Lollipop 上的 "PackageInstaller" class 是什么，如何使用它？

Question

背景

我注意到 PackageManager 上有一个名为“getPackageInstaller”的新函数，具有 minAPI 21 (Lollipop)。

我到达了“PackageInstaller”class，这是关于它的内容：

Offers the ability to install, upgrade, and remove applications on the device. This includes support for apps packaged either as a single "monolithic" APK, or apps packaged as multiple "split" APKs.

An app is delivered for installation through a PackageInstaller.Session, which any app can create. Once the session is created, the installer can stream one or more APKs into place until it decides to either commit or destroy the session. Committing may require user intervention to complete the installation.

Sessions can install brand new apps, upgrade existing apps, or add new splits into an existing app.

问题

这个class有什么用？它是否可用于第三方应用程序（我没有看到任何提及）？
它真的可以安装应用程序吗？
它在后台执行吗？
有什么限制？
是否需要权限？如果有，是哪个？
有没有使用教程？

Answer 1

好的，我找到了一些答案：

可用于 installing/updating 个 APK 文件，包括 split-APK 个文件。甚至更多。
是的，但需要用户确认，一个接一个。
也许如果应用是内置的。
似乎在请求用户安装之前需要阅读整个 APK file/s。
需要权限REQUEST_INSTALL_PACKAGES
还没有找到，但有人在这里向我展示了如何安装 split-apk 文件，这里是如何使用 SAF 为单个文件安装和不安装 PackageInstaller。请注意，这只是一个示例。我不认为在 UI 线程上完成所有操作是一个好习惯。

清单

<manifest xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools"
          package="com.android.apkinstalltest">
    <uses-permission android:name="android.permission.REQUEST_INSTALL_PACKAGES"/>

    <application tools:ignore="AllowBackup,GoogleAppIndexingWarning"
                 android:allowBackup="true"
                 android:icon="@mipmap/ic_launcher"
                 android:label="@string/app_name"
                 android:roundIcon="@mipmap/ic_launcher_round"
                 android:supportsRtl="true"
                 android:theme="@style/AppTheme">
        <activity
                android:name=".MainActivity"
                android:label="@string/app_name"
                android:theme="@style/AppTheme.NoActionBar">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>

                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>

        <service android:name=".APKInstallService"/>

    </application>

</manifest>

APKInstallService

class APKInstallService : Service() {
    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
    override fun onStartCommand(intent: Intent, flags: Int, startId: Int): Int {
        when (intent.getIntExtra(PackageInstaller.EXTRA_STATUS, PackageInstaller.STATUS_FAILURE)) {
            PackageInstaller.STATUS_PENDING_USER_ACTION -> {
                Log.d("AppLog", "Requesting user confirmation for installation")
                val confirmationIntent = intent.getParcelableExtra<Intent>(Intent.EXTRA_INTENT)
                confirmationIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
                try {
                    startActivity(confirmationIntent)
                } catch (e: Exception) {
                }
            }
            PackageInstaller.STATUS_SUCCESS -> Log.d("AppLog", "Installation succeed")
            else -> Log.d("AppLog", "Installation failed")
        }
        stopSelf()
        return START_NOT_STICKY
    }

    override fun onBind(intent: Intent) = null
}

MainActivity

class MainActivity : AppCompatActivity() {
    private lateinit var packageInstaller: PackageInstaller

    @TargetApi(Build.VERSION_CODES.O)
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        setSupportActionBar(toolbar)
        packageInstaller = packageManager.packageInstaller
        val intent = Intent(Intent.ACTION_OPEN_DOCUMENT)
        intent.addCategory(Intent.CATEGORY_OPENABLE)
        intent.type = "application/vnd.android.package-archive"
        startActivityForResult(intent, 1)
    }

//    override fun onActivityResult(requestCode: Int, resultCode: Int, resultData: Intent?) {
//        super.onActivityResult(requestCode, resultCode, resultData)
//        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP && requestCode == 1 && resultCode == Activity.RESULT_OK && resultData != null) {
//            val uri = resultData.data
//            grantUriPermission(packageName, uri, Intent.FLAG_GRANT_READ_URI_PERMISSION or Intent.FLAG_GRANT_WRITE_URI_PERMISSION)
//            val intent = Intent(Intent.ACTION_INSTALL_PACKAGE)//
//                    .setDataAndType(uri, "application/vnd.android.package-archive")
//                    .putExtra(Intent.EXTRA_NOT_UNKNOWN_SOURCE, true)
//                    .putExtra(Intent.EXTRA_RETURN_RESULT, false)
//                    .addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)
//            startActivity(intent)
//        }

    override fun onActivityResult(requestCode: Int, resultCode: Int, resultData: Intent?) {
        super.onActivityResult(requestCode, resultCode, resultData)
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP && requestCode == 1 && resultCode == Activity.RESULT_OK && resultData != null) {
            val uri = resultData.data ?: return
            grantUriPermission(packageName, uri, Intent.FLAG_GRANT_READ_URI_PERMISSION or Intent.FLAG_GRANT_WRITE_URI_PERMISSION)
            val installParams = PackageInstaller.SessionParams(PackageInstaller.SessionParams.MODE_FULL_INSTALL)
            var cursor: Cursor? = null
            var outputStream: OutputStream? = null
            var inputStream: InputStream? = null
            var session: PackageInstaller.Session? = null
            try {
                cursor = contentResolver.query(uri, null, null, null, null)
                if (cursor != null) {
                    cursor.moveToNext()
                    val fileSize = cursor.getLong(cursor.getColumnIndex(DocumentsContract.Document.COLUMN_SIZE))
                    val fileName = cursor.getString(cursor.getColumnIndex(DocumentsContract.Document.COLUMN_DISPLAY_NAME))
                    installParams.setSize(fileSize)
                    cursor.close()
                    val sessionId = packageInstaller.createSession(installParams)
                    Log.d("AppLog", "Success: created install session [$sessionId] for file $fileName")
                    session = packageInstaller.openSession(sessionId)
                    outputStream = session.openWrite(System.currentTimeMillis().toString(), 0, fileSize)
                    inputStream = contentResolver.openInputStream(uri)
                    inputStream.copyTo(outputStream)
                    session.fsync(outputStream)
                    outputStream.close()
                    outputStream = null
                    inputStream.close()
                    inputStream = null
                    Log.d("AppLog", "Success: streamed $fileSize bytes")
                    val callbackIntent = Intent(applicationContext, APKInstallService::class.java)
                    val pendingIntent = PendingIntent.getService(applicationContext, 0, callbackIntent, 0)
                    session!!.commit(pendingIntent.intentSender)
                    session.close()
                    session = null
                    Log.d("AppLog", "install request sent. sessions:" + packageInstaller.mySessions)
                }
            } catch (e: Exception) {
                Log.d("AppLog", "error:$e")
            } finally {
                outputStream?.close()
                inputStream?.close()
                session?.close()
                cursor?.close()
            }
        }
    }
}

Lollipop 上的 "PackageInstaller" class 是什么，如何使用它？

What's "PackageInstaller" class on Lollipop, and how to use it?

session

android

apk

android-package-managers

packageinstaller

背景

问题