当从代码中调用web资源时，一个常见的任务是构建一个包含所有必要参数的查询字符串。虽然这绝不是火箭科学，但有一些漂亮的细节需要注意，例如，如果不是第一个参数，则添加&，对参数进行编码等。
实现它的代码非常简单，但有点乏味:
StringBuilder SB = new StringBuilder();
if (NeedsToAddParameter A)
{
SB.Append("A="); SB.Append(HttpUtility.UrlEncode("TheValueOfA"));
}
if (NeedsToAddParameter B)
{
if (SB.Length>0) SB.Append("&");
SB.Append("B="); SB.Append(HttpUtility.UrlEncode("TheValueOfB")); }
}
这是一个非常常见的任务，人们希望存在一个实用工具类，使其更加优雅和可读。扫描MSDN，我没有找到一个，这让我想到了以下问题:
你所知道的最优雅干净的方法是什么?
当前回答
另一种方法是创建一个类NameValueCollection的扩展，返回完整的Url:
public static class CustomMethods
{
public static string ToUrl(this System.Collections.Specialized.NameValueCollection collection)
{
if (collection.Count == 0) return "";
string completeUrl = "?";
for (int i = 0; i < collection.Count; i++)
{
completeUrl += new Page().Server.UrlEncode(collection.GetKey(i)) + "=" + new Page().Server.UrlEncode(collection.Get(i));
if ((i + 1) < collection.Count) completeUrl += "&";
}
return completeUrl;
}
}
然后，你可以使用你的新方法，例如:
System.Collections.Specialized.NameValueCollection qString = new System.Collections.Specialized.NameValueCollection();
qString.Add("name", "MyName");
qString.Add("email", "myemail@test.com");
qString.ToUrl(); //Result: "?name=MyName&email=myemail%40test.com"
其他回答
虽然不够优雅，但我选择了一个更简单的版本，它不使用NameValueCollecitons——只是一个包装在StringBuilder周围的构建器模式。
public class UrlBuilder
{
#region Variables / Properties
private readonly StringBuilder _builder;
#endregion Variables / Properties
#region Constructor
public UrlBuilder(string urlBase)
{
_builder = new StringBuilder(urlBase);
}
#endregion Constructor
#region Methods
public UrlBuilder AppendParameter(string paramName, string value)
{
if (_builder.ToString().Contains("?"))
_builder.Append("&");
else
_builder.Append("?");
_builder.Append(HttpUtility.UrlEncode(paramName));
_builder.Append("=");
_builder.Append(HttpUtility.UrlEncode(value));
return this;
}
public override string ToString()
{
return _builder.ToString();
}
#endregion Methods
}
根据现有的答案，我确保使用HttpUtility。UrlEncode调用。它是这样使用的:
string url = new UrlBuilder("http://www.somedomain.com/")
.AppendParameter("a", "true")
.AppendParameter("b", "muffin")
.AppendParameter("c", "muffin button")
.ToString();
// Result: http://www.somedomain.com?a=true&b=muffin&c=muffin%20button
这与公认的答案完全相同，只是稍微更紧凑:
private string ToQueryString(NameValueCollection nvc)
{
return "?" + string.Join("&", nvc.AllKeys.Select(k => string.Format("{0}={1}",
HttpUtility.UrlEncode(k),
HttpUtility.UrlEncode(nvc[k]))));
}
与已接受的解决方案相同，但转换为“点”LINQ语法…
private string ToQueryString(NameValueCollection nvc)
{
if (nvc == null) return String.Empty;
var queryParams =
string.Join("&", nvc.AllKeys.Select(key =>
string.Join("&", nvc.GetValues(key).Select(v => string.Format("{0}={1}", HttpUtility.UrlEncode(key), HttpUtility.UrlEncode(v))))));
return "?" + queryParams;
}
// USAGE
[TestMethod]
public void TestUrlBuilder()
{
Console.WriteLine(
new UrlBuilder("http://www.google.com?A=B")
.AddPath("SomePathName")
.AddPath("AnotherPathName")
.SetQuery("SomeQueryKey", "SomeQueryValue")
.AlterQuery("A", x => x + "C"));
}
输出:
http://www.google.com/SomePathName/AnotherPathName?A=BC&SomeQueryKey=SomeQueryValue
的代码;你们都可以在某个地方，以某种方式感谢我
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
// By Demetris Leptos
namespace TheOperator.Foundation.Web
{
public class UrlBuilder
{
public string Scheme { get; set; }
public string Host { get; set; }
public int? Port { get; set; }
public List<string> Paths { get; set; }
public SortedDictionary<string, string> QueryPairs { get; set; }
public UrlBuilder(string url)
{
this.Paths = new List<string>();
this.QueryPairs = new SortedDictionary<string, string>();
string path = null;
string query = null;
Uri relativeUri = null;
if (!Uri.TryCreate(url, UriKind.Relative, out relativeUri))
{
var uriBuilder = new UriBuilder(url);
this.Scheme = uriBuilder.Scheme;
this.Host = uriBuilder.Host;
this.Port = uriBuilder.Port;
path = uriBuilder.Path;
query = uriBuilder.Query;
}
else
{
var queryIndex = url.IndexOf('?');
if (queryIndex >= 0)
{
path = url.Substring(0, queryIndex);
query = url.Substring(queryIndex + 1);
}
else
{
path = url;
}
}
this.Paths.AddRange(path.Split(new char[] { '/' }, StringSplitOptions.RemoveEmptyEntries));
if (query != null)
{
var queryKeyValuePairs = HttpUtility.ParseQueryString(query);
foreach (var queryKey in queryKeyValuePairs.AllKeys)
{
this.QueryPairs[queryKey] = queryKeyValuePairs[queryKey];
}
}
}
public UrlBuilder AddPath(string value)
{
this.Paths.Add(value);
return this;
}
public UrlBuilder SetQuery(string key, string value)
{
this.QueryPairs[key] = value;
return this;
}
public UrlBuilder RemoveQuery(string key)
{
this.QueryPairs.Remove(key);
return this;
}
public UrlBuilder AlterQuery(string key, Func<string, string> alterMethod, bool removeOnNull = false)
{
string value;
this.QueryPairs.TryGetValue(key, out value);
value = alterMethod(value);
if (removeOnNull && value == null)
{
return this.RemoveQuery(key);
}
else
{
return this.SetQuery(key, value);
}
}
public override string ToString()
{
var path = !string.IsNullOrWhiteSpace(this.Host)
? string.Join("/", this.Host, string.Join("/", this.Paths))
: string.Join("/", this.Paths);
var query = string.Join("&", this.QueryPairs.Select(x => string.Concat(x.Key, "=", HttpUtility.UrlEncode(x.Value))));
return string.Concat(
!string.IsNullOrWhiteSpace(this.Scheme) ? string.Concat(this.Scheme, "://") : null,
path,
!string.IsNullOrWhiteSpace(query) ? string.Concat("?", query) : null);
}
}
}
我刚才回答了一个类似的问题。基本上，最好的方法是使用HttpValueCollection类。净的请求。QueryString属性实际上是，不幸的是，它是。net框架内部的。 您可以使用Reflector来抓取它(并将其放入您的Utils类中)。通过这种方式，您可以像操作NameValueCollection一样操作查询字符串，但是需要考虑所有url编码/解码问题。
HttpValueCollection扩展了NameValueCollection，并有一个接受编码查询字符串(包括&和问号)的构造函数，它覆盖了ToString()方法，以便稍后从底层集合重新构建查询字符串。
例子:
var coll = new HttpValueCollection();
coll["userId"] = "50";
coll["paramA"] = "A";
coll["paramB"] = "B";
string query = coll.ToString(true); // true means use urlencode
Console.WriteLine(query); // prints: userId=50¶mA=A¶mB=B
