NameValueCollection 类
定义
重要
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public ref class NameValueCollection : System::Collections::Specialized::NameObjectCollectionBasepublic class NameValueCollection : System.Collections.Specialized.NameObjectCollectionBase[System.Serializable]
public class NameValueCollection : System.Collections.Specialized.NameObjectCollectionBasetype NameValueCollection = class
inherit NameObjectCollectionBase[<System.Serializable>]
type NameValueCollection = class
inherit NameObjectCollectionBasePublic Class NameValueCollection
Inherits NameObjectCollectionBase- 继承
- 派生
- 属性
示例
#using <System.dll>
using namespace System;
using namespace System::Collections;
using namespace System::Collections::Specialized;
void PrintKeysAndValues( NameValueCollection^ myCol );
void PrintKeysAndValues2( NameValueCollection^ myCol );
int main()
{
// Creates and initializes a new NameValueCollection.
NameValueCollection^ myCol = gcnew NameValueCollection;
myCol->Add( "red", "rojo" );
myCol->Add( "green", "verde" );
myCol->Add( "blue", "azul" );
myCol->Add( "red", "rouge" );
// Displays the values in the NameValueCollection in two different ways.
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.
Console::WriteLine( "Index 1 contains the value {0}.", myCol[ 1 ] );
Console::WriteLine( "Key \"red\" has the value {0}.", myCol[ "red" ] );
Console::WriteLine();
// Copies the values to a string array and displays the string array.
array<String^>^myStrArr = gcnew array<String^>(myCol->Count);
myCol->CopyTo( myStrArr, 0 );
Console::WriteLine( "The string array contains:" );
for each ( String^ s in myStrArr )
Console::WriteLine( " {0}", s );
Console::WriteLine();
// Searches for a key and deletes it.
myCol->Remove( "green" );
Console::WriteLine( "The collection contains the following elements after removing \"green\":" );
PrintKeysAndValues( myCol );
// Clears the entire collection.
myCol->Clear();
Console::WriteLine( "The collection contains the following elements after it is cleared:" );
PrintKeysAndValues( myCol );
}
void PrintKeysAndValues( NameValueCollection^ myCol )
{
Console::WriteLine( " KEY VALUE" );
for each ( String^ s in myCol->AllKeys )
Console::WriteLine( " {0,-10} {1}", s, myCol[s] );
Console::WriteLine();
}
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();
}
/*
This code produces the following output.
Displays the elements using the AllKeys property and the Item (indexer) property:
KEY VALUE
red rojo,rouge
green verde
blue azul
Displays the elements using GetKey and Get:
[INDEX] KEY VALUE
[0] red rojo,rouge
[1] green verde
[2] blue azul
Index 1 contains the value verde.
Key "red" has the value rojo,rouge.
The string array contains:
rojo,rouge
verde
azul
The collection contains the following elements after removing "green":
KEY VALUE
red rojo,rouge
blue azul
The collection contains the following elements after it is cleared:
KEY VALUE
*/
using System;
using System.Collections;
using System.Collections.Specialized;
public class SamplesNameValueCollection {
public static void Main() {
// Creates and initializes a new NameValueCollection.
NameValueCollection myCol = new NameValueCollection();
myCol.Add( "red", "rojo" );
myCol.Add( "green", "verde" );
myCol.Add( "blue", "azul" );
myCol.Add( "red", "rouge" );
// Displays the values in the NameValueCollection in two different ways.
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.
Console.WriteLine( "Index 1 contains the value {0}.", myCol[1] );
Console.WriteLine( "Key \"red\" has the value {0}.", myCol["red"] );
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();
// Searches for a key and deletes it.
myCol.Remove( "green" );
Console.WriteLine( "The collection contains the following elements after removing \"green\":" );
PrintKeysAndValues( myCol );
// Clears the entire collection.
myCol.Clear();
Console.WriteLine( "The collection contains the following elements after it is cleared:" );
PrintKeysAndValues( myCol );
}
public static void PrintKeysAndValues( NameValueCollection myCol ) {
Console.WriteLine( " KEY VALUE" );
foreach ( String s in myCol.AllKeys )
Console.WriteLine( " {0,-10} {1}", s, myCol[s] );
Console.WriteLine();
}
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();
}
}
/*
This code produces the following output.
Displays the elements using the AllKeys property and the Item (indexer) property:
KEY VALUE
red rojo,rouge
green verde
blue azul
Displays the elements using GetKey and Get:
[INDEX] KEY VALUE
[0] red rojo,rouge
[1] green verde
[2] blue azul
Index 1 contains the value verde.
Key "red" has the value rojo,rouge.
The string array contains:
rojo,rouge
verde
azul
The collection contains the following elements after removing "green":
KEY VALUE
red rojo,rouge
blue azul
The collection contains the following elements after it is cleared:
KEY VALUE
*/
' The following code example demonstrates several of the properties and methods of ListDictionary.
Imports System.Collections
Imports System.Collections.Specialized
Public Class SamplesNameValueCollection
Public Shared Sub Main()
' Creates and initializes a new NameValueCollection.
Dim myCol As New NameValueCollection()
myCol.Add("red", "rojo")
myCol.Add("green", "verde")
myCol.Add("blue", "azul")
myCol.Add("red", "rouge")
' Displays the values in the NameValueCollection in two different ways.
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.
Console.WriteLine("Index 1 contains the value {0}.", myCol(1))
Console.WriteLine("Key ""red"" has the value {0}.", myCol("red"))
Console.WriteLine()
' Copies the values to a string array and displays the string array.
Dim myStrArr(myCol.Count) As String
myCol.CopyTo(myStrArr, 0)
Console.WriteLine("The string array contains:")
Dim s As String
For Each s In myStrArr
Console.WriteLine(" {0}", s)
Next s
Console.WriteLine()
' Searches for a key and deletes it.
myCol.Remove("green")
Console.WriteLine("The collection contains the following elements after removing ""green"":")
PrintKeysAndValues(myCol)
' Clears the entire collection.
myCol.Clear()
Console.WriteLine("The collection contains the following elements after it is cleared:")
PrintKeysAndValues(myCol)
End Sub
Public Shared Sub PrintKeysAndValues(myCol As NameValueCollection)
Console.WriteLine(" KEY VALUE")
Dim s As String
For Each s In myCol.AllKeys
Console.WriteLine(" {0,-10} {1}", s, myCol(s))
Next s
Console.WriteLine()
End Sub
Public Shared Sub PrintKeysAndValues2(myCol As NameValueCollection)
Console.WriteLine(" [INDEX] KEY VALUE")
Dim i As Integer
For i = 0 To myCol.Count - 1
Console.WriteLine(" [{0}] {1,-10} {2}", i, myCol.GetKey(i), myCol.Get(i))
Next i
Console.WriteLine()
End Sub
End Class
'This code produces the following output.
'
'Displays the elements using the AllKeys property and the Item (indexer) property:
' KEY VALUE
' red rojo,rouge
' green verde
' blue azul
'
'Displays the elements using GetKey and Get:
' [INDEX] KEY VALUE
' [0] red rojo,rouge
' [1] green verde
' [2] blue azul
'
'Index 1 contains the value verde.
'Key "red" has the value rojo,rouge.
'
'The string array contains:
' red
' green
' blue
'
'
'The collection contains the following elements after removing "green":
' KEY VALUE
' red rojo,rouge
' blue azul
'
'The collection contains the following elements after it is cleared:
' KEY VALUE
'
'
注解
此集合基于 NameObjectCollectionBase 类。 集合的每个元素都是一个键/值对。 但是，与 不同， NameObjectCollectionBase此类可以在单个键下存储多个字符串值。
此类可用于标头、查询字符串和表单数据。
此类型的集合不保留元素的顺序，枚举集合时不保证特定的排序。
的 NameValueCollection 容量是 可以容纳的元素 NameValueCollection 数。 添加元素时，会根据需要通过重新分配自动增加其容量。
哈希代码提供程序为 中的 NameValueCollection键分配哈希代码。 默认哈希代码提供程序为 CaseInsensitiveHashCodeProvider。
比较器确定两个键是否相等。 默认比较器是使用CaseInsensitiveComparer固定区域性约定的 ;也就是说，默认情况下，键比较不区分大小写。 若要执行区分大小写的键比较，请调用 NameValueCollection.NameValueCollection(IEqualityComparer) 构造函数，并提供 、 StringComparer.InvariantCulture或 StringComparer.Ordinal 的值StringComparer.CurrentCulture作为equalityComparer参数。 有关区域性如何影响比较和排序的详细信息，请参阅 执行 Culture-Insensitive 字符串操作。
null 允许作为键或值。
注意
方法 Get 不区分 null 因找不到指定的键而返回的和 null 返回的，因为与键 null关联的值为 。
构造函数
属性
| AllKeys |
获取 NameValueCollection 中的所有键。 |
| Count |
获取包含在 NameObjectCollectionBase 实例中的键/值对的数目。 (继承自 NameObjectCollectionBase) |
| IsReadOnly |
获取或设置一个值，通过该值指示 NameObjectCollectionBase 实例是否为只读的。 (继承自 NameObjectCollectionBase) |
| Item[Int32] |
获取 NameValueCollection 中指定索引处的项。 |
| Item[String] |
获取或设置 NameValueCollection 中具有指定键的项。 |
| Keys |
获取包含 NameObjectCollectionBase.KeysCollection 实例中所有键的 NameObjectCollectionBase 实例。 (继承自 NameObjectCollectionBase) |
方法
显式接口实现
| ICollection.CopyTo(Array, Int32) |
从目标数组的指定索引处开始将整个 NameObjectCollectionBase 复制到兼容的一维 Array。 (继承自 NameObjectCollectionBase) |
| ICollection.IsSynchronized |
获取一个值，该值指示对 NameObjectCollectionBase 对象的访问是否同步（线程安全）。 (继承自 NameObjectCollectionBase) |
| ICollection.SyncRoot |
获取一个对象，该对象可用于同步对 NameObjectCollectionBase 对象的访问。 (继承自 NameObjectCollectionBase) |
扩展方法
| Cast<TResult>(IEnumerable) |
将 IEnumerable 的元素强制转换为指定的类型。 |
| OfType<TResult>(IEnumerable) |
根据指定类型筛选 IEnumerable 的元素。 |
| AsParallel(IEnumerable) |
启用查询的并行化。 |
| AsQueryable(IEnumerable) |
将 IEnumerable 转换为 IQueryable。 |
适用于
线程安全性
Visual Basic 中的公共静态 (Shared) 此类型的成员是线程安全的。 但不保证所有实例成员都是线程安全的。
此实现不会为 NameValueCollection提供同步 (线程安全的) 包装器，但派生类可以使用 类的 NameValueCollectionSyncRootNameObjectCollectionBase 属性创建自己的同步版本的 。
通过集合枚举本质上不是线程安全的过程。 即使某个集合已同步，其他线程仍可以修改该集合，这会导致枚举数引发异常。 若要确保枚举过程中的线程安全性，可以在整个枚举期间锁定集合，或者捕获由其他线程进行的更改所导致的异常。
