一、前言

      保证一个类仅有一个实例，并提供一个该实例的全局访问点。

二、代码

public class ApplicationServices{        public static readonly Lazy
     
       ServicesInstance               = new Lazy
      
       (() => new                ApplicationServices()); //Lazy加载        private ProjectSettingManager _projectManager;        public ProjectSettingManager ProjectManager        {            get { return _projectManager;        }        public static ApplicationServices Instance        {            get { return ServicesInstance.Value; }        }        public ApplicationServices()        {                      }}