C# NameValueCollection集合 .

案例：

NameValueCollection nameValueCollection = Request.Params;//获得连接地址中的所有参数

//获取各个参数，eg:
var a = nameValueCollection.Get("ID");
var name = nameValueCollection.Get("Name");

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();

转自：/article/2904298.html