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
从Roy Tinker的评论中得到灵感，我最终在Uri类上使用了一个简单的扩展方法，使我的代码简洁干净:
using System.Web;
public static class HttpExtensions
{
public static Uri AddQuery(this Uri uri, string name, string value)
{
var httpValueCollection = HttpUtility.ParseQueryString(uri.Query);
httpValueCollection.Remove(name);
httpValueCollection.Add(name, value);
var ub = new UriBuilder(uri);
ub.Query = httpValueCollection.ToString();
return ub.Uri;
}
}
用法:
Uri url = new Uri("http://localhost/rest/something/browse").
AddQuery("page", "0").
AddQuery("pageSize", "200");
编辑-标准兼容的变体
正如一些人指出的那样，httpValueCollection.ToString()以一种不符合标准的方式编码Unicode字符。这是通过调用HttpUtility来处理此类字符的相同扩展方法的变体。UrlEncode方法代替已弃用的HttpUtility方法。UrlEncodeUnicode方法。
using System.Web;
public static Uri AddQuery(this Uri uri, string name, string value)
{
var httpValueCollection = HttpUtility.ParseQueryString(uri.Query);
httpValueCollection.Remove(name);
httpValueCollection.Add(name, value);
var ub = new UriBuilder(uri);
// this code block is taken from httpValueCollection.ToString() method
// and modified so it encodes strings with HttpUtility.UrlEncode
if (httpValueCollection.Count == 0)
ub.Query = String.Empty;
else
{
var sb = new StringBuilder();
for (int i = 0; i < httpValueCollection.Count; i++)
{
string text = httpValueCollection.GetKey(i);
{
text = HttpUtility.UrlEncode(text);
string val = (text != null) ? (text + "=") : string.Empty;
string[] vals = httpValueCollection.GetValues(i);
if (sb.Length > 0)
sb.Append('&');
if (vals == null || vals.Length == 0)
sb.Append(val);
else
{
if (vals.Length == 1)
{
sb.Append(val);
sb.Append(HttpUtility.UrlEncode(vals[0]));
}
else
{
for (int j = 0; j < vals.Length; j++)
{
if (j > 0)
sb.Append('&');
sb.Append(val);
sb.Append(HttpUtility.UrlEncode(vals[j]));
}
}
}
}
}
ub.Query = sb.ToString();
}
return ub.Uri;
}
其他回答
// 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);
}
}
}
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;
}
查询字符串可以通过以下方式添加到URL:
创建名称值集合对象 将查询字符串项及其值添加到此对象 将此名称值集合对象编码为下面链接中提供的代码的url
https://blog.codingnovice.com/blog
public ActionResult Create()
{
//declaring name value collection object
NameValueCollection collection = new NameValueCollection();
//adding new value to the name value collection object
collection.Add("Id1", "wwe323");
collection.Add("Id2", "454w");
collection.Add("Id3", "tyt5656");
collection.Add("Id4", "343wdsd");
//generating query string
string url = GenerateQueryString(collection);
return View();
}
private string GenerateQueryString(NameValueCollection collection)
{
var querystring = (
from key in collection.AllKeys
from value in collection.GetValues(key)
select string.Format("{0}={1}",
HttpUtility.UrlEncode(key),
HttpUtility.UrlEncode(value))
).ToArray();
return "?" + string.Join("&", querystring);
}
我需要为我正在开发的可移植类库(PCL)解决同样的问题。在这种情况下，我没有访问系统的权限。所以我不能用ParseQueryString。
相反，我使用System.Net.Http.FormUrlEncodedContent像这样:
var url = new UriBuilder("http://example.com");
url.Query = new FormUrlEncodedContent(new Dictionary<string,string>()
{
{"param1", "val1"},
{"param2", "val2"},
{"param3", "val3"},
}).ReadAsStringAsync().Result;
我为我的剃刀项目写了一个助手，使用了其他答案的一些提示。
ParseQueryString业务是必要的，因为我们不允许篡改当前请求的QueryString对象。
@helper GetQueryStringWithValue(string key, string value) {
var queryString = System.Web.HttpUtility.ParseQueryString(HttpContext.Current.Request.QueryString.ToString());
queryString[key] = value;
@Html.Raw(queryString.ToString())
}
我是这样使用的:
location.search = '?@Helpers.GetQueryStringWithValue("var-name", "var-value")';
如果希望它接受多个值，只需将参数更改为Dictionary，并将对添加到查询字符串中。
