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C# 效能優化 --- Lazy<T> 用法學習

參考原文:https://kb.cnblogs.com/page/99182/

延遲例項化,對於需要建立大量物件,而又不需要立即使用的場景非常有用。一下例項說明了Lazy<T>的用法。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace LazyDemo
{
    class Program
    {
        static void Main(string[] args)
        {
            BlogUser blogUser 
= new BlogUser(1); Console.WriteLine("blogUser has been initialized"); //使用延遲載入 //foreach (var article in blogUser.Articles.Value) //不使用延遲載入,要做比較將下面註釋放開,上面那句註釋即可 foreach (var article in blogUser.Articles) { Console.WriteLine(article.Title); } Console.Read(); } }
public class BlogUser { public int Id { get; private set; } //使用延遲載入 //public Lazy<List<Article>> Articles { get; set; } //不使用延遲載入,要做比較將下面註釋放開,上面那句註釋即可 public List<Article> Articles { get; set; } public BlogUser(int id) {
this.Id = id; //使用延遲載入 //Articles = new Lazy<List<Article>>(() => ArticleServices.GetArticesByID(id)); //不使用延遲載入,要做比較將下面註釋放開,上面那句註釋即可 Articles = ArticleServices.GetArticesByID(id); Console.WriteLine("BlogUser Initializer"); } } public class Article { public int Id { get; set; } public string Title { get; set; } public DateTime PublishDate { get; set; } } public class ArticleServices { public static List<Article> GetArticesByID(int blogUserID) { List<Article> articles = new List<Article> { new Article{Id=1,Title="Lazy Load",PublishDate=DateTime.Parse("2011-4-20")}, new Article{Id=2,Title="Delegate",PublishDate=DateTime.Parse("2011-4-21")}, new Article{Id=3,Title="Event",PublishDate=DateTime.Parse("2011-4-22")}, new Article{Id=4,Title="Thread",PublishDate=DateTime.Parse("2011-4-23")} }; Console.WriteLine("Article Initalizer"); return articles; } } }

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