用Flutter开发自定义Plugin的方法示例
当你在开发flutter应用的时候,有时会需要调用native的api,往往遇到flutter并没有相应的package, 这时候flutter plugin就开始发挥作用了,这篇文章将会讲解开发一个简单flutter plugin的步骤和方法,好了,让我们开始动手吧。
1.在Android Studio 中创建一个Flutter Plugin 项目,如下图
上图中你能看到项目描述中写到,如果需要暴露Andorid或iOS的API给开发者时,选择"Plugin"项目类型。
这个项目我们命名为:flutter_native_log_plugin, 当我们完成创建项目后,有两个文件我们需要看一看, 一个是位于android/src下的FlutterNativeLogPlugin.java, 这段代码是用来和本地设备交互,然后将交互结果返回供flutter前端调用, 如下所示:
package com.cube8.flutter_native_log_plugin; 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.common.PluginRegistry.Registrar; /** FlutterNativeLogPlugin */ public class FlutterNativeLogPlugin implements MethodCallHandler { /** Plugin registration. */ public static void registerWith(Registrar registrar) { final MethodChannel channel = new MethodChannel(registrar.messenger(), "flutter_native_log_plugin"); channel.setMethodCallHandler(new FlutterNativeLogPlugin()); } @Override public void onMethodCall(MethodCall call, Result result) { if (call.method.equals("getPlatformVersion")) { result.success("Android " + android.os.Build.VERSION.RELEASE); } else { result.notImplemented(); } } }
另一个 /lib/mian.dart文件,这段代码是主要用来和native代码交互, 如下所示:
import 'dart:async'; import 'package:flutter/services.dart'; class FlutterNativeLogPlugin { static const MethodChannel _channel = const MethodChannel('flutter_native_log_plugin'); static Future<String> get platformVersion async { final String version = await _channel.invokeMethod('getPlatformVersion'); return version; } }
2.现在我们开始编写我们的Plugin.
在lib/flutter_native_log_plugin.dart 文件中,我们先创建一个新的方法,代码如下:
import 'dart:async'; import 'package:flutter/material.dart'; import 'package:flutter/services.dart'; enum Log { DEBUG, WARNING, ERROR } class FlutterNativeLogPlugin { static const MethodChannel _channel = const MethodChannel('flutter_native_log_plugin'); static Future<String> printLog( {Log logType, @required String tag, @required String msg}) async { String log = "debug"; if (logType == Log.WARNING) { log = "warning"; } else if (logType == Log.ERROR) { log = "error"; } else { log = "debug"; } final Map<String, dynamic> params = <String, dynamic>{ 'tag': tag, 'msg': msg, 'logType': log }; final String result = await _channel.invokeMethod('printLog', params); return result; } }
在Android端,我们将android/src下的FlutterNativePlugin.java改写如下:
package com.cube8.flutter_native_log_plugin; import android.util.Log; 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.common.PluginRegistry.Registrar; /** * FlutterNativeLogPlugin */ public class FlutterNativeLogPlugin implements MethodCallHandler { /** * Plugin registration. */ public static void registerWith(Registrar registrar) { final MethodChannel channel = new MethodChannel(registrar.messenger(), "flutter_native_log_plugin"); channel.setMethodCallHandler(new FlutterNativeLogPlugin()); } @Override public void onMethodCall(MethodCall call, Result result) { if (call.method.equals("printLog")) { String msg = call.argument("msg"); String tag = call.argument("tag"); String logType = call.argument("logType"); if (logType.equals("warning")) { Log.w(tag, msg); } else if (logType.equals("error")) { Log.e(tag, msg); } else { Log.d(tag, msg); } result.success("Logged Successfully!"); } else { result.notImplemented(); } } }
3.测试plugin。当开发完了我们的plugin之后,我们需要测试这个新plugin是否可用,于是对example/lib的main.dart文件作如下修改:
import 'package:flutter/material.dart'; import 'package:flutter_native_log_plugin/flutter_native_log_plugin.dart'; void main() => runApp(MyApp()); class MyApp extends StatefulWidget { @override _MyAppState createState() => _MyAppState(); } class _MyAppState extends State<MyApp> { @override void initState() { super.initState(); } void printLogs() async { print(await FlutterNativeLogPlugin.printLog( tag: "Debug", msg: "This is ordinary Log")); // default logType print(await FlutterNativeLogPlugin.printLog( tag: "Debug", msg: "This is warning Log", logType: Log.WARNING)); // logType = warning print(await FlutterNativeLogPlugin.printLog( tag: "Debug", msg: "This is error Log", logType: Log.ERROR)); // logType = error print(await FlutterNativeLogPlugin.printLog( tag: "Debug", msg: "This is debug Log", logType: Log.DEBUG)); // logType = debug } @override Widget build(BuildContext context) { return MaterialApp( home: Scaffold( appBar: AppBar( title: const Text('Plugin example app'), ), body: Center( child: RaisedButton( child: Text("PrintLogs"), onPressed: printLogs, ), ), ), ); } }
点击app中的按钮,控制台将看到如下输出,说明plugin可以顺利运行了。
4.最后一步就是将我们开发的plugin发布到dart pub供以后直接调用。打开控制台,需要确认定位到plugin项目的根目录,然后输入如下命令:
flutter packages pub publish --dry-run
这段命令会做一个程序相关文件和信息的检查,确保待发布的plugin信息完整,根据控制台的提示完善信息后,与下图相似:
接着输入如下命令,正式将plugin发布到dart pub中:
flutter packages pub publish
以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持脚本之家。
- JavaScript 教程
- JavaScript 编辑工具
- JavaScript 与HTML
- JavaScript 与Java
- JavaScript 数据结构
- JavaScript 基本数据类型
- JavaScript 特殊数据类型
- JavaScript 运算符
- JavaScript typeof 运算符
- JavaScript 表达式
- JavaScript 类型转换
- JavaScript 基本语法
- JavaScript 注释
- Javascript 基本处理流程
- Javascript 选择结构
- Javascript if 语句
- Javascript if 语句的嵌套
- Javascript switch 语句
- Javascript 循环结构
- Javascript 循环结构实例
- Javascript 跳转语句
- Javascript 控制语句总结
- Javascript 函数介绍
- Javascript 函数的定义
- Javascript 函数调用
- Javascript 几种特殊的函数
- JavaScript 内置函数简介
- Javascript eval() 函数
- Javascript isFinite() 函数
- Javascript isNaN() 函数
- parseInt() 与 parseFloat()
- escape() 与 unescape()
- Javascript 字符串介绍
- Javascript length属性
- javascript 字符串函数
- Javascript 日期对象简介
- Javascript 日期对象用途
- Date 对象属性和方法
- Javascript 数组是什么
- Javascript 创建数组
- Javascript 数组赋值与取值
- Javascript 数组属性和方法