无法分别构建 Flutter Web 和 Flutter Mobile 应用

Question

我正在构建一个 Flutter 项目，但在将 Web 和移动代码集成到一个项目中时遇到了问题。我想在我的移动代码中使用 Moor 和 Moor_FFI，但是即使我的 web 入口点 (main.dart) 和移动代码 (main.dev.dart) 配置为与调试不同，它仍然会尝试编译用于网络的移动代码。这会导致一个问题，因为 Flutter Web 目前不支持 FFI 和其他 Dart 插件，从而导致大量错误消息。

Error compiling dartdevc module:ffi|lib/ffi.ddc.js

packages/ffi/src/utf8.dart:6:8: Error: Not found: 'dart:ffi'
import 'dart:ffi';
       ^
packages/ffi/src/utf16.dart:6:8: Error: Not found: 'dart:ffi'
import 'dart:ffi';
       ^
packages/ffi/src/allocation.dart:5:8: Error: Not found: 'dart:ffi'
import 'dart:ffi';
       ^
packages/ffi/src/utf8.dart:23:20: Error: Type 'Struct' not found.
class Utf8 extends Struct {
                   ^^^^^^
packages/ffi/src/utf8.dart:26:21: Error: Type 'Pointer' not found.
  static int strlen(Pointer<Utf8> string) {
                    ^^^^^^^
packages/ffi/src/utf8.dart:26:21: Error: Expected 0 type arguments.
  static int strlen(Pointer<Utf8> string) {
                    ^
packages/ffi/src/utf8.dart:41:26: Error: Type 'Pointer' not found.
  static String fromUtf8(Pointer<Utf8> string) {
                         ^^^^^^^
packages/ffi/src/utf8.dart:41:26: Error: Expected 0 type arguments.
  static String fromUtf8(Pointer<Utf8> string) {
                         ^
packages/ffi/src/utf8.dart:54:10: Error: Type 'Pointer' not found.
  static Pointer<Utf8> toUtf8(String string) {
         ^^^^^^^
packages/ffi/src/utf8.dart:54:10: Error: Expected 0 type arguments.
  static Pointer<Utf8> toUtf8(String string) {
         ^
packages/ffi/src/utf16.dart:16:21: Error: Type 'Struct' not found.
class Utf16 extends Struct {
                    ^^^^^^
packages/ffi/src/utf16.dart:24:10: Error: Type 'Pointer' not found.
  static Pointer<Utf16> toUtf16(String s) {
         ^^^^^^^
packages/ffi/src/utf16.dart:24:10: Error: Expected 0 type arguments.
  static Pointer<Utf16> toUtf16(String s) {
         ^
packages/ffi/src/allocation.dart:9:7: Error: Type 'DynamicLibrary' not found.
final DynamicLibrary stdlib = Platform.isWindows
      ^^^^^^^^^^^^^^
packages/ffi/src/allocation.dart:13:29: Error: Type 'Pointer' not found.
typedef PosixMallocNative = Pointer Function(IntPtr);
                            ^^^^^^^
packages/ffi/src/allocation.dart:13:46: Error: Type 'IntPtr' not found.
typedef PosixMallocNative = Pointer Function(IntPtr);
                                             ^^^^^^
packages/ffi/src/allocation.dart:14:23: Error: Type 'Pointer' not found.
typedef PosixMalloc = Pointer Function(int);
                      ^^^^^^^
packages/ffi/src/allocation.dart:18:27: Error: Type 'Void' not found.
typedef PosixFreeNative = Void Function(Pointer);
                          ^^^^
packages/ffi/src/allocation.dart:18:41: Error: Type 'Pointer' not found.
typedef PosixFreeNative = Void Function(Pointer);
                                        ^^^^^^^
packages/ffi/src/allocation.dart:19:35: Error: Type 'Pointer' not found.
typedef PosixFree = void Function(Pointer);
                                  ^^^^^^^
packages/ffi/src/allocation.dart:23:31: Error: Type 'Pointer' not found.
typedef WinGetProcessHeapFn = Pointer Function();
                              ^^^^^^^
packages/ffi/src/allocation.dart:26:7: Error: Type 'Pointer' not found.
final Pointer processHeap = winGetProcessHeap();
      ^^^^^^^

And so on.....

有没有办法将编译器配置为只为各自的运行构建与 Web 或 Mobile 相关的文件？

供参考：Github repo 重新创建了错误：https://github.com/JoshMarkF/MoorFFIIntegrationDemo

Answer 1

编辑
flutter build web 和 flutter run -d chrome 一切正常。
因为 web ui 代码 (webui.dart) 和移动 ui 代码 (mobileui.dart) 在不同的 dart 文件中，
所以这两个文件可以有不同的import

您可以复制粘贴运行3下面三个文件，main.dart、webui.dart和mobileui.dart
您可以使用conditional import 来区分不同的网络和移动工具
所以网络和移动可以有完全不同的逻辑

使用前缀 multiPlatform 编码 sn-p 调用

import 'mobileui.dart' if (dart.library.html) 'webui.dart' as multiPlatform;
...
home:  multiPlatform.TestPlugin(),

使用Android Studio 时的工作演示与Android Emulator 和Chrome 一起运行

main.dart

import 'package:flutter/material.dart';
import 'mobileui.dart' if (dart.library.html) 'webui.dart' as multiPlatform;

void main() => runApp(MyApp());

class MyApp extends StatelessWidget { 
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(        
        primarySwatch: Colors.blue,
      ),
      home:  multiPlatform.TestPlugin(),
    );
  }
}

mobileui.dart

import 'package:flutter/material.dart';

class TestPlugin extends StatefulWidget {
  @override
  _TestPluginState createState() => _TestPluginState();
}

class _TestPluginState extends State<TestPlugin> {
  @override
  Widget build(BuildContext context) {
    return Text("Mobile");
  }
}

webui.dart

import 'package:flutter/material.dart';
import 'dart:html' as html;
import 'dart:js' as js;
import 'dart:ui' as ui;


class TestPlugin extends StatefulWidget {
  TestPlugin();

  _TestPluginState createState() => _TestPluginState();
}

class _TestPluginState extends State<TestPlugin> {
  String createdViewId = 'map_element';

  @override
  void initState() {
    // ignore: undefined_prefixed_name
    ui.platformViewRegistry.registerViewFactory(
        createdViewId,
            (int viewId) => html.IFrameElement()
          ..width = MediaQuery.of(context).size.width.toString() //'800'
          ..height = MediaQuery.of(context).size.height.toString() //'400'
          ..srcdoc = """<!DOCTYPE html><html>
          <head><title>Page Title</title></head><body><h1>This is a Heading</h1><p>This is a paragraph.</p></body></html>"""
        /*..src = "http://f12apidev32.umc.com/Tableau/jsapi_practice.aspx"*/
          ..style.border = 'none');

    super.initState();
  }

  @override
  void dispose() {
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Container(
        padding: EdgeInsets.symmetric(horizontal: 10),
        decoration: BoxDecoration(
            color: Colors.white,
            border: Border.all(color: Colors.grey[300], width: 1),
            borderRadius: BorderRadius.all(Radius.circular(5))),
        width: 200,
        height: 200,
        child: Directionality(
            textDirection: TextDirection.ltr,
            child: HtmlElementView(
              viewType: createdViewId,
            )));
  }
}