基于@ uroovic podkrinik的回答。

通过APK安装应用程序对于不同版本的android可能有所不同(API级别21-30):

private var uri: Uri? = null
private var manager: DownloadManager? = null
private var file: File? = null
private var request: DownloadManager.Request? = null

private val REQUEST_WRITE_PERMISSION = 786
private val REQUEST_INSTALL_PACKAGE = 1234

private var receiver: BroadcastReceiver? = null
private var installIntent: Intent? = null

...
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
    val externalStorageDir = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
        context?.getExternalFilesDir(Environment.DIRECTORY_DOWNLOADS)
    } else {
        @Suppress("DEPRECATION")
        Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS)
    }
    val destination = "$externalStorageDir/Application.apk"
    uri = Uri.parse("file://$destination")

    file = File(destination)
    file?.let { if (it.exists()) it.delete() }
    
    request = DownloadManager.Request(Uri.parse("https://path_to_file/application.apk"))
    request?.let {
        it.setDescription("Update App")
        it.setTitle("Application")
        it.setDestinationUri(uri)
    }
    manager = context?.getSystemService(Context.DOWNLOAD_SERVICE) as DownloadManager

    // for level android api >= 23 needs permission to write to external storage
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
        if (ContextCompat.checkSelfPermission(context!!, Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {
            // here you can display the loading diagram
            registerReceiver()
        } else {
            // request for permission to write to external storage
            requestPermissions(
                arrayOf(Manifest.permission.WRITE_EXTERNAL_STORAGE),
                REQUEST_WRITE_PERMISSION
            )
        }
    } else {
        // here you can display the loading diagram
        registerReceiver()
    }
}

创建并注册接收者:

private val onDownloadComplete = object : BroadcastReceiver() {
    // install app when apk is loaded
    override fun onReceive(ctxt: Context, intent: Intent) {
        val mimeType = "application/vnd.android.package-archive"
        receiver = this
        try {
            installIntent = Intent(Intent.ACTION_VIEW)
            installIntent?.flags = Intent.FLAG_ACTIVITY_CLEAR_TOP

            // for android api >= 24 requires FileProvider
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
                installIntent?.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)

                val fileProviderURI = FileProvider.getUriForFile(
                    context!!,
                    context!!.applicationContext.packageName + ".provider",
                    file!!)

                installIntent?.setDataAndType(fileProviderURI, mimeType)

                // for android api >= 26 requires permission to install from APK in settings
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
                    if (context!!.applicationContext.packageManager.canRequestPackageInstalls()) {
                        installFromAPK()
                    } else goToSecuritySettings()
                } else installFromAPK()
            } else {
                // for android api < 24 used file:// instead content://
                // (no need to use FileProvider)
                installIntent?.setDataAndType(uri, mimeType)
                installFromAPK()
            }
        } catch (e: Exception) {
            // view error message
        }
    }
}

private fun registerReceiver() {
    manager!!.enqueue(request)
    context?.registerReceiver(
        onDownloadComplete,
        IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE)
    )
}

private fun installFromAPK() {
    try {
        startActivity(installIntent)
        context?.unregisterReceiver(receiver)
        activity?.finish()
    } catch (e: Exception) {
        // view error message
    }
}

// go to settings for get permission install from APK
private fun goToSecuritySettings() {
    val intent = Intent(Settings.ACTION_MANAGE_UNKNOWN_APP_SOURCES).setData(
        Uri.parse(String.format(
            "package:%s",
            context!!.applicationContext.packageName
        ))
    )
    try {
        startActivityForResult(intent, REQUEST_INSTALL_PACKAGE)
    } catch (e: Exception) {
        // view error message
    }
}

拦截权限请求WRITE_EXTERNAL_STORAGE的结果:

override fun onRequestPermissionsResult(
        requestCode: Int,
        permissions: Array<String>,
        grantResults: IntArray
) {
    super.onRequestPermissionsResult(requestCode, permissions, grantResults)
    if (requestCode == REQUEST_WRITE_PERMISSION
            && grantResults.isNotEmpty()
            && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
        try {
            // here you can display the loading diagram
            registerReceiver()
        } catch (e: Exception) {
            // view error message
        }
    }
}

在安全设置中拦截用户选择的结果:

@RequiresApi(api = Build.VERSION_CODES.O)
override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
    super.onActivityResult(requestCode, resultCode, data)
    if (requestCode == REQUEST_INSTALL_PACKAGE
            && resultCode == AppCompatActivity.RESULT_OK) {
        if (context!!.applicationContext.packageManager.canRequestPackageInstalls()) {
            installFromAPK()
        }
    } else {
        // view error message
    }
}

添加到您的清单:

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.REQUEST_INSTALL_PACKAGES"/>
<application...>
    ...
    <provider
        android:name="androidx.core.content.FileProvider"
        android:authorities="${applicationId}.provider"
        android:exported="false"
        android:grantUriPermissions="true">
        <meta-data
            android:name="android.support.FILE_PROVIDER_PATHS"
            android:resource="@xml/provider_paths" />
    </provider>
    ...
</application>

将provider_paths.xml文件添加到res/xml:

<?xml version="1.0" encoding="utf-8"?>
<paths>
    <external-path name="external_files" path="."/>
</paths>

对于android API级别= 30，从安全设置返回不工作， 所以使用浏览器安装:

try {
    val intent = Intent(Intent.ACTION_VIEW)
    intent.data = Uri.parse("https://path_to_file/application.apk")
    startActivity(intent)
    activity?.finish()
} catch (e: ActivityNotFoundException) { }

好吧，我深入挖掘，并从Android源代码中找到了PackageInstaller应用程序的源代码。

https://github.com/android/platform_packages_apps_packageinstaller

从manifest中我发现它需要许可:

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

而实际安装过程发生在确认之后

Intent newIntent = new Intent();
newIntent.putExtra(PackageUtil.INTENT_ATTR_APPLICATION_INFO, mPkgInfo.applicationInfo);
newIntent.setData(mPackageURI);
newIntent.setClass(this, InstallAppProgress.class);
String installerPackageName = getIntent().getStringExtra(Intent.EXTRA_INSTALLER_PACKAGE_NAME);
if (installerPackageName != null) {
   newIntent.putExtra(Intent.EXTRA_INSTALLER_PACKAGE_NAME, installerPackageName);
}
startActivity(newIntent);

试试这个 -在舱单上填写:

uses-permission android:name="android.permission.INSTALL_PACKAGES"
        tools:ignore="ProtectedPermissions"

编写代码:

File sdCard = Environment.getExternalStorageDirectory();
String fileStr = sdCard.getAbsolutePath() + "/Download";// + "app-release.apk";
File file = new File(fileStr, "app-release.apk");
Intent promptInstall = new Intent(Intent.ACTION_VIEW).setDataAndType(Uri.fromFile(file),
                        "application/vnd.android.package-archive");

startActivity(promptInstall);

这可以帮助别人很多!

第一:

private static final String APP_DIR = Environment.getExternalStorageDirectory().getAbsolutePath() + "/MyAppFolderInStorage/";

private void install() {
    File file = new File(APP_DIR + fileName);

    if (file.exists()) {
        Intent intent = new Intent(Intent.ACTION_VIEW);
        String type = "application/vnd.android.package-archive";

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
            Uri downloadedApk = FileProvider.getUriForFile(getContext(), "ir.greencode", file);
            intent.setDataAndType(downloadedApk, type);
            intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
        } else {
            intent.setDataAndType(Uri.fromFile(file), type);
            intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        }

        getContext().startActivity(intent);
    } else {
        Toast.makeText(getContext(), "ّFile not found!", Toast.LENGTH_SHORT).show();
    }
}

第二:对于android 7及以上，你应该在manifest中定义一个提供商，如下所示!

    <provider
        android:name="android.support.v4.content.FileProvider"
        android:authorities="ir.greencode"
        android:exported="false"
        android:grantUriPermissions="true">
        <meta-data
            android:name="android.support.FILE_PROVIDER_PATHS"
            android:resource="@xml/paths" />
    </provider>

第三:在res/xml文件夹中定义path.xml，如下所示! 我使用这个路径内部存储，如果你想改变它的东西有一些方法!你可以进入这个链接: FileProvider

<?xml version="1.0" encoding="utf-8"?>
<paths xmlns:android="http://schemas.android.com/apk/res/android">
    <external-path name="your_folder_name" path="MyAppFolderInStorage/"/>
</paths>

第四:您应该在manifest中添加此权限:

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

允许应用程序请求安装包。针对api大于25的应用程序必须拥有此权限才能使用Intent.ACTION_INSTALL_PACKAGE。 请确保提供者权限相同!

大概两个月前，我发现了这个问题。今天回来了，一点头绪也没有。据我所知，我的设置没有任何改变，所以很明显，无论过去的我想到什么，对现在的我来说都不够强大。我终于设法让一些东西重新工作了，所以在这里记录它，以便将来的我和其他可能从另一次尝试中受益的人。

这一尝试代表了原始Android Java安装APK - Session API示例的直接Xamarin c#翻译。它可能需要一些额外的工作，但这至少是一个开始。我让它运行在Android 9设备上，尽管我的项目针对的是Android 11。

InstallApkSessionApi.cs

namespace LauncherDemo.Droid
{
    using System;
    using System.IO;

    using Android.App;
    using Android.Content;
    using Android.Content.PM;
    using Android.OS;
    using Android.Widget;

    [Activity(Label = "InstallApkSessionApi", LaunchMode = LaunchMode.SingleTop)]
    public class InstallApkSessionApi : Activity
    {
        private static readonly string PACKAGE_INSTALLED_ACTION =
                "com.example.android.apis.content.SESSION_API_PACKAGE_INSTALLED";

        protected override void OnCreate(Bundle savedInstanceState)
        {
            base.OnCreate(savedInstanceState);
            this.SetContentView(Resource.Layout.install_apk_session_api);

            // Watch for button clicks.
            Button button = this.FindViewById<Button>(Resource.Id.install);
            button.Click += this.Button_Click;
        }

        private void Button_Click(object sender, EventArgs e)
        {
            PackageInstaller.Session session = null;
            try
            {
                PackageInstaller packageInstaller = this.PackageManager.PackageInstaller;
                PackageInstaller.SessionParams @params = new PackageInstaller.SessionParams(
                        PackageInstallMode.FullInstall);
                int sessionId = packageInstaller.CreateSession(@params);
                session = packageInstaller.OpenSession(sessionId);
                this.AddApkToInstallSession("HelloActivity.apk", session);

                // Create an install status receiver.
                Context context = this;
                Intent intent = new Intent(context, typeof(InstallApkSessionApi));
                intent.SetAction(PACKAGE_INSTALLED_ACTION);
                PendingIntent pendingIntent = PendingIntent.GetActivity(context, 0, intent, 0);
                IntentSender statusReceiver = pendingIntent.IntentSender;

                // Commit the session (this will start the installation workflow).
                session.Commit(statusReceiver);
            }
            catch (IOException ex)
            {
                throw new InvalidOperationException("Couldn't install package", ex);
            }
            catch
            {
                if (session != null)
                {
                    session.Abandon();
                }

                throw;
            }
        }

        
        private void AddApkToInstallSession(string assetName, PackageInstaller.Session session)
        {
            // It's recommended to pass the file size to openWrite(). Otherwise installation may fail
            // if the disk is almost full.
            using Stream packageInSession = session.OpenWrite("package", 0, -1);
            using Stream @is = this.Assets.Open(assetName);
            byte[] buffer = new byte[16384];
            int n;
            while ((n = @is.Read(buffer)) > 0)
            {
                packageInSession.Write(buffer, 0, n);
            }
        }

        // Note: this Activity must run in singleTop launchMode for it to be able to receive the intent
        // in onNewIntent().
        protected override void OnNewIntent(Intent intent)
        {
            Bundle extras = intent.Extras;
            if (PACKAGE_INSTALLED_ACTION.Equals(intent.Action))
            {
                PackageInstallStatus status = (PackageInstallStatus)extras.GetInt(PackageInstaller.ExtraStatus);
                string message = extras.GetString(PackageInstaller.ExtraStatusMessage);
                switch (status)
                {
                    case PackageInstallStatus.PendingUserAction:
                        // This test app isn't privileged, so the user has to confirm the install.
                        Intent confirmIntent = (Intent) extras.Get(Intent.ExtraIntent);
                        this.StartActivity(confirmIntent);
                        break;
                    case PackageInstallStatus.Success:
                        Toast.MakeText(this, "Install succeeded!", ToastLength.Short).Show();
                        break;
                    case PackageInstallStatus.Failure:
                    case PackageInstallStatus.FailureAborted:
                    case PackageInstallStatus.FailureBlocked:
                    case PackageInstallStatus.FailureConflict:
                    case PackageInstallStatus.FailureIncompatible:
                    case PackageInstallStatus.FailureInvalid:
                    case PackageInstallStatus.FailureStorage:
                        Toast.MakeText(this, "Install failed! " + status + ", " + message,
                                ToastLength.Short).Show();
                        break;
                    default:
                        Toast.MakeText(this, "Unrecognized status received from installer: " + status,
                                ToastLength.Short).Show();
                        break;
                }
            }
        }
    }
}

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" android:versionCode="1" android:versionName="1.0" package="com.companyname.launcherdemo" android:installLocation="auto">
    <uses-sdk android:minSdkVersion="21" android:targetSdkVersion="30" />
    <application android:label="LauncherDemo.Android" android:theme="@style/MainTheme" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.REQUEST_INSTALL_PACKAGES" />
</manifest>

What I particularly like about this approach is that it does not require any special work in the manifest - no broadcast receivers, file providers, etc. Granted, this takes as its source some APK in the app's assets, whereas a more useful system will probably use some given APK path. I imagine that will introduce a certain level of additional complexity. In addition, I never ran into any issues here (at least as far as I could tell) with the Xamarin GC closing streams before Android was done with them. Nor did I have any issues with the APK not being parsed. I made sure to use a signed APK (the one generated by Visual Studio when deploying to the device worked just fine), and again I did not run into any file access permission issues simply due to using an APK from the app's assets in this example.

这里的一些其他答案提供的一件事是使侧面加载许可授予更加简化的想法。Yabaze Cool的回答提供了如下特色:

Intent unKnownSourceIntent = new Intent(Settings.ACTION_MANAGE_UNKNOWN_APP_SOURCES). setdata (Uri.parse(字符串。格式(“包:% s activity.getPackageName ()))); 如果(Build.VERSION。SDK_INT >= Build.VERSION_CODES.O) { if (!activity.getPackageManager(). canrequestpackageinstaller ()) { startActivityForResult (unKnownSourceIntent Constant.UNKNOWN_RESOURCE_INTENT_REQUEST_CODE); .．.

当我测试我的翻译时，我卸载了启动器演示程序和它安装的应用程序。没有向canrequestpackageinstalled提供检查，导致我不得不手动按下一个额外的设置按钮，将我带到与上面的ACTION_MANAGE_UNKNOWN_APP_SOURCES意图相同的对话框。因此，添加这个逻辑可以帮助在一定程度上简化用户的安装过程。

您可以轻松启动市场链接或安装提示:

Intent promptInstall = new Intent(Intent.ACTION_VIEW)
    .setDataAndType(Uri.parse("file:///path/to/your.apk"), 
                    "application/vnd.android.package-archive");
startActivity(promptInstall); 

源

Intent goToMarket = new Intent(Intent.ACTION_VIEW)
    .setData(Uri.parse("market://details?id=com.package.name"));
startActivity(goToMarket);

源

但是，没有用户的明确许可，你不能安装。apks;除非设备和您的程序已经扎根。