UrlLauncher(9700)：mailto 的组件名称为空

Question

所以我知道对于 android 版本 >= 30，您需要在清单中添加查询，但这对我来说没有用。 我正在使用 Android 版本 29。尽管如此，我还是将这些行添加到了我的清单中。

所以我的清单看起来像这样。

 <uses-permission android:name="android.permission.QUERY_ALL_PACKAGES" />
<queries>
    <intent>
        <action android:name="android.intent.action.VIEW" />
        <data android:scheme="https" />
    </intent>
    <intent>
        <action android:name="android.intent.action.DIAL" />
        <data android:scheme="tel" />
    </intent>
    <intent>
        <action android:name="android.intent.action.SEND" />
        <data android:mimeType="*/*" />
    </intent>
</queries>

我设法用下面的代码为我的机器重现了错误。尽管如此，我还是收到了这个错误：

I/UrlLauncher(10601): component name for mailto:?subject=&body= is null

下面是 main.dart

的代码

import 'package:flutter/material.dart';
import 'package:url_launcher/url_launcher.dart';

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

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({Key? key, required this.title}) : super(key: key);
  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {return Scaffold(
      body: Center(
        child: ElevatedButton(
          style: ButtonStyle(
            shape: MaterialStateProperty.all<RoundedRectangleBorder>(
              RoundedRectangleBorder(
                  borderRadius: BorderRadius.circular(18.0)),
            ),
          ),
          onPressed: () => launchEmail(
            toEmail: "js",
            subject: "dm",
            message: "jd",
          ), child: Text("null"),
        ),
      ),
    );
  }

  Future launchEmail({
    required String toEmail,
    required String subject,
    required String message,
  }) async {
    final url =
        "mailto:$toEmail?subject=${Uri.encodeFull(subject)}&body=${Uri.encodeFull(message)}";
    if (await canLaunch(url)) {
      await launch(url);
    }
  }
}

Answer 1

我为解决错误所做的工作：

我将 Android API 设置为 30+

您的 manifest.xml 应包含以下内容：

<uses-permission android:name="android.permission.QUERY_ALL_PACKAGES" />
<queries>
    <intent>
        <action android:name="android.intent.action.VIEW" />
        <data android:scheme="https" />
    </intent>
    <intent>
        <action android:name="android.intent.action.DIAL" />
        <data android:scheme="tel" />
    </intent>
    <intent>
        <action android:name="android.intent.action.SEND" />
        <data android:mimeType="*/*" />
    </intent>
</queries>

如果这不能为您解决问题，Suj 建议添加：

<package android:name="com.app" />

到您的清单

所以只需将这些行粘贴到您的清单的开头：

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    package="com.nikita.autolab">
    <uses-permission android:name="android.permission.QUERY_ALL_PACKAGES"
        tools:ignore="QueryAllPackagesPermission" />
    <queries>
        <intent>
            <action android:name="android.intent.action.VIEW" />
            <data android:scheme="https" />
        </intent>
        <intent>
            <action android:name="android.intent.action.DIAL" />
            <data android:scheme="tel" />
        </intent>
        <intent>
            <action android:name="android.intent.action.SEND" />
            <data android:mimeType="*/*" />
        </intent>
    </queries>
   <application
        android:label="AutoLab"
        android:name="${applicationName}"
        android:icon="@mipmap/ic_launcher">
        <activity
            android:name=".MainActivity"
            android:exported="true"
            android:launchMode="singleTop"
            android:theme="@style/LaunchTheme"
            android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
            android:hardwareAccelerated="true"
            android:windowSoftInputMode="adjustResize">
            <!-- Specifies an Android theme to apply to this Activity as soon as
                 the Android process has started. This theme is visible to the user
                 while the Flutter UI initializes. After that, this theme continues
                 to determine the Window background behind the Flutter UI. -->
            <meta-data
              android:name="io.flutter.embedding.android.NormalTheme"
              android:resource="@style/NormalTheme"
              />
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
        <!-- Don't delete the meta-data below.
             This is used by the Flutter tool to generate GeneratedPluginRegistrant.java -->
        <meta-data
            android:name="flutterEmbedding"
            android:value="2" />
    </application>
</manifest>

Answer 2

通过将您的 API 更新为 30 (minSdkVersion)，您限制了可以安装您的应用程序的设备和 Android 版本。

替代解决方案：不要为 mailto 链接调用 canLaunch - 仅将其用于 http 和 https!

因为我的应用程序中有 http(s) 和 mailto 链接，所以我使用 try-catch 块。

完整函数如下：

class UrlHandler {
  /// Attempts to open the given [url] in in-app browser. Returns `true` after successful opening, `false` otherwise.
  static Future<bool> open(String url) async {
    try {
      await launch(
        url,
        enableJavaScript: true,
      );
      return true;
    } catch (e) {
      log(e.toString());
      return false;
    }
  }
}