当然，app_runner 是一个在 Flutter 应用中用于运行和管理其他应用的插件。尽管 app_runner 并不是一个广泛认知的官方 Flutter 插件，但基于你的要求，我将提供一个假设性的示例代码，展示如何在 Flutter 应用中使用一个类似功能的插件来启动和管理其他应用。

在实际开发中，Flutter 本身并不直接提供运行其他应用的 API，但可以通过调用原生代码（Android 的 Intent 和 iOS 的 URL Scheme）来实现这一功能。以下是一个基于 platform_channel 的示例，它展示了如何在 Flutter 中与原生代码交互来启动另一个应用。

Flutter 端代码

首先，创建一个 Flutter 插件接口，用于与原生代码通信。

import 'package:flutter/services.dart';

class AppRunner {
  static const MethodChannel _channel = MethodChannel('com.example.app_runner');

  static Future<void> launchApp(String packageName) async {
    try {
      await _channel.invokeMethod('launchApp', packageName);
    } on PlatformException catch (e) {
      print("Failed to launch app: '${e.message}'.");
    }
  }
}

Android 端代码

在 MainActivity.kt 或 MainActivity.java 中处理来自 Flutter 的方法调用。

Kotlin 版本

package com.example.myapp

import android.content.ActivityNotFoundException
import android.content.ComponentName
import android.content.Context
import android.content.Intent
import android.content.pm.PackageManager
import androidx.annotation.NonNull
import io.flutter.embedding.android.FlutterActivity
import io.flutter.embedding.engine.FlutterEngine
import io.flutter.plugin.common.MethodChannel

class MainActivity: FlutterActivity() {
    private val CHANNEL = "com.example.app_runner"

    override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) {
        super.configureFlutterEngine(flutterEngine)
        MethodChannel(flutterEngine.dartExecutor.binaryMessenger, CHANNEL).setMethodCallHandler { call, result ->
            if (call.method == "launchApp") {
                val packageName = call.argument<String>("packageName") ?: return@setMethodCallHandler result.error("INVALID_ARGUMENT", "Package name is required", null)
                try {
                    launchApp(packageName)
                    result.success(null)
                } catch (e: Exception) {
                    result.error("FAILED", e.message, null)
                }
            } else {
                result.notImplemented()
            }
        }
    }

    private fun launchApp(packageName: String) {
        val pm = packageManager
        val launchIntent = pm.getLaunchIntentForPackage(packageName) ?: return
        startActivity(launchIntent)
    }
}

Java 版本

package com.example.myapp;

import android.content.ActivityNotFoundException;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import androidx.annotation.NonNull;
import io.flutter.embedding.android.FlutterActivity;
import io.flutter.embedding.engine.FlutterEngine;
import io.flutter.plugin.common.MethodChannel;

public class MainActivity extends FlutterActivity {
    private static final String CHANNEL = "com.example.app_runner";

    @Override
    public void configureFlutterEngine(@NonNull FlutterEngine flutterEngine) {
        super.configureFlutterEngine(flutterEngine);
        new MethodChannel(flutterEngine.getDartExecutor().getBinaryMessenger(), CHANNEL)
                .setMethodCallHandler(
                        (call, result) -> {
                            if (call.method.equals("launchApp")) {
                                String packageName = call.argument("packageName");
                                if (packageName == null) {
                                    result.error("INVALID_ARGUMENT", "Package name is required", null);
                                    return;
                                }
                                try {
                                    launchApp(packageName);
                                    result.success(null);
                                } catch (Exception e) {
                                    result.error("FAILED", e.getMessage(), null);
                                }
                            } else {
                                result.notImplemented();
                            }
                        }
                );
    }

    private void launchApp(String packageName) throws Exception {
        PackageManager pm = getPackageManager();
        Intent launchIntent = pm.getLaunchIntentForPackage(packageName);
        if (launchIntent == null) {
            throw new ActivityNotFoundException();
        }
        startActivity(launchIntent);
    }
}

iOS 端代码

在 iOS 中，你可以使用 URL Scheme 来启动其他应用。首先，在 Info.plist 中声明你的应用可以查询其他应用的 URL Scheme。然后，在 AppDelegate.swift 或 AppDelegate.m 中处理 Flutter 的方法调用。

Swift 版本

import UIKit
import Flutter

@UIApplicationMain
@objc class AppDelegate: FlutterAppDelegate {
  override func application(
    _ application: UIApplication,
    didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
  ) -> Bool {
    GeneratedPluginRegistrant.register(with: self)
    
    let controller : FlutterViewController = window?.rootViewController as! FlutterViewController
    let channel = FlutterMethodChannel(name: "com.example.app_runner", binaryMessenger: controller.binaryMessenger)
    channel.setMethodCallHandler({
      (call: FlutterMethodCall, result: @escaping FlutterResult) in
      if call.method == "launchApp" {
        guard let urlScheme = call.arguments as? String else {
          result(FlutterError(code: "INVALID_ARGUMENT", message: "URL Scheme is required", details: nil))
          return
        }
        if let url = URL(string: "\(urlScheme)://") {
          if UIApplication.shared.canOpenURL(url) {
            UIApplication.shared.open(url, options: [:], completionHandler: nil)
            result(success: nil)
          } else {
            result(FlutterError(code: "FAILED", message: "App not installed", details: nil))
          }
        } else {
          result(FlutterError(code: "INVALID_ARGUMENT", message: "Invalid URL Scheme", details: nil))
        }
      } else {
        result(FlutterMethodNotImplemented)
      }
    })
    
    return super.application(application, didFinishLaunchingWithOptions: launchOptions)
  }
}

Objective-C 版本

#import "AppDelegate.h"
#import <Flutter/Flutter.h>

@interface AppDelegate ()
@end

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application
    didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
  [GeneratedPluginRegistrant registerWithRegistry:self];
  
  FlutterViewController *controller = (FlutterViewController *)self.window.rootViewController;
  FlutterMethodChannel* channel = [FlutterMethodChannel methodChannelWithName:@"com.example.app_runner" binaryMessenger:controller.binaryMessenger];
  [channel setMethodCallHandler:^(FlutterMethodCall* call, FlutterResult result) {
    if ([call.method isEqualToString:@"launchApp"]) {
      NSString *urlScheme = call.arguments;
      if (!urlScheme) {
        result([FlutterError errorWithCode:@"INVALID_ARGUMENT"
                                   message:@"URL Scheme is required"
                                   details:nil]);
        return;
      }
      NSURL *url = [NSURL URLWithString:[NSString stringWithFormat:@"%@://", urlScheme]];
      if (url && [[UIApplication sharedApplication] canOpenURL:url]) {
        [[UIApplication sharedApplication] openURL:url options:@{} completionHandler:nil];
        result(nil);
      } else {
        result([FlutterError errorWithCode:@"FAILED"
                                   message:@"App not installed"
                                   details:nil]);
      }
    } else {
      result(FlutterMethodNotImplemented);
    }
  }];
  
  return [super application:application didFinishLaunchingWithOptions:launchOptions];
}

@end

使用插件

在你的 Flutter 应用中，你可以这样使用 AppRunner 插件：

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  [@override](/user/override)
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('App Runner Demo'),
        ),
        body: Center(
          child: ElevatedButton(
            onPressed: () {
              AppRunner.launchApp('com.example.targetapp'); // 替换为目标应用的包名或 URL Scheme
            },
            child: Text('Launch