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

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);
}

其他回答

未经测试,但我认为沿着这些路线的东西会工作得很好

public class QueryString
{
    private Dictionary<string,string> _Params = new Dictionary<string,string>();

    public overide ToString()
    {
        List<string> returnParams = new List<string>();

        foreach (KeyValuePair param in _Params)
        {
            returnParams.Add(String.Format("{0}={1}", param.Key, param.Value));
        }

        // return String.Format("?{0}", String.Join("&", returnParams.ToArray())); 

        // credit annakata
        return "?" + String.Join("&", returnParams.ToArray());
    }

    public void Add(string key, string value)
    {
        _Params.Add(key, HttpUtility.UrlEncode(value));
    }
}

QueryString query = new QueryString();

query.Add("param1", "value1");
query.Add("param2", "value2");

return query.ToString();

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

HttpValueCollection的可链接包装类:

namespace System.Web.Mvc {
    public class QueryStringBuilder {
        private NameValueCollection collection;
        public QueryStringBuilder() {
            collection = System.Web.HttpUtility.ParseQueryString(string.Empty);
        }
        public QueryStringBuilder Add(string key, string value) {
            collection.Add(key, value);
            return this;
        }
        public QueryStringBuilder Remove(string key) {
            collection.Remove(key);
            return this;
        }
        public string this[string key] {
            get { return collection[key]; }
            set { collection[key] = value; }
        }
        public string ToString() {
            return collection.ToString();
        }
    }
}

使用示例:

QueryStringBuilder parameters = new QueryStringBuilder()
    .Add("view", ViewBag.PageView)
    .Add("page", ViewBag.PageNumber)
    .Add("size", ViewBag.PageSize);
string queryString = parameters.ToString();

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();
}

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);