Question

滚动AppBarLayout时，我有RecyclerView滚动屏幕。在RecyclerView下面有一个RelativeLayout页脚。

仅在向上滚动后才会显示页脚 - 它的行为与

相似

layout_scrollFlags="scroll|enterAlways"

但它没有任何滚动标志 - 它是一个错误还是我做错了什么？我希望它始终可见

滚动前的

enter image description here

滚动后

enter image description here

更新

在这上面打开了一个google issue - 它被标记为'WorkingAsIntended'，这仍然无济于事，因为我想在片段中找到一个有效的页脚解决方案。

更新2

you can find the activity and the fragment xmls here -

请注意，如果activity.xml中的第34行 - 包含app:layout_behavior="@string/appbar_scrolling_view_behavior"的行已注释掉，则结束文本从一开始就可见 - 否则，只有在滚动后才会显示

Answer 1

我使用了Learn OpenGL ES解决方案的简化版本（https://stackoverflow.com/a/33396965/778951） - 这改进了Noa的解决方案（https://stackoverflow.com/a/31140112/1317564）。它适用于TabLayout上方的简单快速返回工具栏，并在每个标签的ViewPager内容中都有页脚按钮。

只需将FixScrollingFooterBehavior设置为要在屏幕底部保持对齐的View / ViewGroup上的layout_behavior。

布局：

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

            <android.support.v7.widget.Toolbar
                android:id="@+id/toolbar"
                android:layout_width="match_parent"
                android:layout_height="?android:attr/actionBarSize"
                android:minHeight="?android:attr/actionBarSize"
                app:title="Foo"
                app:layout_scrollFlags="scroll|enterAlways|snap"
                />

            <android.support.design.widget.TabLayout
                android:id="@+id/tabs"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                app:tabMode="fixed"/>

    </android.support.design.widget.AppBarLayout>

    <android.support.v4.view.ViewPager
        android:id="@+id/viewpager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="com.spreeza.shop.ui.widgets.FixScrollingFooterBehavior"
        />

</android.support.design.widget.CoordinatorLayout>

行为：

public class FixScrollingFooterBehavior extends AppBarLayout.ScrollingViewBehavior {

    private AppBarLayout appBarLayout;

    public FixScrollingFooterBehavior() {
        super();
    }

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

    @Override
    public boolean onDependentViewChanged(CoordinatorLayout parent, View child, View dependency) {

        if (appBarLayout == null) {
            appBarLayout = (AppBarLayout) dependency;
        }

        final boolean result = super.onDependentViewChanged(parent, child, dependency);
        final int bottomPadding = calculateBottomPadding(appBarLayout);
        final boolean paddingChanged = bottomPadding != child.getPaddingBottom();
        if (paddingChanged) {
            child.setPadding(
                child.getPaddingLeft(),
                child.getPaddingTop(),
                child.getPaddingRight(),
                bottomPadding);
            child.requestLayout();
        }
        return paddingChanged || result;
    }


    // Calculate the padding needed to keep the bottom of the view pager's content at the same location on the screen.
    private int calculateBottomPadding(AppBarLayout dependency) {
        final int totalScrollRange = dependency.getTotalScrollRange();
        return totalScrollRange + dependency.getTop();
    }
}

Answer 2

Update

The solution below doesn't work for 5.1 as it works in 5 - instead of getTop use getTranslationY in any of the calculations you do.

layout.getTop()-->(int)layout.getTranslationY()
appbar.getTop()+toolbar.getHeight()-->(int)(appbar.getTranslationY()+toolbar.getHeight())

Update 2 with the new support library - 22.2.1 - there is no diff between 5.1 and prev versions, you should only use getTop and ignore the previous update in this answer

Original solution After looking into many directions turns out the solution is actually simple - add paddingBottom to the fragment and adjust it as the page scrolls.

The padding is needed to cover for the changes in the toolbar y position - the coordinator layout is moving the entire page up and down as the toolbar disappears and reappears.

This can be achieved by extending AppBarLayout.ScrollingViewBehavior and setting this as the behavior of the fragment element of the activity.

Here are the basics of the code - it works for an activity with only a toolbar - you can replace it with appbar.getTop() + toolbar.getHeight() and this will work better if your appbar includes tabs.

activity.xml

<android.support.design.widget.CoordinatorLayout
android:id="@+id/main"
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.design.widget.AppBarLayout
    android:id="@+id/appbar"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:elevation="3dp"
    app:elevation="3dp">
    <android.support.v7.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        app:layout_scrollFlags="scroll|enterAlways"
        />
</android.support.design.widget.AppBarLayout>
<fragment
    android:id="@+id/fragment"
    android:name="com.example.noa.footer2.MainActivityFragment"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_behavior="com.example.noa.footer2.MyBehavior"
    tools:layout="@layout/fragment"/>
</android.support.design.widget.CoordinatorLayout>

fragment.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
            xmlns:tools="http://schemas.android.com/tools"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:paddingBottom="48dp"
            android:background="@android:color/holo_green_dark"
            tools:context=".MainActivityFragment">
<android.support.v7.widget.RecyclerView
    android:id="@+id/list"
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@null"/>
<View
    android:layout_width="match_parent"
    android:layout_height="100dp"
    android:layout_alignParentBottom="true"
    android:background="@android:color/holo_red_light"/>
</RelativeLayout>

MainActivityFragment#onActivityCreated

    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        CoordinatorLayout.LayoutParams lp = (LayoutParams) getView().getLayoutParams();
        MyBehavior behavior = (MyBehavior) lp.getBehavior();
        behavior.setLayout(getView());
    }

MyBehavior

public class MyBehavior extends AppBarLayout.ScrollingViewBehavior {

    private View layout;

    public MyBehavior() {
    }

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

    @Override
    public boolean onDependentViewChanged(CoordinatorLayout parent, View child, View dependency) {
        boolean result = super.onDependentViewChanged(parent, child, dependency);
        if (layout != null) {
            layout.setPadding(layout.getPaddingLeft(), layout.getPaddingTop(), layout
                .getPaddingRight(), layout.getTop());
        }
        return result;
    }

    public void setLayout(View layout) {
        this.layout = layout;
    }
}

Answer 3

我从Noa的解决方案（https://stackoverflow.com/a/31140112/1317564）开始，它适用于手指拖动，但我遇到了晃动的麻烦。花了一些时间来追踪方法调用并尝试不同的想法，这是我最终得到的解决方案：

// Workaround for https://code.google.com/p/android/issues/detail?id=177195
// Based off of solution originally found here: https://stackoverflow.com/a/31140112/1317564
@SuppressWarnings("unused")
public class CustomScrollingViewBehavior extends AppBarLayout.ScrollingViewBehavior {
    private AppBarLayout appBarLayout;
    private boolean onAnimationRunnablePosted = false;

    @SuppressWarnings("unused")
    public CustomScrollingViewBehavior() {

    }

    @SuppressWarnings("unused")
    public CustomScrollingViewBehavior(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    public boolean onStartNestedScroll(CoordinatorLayout coordinatorLayout, View child, View directTargetChild, View target, int nestedScrollAxes) {
        if (appBarLayout != null) {
            // We need to check from when a scroll is started, as we may not have had the chance to update the layout at
            // the start of a scroll or fling event.
            startAnimationRunnable(child, appBarLayout);
        }
        return super.onStartNestedScroll(coordinatorLayout, child, directTargetChild, target, nestedScrollAxes);
    }

    @Override
    public boolean onMeasureChild(CoordinatorLayout parent, final View child, int parentWidthMeasureSpec, int widthUsed,
                                  int parentHeightMeasureSpec, int heightUsed) {
        if (appBarLayout != null) {
            final int bottomPadding = calculateBottomPadding(appBarLayout);
            if (bottomPadding != child.getPaddingBottom()) {
                // We need to update the padding in onMeasureChild as otherwise we won't have the correct padding in
                // place when the view is flung, and the changes done in onDependentViewChanged will only take effect on
                // the next animation frame, which means it will be out of sync with the new scroll offset. This is only
                // needed when the view is flung -- when dragged with a finger, things work fine with just
                // implementing onDependentViewChanged().
                child.setPadding(child.getPaddingLeft(), child.getPaddingTop(), child.getPaddingRight(), bottomPadding);
            }
        }

        return super.onMeasureChild(parent, child, parentWidthMeasureSpec, widthUsed, parentHeightMeasureSpec, heightUsed);
    }

    @Override
    public boolean onDependentViewChanged(CoordinatorLayout parent, final View child, final View dependency) {
        if (appBarLayout == null)
            appBarLayout = (AppBarLayout) dependency;

        final boolean result = super.onDependentViewChanged(parent, child, dependency);
        final int bottomPadding = calculateBottomPadding(appBarLayout);
        final boolean paddingChanged = bottomPadding != child.getPaddingBottom();
        if (paddingChanged) {
            // If we've changed the padding, then update the child and make sure a layout is requested.
            child.setPadding(child.getPaddingLeft(),
                    child.getPaddingTop(),
                    child.getPaddingRight(),
                    bottomPadding);
            child.requestLayout();
        }

        // Even if we didn't change the padding, if onDependentViewChanged was called then that means that the app bar
        // layout was changed or was flung. In that case, we want to check for these changes over the next few animation
        // frames so that we can ensure that we capture all the changes and update the view pager padding to match.
        startAnimationRunnable(child, dependency);
        return paddingChanged || result;
    }

    // Calculate the padding needed to keep the bottom of the view pager's content at the same location on the screen.
    private int calculateBottomPadding(AppBarLayout dependency) {
        final int totalScrollRange = dependency.getTotalScrollRange();
        return totalScrollRange + dependency.getTop();
    }

    private void startAnimationRunnable(final View child, final View dependency) {
        if (onAnimationRunnablePosted)
            return;

        final int onPostChildTop = child.getTop();
        final int onPostDependencyTop = dependency.getTop();
        onAnimationRunnablePosted = true;
        // Start looking for changes at the beginning of each animation frame. If there are any changes, we have to
        // ensure that layout is run again so that we can update the padding to take the changes into account.
        child.postOnAnimation(new Runnable() {
            private static final int MAX_COUNT_OF_FRAMES_WITH_NO_CHANGES = 5;
            private int previousChildTop = onPostChildTop;
            private int previousDependencyTop = onPostDependencyTop;
            private int countOfFramesWithNoChanges;

            @Override
            public void run() {
                // Make sure we request a layout at the beginning of each animation frame, until we notice a few
                // frames where nothing changed.
                final int currentChildTop = child.getTop();
                final int currentDependencyTop = dependency.getTop();
                boolean hasChanged = false;

                if (currentChildTop != previousChildTop) {
                    previousChildTop = currentChildTop;
                    hasChanged = true;
                    countOfFramesWithNoChanges = 0;
                }
                if (currentDependencyTop != previousDependencyTop) {
                    previousDependencyTop = currentDependencyTop;
                    hasChanged = true;
                    countOfFramesWithNoChanges = 0;
                }
                if (!hasChanged) {
                    countOfFramesWithNoChanges++;
                }
                if (countOfFramesWithNoChanges <= MAX_COUNT_OF_FRAMES_WITH_NO_CHANGES) {
                    // We can still look for changes on subsequent frames.
                    child.requestLayout();
                    child.postOnAnimation(this);
                } else {
                    // We've encountered enough frames with no changes. Do a final layout request, and don't repost.
                    child.requestLayout();
                    onAnimationRunnablePosted = false;
                }
            }
        });
    }
}

我不是在每个动画帧上重新检查布局的粉丝，而且这个解决方案并不完美，因为如果以编程方式扩展/折叠应用栏布局，我会看到一些问题，但对于现在我还没有找到更好的解决方案。新设备的性能良好，旧设备可以接受。如果其他人这样做，请随时将我的答案作为来源并重新发布。

Answer 4

package pl.mkaras.utils;

import android.content.Context;
import android.support.design.widget.AppBarLayout;
import android.support.design.widget.CoordinatorLayout;
import android.support.v4.view.ViewCompat;
import android.support.v7.widget.Toolbar;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
import java.util.List;

public class ScrollViewBehaviorFix extends AppBarLayout.ScrollingViewBehavior {

    public ScrollViewBehaviorFix() {
        super();
    }

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

    public boolean onMeasureChild(CoordinatorLayout parent, View child, int parentWidthMeasureSpec, int widthUsed, int parentHeightMeasureSpec,
                                  int heightUsed) {
        if (child.getLayoutParams().height == -1) {
            List<View> dependencies = parent.getDependencies(child);
            if (dependencies.isEmpty()) {
                return false;
            }

            final AppBarLayout appBar = findFirstAppBarLayout(dependencies);
            if (appBar != null && ViewCompat.isLaidOut(appBar)) {
                int availableHeight = View.MeasureSpec.getSize(parentHeightMeasureSpec);
                if (availableHeight == 0) {
                    availableHeight = parent.getHeight();
                }

                final int height = availableHeight - appBar.getMeasuredHeight();
                int heightMeasureSpec = View.MeasureSpec.makeMeasureSpec(height, View.MeasureSpec.AT_MOST);

                parent.onMeasureChild(child, parentWidthMeasureSpec, widthUsed, heightMeasureSpec, heightUsed);
                int childContentHeight = getContentHeight(child);

                if (childContentHeight <= height) {
                    updateToolbar(parent, appBar, parentWidthMeasureSpec, widthUsed, parentHeightMeasureSpec, heightUsed, false);

                    heightMeasureSpec = View.MeasureSpec.makeMeasureSpec(height, View.MeasureSpec.EXACTLY);
                    parent.onMeasureChild(child, parentWidthMeasureSpec, widthUsed, heightMeasureSpec, heightUsed);

                    return true;
                } else {
                    updateToolbar(parent, appBar, parentWidthMeasureSpec, widthUsed, parentHeightMeasureSpec, heightUsed, true);

                    return super.onMeasureChild(parent, child, parentWidthMeasureSpec, widthUsed, parentHeightMeasureSpec, heightUsed);
                }
            }
        }

        return false;
    }

    private static int getContentHeight(View view) {
        if (view instanceof ViewGroup) {
            ViewGroup viewGroup = (ViewGroup) view;

            int contentHeight = 0;
            for (int index = 0; index < viewGroup.getChildCount(); ++index) {
                View child = viewGroup.getChildAt(index);
                contentHeight += child.getMeasuredHeight();
            }
            return contentHeight;
        } else {
            return view.getMeasuredHeight();
        }
    }

    private static AppBarLayout findFirstAppBarLayout(List<View> views) {
        int i = 0;

        for (int z = views.size(); i < z; ++i) {
            View view = views.get(i);
            if (view instanceof AppBarLayout) {
                return (AppBarLayout) view;
            }
        }

        throw new IllegalArgumentException("Missing AppBarLayout in CoordinatorLayout dependencies");
    }

    private void updateToolbar(CoordinatorLayout parent, AppBarLayout appBar, int parentWidthMeasureSpec, int widthUsed, int parentHeightMeasureSpec,
                               int heightUsed, boolean toggle) {
        toggleToolbarScroll(appBar, toggle);

        appBar.forceLayout();
        parent.onMeasureChild(appBar, parentWidthMeasureSpec, widthUsed, parentHeightMeasureSpec, heightUsed);
    }

    private void toggleToolbarScroll(AppBarLayout appBar, boolean toggle) {
        for (int index = 0; index < appBar.getChildCount(); ++index) {
            View child = appBar.getChildAt(index);

            if (child instanceof Toolbar) {
                Toolbar toolbar = (Toolbar) child;
                AppBarLayout.LayoutParams params = (AppBarLayout.LayoutParams) toolbar.getLayoutParams();
                int scrollFlags = params.getScrollFlags();

                if (toggle) {
                    scrollFlags |= AppBarLayout.LayoutParams.SCROLL_FLAG_SCROLL;
                } else {
                    scrollFlags &= ~AppBarLayout.LayoutParams.SCROLL_FLAG_SCROLL;
                }

                params.setScrollFlags(scrollFlags);
            }
        }
    }
}

当从属视图（SCROLL，AppBarLayout）中的滚动内容小于视图高度时，此行为基本上会从RecyclerView中删除滚动标记NestedScrollView，即。当不需要滚动时。它还会覆盖偏移滚动视图，通常由AppBarLayout.ScrollingViewBehavior完成。添加页脚时效果很好，即。按钮，滚动视图或ViewPager，其中每页的内容长度可能不同。

Answer 5

我认为创建一个固定的页眉和页脚可以解决您的问题。我会在评论中写这个，但我没有50个代表。你可以弄清楚如何做到here

Answer 6

我做了一些确保我添加的内容 android:layout_gravity="end|bottom" 到CoordinatorLayout

底部我想要的XML布局

然后在代码中设置：

 mRecyclerView.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
        @SuppressLint("NewApi")
        @SuppressWarnings("deprecation")
        @Override
        public void onGlobalLayout() {
            if (mFooterView != null) {
                final int height = mFooterView.getHeight();
                mRecyclerView.setPadding(0, 0, 0, height);
                mRecyclerView.getViewTreeObserver().removeOnGlobalLayoutListener(this);
            }
        }
    });

注意：页脚View / ViewGroup需要在z轴上更高（在XML中的RecyclerView下面列出）才能正常运行

Answer 7

使用线性布局对元素进行环绕，如下所示：

<android.support.design.widget.CoordinatorLayout >

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

    <android.support.design.widget.AppBarLayout>
      <android.support.v7.widget.Toolbar />
    </android.support.design.widget.AppBarLayout>
    <include layout="@layout/content_main" />

    </LinearLayout>

</android.support.design.widget.CoordinatorLayout>

Answer 8

Android CoordinatorLayout底部布局行为示例

activity_bottom.xml

<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/app_bar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimaryDark"
            app:layout_scrollFlags="scroll|enterAlways"
            app:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar" />
    </android.support.design.widget.AppBarLayout>

    <android.support.v7.widget.RecyclerView
        android:id="@+id/list"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="#C0C0C0"
        app:layout_behavior="@string/appbar_scrolling_view_behavior" />

    <com.example.android.coordinatedeffort.widget.FooterBarLayout
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:layout_gravity="bottom">

        <TextView
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="#007432"
            android:gravity="center"
            android:text="Footer View"
            android:textColor="@android:color/white"
            android:textSize="25sp" />
    </com.example.android.coordinatedeffort.widget.FooterBarLayout>

</android.support.design.widget.CoordinatorLayout>

FooterBarLayout.java

FooterBarBehavior.java

Answer 9

您的问题有一个库。希望这对你有所帮助 Here is the library

你提到的另一个问题是修复页脚。下面是相对布局，因此请使用页脚上的功能android:layout_alignParentBottom="true"。

希望你我已经解决了这个问题

Android-footer在CoordinatorLayout中使用时滚动屏幕

9 个答案:

Android CoordinatorLayout底部布局行为示例