Bing Maps REST服务工具包-代表以外的访问价值 [英] Bing Maps REST Services Toolkit - Access Value Outside of Delegate
问题描述
Bing Maps REST服务工具包的此示例代码使用委托获取响应,然后从委托方法中输出消息.但是,它没有演示如何从GetResponse调用之外访问响应.我无法弄清楚如何从此委托返回值.换句话说,让我们说我想在 Console.ReadLine();
行之前使用 longitude
变量的值?
This sample code for the Bing Maps REST Services Toolkit uses a delegate to get the response and then outputs a message from within the delegate method. However, it does not demonstrate how to access the response from outside of the invocation of GetResponse. I cannot figure out how to return a value from this delegate. In other words, let us say I want to use the value of the longitude
variable right before the line Console.ReadLine();
How do I access that variable in that scope?
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using BingMapsRESTToolkit;
using System.Configuration;
using System.Net;
using System.Runtime.Serialization.Json;
namespace RESTToolkitTestConsoleApp
{
class Program
{
static private string _ApiKey = System.Configuration.ConfigurationManager.AppSettings.Get("BingMapsKey");
static void Main(string[] args)
{
string query = "1 Microsoft Way, Redmond, WA";
Uri geocodeRequest = new Uri(string.Format("http://dev.virtualearth.net/REST/v1/Locations?q={0}&key={1}", query, _ApiKey));
GetResponse(geocodeRequest, (x) =>
{
Console.WriteLine(x.ResourceSets[0].Resources.Length + " result(s) found.");
decimal latitude = (decimal)((Location)x.ResourceSets[0].Resources[0]).Point.Coordinates[0];
decimal longitude = (decimal)((Location)x.ResourceSets[0].Resources[0]).Point.Coordinates[1];
Console.WriteLine("Latitude: " + latitude);
Console.WriteLine("Longitude: " + longitude);
});
Console.ReadLine();
}
private static void GetResponse(Uri uri, Action<Response> callback)
{
WebClient wc = new WebClient();
wc.OpenReadCompleted += (o, a) =>
{
if (callback != null)
{
// Requires a reference to System.Runtime.Serialization
DataContractJsonSerializer ser = new DataContractJsonSerializer(typeof(Response));
callback(ser.ReadObject(a.Result) as Response);
}
};
wc.OpenReadAsync(uri);
}
}
}
推荐答案
对于所提供的示例 WebClient.OpenReadCompleted
事件像这样完成:
For the provided example AutoResetEvent class
could be utilized to control the flow, in particular to wait asynchronous WebClient.OpenReadCompleted
Event is completed like this:
class Program
{
private static readonly string ApiKey = System.Configuration.ConfigurationManager.AppSettings.Get("BingMapsKey");
private static readonly AutoResetEvent StopWaitHandle = new AutoResetEvent(false);
public static void Main()
{
var query = "1 Microsoft Way, Redmond, WA";
BingMapsRESTToolkit.Location result = null;
Uri geocodeRequest = new Uri(string.Format("http://dev.virtualearth.net/REST/v1/Locations?q={0}&key={1}",
query, ApiKey));
GetResponse(geocodeRequest, (x) =>
{
if (response != null &&
response.ResourceSets != null &&
response.ResourceSets.Length > 0 &&
response.ResourceSets[0].Resources != null &&
response.ResourceSets[0].Resources.Length > 0)
{
result = response.ResourceSets[0].Resources[0] as BingMapsRESTToolkit.Location;
}
});
StopWaitHandle.WaitOne(); //wait for callback
Console.WriteLine(result.Point); //<-access result
Console.ReadLine();
}
private static void GetResponse(Uri uri, Action<Response> callback)
{
var wc = new WebClient();
wc.OpenReadCompleted += (o, a) =>
{
if (callback != null)
{
DataContractJsonSerializer ser = new DataContractJsonSerializer(typeof(Response));
callback(ser.ReadObject(a.Result) as Response);
}
StopWaitHandle.Set(); //signal the wait handle
};
wc.OpenReadAsync(uri);
}
}
选项2
Or to switch to ServiceManager class
that makes it easy when working via asynchronous programming model:
public static void Main()
{
var task = ExecuteQuery("1 Microsoft Way, Redmond, WA");
task.Wait();
Console.WriteLine(task.Result);
Console.ReadLine();
}
其中
public static async Task<BingMapsRESTToolkit.Location> ExecuteQuery(string queryText)
{
//Create a request.
var request = new GeocodeRequest()
{
Query = queryText,
MaxResults = 1,
BingMapsKey = ApiKey
};
//Process the request by using the ServiceManager.
var response = await request.Execute();
if (response != null &&
response.ResourceSets != null &&
response.ResourceSets.Length > 0 &&
response.ResourceSets[0].Resources != null &&
response.ResourceSets[0].Resources.Length > 0)
{
return response.ResourceSets[0].Resources[0] as BingMapsRESTToolkit.Location;
}
return null;
}
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