12月, 2019 | ソフトウェアブログ

dart, add XmlElement

dart, flutter で XmlElementを追加する方法です。

import 'package:flutter/material.dart';

import 'package:xml/xml.dart' as xml;

import 'dart:async';

import 'dart:io';

import 'dart:core';

var bookshelfXml = '''<?xml version="1.0"?>

<book>

<title lang="english">Growing a Language</title>

</book>

<book>

<title lang="english">Learning XML</title>

</book>

</bookshelf>''';

var document = xml.parse(bookshelfXml);

var element_book = xml.XmlElement(xml.XmlName('book'));

var element_title = xml.xmlElement(xml.XmlName('title'))..attributes.add(xml.XmlAttribute(xml.XmlName('lang'), 'english'))..children.add(xml.XmlText('My book'));

var element_price = xml.XmlElement(xml.XmlName('price'))..children.add(xml.XmlText('19.95'));

element_book..children.add(element_title);

element_book..children.add(element_price);

document.rootElement.children.add(element_book);

import 'package:flutter/material.dart'; import 'package:xml/xml.dart' as xml; import 'dart:async'; import 'dart:io'; import 'dart:core'; var bookshelfXml = '''<?xml version="1.0"?> <bookshelf> <book> <title lang="english">Growing a Language</title> <price>29.99</price> </book> <book> <title lang="english">Learning XML</title> <price>39.95</price> </book> </bookshelf>'''; var document = xml.parse(bookshelfXml); var element_book = xml.XmlElement(xml.XmlName('book')); var element_title = xml.xmlElement(xml.XmlName('title'))..attributes.add(xml.XmlAttribute(xml.XmlName('lang'), 'english'))..children.add(xml.XmlText('My book')); var element_price = xml.XmlElement(xml.XmlName('price'))..children.add(xml.XmlText('19.95')); element_book..children.add(element_title); element_book..children.add(element_price); document.rootElement.children.add(element_book);

import 'package:flutter/material.dart';
import 'package:xml/xml.dart' as xml;
import 'dart:async';
import 'dart:io';
import 'dart:core';

var bookshelfXml = '''<?xml version="1.0"?>
    <bookshelf>
      <book>
        <title lang="english">Growing a Language</title>
        <price>29.99</price>
      </book>
      <book>
        <title lang="english">Learning XML</title>
        <price>39.95</price>
      </book>
    </bookshelf>''';
var document = xml.parse(bookshelfXml);

var element_book = xml.XmlElement(xml.XmlName('book'));
var element_title = xml.xmlElement(xml.XmlName('title'))..attributes.add(xml.XmlAttribute(xml.XmlName('lang'), 'english'))..children.add(xml.XmlText('My book'));
var element_price = xml.XmlElement(xml.XmlName('price'))..children.add(xml.XmlText('19.95'));
element_book..children.add(element_title);
element_book..children.add(element_price);
document.rootElement.children.add(element_book);

この方法でbook要素に title が My book, price が 19.95 の book が追加されます。

<?xml version="1.0"?>

<book>

<title lang="english">Growing a Language</title>

</book>

<book>

<title lang="english">Learning XML</title>

</book>

<book>

</book>

</bookshelf>

<?xml version="1.0"?> <bookshelf> <book> <title lang="english">Growing a Language</title> <price>29.99</price> </book> <book> <title lang="english">Learning XML</title> <price>39.95</price> </book> <book> <title lang="english">My book</title> <price>19.95</price> </book> </bookshelf>

<?xml version="1.0"?>
    <bookshelf>
      <book>
        <title lang="english">Growing a Language</title>
        <price>29.99</price>
      </book>
      <book>
        <title lang="english">Learning XML</title>
        <price>39.95</price>
      </book>
      <book>
        <title lang="english">My book</title>
        <price>19.95</price>
      </book>
    </bookshelf>

children.add に別のXmlDocumentのXmlNode, XmlElement などを配置すると例外が発生します。xml.XmlElement(xml.XmlName(“book”)) 等で生成または、xml.XmlElement.copy() を使用する必要があります。

Call Kotlin method from Flutter(FlutterからKotlinのコード内のメソッドを呼び出す)

MainActivity.kt (Kotlin)

package (your.app)

import android.content.res.Configuration

import android.os.Bundle

import android.os.PersistableBundle

import androidx.annotation.NonNull

import io.flutter.embedding.android.FlutterActivity

import io.flutter.embedding.engine.FlutterEngine

import io.flutter.plugins.GeneratedPluginRegistrant

import io.flutter.embedding.android.FlutterFragment

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 io.flutter.plugin.platform.PlatformViewsController

class MainActivity: FlutterActivity() {

override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) {

GeneratedPluginRegistrant.registerWith(flutterEngine)

MethodChannel(flutterEngine.dartExecutor, CHANNEL).setMethodCallHandler { methodCall, result ->

val args = methodCall.arguments

when (methodCall.method) {

"method1" -> {

val number = 10

result.success(number)

}

companion object {

private val CHANNEL = "com.your.app.flutter/method1"

}

package (your.app) import android.content.res.Configuration import android.os.Bundle import android.os.PersistableBundle import androidx.annotation.NonNull import io.flutter.embedding.android.FlutterActivity import io.flutter.embedding.engine.FlutterEngine import io.flutter.plugins.GeneratedPluginRegistrant import io.flutter.embedding.android.FlutterFragment 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 io.flutter.plugin.platform.PlatformViewsController class MainActivity: FlutterActivity() { override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) { GeneratedPluginRegistrant.registerWith(flutterEngine) MethodChannel(flutterEngine.dartExecutor, CHANNEL).setMethodCallHandler { methodCall, result -> val args = methodCall.arguments when (methodCall.method) { "method1" -> { val number = 10 result.success(number) } } } } companion object { private val CHANNEL = "com.your.app.flutter/method1" } }

package (your.app)

import android.content.res.Configuration
import android.os.Bundle
import android.os.PersistableBundle
import androidx.annotation.NonNull
import io.flutter.embedding.android.FlutterActivity
import io.flutter.embedding.engine.FlutterEngine
import io.flutter.plugins.GeneratedPluginRegistrant

import io.flutter.embedding.android.FlutterFragment
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 io.flutter.plugin.platform.PlatformViewsController


class MainActivity: FlutterActivity() {
    override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) {
        GeneratedPluginRegistrant.registerWith(flutterEngine)

        MethodChannel(flutterEngine.dartExecutor, CHANNEL).setMethodCallHandler { methodCall, result ->
            val args = methodCall.arguments
            when (methodCall.method) {
                "method1" -> {
                    val number = 10
                    result.success(number)
                }
            }
        }
    }

    companion object {
        private val CHANNEL = "com.your.app.flutter/method1"
    }

}

Dart

static const platform = const MethodChannel('com.your.app.flutter/method1');

Future<void> _Method1() async{

int _number;

try {

final int result = await platform.invokeMethod('method1');

_number = result;

setState(() {

number = _number;

});

} on PlatformException catch (e)

{

setState(() {

number = -1;

});

}

int number;

Widget ShowNumber()

{

Text(number.toString());

}

static const platform = const MethodChannel('com.your.app.flutter/method1'); Future<void> _Method1() async{ int _number; try { final int result = await platform.invokeMethod('method1'); _number = result; setState(() { number = _number; }); } on PlatformException catch (e) { setState(() { number = -1; }); } } int number; Widget ShowNumber() { Text(number.toString()); }

static const platform = const MethodChannel('com.your.app.flutter/method1');

Future<void> _Method1() async{
    int _number;
    try {
      final int result = await platform.invokeMethod('method1');
      _number = result;

      setState(() {
        number = _number;
      });

    } on PlatformException catch (e)
    {
      setState(() {
        number = -1;
      });
    }
}

int number;

Widget ShowNumber()
{
  Text(number.toString());
}

_Method1() を呼び出すと Kotlin側のmethod1 -> {} が実行され、結果が Flutter側の result に戻ります。

String testString = “abc”;
platform.invokeMethod(‘method1’, testString); でtestStringを引数にできます。
Kotlin側の methodCall.arguments で引数を取得できます。

io.flutter.app.FlutterActivity の FlutterActivity には FlutterEngine が存在しないのでGeneratedPluginRegistrant.registerWith(this) ではregistできません。またMethodCall の flutterView の代わり(java では getFlutterView() )に flutterEngine.dartExecutor を使用します。

2019-12-05の時点で app/build.gradle 内で Cannot resolve symbol ‘GradleException’ が、MainActivity.kt で Unresolved reference: NonNull がそれぞれ赤字で表示されます。2019-12-07のAndroid Studio アップデートとFlutter Pluginのアップデートで表示されなくなったようです。

GradleException, androidx.annotation.NonNull

Kotlin Complier の Kotlin JVM Version を 1.6 から 1.8 に変更したところエラーがなくなりました。

こちらのサイトの情報が参考になりました。

https://github.com/flutter/flutter/issues/41102
https://qiita.com/tasogarei/items/bf3761139d46c43d5896
https://qiita.com/unsoluble_sugar/items/ae42b5faf52a491f6470
https://flutter.keicode.com/basics/method-channel-java.php

Google Play Licensing Verification Library (LVL)

Android Studio 3.5 でGoogle Play Licensing Verification Library (LVL) をインポートする方法です。

File – New – Import Module .. を選択して Source directory: に [ANDROID_SDK]/extras/google/market_licensing/library を指定します。Finishをクリックします。プロジェクト内にlibrary ディレクトリーが作成され、インポートされます。
library/src/main/java/com を android/app/src/main/java/com にコピーします。
AndroidManifest.xmlに次の要素を追加します。

<!-- Devices >= 3 have version of Google Play that supports licensing. -->
<uses-sdk android:minSdkVersion="3" />
<!-- Required permission to check licensing. -->
<uses-permission android:name="com.android.vending.CHECK_LICENSE" />