Question

我想获取和显示数据，但它不能正常工作并在此行之后

var response = await client.GetAsync(uri).ConfigureAwait(false);

代码从未执行过甚至不抛出异常

public async Task<List<Restresponse>> RefreshDataAsync()
{
    var Items = new List<Restresponse>();
    try
    {
        HttpClient client = new HttpClient();
        var uri = new Uri(string.Format("https://jsonplaceholder.typicode.com/posts", string.Empty));
        var response = await client.GetAsync(uri).ConfigureAwait(false);
        if (response.IsSuccessStatusCode)
        {
            var content = await response.Content.ReadAsStringAsync().ConfigureAwait(false); ;
           // Items = JsonConvert.DeserializeObject<List<TodoItem>>(content);
        }
    }
    catch (Exception e)
    {
        Log.WriteLine(LogPriority.Debug, "EXception from restservice", e.Message);
    }
    return Items;

}

我在片段

中的OncreateView中调用了这个函数

public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
        {
            View view = inflater.Inflate(Resource.Layout.recycleview, container, false);

            mRecyclerView = view.FindViewById<RecyclerView>(Resource.Id.recyclerView);

            mLayoutManager = new LinearLayoutManager(this.Activity);
            mRecyclerView.SetLayoutManager(mLayoutManager);

            // Prepare the data source:
            listItem = new List<Restresponse>();
            try
            {
                listItem = RefreshDataAsync().Result;

                // Instantiate the adapter and pass in its data source:
                mAdapter = new RecycleViewAdapter(listItem, this.Activity);

                // Plug the adapter into the RecyclerView:
                mRecyclerView.SetAdapter(mAdapter);
            }
            catch (System.Exception e)
            {
                Log.WriteLine(LogPriority.Debug, "EXception from fragmenbt", e.Message);
            }
            return view;
        }

Answer 1

当然你遇到了僵局。

如果您是从构造函数或事件RefreshDataAsync().Result;进行调用，则应从函数中删除.ConfigureAwait(false);，因为如果您在主线程中它将永远不会完成。

评论后的另一个选项 我认为如果您需要异步处理，最好的方法是在创建视图后使用OnResume。

    public async override void OnResume()
    {
        base.OnResume();
        try
        {
            listItem = RefreshDataAsync().Result;

            // Instantiate the adapter and pass in its data source:
            mAdapter = new RecycleViewAdapter(listItem, this.Activity);

            // Plug the adapter into the RecyclerView:
            mRecyclerView.SetAdapter(mAdapter);
        }
        catch (System.Exception e)
        {
            Log.WriteLine(LogPriority.Debug, "EXception from fragmenbt", e.Message);
        }
    }

不要忘记从调用RefreshDataAsync（）的OnCreateView中删除Try / catch块

完整代码片段：

        public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
        {

            try
            {
                View view = inflater.Inflate(Resource.Layout.recycleview, container, false);

                mRecyclerView = view.FindViewById<RecyclerView>(Resource.Id.recyclerView);

                mLayoutManager = new LinearLayoutManager(this.Activity);
                mRecyclerView.SetLayoutManager(mLayoutManager);
            }
            catch (Exception)
            {

                Log.WriteLine(LogPriority.Debug, "EXception from fragment inside OnCreateView", e.Message);
            }



        }

        public async override void OnResume()
        {
            base.OnResume();
            // Prepare the data source:
            try
            {
                using (var client = new HttpClient())
                {
                    var uri = "jsonplaceholder.typicode.com/posts";
                    var result = await client.GetStringAsync(uri);
                    var Restresponse = JsonConvert.DeserializeObject<List<Restresponse>>(result);
                    mAdapter = new RecycleViewAdapter(Restresponse, this.Activity);
                    mRecyclerView.SetAdapter(mAdapter);
                }
            }
            catch (System.Exception e)
            {
                Log.WriteLine(LogPriority.Debug, "EXception from fragment inside OnResume", e.Message);
            }
        }

Xamrine Http呼叫未返回响应

1 个答案: