1

flutter_app/android/app/src/main/AndroidManifest.xml

@@ -1,6 +1,8 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android">
     <uses-permission android:name="android.permission.CAMERA"/>
     <uses-permission android:name="android.permission.INTERNET"/>
+    <!-- App 内更新安装 APK（PackageInstaller 会话安装，见 InstallerChannel.kt） -->
+    <uses-permission android:name="android.permission.REQUEST_INSTALL_PACKAGES"/>
     <application
         android:label="视野"
         android:name="${applicationName}"

flutter_app/android/app/src/main/kotlin/com/example/observer/InstallerChannel.kt

@@ -0,0 +1,139 @@
+package com.example.observer
+
+import android.app.PendingIntent
+import android.content.Intent
+import android.content.pm.PackageInstaller
+import android.net.Uri
+import android.os.Build
+import android.os.Handler
+import android.os.Looper
+import android.provider.Settings
+import java.io.File
+import io.flutter.embedding.android.FlutterActivity
+import io.flutter.embedding.engine.FlutterEngine
+import io.flutter.plugin.common.EventChannel
+import io.flutter.plugin.common.MethodCall
+import io.flutter.plugin.common.MethodChannel
+
+/**
+ * 原生 APK 安装通道（App 内更新安装）：PackageInstaller 会话安装，
+ * 安装进度经 EventChannel 实时回传 Flutter（下载进度由 Flutter 侧 http 流式下载自算）。
+ *
+ * 通道：
+ * - MethodChannel "observer/installer"：install(path)
+ *   - result.success("installing")：已提交安装
+ *   - result.success("permission_required")：未开「安装未知应用」，已拉起系统设置页
+ * - EventChannel "observer/installer/progress"：{event: progress/finished/failed, ...}
+ */
+class InstallerChannel(
+    private val activity: FlutterActivity,
+    private val engine: FlutterEngine,
+) {
+    private val messenger = engine.dartExecutor.binaryMessenger
+    private val method = MethodChannel(messenger, "observer/installer")
+    private val progress = EventChannel(messenger, "observer/installer/progress")
+
+    private var progressSink: EventChannel.EventSink? = null
+    private var activeSession: PackageInstaller.Session? = null
+
+    fun register() {
+        method.setMethodCallHandler { call: MethodCall, result: MethodChannel.Result ->
+            when (call.method) {
+                "install" -> install(call.argument<String>("path") ?: "", result)
+                else -> result.notImplemented()
+            }
+        }
+        progress.setStreamHandler(object : EventChannel.StreamHandler {
+            override fun onListen(arguments: Any?, events: EventChannel.EventSink) {
+                progressSink = events
+            }
+
+            override fun onCancel(arguments: Any?) {
+                progressSink = null
+            }
+        })
+    }
+
+    private fun install(path: String, result: MethodChannel.Result) {
+        val file = File(path)
+        if (!file.exists()) {
+            result.error("FILE_NOT_FOUND", "APK 文件不存在: $path", null)
+            return
+        }
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O &&
+            !activity.packageManager.canRequestPackageInstalls()
+        ) {
+            val intent = Intent(
+                Settings.ACTION_MANAGE_UNKNOWN_APP_SOURCES,
+                Uri.parse("package:${activity.packageName}"),
+            ).addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
+            activity.startActivity(intent)
+            result.success("permission_required")
+            return
+        }
+        try {
+            val pm = activity.packageManager
+            val params = PackageInstaller.SessionParams(PackageInstaller.SessionParams.MODE_FULL_INSTALL).apply {
+                setSize(file.length())
+            }
+            val sessionId = pm.packageInstaller.createSession(params)
+            val session = pm.packageInstaller.openSession(sessionId)
+            activeSession = session
+            // API 36 起 registerSessionCallback(int, ...) 变体被移除，只剩全局注册形式，
+            // 回调按 sessionId 过滤，避免响应其他会话事件
+            val callback = object : PackageInstaller.SessionCallback() {
+                override fun onCreated(id: Int) {}
+
+                override fun onBadgingChanged(id: Int) {}
+
+                override fun onActiveChanged(id: Int, active: Boolean) {}
+
+                override fun onProgressChanged(id: Int, progressPercent: Float) {
+                    if (id != sessionId) return
+                    emit("progress", "progress" to progressPercent.toInt())
+                }
+
+                override fun onFinished(id: Int, success: Boolean) {
+                    if (id != sessionId) return
+                    emit("finished", "success" to success)
+                    pm.packageInstaller.unregisterSessionCallback(this)
+                    activeSession = null
+                }
+            }
+            pm.packageInstaller.registerSessionCallback(callback, Handler(Looper.getMainLooper()))
+            // 写 APK 到会话：1MB 缓冲流式拷贝，完成后 commit 弹系统确认框
+            Thread {
+                try {
+                    session.openWrite("apk", 0, file.length()).use { out ->
+                        file.inputStream().use { input ->
+                            val buf = ByteArray(1 shl 20)
+                            while (true) {
+                                val n = input.read(buf)
+                                if (n < 0) break
+                                out.write(buf, 0, n)
+                            }
+                        }
+                    }
+                    val sender = PendingIntent.getActivity(
+                        activity,
+                        0,
+                        Intent(activity, MainActivity::class.java),
+                        PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE,
+                    ).intentSender
+                    session.commit(sender)
+                } catch (e: Exception) {
+                    session.abandon()
+                    emit("failed", "error" to (e.message ?: "安装会话写入失败"))
+                    activeSession = null
+                }
+            }.start()
+            result.success("installing")
+        } catch (e: Exception) {
+            result.error("INSTALL_FAILED", e.message, null)
+        }
+    }
+
+    private fun emit(event: String, vararg pairs: Pair<String, Any>) {
+        progressSink?.success(mapOf("event" to event, *pairs))
+    }
+}

flutter_app/android/app/src/main/kotlin/com/example/observer/MainActivity.kt

@@ -5,6 +5,7 @@ import io.flutter.embedding.engine.FlutterEngine
 
 class MainActivity : FlutterActivity() {
     private var cameraChannel: CameraChannel? = null
+    private var installerChannel: InstallerChannel? = null
 
     override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
         super.configureFlutterEngine(flutterEngine)
@@ -13,6 +14,8 @@ class MainActivity : FlutterActivity() {
         // configureFlutterEngine（onCreate 阶段）只注册通道与 viewFactory，
         // 实际 bindToLifecycle 由 Flutter 相机页 start 时触发（此时已 RESUMED）
         cameraChannel = CameraChannel(this, flutterEngine).also { it.register() }
+        // App 内更新安装 APK（PackageInstaller 会话安装 + 进度回传）
+        installerChannel = InstallerChannel(this, flutterEngine).also { it.register() }
     }
 
     override fun onDestroy() {