我的項目中有一個類，我只想通過構造函數傳遞特定參數來實例化它一次，但是當我傳遞不同的參數時，它應該實例化一個新的參數。我如何使用單例設計模式實現這一目標？或者，如果單例無法實現，您能否建議另一種設計模式？class Program{static void Main(){ SiteStructure s = SiteStructure.Instance;}}public sealed class SiteStructure{static readonly SiteStructure _instance = new SiteStructure();public static SiteStructure Instance{ get { return _instance; }}SiteStructure(){ // Initialize.}}
2 回答
皈依舞
TA貢獻1851條經驗 獲得超3個贊
您必須修改_instance變量的初始化方式，使用接受您想要傳入的參數值的函數。此外，_instance變量不能再readonly像它需要在新函數內部初始化一樣。
[TestMethod]
public void CreateSingletonInstance()
{
SiteStructure s = SiteStructure.GetInstance("Abc123");
Debug.Print(s.Parameter); // outputs Abc123
SiteStructure s2 = SiteStructure.GetInstance("Is it really a singleton?");
Debug.Print(s2.Parameter); // outputs Is it really a singleton?
SiteStructure s3 = SiteStructure.GetInstance("Abc123");
Debug.Print(s3.Parameter); // outputs Abc123
Assert.AreNotEqual(s, s2); // Check to make sure they are different instances
Assert.AreEqual(s, s3); // Check to make sure they are the same instance
}
public sealed class SiteStructure
{
static Dictionary<string, SiteStructure> _siteStructures = new Dictionary<string, SiteStructure>();
static object _instance_Lock = new object();
public static SiteStructure GetInstance(string parameter)
{
if (!_siteStructures.ContainsKey(parameter))
{
lock (_instance_Lock)
{
if (!_siteStructures.ContainsKey(parameter))
{
_siteStructures.Add(parameter, new SiteStructure(parameter));
}
}
}
return _siteStructures[parameter];
}
private SiteStructure(string parameter)
{
// Initialize.
Parameter = parameter;
}
public string Parameter { get; set; }
}
慕的地10843
TA貢獻1785條經驗 獲得超8個贊
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;
namespace Rextester
{
public class Program
{
public static void Main(string[] args)
{
var g = SiteStructure.Instance(4);
}
}
public sealed class SiteStructure {
public static SiteStructure Instance()
{ return new SiteStructure();
}
public static SiteStructure Instance (int x)
{ return new SiteStructure (x);
}
SiteStructure() { }
SiteStructure(int x) { Console.WriteLine("Hello"); }
}
}
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