Flutter创建自定义包插件flutter_create_own_package的使用

在Flutter开发中，有时我们需要创建自己的自定义包或插件来复用代码或者与原生代码进行交互。本文将展示如何创建一个简单的Flutter自定义包插件，并通过示例演示其使用方法。

创建自定义包插件

步骤 1: 初始化一个新的Flutter项目

首先，确保你已经安装了Flutter SDK，并且环境配置正确。然后，创建一个新的Flutter项目：

flutter create my_flutter_plugin

这会生成一个名为my_flutter_plugin的目录。

步骤 2: 进入插件目录并初始化为插件

进入项目目录并运行以下命令将其初始化为插件：

cd my_flutter_plugin
flutter pub add flutter_test
flutter pub get
flutter create --template=plugin .

步骤 3: 编写插件逻辑

在lib/my_flutter_plugin.dart文件中编写插件的核心逻辑。例如，我们创建一个简单的插件，用于返回当前时间的字符串。

// lib/my_flutter_plugin.dart
import 'dart:async';
import 'package:flutter/services.dart';

class MyFlutterPlugin {
  static const MethodChannel _channel = const MethodChannel('my_flutter_plugin');

  // 返回当前时间的字符串
  static Future<String> getCurrentTime() async {
    final String currentTime = await _channel.invokeMethod('getCurrentTime');
    return currentTime;
  }
}

步骤 4: 配置平台特定的实现

Android 实现

在Android平台上，我们需要在android/src/main/java/com/example/my_flutter_plugin/MyFlutterPlugin.java中添加原生代码。

// android/src/main/java/com/example/my_flutter_plugin/MyFlutterPlugin.java
package com.example.my_flutter_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;

public class MyFlutterPlugin implements FlutterPlugin, MethodCallHandler {
  private MethodChannel channel;

  @Override
  public void onAttachedToEngine(@NonNull FlutterPluginBinding binding) {
    channel = new MethodChannel(binding.getBinaryMessenger(), "my_flutter_plugin");
    channel.setMethodCallHandler(this);
  }

  @Override
  public void onMethodCall(@NonNull MethodCall call, @NonNull Result result) {
    if (call.method.equals("getCurrentTime")) {
      result.success(java.time.LocalTime.now().toString()); // 返回当前时间
    } else {
      result.notImplemented();
    }
  }

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

iOS 实现

在iOS平台上，我们需要在ios/Classes/SwiftMyFlutterPlugin.swift中添加原生代码。

// ios/Classes/SwiftMyFlutterPlugin.swift
import Flutter
import UIKit

public class SwiftMyFlutterPlugin: NSObject, FlutterPlugin {
  public static func register(with registrar: FlutterPluginRegistrar) {
    let channel = FlutterMethodChannel(name: "my_flutter_plugin", binaryMessenger: registrar.messenger())
    let instance = SwiftMyFlutterPlugin()
    registrar.addMethodCallDelegate(instance, channel: channel)
  }

  public func handle(_ call: FlutterMethodCall, result: @escaping FlutterResult) {
    if call.method == "getCurrentTime" {
      result(LocalTime.now()) // 返回当前时间
    } else {
      result(FlutterMethodNotImplemented)
    }
  }
}

使用自定义插件

步骤 1: 添加依赖

在需要使用该插件的Flutter项目中，将插件作为依赖项添加到项目的pubspec.yaml文件中：

dependencies:
  my_flutter_plugin: ^0.0.1

然后运行以下命令以获取依赖项：

flutter pub get

步骤 2: 调用插件

在需要使用插件的Dart代码中，导入并调用插件的功能。例如：

// main.dart
import 'package:flutter/material.dart';
import 'package:my_flutter_plugin/my_flutter_plugin.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 自定义插件示例')),
        body: Center(
          child: FutureBuilder<String>(
            future: MyFlutterPlugin.getCurrentTime(),
            builder: (context, snapshot) {
              if (snapshot.connectionState == ConnectionState.done) {
                return Text(snapshot.data ?? '加载失败');
              } else {
                return CircularProgressIndicator();
              }
            },
          ),
        ),
      ),
    );
  }
}