NameValueCollection

（转自 http://www.studyofnet.com/news/623.html）

NameValueCollection类集合是基于 NameObjectCollectionBase 类，但与 NameObjectCollectionBase 不同，

该类在一个键下存储多个字符串值（就是键相同，值就连接起来），每个元素都是一个键/值对。

NameValueCollection类的命名空间为：using System.Collections.Specialized。

NameValueCollection中当存在一个key的时候，你在add的话，会追加进当前key中，而不是简单替换。

例如

C# 代码   复制

 NameValueCollection myCol = new NameValueCollection();
 myCol.Add("red", "rojo");//如果键值red相同结果合并 rojo,rouge
 myCol.Add("green", "verde");
 myCol.Add("blue", "azul");
 myCol.Add("red", "rouge");

一、NameValueCollection属性

二、NameValueCollection方法 

三、NameValueCollection获取URL参数

C# 代码   复制

        public static NameValueCollection ParseQueryString(string url)

        {
            NameValueCollection cPar = new NameValueCollection();
            url = url.StartsWith("?") ? url.Substring(1) : url;
            string[] pairs = url.Split(new char[] { ‘&‘ });
            int tmpIndex;
            foreach (string pair in pairs)
            {
                if (string.IsNullOrEmpty(pair))
                    continue;
                tmpIndex = pair.IndexOf(‘=‘);
                if (tmpIndex == -1)
                    continue;
                cPar.Add(pair.Substring(0, tmpIndex), pair.Substring(tmpIndex + 1));
            }
            return cPar;
        }

四、NameValueCollection使用示例

C# 代码   复制

using System;  using System.Collections;

using System.Collections.Specialized;

namespace SamplesNameValueCollection

{
    class Program
    {

        public static void Main()
        {
            //初始化NameValueCollection需引用using System.Collections.Specialized;
            NameValueCollection myCol = new NameValueCollection();
            myCol.Add("red", "rojo");//如果键值red相同结果合并 rojo,rouge
            myCol.Add("green", "verde");
            myCol.Add("blue", "azul");
            myCol.Add("red", "rouge");

            // Displays the values in the NameValueCollection in two different ways.
            //显示键，值
            Console.WriteLine("Displays the elements using the AllKeys property and the Item (indexer) property:");
            PrintKeysAndValues(myCol);
            Console.WriteLine("Displays the elements using GetKey and Get:");
            PrintKeysAndValues2(myCol);

            // Gets a value either by index or by key.
            //按索引或值获取
            Console.WriteLine("Index 1 contains the value {0}.", myCol[1]);//索引1的值
            Console.WriteLine("Key /"red/" has the value {0}.", myCol["red"]);//键为red的对应值rouge
            Console.WriteLine();

            // Copies the values to a string array and displays the string array.
            String[] myStrArr = new String[myCol.Count];
            myCol.CopyTo(myStrArr, 0);
            Console.WriteLine("The string array contains:");
            foreach (String s in myStrArr)
                Console.WriteLine("   {0}", s);
            Console.WriteLine();

            //查找green键值然后删除
            myCol.Remove("green");
            Console.WriteLine("The collection contains the following elements after removing /"green/":");
            PrintKeysAndValues(myCol);

            //清空集合
            myCol.Clear();
            Console.WriteLine("The collection contains the following elements after it is cleared:");
            PrintKeysAndValues(myCol);

        }
        //显示键，值
        public static void PrintKeysAndValues(NameValueCollection myCol)
        {
            IEnumerator myEnumerator = myCol.GetEnumerator();
            Console.WriteLine("   KEY        VALUE");
            foreach (String s in myCol.AllKeys)
                Console.WriteLine("   {0,-10} {1}", s, myCol[s]);
            Console.WriteLine();
        }
        //显示索引, 键,值
        public static void PrintKeysAndValues2(NameValueCollection myCol)
        {
            Console.WriteLine("   [INDEX] KEY        VALUE");
            for (int i = 0; i < myCol.Count; i++)
                Console.WriteLine("   [{0}]     {1,-10} {2}", i, myCol.GetKey(i), myCol.Get(i));
            Console.WriteLine();
        }
    }

}

五、NameValueCollection与Hashtable的区别

NameValueCollection 键允许重复.

HashTable 是键-值集合,但键不能出现重复.