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
这是我最近的记录。由于种种原因，我不喜欢其他的，所以我自己写了一个。
这个版本的特点:
Use of StringBuilder only. No ToArray() calls or other extension methods. It doesn't look as pretty as some of the other responses, but I consider this a core function so efficiency is more important than having "fluent", "one-liner" code which hide inefficiencies. Handles multiple values per key. (Didn't need it myself but just to silence Mauricio ;) public string ToQueryString(NameValueCollection nvc) { StringBuilder sb = new StringBuilder("?"); bool first = true; foreach (string key in nvc.AllKeys) { foreach (string value in nvc.GetValues(key)) { if (!first) { sb.Append("&"); } sb.AppendFormat("{0}={1}", Uri.EscapeDataString(key), Uri.EscapeDataString(value)); first = false; } } return sb.ToString(); }
示例使用
var queryParams = new NameValueCollection()
{
{ "x", "1" },
{ "y", "2" },
{ "foo", "bar" },
{ "foo", "baz" },
{ "special chars", "? = &" },
};
string url = "http://example.com/stuff" + ToQueryString(queryParams);
Console.WriteLine(url);
输出
http://example.com/stuff?x=1&y=2&foo=bar&foo=baz&special%20chars=%3F%20%3D%20%26
其他回答
我的提供:
public static Uri AddQuery(this Uri uri, string name, string value)
{
// this actually returns HttpValueCollection : NameValueCollection
// which uses unicode compliant encoding on ToString()
var query = HttpUtility.ParseQueryString(uri.Query);
query.Add(name, value);
var uriBuilder = new UriBuilder(uri)
{
Query = query.ToString()
};
return uriBuilder.Uri;
}
用法:
var uri = new Uri("http://stackoverflow.com").AddQuery("such", "method")
.AddQuery("wow", "soFluent");
// http://stackoverflow.com?such=method&wow=soFluent
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
这里有很多很好的答案，但对于使用现代c#的人来说，这可能是一个很好的实用程序类。
public class QueryParamBuilder
{
private readonly Dictionary<string, string> _fields = new();
public QueryParamBuilder Add(string key, string value)
{
_fields.Add(key, value);
return this;
}
public string Build()
{
return $"?{String.Join("&", _fields.Select(pair => $"{HttpUtility.UrlEncode(pair.Key)}={HttpUtility.UrlEncode(pair.Value)}"))}";
}
public static QueryParamBuilder New => new();
}
我在这里使用了一个内部Dictionary，因为字典在内部是可枚举的键值对，这使得遍历它们比NameValueCollection容易得多。
那么查询字符串本身就是一个简单的带有连接的插值字符串。
另外，我为构造函数提供了一个静态接口，使构造新的构造器非常容易，并且只允许一个公开的方法Add来添加新的查询参数值。最后，使用Build()终止链以实际获得最终字符串。
下面是它用法的一个例子
var queryString = QueryParamBuilder.New
.Add("id", "0123")
.Add("value2", 1234.ToString())
.Add("valueWithSpace","value with spa12!@#@!ce")
.Build();
结果和预期的一样
?id=0123&value2=1234&valueWithSpace=value+with+spa12!%40%23%40!ce
希望你们中的一些人会觉得这个很好很优雅。
// 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);
}
}
}
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"
