class Program
{
    static void Main(string[] args)
    {
      Logger log = Logger.GetInstance();
      log.WriteToFile();
      Console.Read();
    }
}
public class Logger
{
    private static Logger logger = new Logger();
    private Logger(){}
    public static Logger GetInstance()
    {
      return logger;
    }
    public void WriteToFile()
    {
      Console.WriteLine("錯(cuò)誤被寫入文件了~~");
    }
}

2.延遲加載的單例模式

直到調(diào)用類的靜態(tài)方法，才產(chǎn)生類的實(shí)例。

public class Logger
{
    private static Logger logger = null;
    private Logger(){}
    public static Logger GetInstance()
    {
      if (null == logger)
      {
        logger = new Logger();
      }
      return logger;
    }
    public void WriteToFile()
    {
      Console.WriteLine("錯(cuò)誤被寫入文件了~~");
    }
}

3.線程安全的單例模式

直到調(diào)用類的靜態(tài)方法，保證只有一個(gè)線程進(jìn)入產(chǎn)生類的實(shí)例。

public class Logger
{
    private static Logger logger = null;
    private static object lockObj = new object();
    private Logger(){}
    public static Logger GetInstance()
    {
      lock (lockObj)
      {
        if (logger == null)
        {
          logger = new Logger();
        }
        return logger;
      }
    }
    public void WriteToFile()
    {
      Console.WriteLine("錯(cuò)誤被寫入文件了~~");
    }
}

總結(jié)：靜態(tài)單例類型的私有字段，私有構(gòu)造函數(shù)，獲取單例的方法是構(gòu)成單例模式的3個(gè)必要元素。希望本文所述對(duì)大家的C#程序設(shè)計(jì)有所幫助。

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