NameValueCollection

1.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，值就连接起来如下例子）。该类可用于标头、查询字符串和窗体数据。

每个元素都是一个键/值对。NameValueCollection 的容量是 NameValueCollection 可以保存的元素数。

NameValueCollection 的默认初始容量为零。随着向 NameValueCollection 中添加元素，容量通过重新分配按需自动增加。

如下例子：

 

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"); 

2.NameValueCollection与Hashtable的区别

a.引用区别

hashtable:using System.Collections;

NameValueCollection:using System.Collections.Specialized;

b.键是否重复

NameValueCollection:允许重复.

HashTable是键-值集合,但键不能出现重复.

Hashtable ht = new Hashtable(); 

ht.Add("key","value"); 

ht.Add("key", "value1"); //出错 

ht["key"] = "value1"; //正确 

3.初始化NameValueCollection

初始化NameValueCollection需引用using System.Collections.Specialized;

完整例子源码：

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(); 

        } 

    } 

 

} 

4.NameValueCollection遍历

与Hashtable相似:

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["red"] = "dd"; 

 

foreach (string key in myCol.Keys) 

{ 

    Console.WriteLine("{0}:{1}", key, myCol[key]); 

} 

Console.ReadLine(); 
http://www.cnblogs.com/mrray/archive/2011/09/28/2193831.html