Async,await在Silverlight中的应用

silverlight 可以使用AsyncCTP了。这样可以使得代码更简单。于一个简单的调用RIA Service为例。

RIA 代码

 [EnableClientAccess()]
    public class AsyncDomainService : DomainService
    {
        public IQueryable<Data> GetDatas()
        {
            List<Data> dats = new List<Data>
            {
                new Data {Name ="Dat 1"},
                new Data {Name ="Dat 2"},
                new Data {Name ="Dat 3"},
                new Data {Name ="Dat 4"},
            };
            Thread.Sleep(1000 * 7);
            return dats.AsQueryable();
        }

        [Invoke]
        public int GetInt()
        {
            return 1;
        }
    }

    public class Data
    {
        [Key]
        public string Name { get; set; }
    }

SL 代码：

首先添加一个扩展方法(微软  Kyle McClellan)

    public static class OperationExtensions
    {
        public static  Task<T> AsTask<T>(this T operation)
          where T : OperationBase
        {
            TaskCompletionSource<T> tcs =
              new TaskCompletionSource<T>(operation.UserState);

            operation.Completed += (sender, e) =>
            {
                if (operation.HasError && !operation.IsErrorHandled)
                {
                    tcs.TrySetException(operation.Error);
                    operation.MarkErrorAsHandled();
                }
                else if (operation.IsCanceled)
                {
                    tcs.TrySetCanceled();
                }
                else
                {
                    tcs.TrySetResult(operation);
                }
            };

            return tcs.Task;
        }
    }

在要显示结果的页面的.cs文件里面添加测试

 public async void  test()
        {           
            AsyncDomainContext context = new AsyncDomainContext();
            LoadOperation<Data> loadOperation = await context.Load<Data>(context.GetDatasQuery()).AsTask();
            List<Data> dats = new List<Data>(loadOperation.Entities);
            textBlock1.Text = "Get "+dats.Count.ToString()+" Data.";
            dataGrid1.ItemsSource = dats ;
            dataGrid1.AutoGenerateColumns = true;
            InvokeOperation<int> invokeOperation = await context.GetInt().AsTask();
            textBlock1.Text += " And Get Int=" + invokeOperation.Value;
        }

Ok ！