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

适用于NameValueCollection中每个键的多个值。

例:{{“k1”、“v1”},{“k1”、“v1”}}= > ? k1 = v1&k1 = v1

/// <summary>
/// Get query string for name value collection.
/// </summary>
public static string ToQueryString(this NameValueCollection collection,
    bool prefixQuestionMark = true)
{
    collection.NullArgumentCheck();
    if (collection.Keys.Count == 0)
    {
        return "";
    }
    var buffer = new StringBuilder();
    if (prefixQuestionMark)
    {
        buffer.Append("?");
    }
    var append = false;
    for (int i = 0; i < collection.Keys.Count; i++)
    {
        var key = collection.Keys[i];
        var values = collection.GetValues(key);
        key.NullCheck();
        values.NullCheck();
        foreach (var value in values)
        {
            if (append)
            {
                buffer.Append("&");
            }
            append = true;
            buffer.AppendFormat("{0}={1}", key.UrlEncode(), value.UrlEncode());
        }
    }
    return buffer.ToString();
}

其他回答

如何创建扩展方法,允许您以这样流畅的风格添加参数?

string a = "http://www.somedomain.com/somepage.html"
    .AddQueryParam("A", "TheValueOfA")
    .AddQueryParam("B", "TheValueOfB")
    .AddQueryParam("Z", "TheValueOfZ");

string b = new StringBuilder("http://www.somedomain.com/anotherpage.html")
    .AddQueryParam("A", "TheValueOfA")
    .AddQueryParam("B", "TheValueOfB")
    .AddQueryParam("Z", "TheValueOfZ")
    .ToString(); 

下面是使用字符串的重载:

public static string AddQueryParam(
    this string source, string key, string value)
{
    string delim;
    if ((source == null) || !source.Contains("?"))
    {
        delim = "?";
    }
    else if (source.EndsWith("?") || source.EndsWith("&"))
    {
        delim = string.Empty;
    }
    else
    {
        delim = "&";
    }

    return source + delim + HttpUtility.UrlEncode(key)
        + "=" + HttpUtility.UrlEncode(value);
}

这里是使用StringBuilder的重载:

public static StringBuilder AddQueryParam(
    this StringBuilder source, string key, string value)
{
    bool hasQuery = false;
    for (int i = 0; i < source.Length; i++)
    {
        if (source[i] == '?')
        {
            hasQuery = true;
            break;
        }
    }

    string delim;
    if (!hasQuery)
    {
        delim = "?";
    }
    else if ((source[source.Length - 1] == '?')
        || (source[source.Length - 1] == '&'))
    {
        delim = string.Empty;
    }
    else
    {
        delim = "&";
    }

    return source.Append(delim).Append(HttpUtility.UrlEncode(key))
        .Append("=").Append(HttpUtility.UrlEncode(value));
}
// 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);
        }
    }
}

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

我将以下方法添加到PageBase类中。

protected void Redirect(string url)
    {
        Response.Redirect(url);
    }
protected void Redirect(string url, NameValueCollection querystrings)
    {
        StringBuilder redirectUrl = new StringBuilder(url);

        if (querystrings != null)
        {
            for (int index = 0; index < querystrings.Count; index++)
            {
                if (index == 0)
                {
                    redirectUrl.Append("?");
                }

                redirectUrl.Append(querystrings.Keys[index]);
                redirectUrl.Append("=");
                redirectUrl.Append(HttpUtility.UrlEncode(querystrings[index]));

                if (index < querystrings.Count - 1)
                {
                    redirectUrl.Append("&");
                }
            }
        }

        this.Redirect(redirectUrl.ToString());
    }

电话:

NameValueCollection querystrings = new NameValueCollection();    
querystrings.Add("language", "en");
querystrings.Add("id", "134");
this.Redirect("http://www.mypage.com", querystrings);

结合顶部的答案创建一个匿名对象版本:

var queryString = HttpUtility2.BuildQueryString(new
{
    key2 = "value2",
    key1 = "value1",
});

这会产生这样的结果:

key2 = value2&key1 = value1

代码如下:

public static class HttpUtility2
{
    public static string BuildQueryString<T>(T obj)
    {
        var queryString = HttpUtility.ParseQueryString(string.Empty);

        foreach (var property in TypeDescriptor.GetProperties(typeof(T)).Cast<PropertyDescriptor>())
        {
            var value = (property.GetValue(obj) ?? "").ToString();
            queryString.Add(property.Name, value);
        }

        return queryString.ToString();
    }
}