一、思路

• 1.使用dio下载apk包存放到应用的根目录下
• 2.使用channel通讯的方式调用安卓原生方法，使用FileProvider安装应用
  PS：注意需要添加相应的权限 和 配置FileProvider

二、实施

• 1.dart端创建DownloadAndUpdatePage类 实现下载apk功能，并调用通道方法安装apk

import 'package:app_update_plugin/app_update_plugin.dart';
import 'package:flutter/material.dart';
import 'package:dio/dio.dart';
import 'package:path_provider/path_provider.dart';
import 'dart:io';

class DownloadAndUpdatePage extends StatefulWidget {
  final String updateUrl;// 替换为实际的APK下载链接

  DownloadAndUpdatePage({required this.updateUrl});

  @override
  _DownloadAndUpdatePageState createState() => _DownloadAndUpdatePageState();
}

class _DownloadAndUpdatePageState extends State<DownloadAndUpdatePage> {
  late String apkPath;

  void _downloadApk() async {
    String downloadUrl = widget.updateUrl; 

    Dio dio = Dio();
    try {
      // 获取APP的文件目录路径
      Directory appDocDir = await getApplicationDocumentsDirectory();
      apkPath = '${appDocDir.path}/update.apk';

      // 下载文件
      await dio.download(downloadUrl, apkPath, onReceiveProgress: (received, total) {
        if (total != -1) {
          // 下载进度
          print((received / total * 100).toStringAsFixed(0) + "%");
        }
      });

      // 下载完成，调用安装APK函数
      _installApk(apkPath);
    } catch (e) {
      print("下载失败：$e");
    }
  }

Future<void> _installApk(String apkPath) async {
  final plugin = AppUpdatePlugin();
  // AppInstaller.installApk(apkPath);
  print('******************* apkPath ************************\n $apkPath');
  plugin.installApk(apkPath);
}

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('下载并安装APK'),
      ),
      body: Center(
        child: ElevatedButton(
          onPressed: _downloadApk,
          child: Text('下载并安装APK'),
        ),
      ),
    );
  }
}

调用方式

 Navigator.push(context, MaterialPageRoute(builder: (context){
      return DownloadAndUpdatePage(updateUrl: 'http://xxxxxx.apk',);//替换为实际生产上的apk地址
    }));

通讯代码

@override
  void installApk(String appPath){
    methodChannel.invokeMethod('installApk',{'apkPath' : appPath});
  }

• 2.安卓端代码
  创建ApkInstaller类用于安装apk

package com.example.app_update_plugin;


import android.content.Context;
import android.content.Intent;
import android.net.Uri;
import android.os.Build;
import android.os.StrictMode;
import androidx.core.content.FileProvider;
import java.io.File;

public class ApkInstaller {

    /**
     * 安装APK文件
     *
     * @param context  上下文
     * @param apkPath  APK文件的绝对路径
     */
    public static void installApk(Context context, String apkPath) {
        // 创建File对象
        File apkFile = new File(apkPath);

        // 设置文件Uri访问权限
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
            StrictMode.VmPolicy.Builder builder = new StrictMode.VmPolicy.Builder();
            StrictMode.setVmPolicy(builder.build());
        }

        // 安装APK
        Intent intent = new Intent(Intent.ACTION_VIEW);
        intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
            Uri apkUri = FileProvider.getUriForFile(context, context.getPackageName() + ".fileprovider", apkFile);
            intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
            intent.setDataAndType(apkUri, "application/vnd.android.package-archive");
        } else {
            intent.setDataAndType(Uri.fromFile(apkFile), "application/vnd.android.package-archive");
        }
        context.startActivity(intent);
    }
}

PS:其中Uri apkUri = FileProvider.getUriForFile(context, context.getPackageName() + ".fileprovider", apkFile);中的context.getPackageName() + ".fileprovider"要和配置文件中的authorities对应上(后面会提到)
通讯方法实现

package com.example.app_update_plugin;

import androidx.annotation.NonNull;

import io.flutter.embedding.engine.plugins.FlutterPlugin;
import io.flutter.plugin.common.MethodCall;
import io.flutter.plugin.common.MethodChannel;
import io.flutter.plugin.common.MethodChannel.MethodCallHandler;
import io.flutter.plugin.common.MethodChannel.Result;

import android.content.Intent;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.os.StrictMode;
import androidx.core.content.FileProvider;
//import androidx.appcompat.app.AppCompatActivity;
import java.io.File;
import android.text.TextUtils;
import android.content.Context;
import android.util.Log;

import com.example.app_update_plugin.ApkInstaller;
// 其他自定义类的导入语句...


/** AppUpdatePlugin */
public class AppUpdatePlugin implements FlutterPlugin, MethodCallHandler {
  /// The MethodChannel that will the communication between Flutter and native Android
  ///
  /// This local reference serves to register the plugin with the Flutter Engine and unregister it
  /// when the Flutter Engine is detached from the Activity
  private MethodChannel channel;
  private Context context; // 用于存储Context

  @Override
  public void onAttachedToEngine(@NonNull FlutterPluginBinding flutterPluginBinding) {
    channel = new MethodChannel(flutterPluginBinding.getBinaryMessenger(), "app_update_plugin");
    channel.setMethodCallHandler(this);
    // 获取ApplicationContext并存储在变量中
    context = flutterPluginBinding.getApplicationContext();
  }

  @Override
  public void onMethodCall(@NonNull MethodCall call, @NonNull Result result) {
    Log.e("11111","2222222");
    if (call.method.equals("getPlatformVersion")) {
      result.success("Android " + android.os.Build.VERSION.RELEASE);
    } else if (call.method.equals("installApk")) {
      String filePath = call.argument("apkPath");
      if (!TextUtils.isEmpty(filePath)) {
        String apkPath = filePath; // APK文件路径
        ApkInstaller.installApk(context, apkPath);
      } else {
        result.error("installApk", "apkPath is null", null);
      }


    } else {
      result.notImplemented();
    }
  }

  @Override
  public void onDetachedFromEngine(@NonNull FlutterPluginBinding binding) {
    channel.setMethodCallHandler(null);
  }

}

添加权限

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

image.png

添加FileProvider配置

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

PS:其中authorities的内容要和安卓端代码ApkInstaller类中的Uri apkUri = FileProvider.getUriForFile(context, context.getPackageName() + ".fileprovider", apkFile);这行中的context.getPackageName() + ".fileprovider"严格对应上否则会报错配置找不到。
在xml/路径下添加provider_paths.xml文件配置文件访问路径 如果没有这个路径手动创建一个内容如下

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

        <root-path
            name="root"
            path="app_flutter" />

        <external-path
            name="external"
            path="app_flutter" />

        <!--代表外部存储区域的根目录下的文件 Environment.getExternalStorageDirectory()/DCIM/camerademo目录-->
        <external-path
            name="mq_DCIM"
            path="app_flutter" />

        <!--代表外部存储区域的根目录下的文件 Environment.getExternalStorageDirectory()/Pictures/camerademo目录-->
        <external-path
            name="mq_Pictures"
            path="app_flutter" />

        <!--代表app 私有的存储区域 Context.getFilesDir()目录下的images目录 /data/user/0/com.hm.camerademo/files/images-->
        <files-path
            name="mq_private_files"
            path="app_flutter" />

        <!--代表app 私有的存储区域 Context.getCacheDir()目录下的images目录 /data/user/0/com.hm.camerademo/cache/images-->
        <cache-path
            name="mq_private_cache"
            path="app_flutter" />

        <!--代表app 外部存储区域根目录下的文件 Context.getExternalFilesDir(Environment.DIRECTORY_PICTURES)目录下的Pictures目录-->
        <external-files-path
            name="mq_external_files"
            path="app_flutter" />
        <!--代表app 外部存储区域根目录下的文件 Context.getExternalCacheDir目录下的images目录-->
        <external-cache-path
            name="mq_external_cache"
            path="app_flutter" />

        <root-path
            name="mq_external_cache"
            path="" />
    </paths>
</PreferenceScreen>