MASA MAUI Plugin （八）Android相册多选照片（Intent 方式）-六虎

背景

MAUI的呈现，赋予了广阔.Net开发者开发多渠道应用的能力，MAUI 是Xamarin.Forms演化而来，可是比较Xamarin性能更好，可扩展性更强，结构更简略。可是MAUI关于渠道相关的完成并不完好。所以MASA团队开展了一个实验性项目，意在对微软MAUI的补充和扩展@

项目地址github.com/BlazorCompo…

每个功用都有独自的demo演示项目，考虑到app安装文件体积（虽然MAUI已经集成裁剪功用，可是该功用关于代码自身有影响），届时每一个功用都会以独自的nuget包的形式供给，便利测验，现在项目才刚刚开端，可是相信很快就会有能够交付的内容啦。

前语

本系列文章面向移动开发小白，从零开端进行渠道相关功用开发，演示怎么参阅渠道的官方文档运用MAUI技能来开发相应功用。

介绍

项目中有需求从相册多选图片的需求，MAUI供给的MediaPicker.PickPhotoAsync无多选功用，FilePicker.PickMultipleAsync虽然能够完成多选，可是多选文件需求长按，并且没有预览和回来按钮，用户交互作用不好。作为安卓开发小白，自己现在找到两种UI交互杰出并且不需求定制选取界面的办法和大家共享。

一、MAUI完成办法演示作用

MediaPicker.Default.PickPhotoAsync 作用

MASA MAUI Plugin （八）Android相册多选照片（Intent 方式）

FilePicker.Default.PickMultipleAsync 作用

二、完成办法

思路

developer.android.google.cn/about/versi…

咱们参阅一下官方文档，下面为挑选多张相片或者多个视频的示例

JAVA代码
// Launches photo picker in multi-select mode.
// This means that user can select multiple photos/videos, up to the limit
// specified by the app in the extra (10 in this example).
final int maxNumPhotosAndVideos = 10;
Intent intent = new Intent(MediaStore.ACTION_PICK_IMAGES);
intent.putExtra(MediaStore.EXTRA_PICK_IMAGES_MAX, maxNumPhotosAndVideos);
startActivityForResult(intent, PHOTO_PICKER_MULTI_SELECT_REQUEST_CODE);

处理相片挑选器结果

JAVA代码
// onActivityResult() handles callbacks from the photo picker.
@Override
protected void onActivityResult(
    int requestCode, int resultCode, final Intent data) {
    if (resultCode != Activity.RESULT_OK) {
        // Handle error
        return;
    }
    switch(requestCode) {
        case REQUEST_PHOTO_PICKER_SINGLE_SELECT:
            // Get photo picker response for single select.
            Uri currentUri = data.getData();
            // Do stuff with the photo/video URI.
            return;
        case REQUEST_PHOTO_PICKER_MULTI_SELECT:
            // Get photo picker response for multi select
            for (int i = 0; i < data.getClipData().getItemCount(); i++) {
                Uri currentUri = data.getClipData().getItemAt(i).getUri();
                // Do stuff with each photo/video URI.
            }
            return;
    }
}

限定挑选内容范围默认情况下，相片挑选器会既显现相片又显现视频。您还能够在 setType() 办法中设置 MIME 类型，以便按“仅显现相片”或“仅显现视频”进行过滤

JAVA代码
// Launches photo picker for videos only in single select mode.
Intent intent = new Intent(MediaStore.ACTION_PICK_IMAGES);
intent.setType("video/*");
startActivityForResult(intent, PHOTO_PICKER_VIDEO_SINGLE_SELECT_REQUEST_CODE);
// Apps can also change the mimeType to allow users to select
// images only - intent.setType("image/*");
// or a specific mimeType - intent.setType("image/gif");

总结流程如下： 1、经过Intent(MediaStore.ACTION_PICK_IMAGES) 初始化一个翻开相册的Intent 2、intent.setType 设置过滤条件 3、经过startActivityForResult翻开新的Activity（翻开相册），并经过重写onActivityResult 获取选取相片的回来数据 4、从回来的Intent 中拿到文件的Uri从而获取文件内容注意：在一个Activity中，可能会运用startActivityForResult() 办法翻开多个不同的Activity处理不同的事务 ,这时能够在onActivityResult中经过requestCode区分不同事务。

编写完成代码

新建MAUI Blazor项目MediaPickSample，新建Service文件夹，增加IPhotoPickerService.cs接口，增加GetImageAsync1-3，前两种为运用MAUI的两种办法完成，用做比照，不过多介绍，本文重点重视Intent办法完成的GetImageAsync3。示例办法的回来值为文件名+文件base64的字典形式。

namespace MediaPickSample.Service
{
    public interface IPhotoPickerService
    {
        /// <summary>
        /// Maui-MediaPicker
        /// </summary>
        Task<Dictionary<string, string>> GetImageAsync1();
        /// <summary>
        /// MMaui-FilePicker
        /// </summary>
        Task<Dictionary<string, string>> GetImageAsync2();
        /// <summary>
        /// Intent
        /// </summary>
        Task<Dictionary<string, string>> GetImageAsync3();
    }
}

由于StartActivityForResult需求在MainActivity中调用，咱们先定义一个MainActivity的静态示例Instance，便利在事务中运用。编辑Platforms->Android->MainActivity.cs文件

    public class MainActivity : MauiAppCompatActivity
    {
        internal static MainActivity Instance { get; private set; }
        public static readonly int PickImageId = 1000;
        public TaskCompletionSource<Dictionary<string, string>> PickImageTaskCompletionSource { set; get; }
        protected override void OnCreate(Bundle savedInstanceState)
        {
            Instance = this;
            base.OnCreate(savedInstanceState);
        }
        protected override void OnActivityResult(int requestCode, Result resultCode, Android.Content.Intent intent)
        {
            base.OnActivityResult(requestCode, resultCode, intent);
            if (requestCode == PickImageId)
            {
                if ((resultCode == Result.Ok) && (intent != null))
                {
                    var imageNames = intent.ClipData;
                    if (imageNames != null)
                    {
                        var uris = new List<Android.Net.Uri>();
                        for (int i = 0; i < imageNames.ItemCount; i++)
                        {
                            var imageUri = imageNames.GetItemAt(i).Uri;
                            uris.Add(imageUri);
                        }
                        var fileList = Instance.GetImageDicFromUris(uris);
                        PickImageTaskCompletionSource.SetResult(fileList);
                    }
                }
                else
                {
                    PickImageTaskCompletionSource.SetResult(new Dictionary<string, string>());
                }
            }
        }
    }

首要咱们定义了MainActivity的静态实例Instance，并在OnCreate事情中赋值然后增加重写办法OnActivityResult，经过requestCode == PickImageId判别是从相册选取多个文件的事务（咱们重视的事务），经过intent.ClipData获取数据，然后遍历这些数据顺次经过GetItemAt(i).Uri获取一切的文件Uri，然后再经过咱们封装的GetImageDicFromUris办法获取一切文件的内容。GetImageDicFromUris办法如下

        protected Dictionary<string, string> GetImageDicFromUris(List<Android.Net.Uri> list)
        {
            Dictionary<string, string> fileList = new Dictionary<string, string>();
            for (int i = 0; i < list.Count; i++)
            {
                var imageUri = list[i];
                var documentFile = DocumentFile.FromSingleUri(Instance, imageUri);
                if (documentFile != null)
                {
                    using (var stream = Instance.ContentResolver.OpenInputStream(imageUri))
                    {
                        stream.Seek(0, SeekOrigin.Begin);
                        var bs = new byte[stream.Length];
                        var log = Convert.ToInt32(stream.Length);
                        stream.Read(bs, 0, log);
                        var base64Str = Convert.ToBase64String(bs);
                        fileList.Add($"{Guid.NewGuid()}.{Path.GetExtension(documentFile.Name)}", base64Str);
                    }
                }
            }
            return fileList;
        }

DocumentFile位于AndroidX.DocumentFile.Provider命名空间，FromSingleUri办法经过Uri回来DocumentFile，然后经过ContentResolver.OpenInputStream读出文件流 ContentResolver的内容比较多，能够参阅官方文档，这儿咱们简略理解它是一个内容供给程序即可

developer.android.google.cn/guide/topic…

下面开端完成IPhotoPickerService接口在Platforms->Android 新建AndroidPhotoPickerService.cs

namespace MediaPickSample.PlatformsAndroid
{
    public class AndroidPhotoPickerService : IPhotoPickerService
    {
        /// <summary>
        /// Maui-MediaPicker
        /// </summary>
        public async Task<Dictionary<string, string>> GetImageAsync1()
        {
            ...
        }
        /// <summary>
        /// MMaui-FilePicker
        /// </summary>
        public async Task<Dictionary<string, string>> GetImageAsync2()
        {
            ...
        }
        /// <summary>
        /// Intent
        /// </summary>
        public Task<Dictionary<string, string>> GetImageAsync3()
        {
            Intent intent = new Intent(Intent.ActionPick);
            intent.SetDataAndType(MediaStore.Images.Media.ExternalContentUri, "image/*");
            intent.PutExtra(Intent.ExtraAllowMultiple,true);
            MainActivity.Instance.StartActivityForResult(Intent.CreateChooser(intent, "Select Picture"),
                MainActivity.PickImageId);
            MainActivity.Instance.PickImageTaskCompletionSource = new TaskCompletionSource<Dictionary<string, string>>();
            return MainActivity.Instance.PickImageTaskCompletionSource.Task;
        }
    }
}

咱们只重视Intent完成的GetImageAsync3办法

首要先初始化一个Intent.ActionPick类型的Intent，挑选数据咱们需求运用ACTION_PICK 类型。常见的Intent类型参阅官方文档

developer.android.google.cn/guide/compo…

intent.SetDataAndType办法设置Intent的数据和MIME数据类型

developer.android.com/reference/a…

intent.PutExtra 设置能够多选然后就能够经过MainActivity的静态实例Instance的StartActivityForResult办法发动这个intent了，咱们这儿经过Intent.CreateChooser给Intent设置了一个标题，并传递requestCode用以区分事务。

编写演示代码

修正Index.razor文件，界面运用的是MASA Blazor

@page "/"
@using Masa.BuildingBlocks.Storage.ObjectStorage;
@using MediaPickSample.Service;
<MCard Color="#FFFFFF" Class="mx-auto rounded-3 mt-3" Elevation="0">
    <MCardText>
        <div class="d-flex" style="flex-wrap: wrap">
            @if (_phoneDictionary.Any())
            {
                @foreach (var phone in _phoneDictionary)
                {
                    <div style="position: relative; height: 90px; width: 90px;" class="mr-2 mb-2">
                        <MImage Src="@phone.Value" AspectRatio="1" Class="grey lighten-2">
                            <PlaceholderContent>
                                <MRow Class="fill-height" Align="@AlignTypes.Center" Justify="@JustifyTypes.Center">
                                    <MProgressCircular Indeterminate></MProgressCircular>
                                </MRow>
                            </PlaceholderContent>
                        </MImage>
                        <MButton Small Icon Tile Style="position: absolute; top: 0; right: 0; background: #000000; opacity: 0.5;" Dark OnClick="() => RemoveItem(phone.Key)">
                            <MIcon>
                                mdi-close
                            </MIcon>
                        </MButton>
                    </div>
                }
            }
            <MBottomSheet>
                <ActivatorContent>
                    <MButton XLarge Icon Style="background: #F7F8FA;border-radius: 2px; height:80px;width:80px; " @attributes="@context.Attrs">
                        <MIcon XLarge Color="#D8D8D8">mdi-camera</MIcon>
                    </MButton>
                </ActivatorContent>
                <ChildContent>
                    <MCard>
                        <MList>
                            <MListItem OnClick="GetImageAsync1"><MListItemContent><MListItemTitle>Maui-MediaPicker</MListItemTitle></MListItemContent></MListItem>
                            <MListItem OnClick="GetImageAsync2"><MListItemContent><MListItemTitle>Maui-FilePicker</MListItemTitle></MListItemContent></MListItem>
                            <MListItem OnClick="GetImageAsync3"><MListItemContent><MListItemTitle>Intent</MListItemTitle></MListItemContent></MListItem>
                        </MList>
                    </MCard>
                </ChildContent>
            </MBottomSheet>
        </div>
    </MCardText>
</MCard>
@code {
    [Inject]
    private IPhotoPickerService _photoPickerService { get; set; }
    [Inject]
    private IClient _client { get; set; }
    private Dictionary<string, string> _phoneDictionary { get; set; } = new Dictionary<string, string>();
    private async Task GetImageAsync1()
    {
       ...
    }
    private async Task GetImageAsync2()
    {
       ...
    }
    private async Task GetImageAsync3()
    {
        var photoDic = await _photoPickerService.GetImageAsync3();
        foreach (var photo in photoDic)
        {
            var fileUrl = await UploadImageAsync(photo.Value, Path.GetExtension(photo.Key));
            _phoneDictionary.Add(photo.Key, fileUrl);
        }
    }
    private void RemoveItem(string key)
    {
        _phoneDictionary.Remove(key);
    }
    private async Task<string> UploadImageAsync(string fileBase64, string fileExtension)
    {
        byte[] fileBytes = Convert.FromBase64String(fileBase64);
        var newFileName = $"{Guid.NewGuid() + fileExtension}";
        var newFileFullPath = $"images/xxx/xxx/{newFileName}";
        using (var fileStream = new MemoryStream(fileBytes))
        {
            try
            {
                await InvokeAsync(StateHasChanged);
                await _client.PutObjectAsync("xxx", newFileFullPath, fileStream);
                return $"https://img-cdn.xxx.cn/{newFileFullPath}";
            }
            catch (Exception ex)
            {
                if (ex.Message.Contains("x-oss-hash-crc64ecma"))
                {
                    return $"https://img-cdn.xxx.cn/{newFileFullPath}";
                }
                else
                {
                    return string.Empty;
                }
            }
        }
    }
}

代码比较简略，不过多介绍，这儿的UploadImageAsync办法运用的是Masa.BuildingBlocks.Storage供给的SDK完成上传到阿里云存储。不要忘记在MauiProgram.cs增加依赖注入

#if ANDROID
            builder.Services.AddSingleton<IPhotoPickerService, AndroidPhotoPickerService>();
#endif

在AndroidManifest.xml增加必要的权限-android.permission.READ_EXTERNAL_STORAG，并增加android:usesCleartextTraffic=”true”（上传阿里云运用）

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android">
	<application android:allowBackup="true" android:icon="@mipmap/appicon" android:usesCleartextTraffic="true"  android:roundIcon="@mipmap/appicon_round" android:supportsRtl="true"></application>
	<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
	<uses-permission android:name="android.permission.INTERNET" />
	<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
</manifest>

三、演示作用

下一篇咱们介绍别的一种完成办法。

假如你对咱们的 MASA Framework 感兴趣，无论是代码贡献、运用、提 Issue，欢迎联络咱们

WeChat：MasaStackTechOps QQ：7424099

MASA MAUI Plugin （八）Android相册多选照片（Intent 方式）

背景

前语

介绍

一、MAUI完成办法演示作用

二、完成办法

思路

编写完成代码

编写演示代码

三、演示作用

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