c# - Xamarin中如何实现Android 5.0以上的打开文件选择器？

Question

我使用下面的代码打开文件选择器，我不确定如何在 Android 5.0 及更高版本上实现它。

Action<IValueCallback, Java.Lang.String, Java.Lang.String> callback;

public FileChooserWebChromeClient(Action<IValueCallback, Java.Lang.String, Java.Lang.String> callback)
{
    this.callback = callback;
}       

//For Android 4.1
[Java.Interop.Export]
public void openFileChooser(IValueCallback uploadMsg, Java.Lang.String acceptType, Java.Lang.String capture)
{
    callback(uploadMsg, acceptType, capture);
}

// For Android > 5.0
//I am stuck here, taken from Android
[Java.Interop.Export]
public bool onShowFileChooser(WebView webView, ValueCallback<Uri[]> filePathCallback, WebChromeClient.FileChooserParams fileChooserParams)
{
    mUploadCallbackLollipop = filePathCallback;
    openFileChooserActivity();
    return true;
}

回调函数:

var chrome = new FileChooserWebChromeClient((uploadMsg, acceptType, capture) =>
{
    MainActivity.UploadMessage = uploadMsg;
    if(Build.VERSION.SdkInt < BuildVersionCodes.Kitkat)
    {
        var i = new Intent(Intent.ActionGetContent);

        //To set all type of files
        i.SetType("image/*");

        //Here File Chooser dialog is started as Activity, and it gives result while coming back from that Activity.
        ((MainActivity)this.Context).StartActivityForResult(Intent.CreateChooser(i, "File Chooser"), MainActivity.GALLERY_INTENT_CALLED);
    }
    else
    {
        var i = new Intent(Intent.ActionOpenDocument);
        i.AddCategory(Intent.CategoryOpenable);

        //To set all type of files
        i.SetType("image/*");

        //Here File Chooser dialog is started as Activity, and it gives result while coming back from that Activity.
        ((MainActivity)this.Context).StartActivityForResult(Intent.CreateChooser(i, "File Chooser"), MainActivity.GALLERY_KITKAT_INTENT_CALLED);
    }             
});

如何实现Android 5.0以上的回调，请高手帮忙

Answer 1

以下代码在 WebView for Android 5.0 (Lollipop) 中打开文件选择器

// For Android > 5.0
        [Android.Runtime.Register("onShowFileChooser", "(Landroid/webkit/WebView;Landroid/webkit/ValueCallback;Landroid/webkit/WebChromeClient$FileChooserParams;)Z", "GetOnShowFileChooser_Landroid_webkit_WebView_Landroid_webkit_ValueCallback_Landroid_webkit_WebChromeClient_FileChooserParams_Handler")]
        public override Boolean OnShowFileChooser (Android.Webkit.WebView webView, IValueCallback uploadMsg, WebChromeClient.FileChooserParams fileChooserParams)
        {
            try
            {
                callback(uploadMsg, null, null);
            }
            catch(Exception e)
            {

            }
            return true;
        }

回调可以和其他版本一样实现，但是不能直接在OnReceiveValue方法中传递路径。它应该按如下方式传递:

UploadMessage.OnReceiveValue(WebChromeClient.FileChooserParams.ParseResult(Convert.ToInt32(resultCode), intent));

我在使用以下用于旧版本的函数时出现类型转换异常。

UploadMessage.OnReceiveValue(Android.Net.Uri.Parse(string.Format("file://{0}", result.ToString())));

引用:

From Xamarin Documentation

来自 Android 源代码:

https://github.com/anthonycr/Lightning-Browser/issues/253