Xamarin+Prism開發詳解七：Plugin開發與打包測試

如何快速開發Xamarin.Forms的Plugin？自己開發的Plugin如何使用Nuget打包？本地Package如何參照引用？本文通過TextToSpeech實例為你講解。 ...

有了上章【Xamarin+Prism開發詳解六：DependencyService與IPlatformInitializer的關係】的基礎，現在來理解Plugin開發就簡單了。

本文實例代碼地址：https://github.com/NewBLife/XamarinDemo/tree/master/Speecher

簡介

Plugin其實就是各類相對獨立的功能提取出來的Package，一般都不引用Xamarin相關類庫，比如上章的Text To Speech功能（Github庫地址https://github.com/jamesmontemagno/TextToSpeechPlugin）：

xamarin的Plugin有一個專門的統計庫【xamarin/XamarinComponents】，目前統計結果如下:

Name	Description	NuGet	Docs & Source	Creator
Battery Status	Gather battery level, charging status, and type.	NuGet	GitHub	@JamesMontemagno
Barcode Scanner	Scan and create barcodes with ZXing.NET.Mobile.	NuGet	GitHub	@Redth
Bluetooth LE	Scan and connect to Bluetooth devices.	NuGet	GitHub	@allanritchie911
Calendar	Query and modify device calendars	NuGet	GitHub	Caleb Clarke
Compass	Access device compass heading.	NuGet	GitHub	@cbartonnh & @JamesMontemagno
Connectivity	Get network connectivity info such as type and if connection is available.	NuGet	GitHub	@JamesMontemagno
Cryptography	PCL Crypto provides a consistent, portable set of crypto APIs.	NuGet	GitHub	@aarnott
Device Info	Properties about device such as OS, Model, and Id.	NuGet	GitHub	@JamesMontemagno
Device Motion	Provides access to Accelerometer, Gyroscope, Magnetometer, and Compass.	NuGet	GitHub	@rdelrosario
Embedded Resource	Unpack embedded resource cross-platform.	NuGet	GitHub	@JosephHill
External Maps	Launch external maps from Lat/Long or Address.	NuGet	GitHub	@JamesMontemagno
File Storage/File System	PCL Storage offers cross platform storage APIs.	NuGet	GitHub	@dsplaisted
File Picker	Pick and save files.	NuGet	GitHub	@studyxnet
Fingerprint	Access Fingerprint sensor on iOS, Android, and Windows.	NuGet	GitHub	@smstuebe
FFImageLoading	Image loading with caching, placeholders, transformations and more	NuGet	GitHub	@molinch, @daniel-luberda
Geofencing	Monitor regions when user enters/exits.	NuGet	GitHub	@allanritchie911
Geolocator	Easily detect GPS location of device.	NuGet	GitHub	@JamesMontemagno
iBeacon & Estimote	Range and monitor Bluetooth beacons.	NuGet	GitHub	@allanritchie911
Lamp	Access to LED	NuGet	GitHub	@kphillpotts
Local Notifications	Show local notifications	NuGet	GitHub	@EdSnider, @JamesMontemagno
Manage Sleep	Manage auto sleep/auto lock.	NuGet	GitHub	@molinch0
Media	Take or pick photos and videos.	NuGet	GitHub	@JamesMontemagno
Media Manager	Playback for Audio.	NuGet	GitHub	@mhvdijk
Messaging	Make phone call, send sms, and send e-mail	NuGet	GitHub	@cjlotz
Microsoft Band	Connect and communicate with the Microsoft Band from shared code!	NuGet	GitHub	@mattleibow
Mono.Data.Sqlite	Add Mono.Data.Sqlite to any Xamarin or Windows .NET app.	NuGet	GitHub	@mattleibow
Permissions	Easily check and request runtime permissions.	NuGet	GitHub	@JamesMontemagno
Persistent key-value store	Akavache is an asynchronous, persistent (i.e. writes to disk) key-value store.	NuGet	GitHub	@paulcbetts
Portable Razor	Lightweight implemenation of ASP.NET MVC APIs for mobile.	NuGet	GitHub	@JosephHill
Push Notifications	Cross platform iOS and Android Push Notifications.	NuGet	GitHub	@rdelrosario
Secure Storage	Provides secure storage for key value pairs Data	NuGet	GitHub	@sameerIOTApps
Settings	Simple & Consistent cross platform settings API.	NuGet	GitHub	@JamesMontemagno
Share	Easily share text, links, or open a browser.	NuGet	GitHub	@JamesMontemagno & @Jakob Gürtl
Sockets	TCP & UDP Listeners and Clients + UDP multicast.	NuGet	GitHub	@rdavis_au
Speech Recognition	Speech to Text.	NuGet	GitHub	@allanritchie911
Text To Speech	Talk back text from shared code.	NuGet	GitHub	@JamesMontemagno
Toast	A simple way of showing toast/pop-up notifications.	NuGet	GitHub	@AdamPed & @EgorBo
User Dialogs	Message box style dialogs.	NuGet	GitHub	@allanritchie911
Version Tracking	Track which versions of your app a user has previously installed.	NuGet	GitHub	@ColbyLWilliams
Vibrate	Vibrate any device.	NuGet	GitHub	@JamesMontemagno

開發實踐

Xamarin為Plugin開發提供了一個Visual Studio模板，通過它你可以快速開發各類Plugin。

1、安裝Plugin for Xamarin Templates

2、從Plugin for Xamarin模板新建項目

整體項目結構：

通過模板創建的項目包含三類工程文件：

Plugin.功能名（PCL）：懶漢式實例創建文件，生成Plugin.功能名.dll。（共用類文件）
Plugin.功能名.Abstractions(PCL)：介面和Enums的定義，生成Plugin.功能名.Abstractions.dll。
Plugin.功能名.平臺名（n個）：介面實現，生成Plugin.功能名.dll。

3、添加介面

namespace Plugin.Speecher.Abstractions
{
    /// <summary>
    /// Interface for Speecher
    /// </summary>
    public interface ISpeecher
    {
        void Speak(string text);
    }
}

4、各個平臺介面實現

iOS平臺

using AVFoundation;
using Plugin.Speecher.Abstractions;


namespace Plugin.Speecher
{
    /// <summary>
    /// Implementation for Speecher
    /// </summary>
    public class SpeecherImplementation : ISpeecher
    {
        public void Speak(string text)
        {
            var speechSynthesizer = new AVSpeechSynthesizer();

            var speechUtterance = new AVSpeechUtterance(text)
            {
                Rate = AVSpeechUtterance.MaximumSpeechRate / 4,
                Voice = AVSpeechSynthesisVoice.FromLanguage("en-US"),
                Volume = 0.5f,
                PitchMultiplier = 1.0f
            };

            speechSynthesizer.SpeakUtterance(speechUtterance);
        }
    }
}

Android平臺（由於沒有Xamarin.Forms,所以這裡使用Application.Context）

using Android.App;
using Android.Runtime;
using Android.Speech.Tts;
using Plugin.Speecher.Abstractions;
using System.Collections.Generic;

namespace Plugin.Speecher
{
    /// <summary>
    /// Implementation for Feature
    /// </summary>
    public class SpeecherImplementation : Java.Lang.Object, ISpeecher, TextToSpeech.IOnInitListener
    {
        TextToSpeech speaker;
        string toSpeak;
        public SpeecherImplementation() { }

        public void Speak(string text)
        {
            var ctx = Application.Context;
            toSpeak = text;
            if (speaker == null)
            {
                speaker = new TextToSpeech(ctx, this);
            }
            else
            {
                var p = new Dictionary<string, string>();
                speaker.Speak(toSpeak, QueueMode.Flush, p);
            }
        }

        public void OnInit([GeneratedEnum] OperationResult status)
        {
            if (status.Equals(OperationResult.Success))
            {
                var p = new Dictionary<string, string>();
                speaker.Speak(toSpeak, QueueMode.Flush, p);
            }
            else
            {
                System.Diagnostics.Debug.WriteLine("was quiet");
            }
        }
    }
}

UWP平臺

using Plugin.Speecher.Abstractions;
using System;
using Windows.Media.SpeechSynthesis;
using Windows.UI.Xaml.Controls;

namespace Plugin.Speecher
{
    /// <summary>
    /// Implementation for Feature
    /// </summary>
    public class SpeecherImplementation : ISpeecher
    {
        public async void Speak(string text)
        {
            MediaElement mediaElement = new MediaElement();

            var synth = new SpeechSynthesizer();
            var stream = await synth.SynthesizeTextToStreamAsync(text);
            mediaElement.SetSource(stream, stream.ContentType);
            mediaElement.Play();
        }
    }
}

備註

如果確定一直使用Prism做開發的話，只需要定義介面與介面的實現就可以了。然後在實際項目各個平臺的RegisterTypes方法中註冊介面到IOC容器，

public void RegisterTypes(IUnityContainer container)
{
container.RegisterType<ISpeecher, SpeecherImplementation>();
}

使用IOC容器管理對象生存周期，比懶漢式載入更加自由方便。比如在Prism.Forms中只需構造函數添加介面作為參數就可以自動創建對象。

打包並測試

在安裝Plugin for Xamarin Templates的時候其實已經安裝了另外一個打包用的模板【Plugin for Xamarin NuSpec】，通過它可以快速打包。

1、添加Package配置文件【Speecher.Plugin.nuspec】

預設生成的文件如下，包含所有平臺：

<?xml version="1.0" encoding="utf-8"?>
<package xmlns="http://schemas.microsoft.com/packaging/2010/07/nuspec.xsd">
    <metadata minClientVersion="2.8.3">
        <id>Plugin.Speecher</id>
        <version>1.0.0</version>
        <title>Speecher Plugin for Xamarin and Windows</title>
        <authors>Your Name</authors>
        <owners>Your Name</owners>
        <licenseUrl/>
        <projectUrl/>
        <!--Default Icon, a template can be found:  https://raw.githubusercontent.com/jamesmontemagno/Xamarin-Templates/master/Plugins-Templates/icons/plugin_icon.png-->  
        <iconUrl>https://raw.githubusercontent.com/jamesmontemagno/Xamarin-Templates/master/Plugins-Templates/icons/plugin_icon_nuget.png</iconUrl>

        <requireLicenseAcceptance>false</requireLicenseAcceptance>
        <description>
         Long description for your plugin.
        </description>
        <summary>Short description for your plugin.</summary>
        <tags>xamarin, pcl, xam.pcl, plugin, plugin for xamarin, windows phone, winphone, wp8, winrt, android, xamarin.forms, ios</tags>
        <dependencies>
            <group targetFramework="net">
            </group>
            <group targetFramework="win">
            </group>
            <group targetFramework="wp">
            </group>
            <group targetFramework="wpa">
            </group>
            <group targetFramework="MonoAndroid">
            </group>
            <group targetFramework="Xamarin.iOS10">
            </group>
            <group targetFramework="Xamarin.Mac20">
            </group>
            <group targetFramework="portable-net45+win+wpa81+wp80">
            </group>
            <group targetFramework="uap">
            </group>
            <group targetFramework="dotnet">
            </group>
        </dependencies>
    </metadata>
    <files>
        <!--Core-->
        <file src="Speecher\Plugin.Speecher\bin\Release\Plugin.Speecher.dll" target="lib\portable-net45+wp8+wpa81+win8+MonoAndroid10+MonoTouch10+Xamarin.iOS10+UAP10\Plugin.Speecher.dll" />
        <file src="Speecher\Plugin.Speecher\bin\Release\Plugin.Speecher.xml" target="lib\portable-net45+wp8+wpa81+win8+MonoAndroid10+MonoTouch10+Xamarin.iOS10+UAP10\Plugin.Speecher.xml" />
        <file src="Speecher\Plugin.Speecher\bin\Release\Plugin.Speecher.pdb" target="lib\portable-net45+wp8+wpa81+win8+MonoAndroid10+MonoTouch10+Xamarin.iOS10+UAP10\Plugin.Speecher.pdb" />
        <file src="Speecher\Plugin.Speecher.Abstractions\bin\Release\Plugin.Speecher.Abstractions.dll" target="lib\portable-net45+wp8+wpa81+win8+MonoAndroid10+MonoTouch10+Xamarin.iOS10+UAP10\Plugin.Speecher.Abstractions.dll" />
        <file src="Speecher\Plugin.Speecher.Abstractions\bin\Release\Plugin.Speecher.Abstractions.xml" target="lib\portable-net45+wp8+wpa81+win8+MonoAndroid10+MonoTouch10+Xamarin.iOS10+UAP10\Plugin.Speecher.Abstractions.xml" />
        <file src="Speecher\Plugin.Speecher.Abstractions\bin\Release\Plugin.Speecher.Abstractions.pdb" target="lib\portable-net45+wp8+wpa81+win8+MonoAndroid10+MonoTouch10+Xamarin.iOS10+UAP10\Plugin.Speecher.Abstractions.pdb" />        
        
        <!--dotnet-->
        <file src="Speecher\Plugin.Speecher\bin\Release\Plugin.Speecher.dll" target="lib\dotnet\Plugin.Speecher.dll" />
        <file src="Speecher\Plugin.Speecher\bin\Release\Plugin.Speecher.xml" target="lib\dotnet\Plugin.Speecher.xml" />
        <file src="Speecher\Plugin.Speecher\bin\Release\Plugin.Speecher.pdb" target="lib\dotnet\Plugin.Speecher.pdb" />
        <file src="Speecher\Plugin.Speecher.Abstractions\bin\Release\Plugin.Speecher.Abstractions.dll" target="lib\dotnet\Plugin.Speecher.Abstractions.dll" />
        <file src="Speecher\Plugin.Speecher.Abstractions\bin\Release\Plugin.Speecher.Abstractions.xml" target="lib\dotnet\Plugin.Speecher.Abstractions.xml" />
        <file src="Speecher\Plugin.Speecher.Abstractions\bin\Release\Plugin.Speecher.Abstractions.pdb" target="lib\dotnet\Plugin.Speecher.Abstractions.pdb" />
        
        <!--Win Phone Silverlight-->
        <file src="Speecher\Plugin.Speecher.WindowsPhone8\bin\Release\Plugin.Speecher.dll" target="lib\wp8\Plugin.Speecher.dll" />
        <file src="Speecher\Plugin.Speecher.WindowsPhone8\bin\Release\Plugin.Speecher.xml" target="lib\wp8\Plugin.Speecher.xml" />
        <file src="Speecher\Plugin.Speecher.WindowsPhone8\bin\Release\Plugin.Speecher.pdb" target="lib\wp8\Plugin.Speecher.pdb" />
        <file src="Speecher\Plugin.Speecher.Abstractions\bin\Release\Plugin.Speecher.Abstractions.dll" target="lib\wp8\Plugin.Speecher.Abstractions.dll" />
        <file src="Speecher\Plugin.Speecher.Abstractions\bin\Release\Plugin.Speecher.Abstractions.xml" target="lib\wp8\Plugin.Speecher.Abstractions.xml" />
        <file src="Speecher\Plugin.Speecher.Abstractions\bin\Release\Plugin.Speecher.Abstractions.pdb" target="lib\wp8\Plugin.Speecher.Abstractions.pdb" />
        
        <!--Win Phone 81-->
        <file src="Speecher\Plugin.Speecher.WindowsPhone81\bin\Release\Plugin.Speecher.dll" target="lib\wpa81\Plugin.Speecher.dll" />
        <file src="Speecher\Plugin.Speecher.WindowsPhone81\bin\Release\Plugin.Speecher.xml" target="lib\wpa81\Plugin.Speecher.xml" />
        <file src="Speecher\Plugin.Speecher.WindowsPhone81\bin\Release\Plugin.Speecher.pdb" target="lib\wpa81\Plugin.Speecher.pdb" />
        <file src="Speecher\Plugin.Speecher.Abstractions\bin\Release\Plugin.Speecher.Abstractions.dll" target="lib\wpa81\Plugin.Speecher.Abstractions.dll" />
        <file src="Speecher\Plugin.Speecher.Abstractions\bin\Release\Plugin.Speecher.Abstractions.xml" target="lib\wpa81\Plugin.Speecher.Abstractions.xml" />
        <file src="Speecher\Plugin.Speecher.Abstractions\bin\Release\Plugin.Speecher.Abstractions.pdb" target="lib\wpa81\Plugin.Speecher.Abstractions.pdb" />
        
        <!--WinStore-->
        <file src="Speecher\Plugin.Speecher.WindowsStore\bin\Release\Plugin.Speecher.dll" target="lib\win8\Plugin.Speecher.dll" />
        <file src="Speecher\Plugin.Speecher.WindowsStore\bin\Release\Plugin.Speecher.xml" target="lib\win8\Plugin.Speecher.xml" />
        <file src="Speecher\Plugin.Speecher.WindowsStore\bin\Release\Plugin.Speecher.pdb" target="lib\win8\Plugin.Speecher.pdb" />
        <file src="Speecher\Plugin.Speecher.Abstractions\bin\Release\Plugin.Speecher.Abstractions.dll" target="lib\win8\Plugin.Speecher.Abstractions.dll" />
        <file src="Speecher\Plugin.Speecher.Abstractions\bin\Release\Plugin.Speecher.Abstractions.xml" target="lib\win8\Plugin.Speecher.Abstractions.xml" />
        <file src="Speecher\Plugin.Speecher.Abstractions\bin\Release\Plugin.Speecher.Abstractions.pdb" target="lib\win8\Plugin.Speecher.Abstractions.pdb" />

        <!--Xamarin.Android-->
        <file src="Speecher\Plugin.Speecher.Android\bin\Release\Plugin.Speecher.dll" target="lib\MonoAndroid10\Plugin.Speecher.dll" />
        <file src="Speecher\Plugin.Speecher.Android\bin\Release\Plugin.Speecher.xml" target="lib\MonoAndroid10\Plugin.Speecher.xml" />
        <file src="Speecher\Plugin.Speecher.Android\bin\Release\Plugin.Speecher.pdb" target="lib\MonoAndroid10\Plugin.Speecher.pdb" />
        <file src="Speecher\Plugin.Speecher.Abstractions\bin\Release\Plugin.Speecher.Abstractions.dll" target="lib\MonoAndroid10\Plugin.Speecher.Abstractions.dll" />
        <file src="Speecher\Plugin.Speecher.Abstractions\bin\Release\Plugin.Speecher.Abstractions.xml" target="lib\MonoAndroid10\Plugin.Speecher.Abstractions.xml" />
        <file src="Speecher\Plugin.Speecher.Abstractions\bin\Release\Plugin.Speecher.Abstractions.pdb" target="lib\MonoAndroid10\Plugin.Speecher.Abstractions.pdb" />

        <!--Xamarin.iOS-->
        <file src="Speecher\Plugin.Speecher.iOS\bin\iPhone\Release\Plugin.Speecher.dll" target="lib\Xamarin.iOS10\Plugin.Speecher.dll" />
        <file src="Speecher\Plugin.Speecher.iOS\bin\iPhone\Release\Plugin.Speecher.xml" target="lib\Xamarin.iOS10\Plugin.Speecher.xml" />
        <file src="Speecher\Plugin.Speecher.Abstractions\bin\Release\Plugin.Speecher.Abstractions.dll" target="lib\Xamarin.iOS10\Plugin.Speecher.Abstractions.dll" />
        <file src="Speecher\Plugin.Speecher.Abstractions\bin\Release\Plugin.Speecher.Abstractions.xml" target="lib\Xamarin.iOS10\Plugin.Speecher.Abstractions.xml" />

        <!--uap-->
        <file src="Speecher\Plugin.Speecher.UWP\bin\Release\Plugin.Speecher.dll" target="lib\UAP10\Plugin.Speecher.dll" />
        <file src="Speecher\Plugin.Speecher.UWP\bin\Release\Plugin.Speecher.xml" target="lib\UAP10\Plugin.Speecher.xml" />
        <file src="Speecher\Plugin.Speecher.UWP\bin\Release\Plugin.Speecher.pdb" target="lib\UAP10\Plugin.Speecher.pdb" />
        <file src="Speecher\Plugin.Speecher.Abstractions\bin\Release\Plugin.Speecher.Abstractions.dll" target="lib\UAP10\Plugin.Speecher.Abstractions.dll" />
        <file src="Speecher\Plugin.Speecher.Abstractions\bin\Release\Plugin.Speecher.Abstractions.xml" target="lib\UAP10\Plugin.Speecher.Abstractions.xml" />
        <file src="Speecher\Plugin.Speecher.Abstractions\bin\Release\Plugin.Speecher.Abstractions.pdb" target="lib\UAP10\Plugin.Speecher.Abstractions.pdb" />
        
        <!--Xamarin.Mac
        <file src="Speecher\Plugin.Speecher.Mac\bin\iPhone\Release\Plugin.Speecher.dll" target="lib\Xamarin.Mac20\Plugin.Speecher.dll" />
        <file src="Speecher\Plugin.Speecher.Mac\bin\iPhone\Release\Plugin.Speecher.xml" target="lib\Xamarin.Mac20\Plugin.Speecher.xml" />
        <file src="Speecher\Plugin.Speecher.Abstractions\bin\Release\Plugin.Speecher.Abstractions.dll" target="lib\Xamarin.Mac20\Plugin.Speecher.Abstractions.dll" />
        <file src="Speecher\Plugin.Speecher.Abstractions\bin\Release\Plugin.Speecher.Abstractions.xml" target="lib\Xamarin.Mac20\Plugin.Speecher.Abstractions.xml" />
        -->
    </files>
</package>

由於只正對iOS，Android，UWP三個平臺，其他的配置都刪除掉
固定文件名用*代替

修改後的文件如下：

<?xml version="1.0" encoding="utf-8"?>
<package xmlns="http://schemas.microsoft.com/packaging/2010/07/nuspec.xsd">
  <metadata minClientVersion="2.8.3">
    <id>Plugin.Speecher</id>
    <version>1.0.0</version>
    <title>Speecher Plugin for Xamarin and Windows</title>
    <authors>NewBlifes</authors>
    <owners>NewBlifes</owners>
    <iconUrl>https://github.com/NewBLife/NewBlife.Core/blob/master/logo.png</iconUrl>
    <requireLicenseAcceptance>false</requireLicenseAcceptance>
    <description>
      Text to speech plugin.
    </description>
    <summary>Text to speech plugin.</summary>
    <tags>xamarin, pcl, xam.pcl, plugin, plugin for xamarin, windows phone, UWP, android, xamarin.forms, ios</tags>
    <dependencies>
      <group targetFramework="MonoAndroid">
      </group>
      <group targetFramework="Xamarin.iOS10">
      </group>
      <group targetFramework="portable-net45+win+wpa81+wp80">
      </group>
      <group targetFramework="uap">
      </group>
    </dependencies>
  </metadata>
  <files>
    <!--Core-->
    <file src="Speecher\Plugin.Speecher\bin\Release\Plugin.Speecher.*" target="lib\portable-net45+wp8+wpa81+win8+MonoAndroid10+MonoTouch10+Xamarin.iOS10+UAP10\" />

    <!--Xamarin.Android-->
    <file src="Speecher\Plugin.Speecher.Android\bin\Release\Plugin.Speecher.*" target="lib\MonoAndroid10\" />

    <!--Xamarin.iOS-->
    <file src="Speecher\Plugin.Speecher.iOS\bin\iPhone\Release\Plugin.Speecher.*" target="lib\Xamarin.iOS10\" />

    <!--uap-->
    <file src="Speecher\Plugin.Speecher.UWP\bin\Release\Plugin.Speecher.*" target="lib\UAP10\" />

  </files>
</package>

2、編譯解決方案的Release版本，使用【nuget pack】命令打包

如果沒有Nuget的命令行工具記得安裝。

3、測試

添加本地包路徑

創建測試項目，添加Package引用

測試代碼

using Plugin.Speecher;
using Prism.Commands;
using Prism.Mvvm;

namespace SpeecherTest.ViewModels
{
    public class MainPageViewModel : BindableBase
    {
        private string _speakText;
        public string SpeakText
        {
            get { return _speakText; }
            set
            {
                SetProperty(ref _speakText, value);
            }
        }

        public MainPageViewModel()
        {
        }

        public DelegateCommand SpeakCommand => new DelegateCommand(
            () =>
            {
                CrossSpeecher.Current.Speak(SpeakText);
            },
            () => !string.IsNullOrEmpty(SpeakText)).ObservesProperty(() => this.SpeakText);
    }
}

總結

通過使用Plugin For xamarin模塊來開發Plugin簡單又快速，你只需要關註真正的邏輯就可以。