Registry.GetValue(String, String, Object) 方法

定义

检索与指定的注册表项中的指定名称关联的值。Retrieves the value associated with the specified name, in the specified registry key. 如果在指定的项中未找到该名称,则返回您提供的默认值;或者,如果指定的项不存在,则返回 nullIf the name is not found in the specified key, returns a default value that you provide, or null if the specified key does not exist.

public:
 static System::Object ^ GetValue(System::String ^ keyName, System::String ^ valueName, System::Object ^ defaultValue);
public static object GetValue (string keyName, string valueName, object defaultValue);
static member GetValue : string * string * obj -> obj
Public Shared Function GetValue (keyName As String, valueName As String, defaultValue As Object) As Object

参数

keyName
String

以有效注册表根(如“HKEY_CURRENT_USER”)开头的键的完整注册表路径。The full registry path of the key, beginning with a valid registry root, such as "HKEY_CURRENT_USER".

valueName
String

名称/值对的名称。The name of the name/value pair.

defaultValue
Object

valueName 不存在时返回的值。The value to return if valueName does not exist.

返回

如果由 null 指定的子项不存在,则返回 keyName;否则,返回与 valueName 关联的值;或者,如果未找到 defaultValue,则返回 valueNamenull if the subkey specified by keyName does not exist; otherwise, the value associated with valueName, or defaultValue if valueName is not found.

异常

该用户没有读取注册表项所需的权限。The user does not have the permissions required to read from the registry key.

包含指定值的 RegistryKey 已标记为删除。The RegistryKey that contains the specified value has been marked for deletion.

keyName 未以有效注册表根开头。keyName does not begin with a valid registry root.

示例

下面的代码示例将多个数据类型的值存储在一个示例键中,按其创建键,然后检索并显示这些值。The following code example stores values of several data types in an example key, creating the key as it does so, and then retrieves and displays the values. 该示例演示了在名称/值对不存在时,存储和检索默认(无名称)名称/值对,并使用 defaultValueThe example demonstrates storing and retrieving the default (nameless) name/value pair, and the use of defaultValue when a name/value pair does not exist.

using namespace System;
using namespace Microsoft::Win32;

int main()
{   
    // The name of the key must include a valid root.
    String^ userRoot = "HKEY_CURRENT_USER";
    String^ subKey = "RegistrySetValueExample2";
    String^ keyName = String::Concat(userRoot, "\\", subKey);
    
    // An int value can be stored without specifying the
    // registry data type, but Int64 values will be stored
    // as strings unless you specify the type. Note that
    // the int is stored in the default name/value
    // pair.
    Registry::SetValue(keyName, "", 5280);
    Registry::SetValue(keyName, "TestInt64", 12345678901234, 
        RegistryValueKind::QWord);
    
    // Strings with expandable environment variables are
    // stored as ordinary strings unless you specify the
    // data type.
    Registry::SetValue(keyName, "TestExpand", "My path: %path%");
    Registry::SetValue(keyName, "TestExpand2", "My path: %path%", 
        RegistryValueKind::ExpandString);
    
    // Arrays of strings are stored automatically as 
    // MultiString. Similarly, arrays of Byte are stored
    // automatically as Binary.
    array<String^>^ strings  = {"One", "Two", "Three"};
    Registry::SetValue(keyName, "TestArray", strings);
    
    // Your default value is returned if the name/value pair
    // does not exist.
    String^ noSuch = (String^)Registry::GetValue(keyName, 
        "NoSuchName", 
        "Return this default if NoSuchName does not exist.");
    Console::WriteLine("\r\nNoSuchName: {0}", noSuch);
    
    // Retrieve the int and Int64 values, specifying 
    // numeric default values in case the name/value pairs
    // do not exist. The int value is retrieved from the
    // default (nameless) name/value pair for the key.
    int testInteger = (int)Registry::GetValue(keyName, "", -1);
    Console::WriteLine("(Default): {0}", testInteger);
    long long testInt64 = (long long)Registry::GetValue(keyName, 
        "TestInt64", System::Int64::MinValue);
    Console::WriteLine("TestInt64: {0}", testInt64);
    
    // When retrieving a MultiString value, you can specify
    // an array for the default return value. 
    array<String^>^ testArray = (array<String^>^)Registry::GetValue(
        keyName, "TestArray", 
        gcnew array<String^> {"Default if TestArray does not exist."});
    for (int i = 0; i < testArray->Length; i++)
    {
        Console::WriteLine("TestArray({0}): {1}", i, testArray[i]);
    }
    
    // A string with embedded environment variables is not
    // expanded if it was stored as an ordinary string.
    String^ testExpand = (String^)Registry::GetValue(keyName, 
        "TestExpand", "Default if TestExpand does not exist.");
    Console::WriteLine("TestExpand: {0}", testExpand);
    
    // A string stored as ExpandString is expanded.
    String^ testExpand2 = (String^)Registry::GetValue(keyName, 
        "TestExpand2", "Default if TestExpand2 does not exist.");
    Console::WriteLine(
        "TestExpand2: {0}...", testExpand2->Substring(0, 40));
    Console::WriteLine(
        "\r\nUse the registry editor to examine the key.");
    Console::WriteLine("Press the Enter key to delete the key.");
    Console::ReadLine();
    Registry::CurrentUser->DeleteSubKey(subKey);
}
//
// This code example produces output similar to the following:
//
// NoSuchName: Return this default if NoSuchName does not exist.
// (Default): 5280
// TestInt64: 12345678901234
// TestArray(0): One
// TestArray(1): Two
// TestArray(2): Three
// TestExpand: My path: %path%
// TestExpand2: My path: D:\Program Files\Microsoft.NET\...
//
// Use the registry editor to examine the key.
// Press the Enter key to delete the key.
using System;
using Microsoft.Win32;

public class Example
{
    public static void Main()
    {
        // The name of the key must include a valid root.
        const string userRoot = "HKEY_CURRENT_USER";
        const string subkey = "RegistrySetValueExample";
        const string keyName = userRoot + "\\" + subkey;

        // An int value can be stored without specifying the
        // registry data type, but long values will be stored
        // as strings unless you specify the type. Note that
        // the int is stored in the default name/value
        // pair.
        Registry.SetValue(keyName, "", 5280);
        Registry.SetValue(keyName, "TestLong", 12345678901234,
            RegistryValueKind.QWord);

        // Strings with expandable environment variables are
        // stored as ordinary strings unless you specify the
        // data type.
        Registry.SetValue(keyName, "TestExpand", "My path: %path%");
        Registry.SetValue(keyName, "TestExpand2", "My path: %path%",
            RegistryValueKind.ExpandString);

        // Arrays of strings are stored automatically as 
        // MultiString. Similarly, arrays of Byte are stored
        // automatically as Binary.
        string[] strings = {"One", "Two", "Three"};
        Registry.SetValue(keyName, "TestArray", strings);

        // Your default value is returned if the name/value pair
        // does not exist.
        string noSuch = (string) Registry.GetValue(keyName, 
            "NoSuchName",
            "Return this default if NoSuchName does not exist.");
        Console.WriteLine("\r\nNoSuchName: {0}", noSuch);

        // Retrieve the int and long values, specifying 
        // numeric default values in case the name/value pairs
        // do not exist. The int value is retrieved from the
        // default (nameless) name/value pair for the key.
        int tInteger = (int) Registry.GetValue(keyName, "", -1);
        Console.WriteLine("(Default): {0}", tInteger);
        long tLong = (long) Registry.GetValue(keyName, "TestLong",
            long.MinValue);
        Console.WriteLine("TestLong: {0}", tLong);

        // When retrieving a MultiString value, you can specify
        // an array for the default return value. 
        string[] tArray = (string[]) Registry.GetValue(keyName,
            "TestArray",
            new string[] {"Default if TestArray does not exist."});
        for(int i=0; i<tArray.Length; i++)
        {
            Console.WriteLine("TestArray({0}): {1}", i, tArray[i]);
        }

        // A string with embedded environment variables is not
        // expanded if it was stored as an ordinary string.
        string tExpand = (string) Registry.GetValue(keyName,
             "TestExpand", 
             "Default if TestExpand does not exist.");
        Console.WriteLine("TestExpand: {0}", tExpand);

        // A string stored as ExpandString is expanded.
        string tExpand2 = (string) Registry.GetValue(keyName,
            "TestExpand2",
            "Default if TestExpand2 does not exist.");
        Console.WriteLine("TestExpand2: {0}...",
            tExpand2.Substring(0, 40));

        Console.WriteLine("\r\nUse the registry editor to examine the key.");
        Console.WriteLine("Press the Enter key to delete the key.");
        Console.ReadLine();
        Registry.CurrentUser.DeleteSubKey(subkey);
    }
}
//
// This code example produces output similar to the following:
//
//NoSuchName: Return this default if NoSuchName does not exist.
//(Default): 5280
//TestLong: 12345678901234
//TestArray(0): One
//TestArray(1): Two
//TestArray(2): Three
//TestExpand: My path: %path%
//TestExpand2: My path: D:\Program Files\Microsoft.NET\...
//
//Use the registry editor to examine the key.
//Press the Enter key to delete the key.
Imports Microsoft.Win32

Public Class Example
    Public Shared Sub Main()
        ' The name of the key must include a valid root.
        Const userRoot As String = "HKEY_CURRENT_USER"
        Const subkey As String = "RegistrySetValueExample"
        Const keyName As String = userRoot & "\" & subkey

        ' Integer values can be stored without specifying the
        ' registry data type, but Long values will be stored
        ' as strings unless you specify the type. Note that
        ' the integer is stored in the default name/value
        ' pair.
        Registry.SetValue(keyName, "", 5280)
        Registry.SetValue(keyName, "TestLong", 12345678901234, _
            RegistryValueKind.QWord)

        ' Strings with expandable environment variables are
        ' stored as ordinary strings unless you specify the
        ' data type.
        Registry.SetValue(keyName, "TestExpand", "My path: %path%")
        Registry.SetValue(keyName, "TestExpand2", "My path: %path%", _
            RegistryValueKind.ExpandString)

        ' Arrays of strings are stored automatically as 
        ' MultiString. Similarly, arrays of Byte are stored
        ' automatically as Binary.
        Dim strings() As String = {"One", "Two", "Three"}
        Registry.SetValue(keyName, "TestArray", strings)

        ' Your default value is returned if the name/value pair
        ' does not exist.
        Dim noSuch As String = _
            Registry.GetValue(keyName, "NoSuchName", _
            "Return this default if NoSuchName does not exist.")
        Console.WriteLine(vbCrLf & "NoSuchName: {0}", noSuch)

        ' Retrieve the Integer and Long values, specifying 
        ' numeric default values in case the name/value pairs
        ' do not exist. The Integer value is retrieved from the
        ' default (nameless) name/value pair for the key.
        Dim tInteger As Integer = _
            Registry.GetValue(keyName, "", -1)
        Console.WriteLine("(Default): {0}", tInteger)
        Dim tLong As Long = Registry.GetValue(keyName, _
             "TestLong", Long.MinValue)
        Console.WriteLine("TestLong: {0}", tLong)

        ' When retrieving a MultiString value, you can specify
        ' an array for the default return value. The value is
        ' declared inline, but could also be declared as:
        ' Dim default() As String = {"Default value."}
        '
        Dim tArray() As String = _
            Registry.GetValue(keyName, "TestArray", _
            New String() {"Default if TestArray does not exist."})
        For i As Integer = 0 To tArray.Length - 1
            Console.WriteLine("TestArray({0}): {1}", i, tArray(i))
        Next

        ' A string with embedded environment variables is not
        ' expanded if it was stored as an ordinary string.
        Dim tExpand As String = Registry.GetValue(keyName, _
             "TestExpand", "Default if TestExpand does not exist.")
        Console.WriteLine("TestExpand: {0}", tExpand)

        ' A string stored as ExpandString is expanded.
        Dim tExpand2 As String = Registry.GetValue(keyName, _
             "TestExpand2", "Default if TestExpand2 does not exist.")
        Console.WriteLine("TestExpand2: {0}...", _
            tExpand2.Substring(0, 40))

        Console.WriteLine(vbCrLf & _
            "Use the registry editor to examine the key.")
        Console.WriteLine("Press the Enter key to delete the key.")
        Console.ReadLine()
        Registry.CurrentUser.DeleteSubKey(subkey)
    End Sub
End Class
'
' This code example produces output similar to the following:
'
'NoSuchName: Return this default if NoSuchName does not exist.
'(Default): 5280
'TestLong: 12345678901234
'TestArray(0): One
'TestArray(1): Two
'TestArray(2): Three
'TestExpand: My path: %path%
'TestExpand2: My path: D:\Program Files\Microsoft.NET\...
'
'Use the registry editor to examine the key.
'Press the Enter key to delete the key.

注解

字符串 valueName 不区分大小写。The string valueName is not case-sensitive.

备注

注册表项可以包含一个不与任何名称关联的值。A registry key can contain one value that is not associated with any name. 在注册表编辑器中显示此未命名值时,将显示字符串 "(默认值)",而不是名称。When this unnamed value is displayed in the registry editor, the string "(Default)" appears instead of a name. 若要检索此未命名值,请为 valueName指定 null 或空字符串("")。To retrieve this unnamed value, specify either null or the empty string ("") for valueName.

有效的根名称为 HKEY_CURRENT_USER、HKEY_LOCAL_MACHINE、HKEY_CLASSES_ROOT、HKEY_USERS、HKEY_PERFORMANCE_DATA、HKEY_CURRENT_CONFIG 和 HKEY_DYN_DATA。Valid root names are HKEY_CURRENT_USER, HKEY_LOCAL_MACHINE, HKEY_CLASSES_ROOT, HKEY_USERS, HKEY_PERFORMANCE_DATA, HKEY_CURRENT_CONFIG, and HKEY_DYN_DATA. 例如,在 Visual Basic 字符串 "HKEY_CURRENT_USER \MyTestKey" 访问 HKEY_CURRENT_USER 根中子项 "MyTestKey" 的键/值对。For example, in Visual Basic the string "HKEY_CURRENT_USER\MyTestKey" accesses key/value pairs for the subkey "MyTestKey" in the HKEY_CURRENT_USER root.

GetValue 方法检索可扩充字符串值(RegistryValueKind.ExpandString)时,它将使用本地环境中的数据展开环境字符串。When the GetValue method retrieves expandable string values (RegistryValueKind.ExpandString), it expands environment strings using data from the local environment. 如果包含对环境变量的可扩充引用的值存储为字符串(RegistryValueKind.String),而不是作为可扩充字符串(RegistryValueKind.ExpandString)存储,则 GetValue 不会将其展开。If a value containing expandable references to environment variables has been stored as a string (RegistryValueKind.String), rather than as an expandable string (RegistryValueKind.ExpandString), GetValue does not expand it. 可以通过调用 Environment.ExpandEnvironmentVariables 方法来扩展此类字符串。You can expand such a string after it has been retrieved by calling the Environment.ExpandEnvironmentVariables method.

备注

从 HKEY_PERFORMANCE_DATA 检索数据的建议方法是使用 PerformanceCounter 类,而不是 RegistryKey.GetValue 方法。The recommended way to retrieve data from HKEY_PERFORMANCE_DATA is to use the PerformanceCounter class rather than the RegistryKey.GetValue method.

GetValueSetValue 方法在每次使用注册表项时都将其打开和关闭,因此在访问大量值时,它们不会执行,也不会执行 RegistryKey 类的方法。The GetValue and SetValue methods open and close registry keys each time they are used, so they do not perform as well as the methods of the RegistryKey class if you access a large number of values.

RegistryKey 还提供了一些方法,使你可以将访问控制列表(ACL)添加到注册表项,以便在检索值之前测试值的数据类型,并删除键。RegistryKey also provides methods that allow you to add an access control list (ACL) to a registry key, to test the data type of a value before retrieving it, and to delete keys.

安全性

RegistryPermission
从注册表进行读取。to read from the registry. 关联的枚举: ReadAssociated enumeration: Read

EnvironmentPermission
若要读取类型 REG_EXPAND_SZ 的注册表项,则为。to read a registry key of type REG_EXPAND_SZ. 关联的枚举: UnrestrictedAssociated enumeration: Unrestricted

适用于