如果缺少信息,我有一个需要更新的项目列表。但是,我正在打电话给谷歌位置服务。我想知道如果可能的话我如何异步附加必要的Lat&Long信息
我的代码
public static void PullInfo()
{
foreach (var item in SAPItems)
{
if(item.MDM_Latitude == null || item.MDM_Longitude == null)
{
var point = GetMapPoint(item.AddressLine1 + " " + item.FiveDigitZip);
item.MDM_Latitude = point.Result.Latitude.ToString();
item.MDM_Longitude = point.Result.Longitude.ToString();
}
}
foreach(var item in SAPItems)
Console.WriteLine(item.MDM_Latitude + " " + item.MDM_Longitude);
}
private static async Task<MapPoint> GetMapPoint(string add)
{
var task = Task.Run(() => LocationService.GetLatLongFromAddress(add));
return await task;
}
您可以使用多个任务异步获取多个映射点(请注意,它需要将PullInfo()
转换为async-await):
public static async Task PullInfo()
{
// Create tasks to update items with latitude and longitude
var tasks
= SAPItems.Where(item => item.Latitude == null || item.Longitude == null)
.Select(item =>
GetMapPoint(item.AddressLine1 + " " + item.FiveDigitZip)
.ContinueWith(pointTask => {
item.MDM_Latitude = pointTask.Result.Latitude.ToString();
item.MDM_Longitude = pointTask.Result.Longitude.ToString();
}));
// Non-blocking await for tasks completion
await Task.WhenAll(tasks);
// Iterate to append Lat and Long
foreach(var item in SAPItems)
Console.WriteLine(item.MDM_Latitude + " " + item.MDM_Longitude);
}
private static Task<MapPoint> GetMapPoint(string add)
{
return Task.Run(() => LocationService.GetLatLongFromAddress(add));
}
如果PullInfo()
无法转换为async-await,则可以强制线程等待结果,但它会阻止当前线程:
public static void PullInfo()
{
// Create tasks to update items with latitude and longitude
var tasks
= SAPItems.Where(item => item.Latitude == null || item.Longitude == null)
.Select(item =>
GetMapPoint(item.AddressLine1 + " " + item.FiveDigitZip)
.ContinueWith(pointTask => {
item.MDM_Latitude = pointTask.Result.Latitude.ToString();
item.MDM_Longitude = pointTask.Result.Longitude.ToString();
}));
// Wait for tasks completion (it will block the current thread)
Task.WaitAll(tasks.ToArray());
// Iterate to append Lat and Long
foreach(var item in SAPItems)
Console.WriteLine(item.MDM_Latitude + " " + item.MDM_Longitude);
}
private static Task<MapPoint> GetMapPoint(string add)
{
return Task.Run(() => LocationService.GetLatLongFromAddress(add));
}
运行最后一个代码示例的示例:https://ideone.com/0uXGlG
你只需要等待获取数据的调用(注意await
是如何从GetMapPoint
移动的):
public static async Task PullInfo()
{
foreach (var item in SAPItems)
{
if(item.Latitude == null || item.Longitude == null)
{
var point = await GetMapPoint(item.AddressLine1 + " " + item.FiveDigitZip);
item.MDM_Latitude = point.Latitude.ToString();
item.MDM_Longitude = point.Longitude.ToString();
}
}
foreach(var item in SAPItems)
Console.WriteLine(item.MDM_Latitude + " " + item.MDM_Longitude);
}
private static Task<MapPoint> GetMapPoint(string add)
{
var task = Task.Run(() => LocationService.GetLatLongFromAddress(add));
return task;
}
你不是要修改你的SAPItems
系列,只是修改每个项目。获得响应后,您只需更新循环中的当前项即可。