1

flutter_app/lib/update/installer.dart

@@ -0,0 +1,49 @@
+import 'package:flutter/services.dart';
+
+/// 安装进度事件（原生 PackageInstaller 会话回调经 EventChannel 回传）
+class InstallEvent {
+  /// progress / finished / failed
+  final String event;
+
+  /// event=progress 时的安装进度 0-100
+  final int progress;
+
+  /// event=finished 时是否安装成功
+  final bool? success;
+
+  /// event=failed 时的错误描述
+  final String? error;
+
+  const InstallEvent({
+    required this.event,
+    this.progress = 0,
+    this.success,
+    this.error,
+  });
+}
+
+/// App 内安装 APK：原生侧 PackageInstaller 会话安装（InstallerChannel.kt）
+class ApkInstaller {
+  static const _method = MethodChannel('observer/installer');
+  static const _progress = EventChannel('observer/installer/progress');
+
+  /// 提交安装。返回 installing（已进入安装流程）/ permission_required
+  /// （未允许「安装未知应用」，原生侧已拉起系统设置页）。
+  static Future<String> install(String path) =>
+      _method.invokeMethod<String>('install', {'path': path}).then(
+            (v) => v ?? 'installing',
+          );
+
+  /// 安装进度流：progress(0-100) → finished(success) / failed(error)
+  static Stream<InstallEvent> progress() {
+    return _progress.receiveBroadcastStream().map((e) {
+      final m = e as Map;
+      return InstallEvent(
+        event: m['event'] as String? ?? '',
+        progress: (m['progress'] as num?)?.toInt() ?? 0,
+        success: m['success'] as bool?,
+        error: m['error'] as String?,
+      );
+    });
+  }
+}

flutter_app/lib/update/update_screen.dart

@@ -1,12 +1,19 @@
+import 'dart:async';
+import 'dart:io';
+
 import 'package:flutter/material.dart';
+import 'package:http/http.dart' as http;
 import 'package:url_launcher/url_launcher.dart';
 
+import 'installer.dart';
+
 /// 强制更新页：检测到新版本时的全屏阻塞页。
-/// PopScope 禁返回（Android 系统返回 / iOS 边缘滑动均不可退出），
-/// 仅「立即更新」跳转系统浏览器下载 APK。
+/// PopScope 禁返回（Android 系统返回 / iOS 边缘滑动均不可退出）。
+/// 点「立即更新」在 App 内流式下载 APK（显示下载进度）→ PackageInstaller
+/// 会话安装（显示安装进度），不再跳浏览器。
 /// 点击更新时回调 onUpdateAccepted（调用方持久化服务器版本号，
 /// 使 APK 版本号不递增时也不反复提示）。
-class UpdateScreen extends StatelessWidget {
+class UpdateScreen extends StatefulWidget {
   final String version;
   final String url;
   final String notes;
@@ -20,20 +27,150 @@ class UpdateScreen extends StatelessWidget {
     this.onUpdateAccepted,
   });
 
+  @override
+  State<UpdateScreen> createState() => _UpdateScreenState();
+}
+
+enum _Stage { idle, downloading, installing, finished, failed }
+
+class _UpdateScreenState extends State<UpdateScreen> {
+  final http.Client _client = http.Client();
+  final File _apkFile = File('${Directory.systemTemp.path}/observer-latest.apk');
+  final File _apkPart =
+      File('${Directory.systemTemp.path}/observer-latest.apk.part');
+
+  _Stage _stage = _Stage.idle;
+
+  /// 进度百分比 0-100；null = 总量未知（不确定进度条）
+  double? _progress;
+  String? _message;
+  StreamSubscription<InstallEvent>? _installSub;
+
+  @override
+  void dispose() {
+    _installSub?.cancel();
+    _client.close();
+    super.dispose();
+  }
+
   Future<void> _launch() async {
-    onUpdateAccepted?.call();
-    final uri = Uri.tryParse(url);
-    if (uri == null) return;
+    if (_stage == _Stage.downloading ||
+        _stage == _Stage.installing ||
+        _stage == _Stage.finished) {
+      return;
+    }
+    setState(() {
+      _stage = _Stage.idle;
+      _message = null;
+    });
+    widget.onUpdateAccepted?.call();
+    if (!Platform.isAndroid) {
+      // 更新检查本就仅 Android 触发，这里兜底非 Android 走浏览器
+      final uri = Uri.tryParse(widget.url);
+      if (uri == null) return;
+      try {
+        await launchUrl(uri, mode: LaunchMode.externalApplication);
+      } catch (_) {}
+      return;
+    }
+    // APK 已下载完成（下载是原子落盘，.part 改名后文件才存在）→ 跳过下载直接安装
+    if (_apkFile.existsSync()) {
+      await _install();
+      return;
+    }
+    await _download();
+  }
+
+  Future<void> _download() async {
+    setState(() {
+      _stage = _Stage.downloading;
+      _progress = 0;
+    });
     try {
-      await launchUrl(uri, mode: LaunchMode.externalApplication);
+      if (_apkPart.existsSync()) _apkPart.deleteSync();
+      final res = await _client.send(http.Request('GET', Uri.parse(widget.url)));
+      if (res.statusCode != 200) {
+        throw HttpException('HTTP ${res.statusCode}');
+      }
+      final total = res.contentLength ?? -1;
+      final sink = _apkPart.openWrite();
+      var received = 0;
+      await for (final chunk in res.stream) {
+        sink.add(chunk);
+        received += chunk.length;
+        if (mounted && total > 0) {
+          setState(() => _progress = received / total * 100);
+        }
+      }
+      await sink.close();
+      // 原子落盘：下载完成后才重命名为正式文件，避免残留半包被当成完整 APK
+      _apkPart.renameSync(_apkFile.path);
+      if (!mounted) return;
+      await _install();
     } catch (_) {
-      // 跳转失败保持页面，用户可重试
+      if (_apkPart.existsSync()) _apkPart.deleteSync();
+      if (!mounted) return;
+      setState(() {
+        _stage = _Stage.failed;
+        _progress = null;
+        _message = '下载失败，请检查网络后重试';
+      });
+    }
+  }
+
+  Future<void> _install() async {
+    setState(() {
+      _stage = _Stage.installing;
+      _progress = 0;
+      _message = null;
+    });
+    await _installSub?.cancel();
+    _installSub = ApkInstaller.progress().listen((e) {
+      if (!mounted) return;
+      switch (e.event) {
+        case 'progress':
+          setState(() => _progress = e.progress.toDouble());
+          break;
+        case 'finished':
+          final ok = e.success == true;
+          setState(() {
+            _stage = ok ? _Stage.finished : _Stage.failed;
+            _message = ok ? '安装完成，请从桌面打开新版应用' : '安装失败，请重试';
+          });
+          break;
+        case 'failed':
+          setState(() {
+            _stage = _Stage.failed;
+            _message = e.error ?? '安装失败，请重试';
+          });
+          break;
+      }
+    }, onError: (Object _) {
+      if (!mounted) return;
+      setState(() {
+        _stage = _Stage.failed;
+        _message = '安装失败，请重试';
+      });
+    });
+    final result = await ApkInstaller.install(_apkFile.path);
+    if (!mounted) return;
+    if (result == 'permission_required') {
+      // 原生侧已拉起系统设置页；APK 已缓存，用户开启后返回再点直达安装
+      setState(() {
+        _stage = _Stage.failed;
+        _message = '请在系统设置中允许「安装未知应用」，返回后再次点击「立即更新」（APK 已缓存，无需重新下载）';
+      });
     }
   }
 
   @override
   Widget build(BuildContext context) {
     final theme = Theme.of(context);
+    final busy = _stage == _Stage.downloading || _stage == _Stage.installing;
+    final progressText = _stage == _Stage.downloading
+        ? (_progress == null ? '下载中…' : '下载中 ${_progress!.round()}%')
+        : (_progress == null ? '安装中…' : '安装中 ${_progress!.round()}%');
+
     return PopScope(
       canPop: false,
       child: Scaffold(
@@ -46,23 +183,47 @@ class UpdateScreen extends StatelessWidget {
                 Icon(Icons.system_update_alt,
                     size: 64, color: theme.colorScheme.primary),
                 const SizedBox(height: 16),
-                Text('发现新版本 $version',
+                Text('发现新版本 ${widget.version}',
                     style: theme.textTheme.headlineSmall),
                 const SizedBox(height: 12),
-                if (notes.isNotEmpty)
-                  Text(notes,
+                if (widget.notes.isNotEmpty)
+                  Text(widget.notes,
                       textAlign: TextAlign.center,
                       style: const TextStyle(height: 1.6)),
                 const SizedBox(height: 24),
+                if (busy) ...[
+                  LinearProgressIndicator(
+                    value: _progress == null ? null : _progress! / 100,
+                    minHeight: 6,
+                  ),
+                  const SizedBox(height: 12),
+                  Text(progressText),
+                  const SizedBox(height: 24),
+                ],
                 FilledButton.icon(
-                  onPressed: _launch,
+                  onPressed: busy || _stage == _Stage.finished
+                      ? null
+                      : _launch,
                   icon: const Icon(Icons.download),
-                  label: const Text('立即更新'),
+                  label: Text(_stage == _Stage.finished ? '已完成' : '立即更新'),
                   style: FilledButton.styleFrom(
                     minimumSize: const Size(200, 48),
                     textStyle: const TextStyle(fontSize: 16),
                   ),
                 ),
+                if (_message != null) ...[
+                  const SizedBox(height: 12),
+                  Text(
+                    _message!,
+                    textAlign: TextAlign.center,
+                    style: TextStyle(
+                      height: 1.5,
+                      color: _stage == _Stage.failed
+                          ? theme.colorScheme.error
+                          : Colors.green,
+                    ),
+                  ),
+                ],
                 const SizedBox(height: 12),
                 Text('不更新将无法继续使用',
                     style: theme.textTheme.bodySmall