学用 ASP.Net 之 System.Collections.Specialized.NameValueCollection 类

NameValueCollection 相当于 Key 和 Value 都是字符串的且能通过索引访问的哈希表.
主要成员:

/* 属性 */
AllKeys; //返回包含所有键的 string[]
Count;   //
Keys;    //键集合

/* 方法 */
Add();       //
Clear();     //
CopyTo();    //
Get();       //根据索引或键取值, 有多个值时会用逗号隔开
GetKey();    //根据索引取键
GetValues(); //根据索引或键取值, 返回 string[]
HasKeys();   //是否包含非 null 键
Remove();    //根据键移除
Set();       //改值; 若键不存在则同 Add()

其 Key 可为 null, 且可对应多个 Value:

protected void Button1_Click(object sender, EventArgs e)
{
    NameValueCollection nv = new NameValueCollection();
    nv.Add("k1", "AAA");
    nv.Add("k2", "BBB");
    nv.Add("k3", "CCC");
    nv.Add(null, "DDD");
    nv.Add("k2", "b");
    nv.Add("k2", "bb");
    nv.Add("k2", "bbb");

    string str1 = nv["k1"]; //AAA
    string str2 = nv["k2"]; //BBB,b,bb,bbb : 多个值会用逗号分开
    string str3 = nv[1];    //BBB,b,bb,bbb
    string str4 = nv[null]; //DDD

    TextBox1.Text = str1 + "\n" + str2 + "\n" + str3 + "\n" + str4;
}

练习:

protected void Button1_Click(object sender, EventArgs e)
{
    NameValueCollection nv = new NameValueCollection();
    nv.Add("k1", "AAA");
    nv.Add("k2", "BBB");
    nv.Add("k3", "CCC");
    nv.Add("k2", "b");
    nv.Add("k2", "bb");
    nv.Add("k2", "bbb");

    int n = nv.Count; //3 : k1、k2、k3

    nv.Set("k1", "aaa");

    string str1 = nv.Get(0);    //aaa
    string str2 = nv.Get("k1"); //aaa
    string str3 = nv.GetKey(0); //k1

    string[] sArr1 = nv.GetValues(0);
    string[] sArr2 = nv.GetValues("k2");

    string str4 = string.Join("; ", sArr1); //aaa
    string str5 = string.Join("; ", sArr2);

    TextBox1.Text = string.Format("{0}\n{1}\n{2}\n{3}\n{4}\n{5}", n, str1, str2, str3, str4, str5);
}

protected void Button2_Click(object sender, EventArgs e)
{
    NameValueCollection nv = new NameValueCollection();
    nv.Add("k1", "AAA");
    nv.Add("k2", "BBB");
    nv.Add("k3", "CCC");
    nv.Add("k2", "b");
    nv.Add("k2", "bb");
    nv.Add("k2", "bbb");

    NameValueCollection.KeysCollection keys = nv.Keys;

    string str1 = "";
    foreach (string s in keys) { str1 += s + ", "; } //k1, k2, k3, 

    string str2 = string.Join("; ", nv.AllKeys);     //k1; k2; k3 

    TextBox1.Text = str1 + "\n" + str2;
}