Question

我正在尝试检测DownloadManager下载何时完成。不幸的是，我尝试使用的本地BroadcastReceiver从未被调用。我见过多个类似的问题，但没有一个解决我的问题。同样，如果BroadcastReceiver不是本地的而是在清单中声明的，那么它确实会被调用，因此DownloadManager不会有问题。

我无法使用外部BroadcastReceiver，因为下载完成后我需要更新UI（更具体地说，打开另一个活动），据我所知，无法从外部接收器完成（请如果我错了，请纠正我。）

DownloadManager调用：

private fun download() {
    val mobileNetSSDConfigRequest: DownloadManager.Request = DownloadManager.Request(
            Uri.parse("https://s3.eu-west-3.amazonaws.com/gotcha-weights/weights/MobileNetSSD/MobileNetSSD.prototxt")
    )
    mobileNetSSDConfigRequest.setDescription("Downloading MobileNetSSD configuration")
    mobileNetSSDConfigRequest.setTitle("MobileNetSSD configuration")

    mobileNetSSDConfigRequest.setDestinationInExternalPublicDir(
            "Android/data/giorgioghisotti.unipr.it.gotcha/files/weights/", "MobileNetSSD.prototxt")

    val manager: DownloadManager = getSystemService(Context.DOWNLOAD_SERVICE) as DownloadManager
    manager.enqueue(mobileNetSSDConfigRequest)
}

在被授予权限时调用：

override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<out String>, grantResults: IntArray) {
    super.onRequestPermissionsResult(requestCode, permissions, grantResults)
    when (requestCode) {
        PERMISSION_REQUEST_CODE -> {
            if (grantResults.isEmpty()
                    || grantResults[0] != PackageManager.PERMISSION_GRANTED
                    || grantResults[1] != PackageManager.PERMISSION_GRANTED
                    || grantResults[2] != PackageManager.PERMISSION_GRANTED
                    || grantResults[3] != PackageManager.PERMISSION_GRANTED
                    || grantResults[4] != PackageManager.PERMISSION_GRANTED) {
                Toast.makeText(this,
                        "Sorry, this app requires camera and storage access to work!",
                        Toast.LENGTH_LONG).show()
                finish()
            } else {
                val mobileSSDConfig = File(sDir + mobileNetSSDConfigPath)
                if (!mobileSSDConfig.exists()) download()
                else {
                    val myIntent = Intent(this, MainMenu::class.java)
                    this.startActivity(myIntent)
                }
            }
        }
    }
}

BroadcastIntent的声明如下（Splash是活动的名称）：

private val broadcastReceiver = object: BroadcastReceiver() {

    override fun onReceive(context: Context?, intent: Intent?) {
        when (intent?.action) {
            DownloadManager.ACTION_DOWNLOAD_COMPLETE -> {
                val myIntent = Intent(this@Splash, MainMenu::class.java)
                this@Splash.startActivity(myIntent)
            }
        }
    }
}

并已在活动的onCreate（）方法中注册：

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)

    LocalBroadcastManager.getInstance(this).registerReceiver(
            broadcastReceiver, IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE)
    )

    ActivityCompat.requestPermissions(this, arrayOf(android.Manifest.permission.CAMERA,
            android.Manifest.permission.READ_EXTERNAL_STORAGE,
            android.Manifest.permission.INTERNET,
            android.Manifest.permission.ACCESS_NETWORK_STATE,
            android.Manifest.permission.WRITE_EXTERNAL_STORAGE), PERMISSION_REQUEST_CODE)
}

我尝试在onResume方法中注册接收器，并在onCreate方法中声明它，没有变化。据我所知，我正在按照我在一些公认的答案中所做的完全做到这一点，但我看不到问题所在。我知道从来没有调用BroadcastReceiver的事实，我通过调试和各种控制台日志进行了检查。由于文件已正确下载且外部服务已正确调用，因此DownloadManager似乎可以正常工作。

我想念什么？

Answer 1

我遇到了类似的问题，结果发现只调用registerReceiver(broadcastReceiver, IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE)却没有得到LocalBroadcastManager的实例就解决了这个问题。

所以可能的问题是接收者正在错误的上下文对象上注册。 [请记住要注意接收者的注销]

我是这样的

public void onResume() 
{
    super.onResume();
    registerReceiver(broadcastReceiver, IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE))
}

public void onPause() 
{
    super.onPause();
    unregisterReceiver(broadcastReceiver);
}

Android / Kotlin-本地BroadcastReceiver永远不会由DownloadManager激活

1 个答案: