Flutter原生代码调用插件dart_ndk的使用

Flutter原生代码调用插件dart_ndk的使用

特性

(特性部分未提供具体内容)

开始使用

在使用 dart_ndk 插件之前,请确保您已经在项目的 pubspec.yaml 文件中添加了该依赖。

dependencies:
  dart_ndk: ^0.1.0

然后运行 flutter pub get 来获取新添加的依赖项。

使用示例

在Dart代码中使用dart_ndk

首先,在您的 Dart 文件中导入 dart_ndk 库:

import 'package:dart_ndk/dart_ndk.dart';

接下来,您可以使用 dart_ndk 提供的功能。以下是一个简单的示例:

void main() async {
  // 创建一个Ndk实例
  var ndk = Ndk();

  // 连接到Nostr网络
  await ndk.connect();

  // 发送一个事件
  var event = Event(content: "Hello, Nostr!", kind: 1);
  await ndk.sendEvent(event);

  // 监听收到的事件
  ndk.onEvent.listen((event) {
    print('Received event: ${event.content}');
  });

  // 断开连接
  await ndk.disconnect();
}

在原生代码中使用dart_ndk

如果您希望在原生代码中使用 dart_ndk,可以通过平台通道来实现。以下是一个简单的 Android 示例:

Android 原生代码

android/src/main/java/com/example/your_app/MainActivity.java 文件中添加以下代码:

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.your_app/dart_ndk";

  [@Override](/user/Override)
  public void configureFlutterEngine([@NonNull](/user/NonNull) FlutterEngine flutterEngine) {
    super.configureFlutterEngine(flutterEngine);
    new MethodChannel(flutterEngine.getDartExecutor().getBinaryMessenger(), CHANNEL).setMethodCallHandler(
      (call, result) -> {
        if (call.method.equals("connect")) {
          // 连接到Nostr网络
          result.success("Connected");
        } else if (call.method.equals("sendEvent")) {
          // 发送一个事件
          result.success("Event sent");
        } else {
          result.notImplemented();
        }
      }
    );
  }
}

Dart 代码

在您的 Dart 文件中,通过平台通道调用原生方法:

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

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(title: Text('Flutter + dart_ndk Demo')),
        body: Center(child: ElevatedButton(
          onPressed: () async {
            // 连接到Nostr网络
            await platform.invokeMethod('connect');

            // 发送一个事件
            await platform.invokeMethod('sendEvent');
          },
          child: Text('Connect & Send Event'),
        )),
      ),
    );
  }
}

final platform = MethodChannel('com.example.your_app/dart_ndk');

完整示例

以下是完整的示例代码,包含 Dart 和 Android 部分:

Dart 代码

import 'package:flutter/material.dart';
import 'package:dart_ndk/dart_ndk.dart';
import 'package:flutter/services.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(title: Text('Flutter + dart_ndk Demo')),
        body: Center(child: ElevatedButton(
          onPressed: () async {
            try {
              // 调用原生方法连接到Nostr网络
              await platform.invokeMethod('connect');

              // 调用原生方法发送事件
              await platform.invokeMethod('sendEvent');
            } on PlatformException catch (e) {
              print("Failed to call native methods: '${e.message}'.");
            }
          },
          child: Text('Connect & Send Event'),
        )),
      ),
    );
  }
}

final platform = MethodChannel('com.example.your_app/dart_ndk');

Android 代码

android/src/main/java/com/example/your_app/MainActivity.java 文件中:

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.your_app/dart_ndk";

  [@Override](/user/Override)
  public void configureFlutterEngine([@NonNull](/user/NonNull) FlutterEngine flutterEngine) {
    super.configureFlutterEngine(flutterEngine);
    new MethodChannel(flutterEngine.getDartExecutor().getBinaryMessenger(), CHANNEL).setMethodCallHandler(
      (call, result) -> {
        if (call.method.equals("connect")) {
          // 连接到Nostr网络
          result.success("Connected");
        } else if (call.method.equals("sendEvent")) {
          // 发送一个事件
          result.success("Event sent");
        } else {
          result.notImplemented();
        }
      }
    );
  }
}

更多关于Flutter原生代码调用插件dart_ndk的使用的实战教程也可以访问 https://www.itying.com/category-92-b0.html

1 回复

更多关于Flutter原生代码调用插件dart_ndk的使用的实战系列教程也可以访问 https://www.itying.com/category-92-b0.html


在 Flutter 中,如果你需要使用原生代码(例如 Android 的 NDK),你可以通过编写平台通道(Platform Channels)来调用原生代码。dart_ndk 是一个用于在 Dart 中调用 Android NDK 代码的插件。以下是如何在 Flutter 项目中使用 dart_ndk 的步骤:

1. 添加依赖

首先,在 pubspec.yaml 文件中添加 dart_ndk 的依赖:

dependencies:
  flutter:
    sdk: flutter
  dart_ndk: ^1.0.0  # 请使用最新版本

然后运行 flutter pub get 来获取依赖。

2. 创建原生代码

在 Android 项目中,你需要创建 NDK 代码。假设你已经在 android/app/src/main/cpp 目录下创建了 native-lib.cpp 文件,内容如下:

#include <jni.h>
#include <string>

extern "C" JNIEXPORT jstring JNICALL
Java_com_example_myapp_MainActivity_stringFromJNI(
        JNIEnv* env,
        jobject /* this */) {
    std::string hello = "Hello from C++";
    return env->NewStringUTF(hello.c_str());
}

3. 配置 CMakeLists.txt

android/app/src/main/cpp 目录下创建 CMakeLists.txt 文件,内容如下:

cmake_minimum_required(VERSION 3.4.1)

add_library( # Sets the name of the library.
             native-lib

             # Sets the library as a shared library.
             SHARED

             # Provides a relative path to your source file(s).
             src/main/cpp/native-lib.cpp )

find_library( # Sets the name of the path variable.
              log-lib

              # Specifies the name of the NDK library that
              # you want CMake to locate.
              log )

target_link_libraries( # Specifies the target library.
                       native-lib

                       # Links the target library to the log library
                       # included in the NDK.
                       ${log-lib} )

4. 修改 build.gradle

android/app/build.gradle 文件中,添加以下配置来启用 CMake:

android {
    ...
    externalNativeBuild {
        cmake {
            path "src/main/cpp/CMakeLists.txt"
        }
    }
    ...
}

5. 创建平台通道

在 Flutter 中,你可以通过平台通道调用原生代码。首先,在 MainActivity.kt 中设置平台通道:

package com.example.myapp

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.myapp/native"

    override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
        super.configureFlutterEngine(flutterEngine)
        MethodChannel(flutterEngine.dartExecutor.binaryMessenger, CHANNEL).setMethodCallHandler { call, result ->
            if (call.method == "getNativeString") {
                result.success(stringFromJNI())
            } else {
                result.notImplemented()
            }
        }
    }

    private external fun stringFromJNI(): String

    companion object {
        init {
            System.loadLibrary("native-lib")
        }
    }
}

6. 在 Dart 中调用原生代码

在 Dart 代码中,你可以通过 dart_ndk 插件调用原生代码:

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

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

class MyApp extends StatelessWidget {
  [@override](/user/override)
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('Flutter NDK Example'),
        ),
        body: Center(
          child: FutureBuilder<String>(
            future: DartNdk.callNativeMethod('getNativeString'),
            builder: (context, snapshot) {
              if (snapshot.connectionState == ConnectionState.waiting) {
                return CircularProgressIndicator();
              } else if (snapshot.hasError) {
                return Text('Error: ${snapshot.error}');
              } else {
                return Text('Result: ${snapshot.data}');
              }
            },
          ),
        ),
      ),
    );
  }
}
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