Xamarin. Android实现下拉刷新功能

public class PullToRefreshBase｛
       public enum Mode｛｝
       public enum State｛｝
       public Mode Mode｛get；set；｝
       public State State｛get；set；｝ 
｝

<attr path="/api/package[@name=‘com.handmark.pulltorefresh.library‘]/class[@name=‘PullToRefreshBase.Mode‘]"
        name="managedName">
    PullToRefreshMode
  </attr>

  <attr path="/api/package[@name=‘com.handmark.pulltorefresh.library‘]/class[@name=‘PullToRefreshBase.State‘]"
        name="managedName">
    PullToRefreshState
  </attr>

<attr     path="/api/package[@name=‘com.handmark.pulltorefresh.library.internal‘]/class[@name=‘RotateLoadingLayout‘]/method[@name=‘onLoadingDrawableSet‘ and count(parameter)=1 and parameter[1][@type=‘android.graphics.drawable.Drawable‘]]"
      name="visibility">protected</attr>

  <attr
       path="/api/package[@name=‘com.handmark.pulltorefresh.library‘]/class[@name=‘PullToRefreshScrollView‘]/method[@name=‘createRefreshableView‘]"
       name="managedReturn"
>Java.Lang.Object</attr>

  <attr
        path="/api/package[@name=‘com.handmark.pulltorefresh.library‘]/class[@name=‘PullToRefreshExpandableListView‘]/method[@name=‘createRefreshableView‘]"
        name="managedReturn"
>Java.Lang.Object</attr>

  <attr
      path="/api/package[@name=‘com.handmark.pulltorefresh.library‘]/class[@name=‘PullToRefreshGridView‘]/method[@name=‘createRefreshableView‘]"
      name="managedReturn"
>Java.Lang.Object</attr>

  <attr
      path="/api/package[@name=‘com.handmark.pulltorefresh.library‘]/class[@name=‘PullToRefreshHorizontalScrollView‘]/method[@name=‘createRefreshableView‘]"
      name="managedReturn"
>Java.Lang.Object</attr>

  <attr
      path="/api/package[@name=‘com.handmark.pulltorefresh.library‘]/class[@name=‘PullToRefreshListView‘]/method[@name=‘createRefreshableView‘]"
      name="managedReturn"
>Java.Lang.Object</attr>

  <attr
    path="/api/package[@name=‘com.handmark.pulltorefresh.library‘]/class[@name=‘PullToRefreshWebView‘]/method[@name=‘createRefreshableView‘]"
    name="managedReturn"
>Java.Lang.Object</attr>

[Activity(Label = "PullToRefresh.Sample", MainLauncher = true, Icon = "@drawable/icon")]
    public class MainActivity : Activity, PullToRefreshBase.IOnRefreshListener, PullToRefreshBase.IOnLastItemVisibleListener
    {        
        private List<string> mListItems;
        private PullToRefreshListView mPullRefreshListView;
        private ArrayAdapter<string> mAdapter;
        private string[] mStrings = { "Abbaye de Belloc", "Abbaye du Mont des Cats", "Abertam", "Abondance", "Ackawi",
            "Acorn", "Adelost", "Affidelice au Chablis", "Afuega‘l Pitu", "Airag", "Airedale", "Aisy Cendre",
            "Allgauer Emmentaler", "Abbaye de Belloc", "Abbaye du Mont des Cats", "Abertam", "Abondance", "Ackawi",
            "Acorn", "Adelost", "Affidelice au Chablis", "Afuega‘l Pitu", "Airag", "Airedale", "Aisy Cendre",
            "Allgauer Emmentaler" };

        protected override void OnCreate(Bundle bundle)
        {
            base.OnCreate(bundle);

            // Set our view from the "main" layout resource
            SetContentView(Resource.Layout.Main);

            mPullRefreshListView = FindViewById<PullToRefreshListView>(Resource.Id.pull_refresh_list);
            var actualListView = (ListView)mPullRefreshListView.RefreshableView;
            mListItems=new List<string>(mStrings);
            mAdapter=new ArrayAdapter<string>(this,Android.Resource.Layout.SimpleListItem1,mListItems);

            var soundListener = new SoundPullEventListener (this);
            soundListener.AddSoundEvent(PullToRefreshBase.PullToRefreshState.PullToRefresh, Resource.Raw.pull_event);
            soundListener.AddSoundEvent(PullToRefreshBase.PullToRefreshState.Reset, Resource.Raw.reset_sound);
            soundListener.AddSoundEvent(PullToRefreshBase.PullToRefreshState.Refreshing, Resource.Raw.refreshing_sound);
           
            mPullRefreshListView.SetOnPullEventListener(soundListener);
            mPullRefreshListView.SetOnRefreshListener(this);
            mPullRefreshListView.SetOnLastItemVisibleListener(this);

            actualListView.Adapter = mAdapter;
        }

        private class GetDataTask : AsyncTask<Java.Lang.Void, Java.Lang.Void, string[]>
        {
            private readonly MainActivity _mainActivity;

            public GetDataTask(MainActivity mainActivity)
            {
                _mainActivity = mainActivity;
            }

            protected override string[] RunInBackground(params Java.Lang.Void[] @params)
            {
                try
                {
                    Thread.Sleep(4000);
                }
                catch (InterruptedException)
                { 
                }

                return _mainActivity.mStrings;
            }

            protected override void OnPostExecute(Object result)
            {
                _mainActivity. mAdapter.Insert("added after refresh:" + DateTime.Now.ToString("t"),0);
                _mainActivity.mAdapter.NotifyDataSetChanged();

                _mainActivity.mPullRefreshListView.OnRefreshComplete();

                base.OnPostExecute(result);
            }
        }

        public void OnRefresh(PullToRefreshBase p0)
        {
            p0.GetLoadingLayoutProxy(true,true).SetLastUpdatedLabel(string.Format("上次更新:{0:t}",DateTime.Now));
            new GetDataTask(this).Execute();
        }

        public void OnLastItemVisible()
        {
            Toast.MakeText(this,"End of List", ToastLength.Short).Show();
        }
}

static interface OnSmoothScrollFinishedListener {
        void onSmoothScrollFinished();
}

    public class MvxPullToRefreshListView:PullToRefreshListView,PullToRefreshBase.IOnRefreshListener
    {
          public MvxPullToRefreshListView(Context context, IAttributeSet attrs)
            : this(context, attrs, new MvxAdapter(context))
        {
        }

        public MvxPullToRefreshListView(Context context, IAttributeSet attrs, IMvxAdapter adapter)
            : base(context, attrs)
        {
            Mode = PullToRefreshMode.Both;
            if (adapter == null)
                return;

            var itemTemplateId = MvxAttributeHelpers.ReadListItemTemplateId(context, attrs);
            adapter.ItemTemplateId = itemTemplateId;
            var lv = (ListView) RefreshableView;
            lv.Adapter = adapter;
            base.SetOnRefreshListener(this);
        }

        public  IMvxAdapter Adapter
        {
            get
            {
                var v = ((ListView)RefreshableView);
                var adapter=((HeaderViewListAdapter) v.Adapter).WrappedAdapter as IMvxAdapter;
                return adapter;
            }
            set
            {
                var existing = Adapter;
                if (existing == value)
                    return;

                if (value != null && existing != null)
                {
                    value.ItemsSource = existing.ItemsSource;
                    value.ItemTemplateId = existing.ItemTemplateId;
                }
                var v = ((ListView)base.RefreshableView);
                v.Adapter = value;
            }
        }

        [MvxSetToNullAfterBinding]
        public IEnumerable ItemsSource
        {
            get { return Adapter.ItemsSource; }
            set { Adapter.ItemsSource = value; }
        }

        public bool IsLoading
        {
            get { return Refreshing; }
            set
            {
                if (!value)
                {
                    OnRefreshComplete();
                }
            }
        }

        public int ItemTemplateId
        {
            get { return Adapter.ItemTemplateId; }
            set { Adapter.ItemTemplateId = value; }
        }

        private ICommand _itemClick;
        public new ICommand ItemClick
        {
            get { return _itemClick; }
            set { _itemClick = value; if (_itemClick != null) EnsureItemClickOverloaded(); }
        }

        private bool _itemClickOverloaded = false;
        private void EnsureItemClickOverloaded()
        {
            if (_itemClickOverloaded)
                return;

            _itemClickOverloaded = true;
            var v = ((ListView)base.RefreshableView);
            v.ItemClick += (sender, args) => ExecuteCommandOnItem(this.ItemClick, args.Position);
        }

        private ICommand _itemLongClick;
        public new ICommand ItemLongClick
        {
            get { return _itemLongClick; }
            set { _itemLongClick = value; if (_itemLongClick != null) EnsureItemLongClickOverloaded(); }
        }

        private bool _itemLongClickOverloaded = false;

        private void EnsureItemLongClickOverloaded()
        {
            if (_itemLongClickOverloaded)
                return;

            _itemLongClickOverloaded = true;
            var v = ((ListView)base.RefreshableView);
            v.ItemLongClick += (sender, args) => ExecuteCommandOnItem(this.ItemLongClick, args.Position);
        }

        protected virtual void ExecuteCommandOnItem(ICommand command, int position)
        {
            if (command == null)
                return;

            var item = Adapter.GetRawItem(position);
            if (item == null)
                return;

            if (!command.CanExecute(item))
                return;

            command.Execute(item);
        }

        public ICommand RefreshCommand { get; set; }

        #region IOnRefreshListener Members

        public void OnRefresh(PullToRefreshBase p0)
        {            
            var lastUpdatedLabel = string.Format("上次更新:{0:T}", DateTime.Now);
            p0.LoadingLayoutProxy.SetLastUpdatedLabel(lastUpdatedLabel);
            if (RefreshCommand != null)
            {
                if (RefreshCommand.CanExecute(null))
                {
                    RefreshCommand.Execute(null);
                }
            }                         
        }

        #endregion
}

/// <summary>
        /// The _refresh command
        /// </summary>
        private MvxCommand _refreshCommand;
        /// <summary>
        /// Gets the refresh command.
        /// </summary>
        /// <value>The refresh command.</value>
        public System.Windows.Input.ICommand RefreshCommand
        {
            get
            {
                _refreshCommand = _refreshCommand ?? new MvxCommand(async()=>await DoRefreshCommand());
                return _refreshCommand;
            }
        }

        /// <summary>
        /// Does the refresh command.
        /// </summary>
        /// <returns>Task.</returns>
        private async Task DoRefreshCommand()
        {
            Users = await LoadDataAsync();
        }

        /// <summary>
        /// load data as an asynchronous operation.
        /// </summary>
        /// <returns>Task{List{UserInfo}}.</returns>
        private async Task<List<UserInfo>> LoadDataAsync()
        {
            IsLoading = true;
           await Task.Delay(SleepMilliSeconds);
            var r = new Random();
            var count = r.Next(1, 6);

           return await Task.Run(() =>
            {
                var list = new List<UserInfo>();
                for (int i = 0; i < count; i++)
                {
                    list.Insert(0, new UserInfo
                    {
                        FirstName = "FirstName" + DateTime.Now.ToString("HH:mm:ss fff") + "__" + i,
                        LastName = "LastName" + DateTime.Now.ToString("T") + "__" + i + r.Next(),
                    });
                }
                IsLoading = false;

                return list;
            });           
        }

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:local="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">    
  <pulltorefreshsample.droid.views.MvxPullToRefreshListView
    android:id="@+id/pull_refresh_list"
       android:layout_width="fill_parent"
       android:layout_height="fill_parent"
       android:cacheColorHint="#00000000"
       android:divider="#FF0C79E9"
       android:dividerHeight="1dp"
       android:fadingEdge="none"
       android:fastScrollEnabled="false"
       android:footerDividersEnabled="false"
       android:headerDividersEnabled="false"
       android:smoothScrollbar="true"
    local:MvxItemTemplate="@layout/user_item"
    local:MvxBind="ItemsSource Users;RefreshCommand RefreshCommand;IsLoading IsLoading"
    />
</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:local="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">
    <TextView
        local:MvxBind="Text FirstName"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/textView1" />
    <TextView
        local:MvxBind="Text LastName"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/textView2" />
</LinearLayout>