如何获取图库选中视频的缩略图？及视频上传服务器URL选择咨询

Hey there! Let's break down your two issues and get you sorted out.

If your ImageView is showing nothing or unexpected results, using Android's built-in MediaMetadataRetriever is the most reliable way to extract and display video thumbnails. Here's how to implement it, plus common fixes for issues you might be hitting:

Example Code (Kotlin) #

First, ensure you have the right permissions:

• For Android 12 and below: Request READ_EXTERNAL_STORAGE (handle runtime permissions for Android 6.0+)
• For Android 13+: Request READ_MEDIA_VIDEO instead

import android.media.MediaMetadataRetriever
import android.widget.ImageView
import android.net.Uri
import android.graphics.Bitmap

fun loadVideoThumbnail(videoUri: Uri, targetImageView: ImageView) {
    val retriever = MediaMetadataRetriever()
    try {
        // Attach the video URI to the retriever
        retriever.setDataSource(targetImageView.context, videoUri)
        // Extract a frame at 1 second (adjust time in microseconds as needed)
        val thumbnailBitmap = retriever.getFrameAtTime(
            1000000,
            MediaMetadataRetriever.OPTION_CLOSEST_SYNC
        )
        
        thumbnailBitmap?.let {
            targetImageView.setImageBitmap(it)
        } ?: run {
            // Fallback to a default image if thumbnail extraction fails
            targetImageView.setImageResource(R.drawable.default_video_thumbnail)
        }
    } catch (e: Exception) {
        e.printStackTrace()
        // Handle errors (e.g., corrupted video, invalid URI)
        targetImageView.setImageResource(R.drawable.default_video_thumbnail)
    } finally {
        retriever.release() // Always release resources to avoid leaks
    }
}

Common Fixes for Failed Thumbnails #

• Permission Issues: Double-check that you've requested and been granted the required storage/video permissions. Runtime permissions are mandatory for Android 6.0+.
• Invalid URI: The gallery might return a content:// URI (not a direct file path) – make sure you're passing this URI correctly to the retriever, not trying to use a file:// path that doesn't exist.
• Corrupted/Unsupported Video: If the video file is damaged or uses an unsupported codec, the retriever can't extract a frame. Add a fallback image to handle this case.

The right choice depends on where your video is stored:

• Local Gallery Video: When you pick a video from the gallery, you'll get a content:// URI. For uploads, avoid using file:// paths (they trigger exceptions on Android 7.0+). Instead:
  1. Upload via InputStream: Use getContentResolver().openInputStream(videoUri) to get a stream of the video file, then pass this stream to your upload client (like OkHttp or Retrofit). This is the most reliable method.
  2. Convert to File Path: If your server requires a file path, use ContentResolver to resolve the content:// URI to a local file path (note: this doesn't work for all gallery URIs, like those from cloud storage apps).
• Remote Video: If the video is already hosted online (e.g., your own server, CDN), use the direct HTTP/HTTPS URL of the video file.

Quick Upload Snippet (InputStream) #

val inputStream = context.contentResolver.openInputStream(videoUri)
// Pass this input stream to your upload library
// Example with OkHttp:
val requestBody = inputStream?.let { RequestBody.create(MediaType.parse("video/*"), it.readBytes()) }
// Then build your upload request

内容的提问来源于stack exchange，提问作者podgradle