我想获得一个在 c# 中使用以下配置生成 http post 的方法。
POST pqs.php HTTP/1.1
Host: nationalmap.gov/epqs/pqs.php
Content-Type: application/x-www-form-urlencoded
Content-Length: length
x=string&y=string&units=string&output=string
我尝试了以下方法,但是我得到了无效的坐标,尽管它们确实存在于 map 中(尝试的示例是 lat = 36.574832 和 lon = -85.411825
这是我使用的代码:
public class ElevationUSGISPull
{
public string responseString = null;
private string BASEURL = "http://nationalmap.gov/epqs/pqs.php";
public bool httpPostElevationRequest( string lon,string lat)
{
try
{
using (WebClient client = new WebClient())
{
byte[] response =
client.UploadValues(BASEURL, new NameValueCollection()
{
{ "x", lon },
{ "y", lat },
{"units", "feet" },
{"output","json" },
});
string result = System.Text.Encoding.UTF8.GetString(response);
responseString = result;
}
return true;
}
catch(Exception eX)
{
return false;
}
}
}
我得到的错误如下:
<error>General failure: Invalid Coordinates</error>
此外,是否有人尝试过 .gov 网站获取高程数据。我使用了谷歌服务器,但是它有很多与请求数量相关的限制,我正在尝试对给定区域进行许多请求。
下面是一个验证纬度和经度的网站,具有良好的 json 响应。
谢谢大家。
我在这里也试过下面的例子: http://ronaldrosiernet.azurewebsites.net/Blog/2013/12/07/posting_urlencoded_key_values_with_httpclient
但是给我以下错误。
Exception thrown: 'System.NullReferenceException'
我将代码修改为:
public async Task<string> HTTPPOST(string lon, string lat)
{
var client = new HttpClient();
client.BaseAddress = new Uri(BASEURL);
var request = new HttpRequestMessage(HttpMethod.Post, "");
var keyValues = new List<KeyValuePair<string, string>>();
keyValues.Add(new KeyValuePair<string, string>("x", lon));
keyValues.Add(new KeyValuePair<string, string>("y", lat));
keyValues.Add(new KeyValuePair<string, string>("units", "feet"));
keyValues.Add(new KeyValuePair<string, string>("output", "json"));
request.Content = new FormUrlEncodedContent(keyValues);
var response = await client.SendAsync(request);
return response.ToString();
}
最佳答案
调试一个小时后,我注意到我将单位作为参数而不是单位 :( ......
public string httpPostElevationRequest( string lon,string lat)
{
try
{
using (WebClient client = new WebClient())
{
byte[] response =
client.UploadValues(BASEURL, new NameValueCollection()
{
{ "x", lon },
{ "y", lat },
{"unit", "feet" },
{"output","json" },
});
string result = System.Text.Encoding.UTF8.GetString(response);
responseString = result;
}
return responseString;
}
catch(Exception eX)
{
return null;
}
}
还有baseurl如下:
private string BASEURL = "https://nationalmap.gov/epqs/pqs.php";
关于c# - 带有 Json 响应的 Http Post C#,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/43160584/