Windows手机，挑文件中使用PickSingleFileAndContinue或PickMultipleFilesAndContinue [英] Windows Phone, pick file using PickSingleFileAndContinue or PickMultipleFilesAndContinue

问题描述

我被困试图实施文件选择Windows Phone的应用程序。我需要使用 FileOpenPicker 来选择库文件。我没有得到它是如何工作的。这里是我的代码：

I got stuck trying to implementing file picker for windows phone app. I need to choose files from gallery using FileOpenPicker. I didn't get how it works. Here is my code:

private readonly FileOpenPicker photoPicker = new FileOpenPicker();

// This is a constructor
public MainPage()
{
    // < ... >

    photoPicker.SuggestedStartLocation = PickerLocationId.PicturesLibrary;
    photoPicker.FileTypeFilter.Add(".jpg");
}

// I have button on the UI. On click, app shows picker where I can choose a file
private void bChoosePhoto_OnClick(object sender, RoutedEventArgs e)
{
    photoPicker.PickMultipleFilesAndContinue();
}

那么，下一步该做什么？我想我需要获得一个文件对象或东西。

So, what to do next? I guess I need to get a file object or something.

我发现此链接。这就是自定义类 ContinuationManager 实施msdn的解释。该解决方案看起来奇怪的和丑陋的。我不知道这是否是最好的之一。请帮助！

I found this link. It is msdn explanation where custom class ContinuationManager is implemented. This solution looks weird and ugly. I am not sure if it is the best one. Please help!

推荐答案

PickAndContinue是的唯一方法，将工作在Windows Phone 8.1。这不是太奇怪和丑陋，在这里不用一个简单的例子没有的 ContinuationManager 的：

PickAndContinue is the only method that would work on Windows Phone 8.1. It's not so weird and ugly, here goes a simple example without ContinuationManager:

让我们假设你要挑一个的 .JPG 的文件，可以使用FileOpenPicker：

Let's assume that you want to pick a .jpg file, you use FileOpenPicker:

FileOpenPicker picker = new FileOpenPicker();
picker.FileTypeFilter.Add(".jpg");
picker.ContinuationData.Add("keyParameter", "Parameter"); // some data which you can pass 
picker.PickSingleFileAndContinue();

一旦运行 PickSingleFileAndContinue（）; ，你的应用程序是停用。当您完成选择一个文件，然后 OnActivated 事件被触发，在那里你可以读取该文件（）你已经选择：

Once you run PickSingleFileAndContinue();, your app is deactivated. When you finish picking a file, then OnActivated event is fired, where you can read the file(s) you have picked:

protected async override void OnActivated(IActivatedEventArgs args)
{
    var continuationEventArgs = args as IContinuationActivatedEventArgs;
    if (continuationEventArgs != null)
    {
        switch (continuationEventArgs.Kind)
        {
            case ActivationKind.PickFileContinuation:
                FileOpenPickerContinuationEventArgs arguments = continuationEventArgs as FileOpenPickerContinuationEventArgs;
                string passedData = (string)arguments.ContinuationData["keyParameter"];
                StorageFile file = arguments.Files.FirstOrDefault(); // your picked file
                // do what you want
                break;
        // rest of the code - other continuation, window activation etc.

请注意，当您运行文件选择器，您的应用程序被停用，在某些罕见的情况下，它可以通过OS被终止（例如资源很少）。

Note that when you run file picker, your app is deactivated and in some rare situations it can be terminated by OS (little resources for example).

的 ContinuationManager 只是一个的帮助的，应该帮助做一些事情变得更加容易。当然，您可以实现简单的情况下，自己的行为。

The ContinuationManager is only a helper that should help to make some things easier. Of course, you can implement your own behaviour for simpler cases.

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