Android下载管理器代码旧设备正常，最新版本设备失效问题求助

1. 解决明文HTTP拦截问题（Android 9及以上） #

Android 9开始默认禁止明文HTTP流量，你的下载链接是http://开头，会被系统拦截。可通过以下两种方式解决：

• 推荐方案：将链接替换为HTTPS协议，把http://commondatastorage.googleapis.com/gtv-videos-bucket/sample/ElephantsDream.mp4改为https://commondatastorage.googleapis.com/gtv-videos-bucket/sample/ElephantsDream.mp4
• 允许指定域名明文流量：在res/xml目录创建network_security_config.xml文件，内容如下：

<?xml version="1.0" encoding="utf-8"?>
<network-security-config>
    <domain-config cleartextTrafficPermitted="true">
        <domain includeSubdomains="true">commondatastorage.googleapis.com</domain>
    </domain-config>
</network-security-config>

然后在AndroidManifest.xml的<application>标签中添加配置：

android:networkSecurityConfig="@xml/network_security_config"

2. 适配Android 13+的通知权限 #

Android 13新增POST_NOTIFICATIONS权限，DownloadManager需要该权限才能推送下载通知，否则可能静默失败：

• 在AndroidManifest.xml中声明权限：

<uses-permission android:name="android.permission.POST_NOTIFICATIONS" />

• 动态申请权限（targetSdk>=33时）：

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU && ContextCompat.checkSelfPermission(this, Manifest.permission.POST_NOTIFICATIONS) != PackageManager.PERMISSION_GRANTED) {
    val requestPermissionLauncher = registerForActivityResult(ActivityResultContracts.RequestPermission()) { isGranted ->
        // 处理权限申请结果
    }
    requestPermissionLauncher.launch(Manifest.permission.POST_NOTIFICATIONS)
}

3. 优化代码健壮性 #

• 移除强制非空断言!!，避免空指针异常：

val dm = getSystemService(DOWNLOAD_SERVICE) as? DownloadManager
dm?.let { downloadManager ->
    val url = "https://commondatastorage.googleapis.com/gtv-videos-bucket/sample/ElephantsDream.mp4"
    val request = DownloadManager.Request(Uri.parse(url))
    val fileName = url.substring(url.lastIndexOf('/') + 1).let {
        it.substring(0, 1).uppercase(Locale.getDefault()) + it.substring(1)
    }
    request.setDestinationInExternalFilesDir(this, Environment.DIRECTORY_DOWNLOADS, fileName)
    // 可选：添加通知标题和描述，提升用户体验
    request.setTitle("视频下载")
    request.setDescription("正在下载ElephantsDream.mp4")
    enqueue = downloadManager.enqueue(request)
}

4. 监听下载状态排查问题 #

添加广播接收器获取下载结果，方便定位失败原因：

private val downloadReceiver = object : BroadcastReceiver() {
    override fun onReceive(context: Context?, intent: Intent?) {
        val downloadId = intent?.getLongExtra(DownloadManager.EXTRA_DOWNLOAD_ID, -1) ?: -1
        if (downloadId == enqueue) {
            dm?.query(DownloadManager.Query().setFilterById(downloadId))?.use { cursor ->
                if (cursor.moveToFirst()) {
                    val status = cursor.getInt(cursor.getColumnIndexOrThrow(DownloadManager.COLUMN_STATUS))
                    when (status) {
                        DownloadManager.STATUS_SUCCESSFUL -> {
                            // 处理下载成功逻辑
                        }
                        DownloadManager.STATUS_FAILED -> {
                            val errorReason = cursor.getInt(cursor.getColumnIndexOrThrow(DownloadManager.COLUMN_REASON))
                            // 根据errorReason排查具体失败原因，比如ERROR_FILE_ERROR、ERROR_UNHANDLED_HTTP_CODE等
                        }
                    }
                }
            }
        }
    }
}

// 在Activity onCreate中注册接收器
registerReceiver(downloadReceiver, IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE))

// 在Activity onDestroy中注销接收器
override fun onDestroy() {
    super.onDestroy()
    unregisterReceiver(downloadReceiver)
}

内容的提问来源于stack exchange，提问作者Khush Parmar