener)
        }
    }

    private var animationDuration = 0L
    private var animator: ValueAnimator? = null

    constructor (context: Context) : super(context) {
        init(context, null)
    }

    constructor (context: Context, attrs: AttributeSet?) : super(context, attrs) {
        init(context, attrs)
    }

    private fun init(context: Context, attrs: AttributeSet?) {
        context.theme.obtainStyledAttributes(
            attrs,
            R.styleable.ViewPager,
            0,
            0
        ).apply {
            try {
                enableAnimation = getBoolean(
                    R.styleable.ViewPager_enableAnimation,
                    enableAnimation
                )
                animationDuration = getInteger(
                    R.styleable.ViewPager_animationDuration,
                    resources.getInteger(android.R.integer.config_shortAnimTime)
                ).toLong()
            } finally {
                recycle()
            }
        }
    }

    override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
        val heightMode = MeasureSpec.getMode(heightMeasureSpec)

        val measuredHeight = if (heightMode == MeasureSpec.EXACTLY) {
            MeasureSpec.getSize(heightMeasureSpec)
        } else {
            val currentViewHeight = findViewByPosition(currentItem)?.also {
                measureView(it)
            }?.measuredHeight ?: 0

            if (heightMode != MeasureSpec.AT_MOST) {
                currentViewHeight
            } else {
                Math.min(
                    currentViewHeight,
                    MeasureSpec.getSize(heightMeasureSpec)
                )
            }
        }

        super.onMeasure(
            widthMeasureSpec,
            MeasureSpec.makeMeasureSpec(measuredHeight, MeasureSpec.EXACTLY)
        )
    }

    private fun measureView(view: View) = with(view) {
        val horizontalMode: Int
        val horizontalSize: Int
        when (layoutParams.width) {
            MATCH_PARENT -> {
                horizontalMode = MeasureSpec.EXACTLY
                horizontalSize = this@ViewPager.measuredWidth
            }
            WRAP_CONTENT -> {
                horizontalMode = MeasureSpec.UNSPECIFIED
                horizontalSize = 0
            }
            else -> {
                horizontalMode = MeasureSpec.EXACTLY
                horizontalSize = layoutParams.width
            }
        }

        val verticalMode: Int
        val verticalSize: Int
        when (layoutParams.height) {
            MATCH_PARENT -> {
                verticalMode = MeasureSpec.EXACTLY
                verticalSize = this@ViewPager.measuredHeight
            }
            WRAP_CONTENT -> {
                verticalMode = MeasureSpec.UNSPECIFIED
                verticalSize = 0
            }
            else -> {
                verticalMode = MeasureSpec.EXACTLY
                verticalSize = layoutParams.height
            }
        }

        val horizontalMeasureSpec = MeasureSpec.makeMeasureSpec(horizontalSize, horizontalMode)
        val verticalMeasureSpec = MeasureSpec.makeMeasureSpec(verticalSize, verticalMode)

        measure(horizontalMeasureSpec, verticalMeasureSpec)
    }

    private fun findViewByPosition(position: Int): View? {
        for (i in 0 until childCount) {
            val childView = getChildAt(i)
            val childLayoutParams = childView.layoutParams as LayoutParams

            val childPosition by lazy {
                val field = childLayoutParams.javaClass.getDeclaredField("position")
                field.isAccessible = true
                field.get(childLayoutParams) as Int
            }

            if (!childLayoutParams.isDecor && position == childPosition) {
                return childView
            }
        }

        return null
    }

    private fun animateContentHeight(childView: View, fromHeight: Int, toHeight: Int) {
        animator?.cancel()

        if (fromHeight == toHeight) {
            return
        }

        animator = ValueAnimator.ofInt(fromHeight, toHeight).apply {
            addUpdateListener {
                measureView(childView)
                if (childView.measuredHeight != toHeight) {
                    animateContentHeight(childView, height, childView.measuredHeight)
                } else {
                    layoutParams.height = animatedValue as Int
                    requestLayout()
                }
            }
            duration = animationDuration
            start()
        }
    }

    private val onPageChangeListener = object : OnPageChangeListener {

        override fun onPageScrollStateChanged(state: Int) {
            /* do nothing */
        }

        override fun onPageScrolled(
            position: Int,
            positionOffset: Float,
            positionOffsetPixels: Int
        ) {
            /* do nothing */
        }

        override fun onPageSelected(position: Int) {
            if (!isAttachedToWindow) {
                return
            }

            findViewByPosition(position)?.let { childView ->
                measureView(childView)
                animateContentHeight(childView, height, childView.measuredHeight)
            }
        }
    }
}

在项目中添加attrs.xml:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="ViewPager">
        <attr name="enableAnimation" format="boolean" />
        <attr name="animationDuration" format="integer" />
    </declare-styleable>
</resources>

和使用:

<one.xcorp.widget.ViewPager
    android:id="@+id/wt_content"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    app:enableAnimation="true" />

我的答案基于Daniel López Lacalle和这篇文章http://www.henning.ms/2013/09/09/viewpager-that-simply-dont-measure-up/。丹尼尔回答的问题是，在某些情况下，我的孩子的身高为零。不幸的是，解决办法是测量两次。

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    int mode = MeasureSpec.getMode(heightMeasureSpec);
    // Unspecified means that the ViewPager is in a ScrollView WRAP_CONTENT.
    // At Most means that the ViewPager is not in a ScrollView WRAP_CONTENT.
    if (mode == MeasureSpec.UNSPECIFIED || mode == MeasureSpec.AT_MOST) {
        // super has to be called in the beginning so the child views can be initialized.
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        int height = 0;
        for (int i = 0; i < getChildCount(); i++) {
            View child = getChildAt(i);
            child.measure(widthMeasureSpec, MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
            int h = child.getMeasuredHeight();
            if (h > height) height = h;
        }
        heightMeasureSpec = MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY);
    }
    // super has to be called again so the new specs are treated as exact measurements
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}

这也允许你在ViewPager上设置一个高度，如果你想要的话，或者只是wrap_content。

我只是在回答一个非常类似的问题，在寻找一个链接来支持我的说法时，碰巧发现了这个，你很幸运:)

我的另一个回答是: ViewPager不支持wrap_content，因为它(通常)不会同时加载所有的子页面，因此无法获得适当的大小(可以选择在每次切换页面时改变大小)。

然而，你可以设置一个精确的尺寸(例如150dp)和match_parent也可以。 您还可以通过更改其LayoutParams中的height-属性，从代码中动态修改维度。

根据你的需要，你可以在它自己的xml文件中创建ViewPager, layout_height设置为200dp，然后在你的代码中，而不是从头创建一个新的ViewPager，你可以扩展这个xml文件:

LayoutInflater inflater = context.getLayoutInflater();
inflater.inflate(R.layout.viewpagerxml, layout, true);

改进丹尼尔López Lacalle回答，重写在Kotlin:

class MyViewPager(context: Context, attrs: AttributeSet): ViewPager(context, attrs) {
    override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
        val zeroHeight = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED)

        val maxHeight = children
            .map { it.measure(widthMeasureSpec, zeroHeight); it.measuredHeight }
            .max() ?: 0

        if (maxHeight > 0) {
            val maxHeightSpec = MeasureSpec.makeMeasureSpec(maxHeight, MeasureSpec.EXACTLY)
            super.onMeasure(widthMeasureSpec, maxHeightSpec)
            return
        }

        super.onMeasure(widthMeasureSpec, heightMeasureSpec)
    }
}

对于有此问题并使用c#编写Xamarin Android代码的人来说，这可能也是一个快速解决方案:

pager.ChildViewAdded += (sender, e) => {
    e.Child.Measure ((int)MeasureSpecMode.Unspecified, (int)MeasureSpecMode.Unspecified);
    e.Parent.LayoutParameters.Height = e.Child.MeasuredHeight;
};

如果您的子视图具有相同的高度，这主要是有用的。否则，您将被要求在您检查的所有子视图上存储某种“minimumHeight”值，即使这样，您可能也不希望在较小的子视图下显示空白区域。

虽然解决方案本身对我来说是不够的，但这是因为我的子项目是listViews，他们的MeasuredHeight似乎没有正确计算。