小编Ild*_*pov的帖子

我正在尝试使用 MotionLayout 实现底部工作表。它在一个微不足道的情况下工作 - 当底部工作表应该仅在屏幕的一半中可见时（例如）。但是当底部工作表扩展并填满整个屏幕时，我无法让它工作。

所以这里可以是 3 个状态：

1. 底部工作表隐藏
2. 底部工作表填满了半个屏幕
3. 底页填满整个屏幕

这是布局：

<androidx.constraintlayout.motion.widget.MotionLayout
       android:layout_width="match_parent"
       android:layout_height="match_parent"
       app:layoutDescription="@xml/scene_description">

         <FrameLayout
            android:id="@+id/fragmentPlaceholder"
            android:layout_width="match_parent"
            android:layout_height="570dp"
            android:elevation="8dp"> some content here </FrameLayout>


</androidx.constraintlayout.motion.widget.MotionLayout>

这里570dp等于半屏（例如）

以及内容scene_description.xml：

<?xml version="1.0" encoding="utf-8"?>
<MotionScene xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <Transition
        android:id="@+id/transition1"
        app:constraintSetStart="@id/bottomSheetHidden"
        app:constraintSetEnd="@id/bottomSheetHalfOpen"
        app:duration="300">

        <OnSwipe
            app:dragDirection="dragDown"
            app:onTouchUp="autoCompleteToStart"
            app:touchAnchorId="@+id/fragmentPlaceholder"
            app:touchAnchorSide="bottom"/>

    </Transition>


    <Transition
        android:id="@+id/transition2"
        app:constraintSetStart="@id/bottomSheetHalfOpen"
        app:constraintSetEnd="@id/bottomSheetOpenFullScreen"
        app:duration="300">

    </Transition>


    <Transition
        android:id="@+id/transition3"
        app:constraintSetStart="@id/bottomSheetHidden"
        app:constraintSetEnd="@id/bottomSheetOpenFullScreen"
        app:duration="300">

        <OnSwipe
            app:dragDirection="dragDown"
            app:touchAnchorId="@+id/fragmentPlaceholder"
            app:touchAnchorSide="bottom" />

    </Transition>


    <ConstraintSet android:id="@+id/bottomSheetHidden">

        <Constraint android:id="@id/fragmentPlaceholder">
            <Layout
                android:layout_width="match_parent"
                android:layout_height="570dp"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintTop_toBottomOf="parent"/> <!-- below screen, not …

我使用以下代码生成允许从 AWS S3 下载 1 个对象的 URL：

 import com.amazonaws.services.s3.AmazonS3;
 import com.amazonaws.services.s3.model.GeneratePresignedUrlRequest;


 private AmazonS3 s3Client;

 public String getDownloadPhotoPresignedRequest(String bucketName, String objectKey) throws Exception {
        java.util.Date expiration = new java.util.Date();
        long expTimeMillis = expiration.getTime();
        expTimeMillis += 1000 * 60 * 5;
        expiration.setTime(expTimeMillis);

        // Generate the presigned URL.
        GeneratePresignedUrlRequest generatePresignedUrlRequest =
                new GeneratePresignedUrlRequest(bucketName, objectKey)
                        .withMethod(HttpMethod.GET)
                        .withExpiration(expiration);
        URL url = s3Client.generatePresignedUrl(generatePresignedUrlRequest);

        return url.toString();
    }

如何生成允许从 S3 下载多个文件的 URL？