{"id":10021166,"date":"2026-01-05T17:26:12","date_gmt":"2026-01-05T09:26:12","guid":{"rendered":"https:\/\/itmax.cn\/?p=10021166"},"modified":"2026-01-05T17:26:12","modified_gmt":"2026-01-05T09:26:12","slug":"%e6%b7%b1%e5%85%a5%e7%90%86%e8%a7%a3-system-lazyt%ef%bc%9ac-net-%e5%bb%b6%e8%bf%9f%e5%88%9d%e5%a7%8b%e5%8c%96%e4%b8%8e%e7%ba%bf%e7%a8%8b%e5%ae%89%e5%85%a8","status":"publish","type":"post","link":"https:\/\/itmax.cn\/?p=10021166","title":{"rendered":"\u6df1\u5165\u7406\u89e3 System.Lazy&lt;T&gt;\uff1aC#.NET \u5ef6\u8fdf\u521d\u59cb\u5316\u4e0e\u7ebf\u7a0b\u5b89\u5168"},"content":{"rendered":"<h3>\u4ec0\u4e48\u662f <code>Lazy&lt;T&gt;<\/code>\uff1f<\/h3>\n<p><code>System.Lazy&lt;T&gt;<\/code> \u662f <code>.NET Framework 4.0<\/code> \u5f15\u5165\uff08\u4f4d\u4e8e <code>System<\/code> \u547d\u540d\u7a7a\u95f4\uff09\u7684\u6cdb\u578b\u7c7b\uff0c\u7528\u4e8e\u5b9e\u73b0\u7ebf\u7a0b\u5b89\u5168\u7684\u5ef6\u8fdf\u521d\u59cb\u5316\uff08<code>Lazy Initialization<\/code>\uff09\u3002\u5b83\u786e\u4fdd\u4e00\u4e2a\u6602\u8d35\u7684\u5bf9\u8c61\u6216\u8d44\u6e90\u53ea\u5728\u7b2c\u4e00\u6b21\u771f\u6b63\u9700\u8981\u65f6\u624d\u88ab\u521b\u5efa\uff0c\u5e76\u4e14\u5728\u591a\u7ebf\u7a0b\u73af\u5883\u4e0b\u4fdd\u8bc1\u521d\u59cb\u5316\u53ea\u53d1\u751f\u4e00\u6b21\u3002<\/p>\n<ul>\n<li>\n<p>\u6838\u5fc3\u7279\u6027\uff1a<\/p>\n<ul>\n<li>\u5ef6\u8fdf\u8ba1\u7b97\uff1a\u503c\u7684\u521b\u5efa\u88ab\u63a8\u8fdf\u5230\u7b2c\u4e00\u6b21\u8bbf\u95ee <code>.Value<\/code> \u5c5e\u6027\u65f6\u3002<\/li>\n<li>\u7ebf\u7a0b\u5b89\u5168\uff1a\u5185\u7f6e\u591a\u79cd\u7ebf\u7a0b\u5b89\u5168\u6a21\u5f0f\uff0c\u9ed8\u8ba4\u60c5\u51b5\u4e0b\u5b8c\u5168\u7ebf\u7a0b\u5b89\u5168\u3002<\/li>\n<li>\u5f02\u5e38\u7f13\u5b58\uff1a\u5982\u679c\u521d\u59cb\u5316\u8fc7\u7a0b\u4e2d\u629b\u51fa\u5f02\u5e38\uff0c\u540e\u7eed\u8bbf\u95ee\u4f1a\u91cd\u590d\u629b\u51fa\u540c\u4e00\u4e2a\u5f02\u5e38\uff08\u4e0d\u91cd\u590d\u6267\u884c\u5de5\u5382\u65b9\u6cd5\uff09\u3002<\/li>\n<li>\u503c\u7f13\u5b58\uff1a\u4e00\u65e6\u521d\u59cb\u5316\u5b8c\u6210\uff0c\u540e\u7eed\u6240\u6709\u8bbf\u95ee\u90fd\u8fd4\u56de\u540c\u4e00\u4e2a\u5b9e\u4f8b\uff08\u5355\u4f8b\u884c\u4e3a\uff09\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\n<p>\u9002\u7528\u573a\u666f\uff1a<\/p>\n<ul>\n<li>\u6602\u8d35\u8d44\u6e90\u521d\u59cb\u5316\uff08\u5982\u6570\u636e\u5e93\u8fde\u63a5\u3001\u5927\u6587\u4ef6\u52a0\u8f7d\u3001\u590d\u6742\u8ba1\u7b97\uff09\u3002<\/li>\n<li>\u914d\u7f6e\u5bf9\u8c61\u3001\u5355\u4f8b\u6a21\u5f0f\uff08\u6bd4\u53cc\u68c0\u67e5\u9501\u66f4\u5b89\u5168\u7b80\u6d01\uff09\u3002<\/li>\n<li>\u907f\u514d\u542f\u52a8\u65f6\u4e0d\u5fc5\u8981\u7684\u5f00\u9500\uff08\u5c24\u5176\u5728\u67d0\u4e9b\u4ee3\u7801\u8def\u5f84\u53ef\u80fd\u4e0d\u4f7f\u7528\u8be5\u5bf9\u8c61\u65f6\uff09\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<h3>\u4e3a\u4ec0\u4e48\u4f7f\u7528 <code>Lazy&lt;T&gt;<\/code>\uff1f<\/h3>\n<p>\u4f20\u7edf\u65b9\u5f0f\uff08\u5982\u76f4\u63a5\u5728\u5b57\u6bb5\u521d\u59cb\u5316\u6216\u624b\u52a8\u53cc\u68c0\u67e5\u9501\uff09\u5b58\u5728\u95ee\u9898\uff1a<\/p>\n<ul>\n<li>\u63d0\u524d\u521d\u59cb\u5316\uff1a\u6d6a\u8d39\u8d44\u6e90\u3002<\/li>\n<li>\u624b\u52a8\u9501\uff1a\u6613\u51fa\u9519\uff08\u6b7b\u9501\u3001\u7ade\u4e89\u6761\u4ef6\u3001<code>ABA<\/code> \u95ee\u9898\uff09\u3002<\/li>\n<li>\u5f02\u5e38\u5904\u7406\u590d\u6742\uff1a\u9700\u624b\u52a8\u7f13\u5b58\u5f02\u5e38\u3002<\/li>\n<\/ul>\n<p><code>Lazy&lt;T&gt;<\/code>\u6027\u80fd\u4f18\u5316\uff1a\u6309\u9700\u521d\u59cb\u5316\u3002<\/p>\n<ul>\n<li>\u7ebf\u7a0b\u5b89\u5168\uff1a\u5fae\u8f6f\u9ad8\u5ea6\u4f18\u5316\uff0c\u65e0\u9501\u6216\u8f7b\u91cf\u9501\u5b9e\u73b0\u3002<\/li>\n<li>\u4ee3\u7801\u7b80\u6d01\uff1a\u4e00\u884c\u4ee3\u7801\u53d6\u4ee3\u590d\u6742\u7684\u53cc\u68c0\u67e5\u9501\u3002<\/li>\n<li>\u9632 <code>ABA<\/code>\uff1a\u5185\u90e8\u4f7f\u7528\u590d\u5408\u72b6\u6001 + <code>CAS<\/code> \u673a\u5236\uff0c\u5f7b\u5e95\u907f\u514d <code>ABA<\/code> \u95ee\u9898\u3002 \u5b8c\u7f8e\u89e3\u51b3\u8fd9\u4e9b\u95ee\u9898\uff1a<\/li>\n<\/ul>\n<h3>\u5982\u4f55\u4f7f\u7528 <code>Lazy&lt;T&gt;<\/code>\uff1f<\/h3>\n<h4>\u6838\u5fc3\u8bed\u6cd5\u4e0e\u5c5e\u6027<\/h4>\n<table>\n<thead>\n<tr>\n<th>\u6210\u5458<\/th>\n<th>\u4f5c\u7528<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td><code>Lazy&lt;T&gt;()<\/code><\/td>\n<td>\u6784\u9020\u51fd\u6570\uff1a\u9ed8\u8ba4\u4f7f\u7528<code>T<\/code>\u7684\u65e0\u53c2\u6784\u9020\u521b\u5efa\u5bf9\u8c61\uff0c\u7ebf\u7a0b\u5b89\u5168\u6a21\u5f0f\u4e3a<code>ExecutionAndPublication<\/code><\/td>\n<\/tr>\n<tr>\n<td><code>Lazy&lt;T&gt;(Func&lt;T&gt; valueFactory)<\/code><\/td>\n<td>\u6784\u9020\u51fd\u6570\uff1a\u81ea\u5b9a\u4e49\u5bf9\u8c61\u521b\u5efa\u903b\u8f91\uff08\u652f\u6301\u4f20\u53c2\u3001\u590d\u6742\u521d\u59cb\u5316\uff09<\/td>\n<\/tr>\n<tr>\n<td><code>Lazy&lt;T&gt;(LazyThreadSafetyMode mode)<\/code><\/td>\n<td>\u6784\u9020\u51fd\u6570\uff1a\u6307\u5b9a\u7ebf\u7a0b\u5b89\u5168\u6a21\u5f0f<\/td>\n<\/tr>\n<tr>\n<td><code>Value<\/code><\/td>\n<td>\u6838\u5fc3\u5c5e\u6027\uff1a\u9996\u6b21\u8bbf\u95ee\u89e6\u53d1\u5bf9\u8c61\u521d\u59cb\u5316\uff0c\u540e\u7eed\u8bbf\u95ee\u8fd4\u56de\u5df2\u521b\u5efa\u7684\u5b9e\u4f8b\uff08\u53ea\u8bfb\uff09<\/td>\n<\/tr>\n<tr>\n<td><code>IsValueCreated<\/code><\/td>\n<td>\u5e03\u5c14\u5c5e\u6027\uff1a\u5224\u65ad\u5bf9\u8c61\u662f\u5426\u5df2\u5b8c\u6210\u521d\u59cb\u5316<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h4>\u57fa\u7840\u793a\u4f8b\uff08\u9ed8\u8ba4\u6784\u9020\uff09<\/h4>\n<pre><code class=\"csharp\">using System;\nusing System.Threading;\n\n\/\/ \u6a21\u62df\u521b\u5efa\u6210\u672c\u9ad8\u7684\u5bf9\u8c61\uff08\u5982\u52a0\u8f7d\u914d\u7f6e\u3001\u8fde\u63a5\u6570\u636e\u5e93\uff09\npublic class ExpensiveObject\n{\n    public ExpensiveObject()\n    {\n        Console.WriteLine(&quot;ExpensiveObject \u5f00\u59cb\u521d\u59cb\u5316\uff08\u8017\u65f6\u64cd\u4f5c\uff09...&quot;);\n        Thread.Sleep(2000); \/\/ \u6a21\u62df2\u79d2\u8017\u65f6\u521d\u59cb\u5316\n        Console.WriteLine(&quot;ExpensiveObject \u521d\u59cb\u5316\u5b8c\u6210\uff01&quot;);\n    }\n\n    public void DoWork() =&gt; Console.WriteLine(&quot;ExpensiveObject \u6267\u884c\u4e1a\u52a1\u903b\u8f91...&quot;);\n}\n\nclass LazyBasicDemo\n{\n    static void Main()\n    {\n        Console.WriteLine(&quot;\u7a0b\u5e8f\u542f\u52a8\uff0c\u521b\u5efaLazy&lt;ExpensiveObject&gt;\u5b9e\u4f8b...&quot;);\n        \/\/ \u6b64\u65f6\u4ec5\u521b\u5efaLazy&lt;T&gt;\u5bb9\u5668\uff0cExpensiveObject\u5e76\u672a\u5b9e\u4f8b\u5316\n        Lazy&lt;ExpensiveObject&gt; lazyObj = new Lazy&lt;ExpensiveObject&gt;();\n\n        Console.WriteLine($&quot;\u5bf9\u8c61\u662f\u5426\u5df2\u521b\u5efa\uff1a{lazyObj.IsValueCreated}&quot;); \/\/ \u8f93\u51fa\uff1aFalse\n\n        \/\/ \u9996\u6b21\u8bbf\u95eeValue\uff1a\u89e6\u53d1ExpensiveObject\u7684\u6784\u9020\u51fd\u6570\n        Console.WriteLine(&quot;\/n=== \u9996\u6b21\u8bbf\u95eeValue ===&quot;);\n        lazyObj.Value.DoWork();\n        Console.WriteLine($&quot;\u5bf9\u8c61\u662f\u5426\u5df2\u521b\u5efa\uff1a{lazyObj.IsValueCreated}&quot;); \/\/ \u8f93\u51fa\uff1aTrue\n\n        \/\/ \u518d\u6b21\u8bbf\u95eeValue\uff1a\u76f4\u63a5\u8fd4\u56de\u5df2\u521b\u5efa\u7684\u5b9e\u4f8b\uff0c\u4e0d\u518d\u521d\u59cb\u5316\n        Console.WriteLine(&quot;\/n=== \u518d\u6b21\u8bbf\u95eeValue ===&quot;);\n        lazyObj.Value.DoWork();\n    }\n}<\/code><\/pre>\n<p>\u8f93\u51fa\u7ed3\u679c\uff1a<\/p>\n<pre><code>\u7a0b\u5e8f\u542f\u52a8\uff0c\u521b\u5efaLazy&lt;ExpensiveObject&gt;\u5b9e\u4f8b...\n\u5bf9\u8c61\u662f\u5426\u5df2\u521b\u5efa\uff1aFalse\n\n=== \u9996\u6b21\u8bbf\u95eeValue ===\nExpensiveObject \u5f00\u59cb\u521d\u59cb\u5316\uff08\u8017\u65f6\u64cd\u4f5c\uff09...\nExpensiveObject \u521d\u59cb\u5316\u5b8c\u6210\uff01\nExpensiveObject \u6267\u884c\u4e1a\u52a1\u903b\u8f91...\n\u5bf9\u8c61\u662f\u5426\u5df2\u521b\u5efa\uff1aTrue\n\n=== \u518d\u6b21\u8bbf\u95eeValue ===\nExpensiveObject \u6267\u884c\u4e1a\u52a1\u903b\u8f91...<\/code><\/pre>\n<h4>\u81ea\u5b9a\u4e49\u5de5\u5382\u65b9\u6cd5\uff08\u5e26\u53c2\u6570\u521d\u59cb\u5316\uff09<\/h4>\n<p>\u82e5\u5bf9\u8c61\u9700\u8981\u4f20\u53c2\u6216\u590d\u6742\u521d\u59cb\u5316\u903b\u8f91\uff0c\u4f7f\u7528 <code>Func&lt;T&gt;<\/code> \u5de5\u5382\u65b9\u6cd5\uff1a<\/p>\n<pre><code class=\"csharp\">\/\/ \u81ea\u5b9a\u4e49\u5e26\u53c2\u6570\u7684\u5bf9\u8c61\u6784\u9020\npublic class ConfigObject\n{\n    private string _configPath;\n    public ConfigObject(string configPath)\n    {\n        _configPath = configPath;\n        Console.WriteLine($&quot;\u52a0\u8f7d\u914d\u7f6e\u6587\u4ef6\uff1a{configPath}&quot;);\n    }\n\n    public string GetConfig() =&gt; $&quot;\u914d\u7f6e\u5185\u5bb9\uff08\u6765\u81ea{_configPath}\uff09&quot;;\n}\n\nclass LazyFactoryDemo\n{\n    static void Main()\n    {\n        \/\/ \u81ea\u5b9a\u4e49\u5de5\u5382\u65b9\u6cd5\uff1a\u521b\u5efaConfigObject\u5e76\u4f20\u5165\u53c2\u6570\n        Lazy&lt;ConfigObject&gt; lazyConfig = new Lazy&lt;ConfigObject&gt;(() =&gt; \n        {\n            Console.WriteLine(&quot;\u6267\u884c\u81ea\u5b9a\u4e49\u5de5\u5382\u65b9\u6cd5...&quot;);\n            return new ConfigObject(&quot;appsettings.json&quot;);\n        });\n\n        Console.WriteLine(&quot;\u9996\u6b21\u8bbf\u95ee\u914d\u7f6e\uff1a&quot;);\n        Console.WriteLine(lazyConfig.Value.GetConfig()); \/\/ \u89e6\u53d1\u5de5\u5382\u65b9\u6cd5\n    }\n}<\/code><\/pre>\n<h4><code>Lazy&lt;T&gt;<\/code> \u7684\u7ebf\u7a0b\u5b89\u5168\u6a21\u5f0f<\/h4>\n<p><code>Lazy&lt;T&gt;<\/code> \u7684\u5173\u952e\u7279\u6027\u662f\u652f\u6301\u591a\u7ebf\u7a0b\u573a\u666f\uff0c\u901a\u8fc7 <code>LazyThreadSafetyMode<\/code> \u679a\u4e3e\u63a7\u5236\u7ebf\u7a0b\u5b89\u5168\u884c\u4e3a<\/p>\n<table>\n<thead>\n<tr>\n<th>\u7ebf\u7a0b\u5b89\u5168\u6a21\u5f0f<\/th>\n<th>\u9002\u7528\u573a\u666f<\/th>\n<th>\u6838\u5fc3\u884c\u4e3a<\/th>\n<th>\u6027\u80fd<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td><code>None<\/code><\/td>\n<td>\u5355\u7ebf\u7a0b\u73af\u5883<\/td>\n<td>\u65e0\u7ebf\u7a0b\u5b89\u5168\u4fdd\u969c\uff0c\u591a\u7ebf\u7a0b\u540c\u65f6\u8bbf\u95ee<code>Value<\/code>\u53ef\u80fd\u521b\u5efa\u591a\u4e2a\u5b9e\u4f8b<\/td>\n<td>\u6700\u9ad8\uff08\u65e0\u9501\uff09<\/td>\n<\/tr>\n<tr>\n<td><code>PublicationOnly<\/code><\/td>\n<td>\u591a\u7ebf\u7a0b + \u5bf9\u8c61\u521b\u5efa\u6210\u672c\u4f4e<\/td>\n<td>\u591a\u7ebf\u7a0b\u53ef\u540c\u65f6\u521d\u59cb\u5316\uff0c\u4f46\u6700\u7ec8\u4ec5\u4fdd\u7559\u4e00\u4e2a\u5b9e\u4f8b\uff08\u5176\u4ed6\u5b9e\u4f8b\u88ab\u4e22\u5f03\uff09\uff0c\u65e0\u9501\u963b\u585e<\/td>\n<td>\u9ad8<\/td>\n<\/tr>\n<tr>\n<td><code>ExecutionAndPublication<\/code>\uff08\u9ed8\u8ba4\uff09<\/td>\n<td>\u591a\u7ebf\u7a0b + \u5bf9\u8c61\u521b\u5efa\u6210\u672c\u9ad8<\/td>\n<td>\u52a0\u9501\u4fdd\u8bc1\u53ea\u6709\u4e00\u4e2a\u7ebf\u7a0b\u6267\u884c\u521d\u59cb\u5316\uff0c\u5176\u4ed6\u7ebf\u7a0b\u7b49\u5f85\uff0c\u7edd\u5bf9\u5355\u5b9e\u4f8b<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>\u793a\u4f8b\uff1a\u591a\u7ebf\u7a0b\u4e0b\u7684\u7ebf\u7a0b\u5b89\u5168\u6a21\u5f0f<\/p>\n<pre><code class=\"csharp\">class LazyThreadSafetyDemo\n{\n    \/\/ \u9ed8\u8ba4\u6a21\u5f0f\uff1aExecutionAndPublication\uff08\u52a0\u9501\u4fdd\u8bc1\u5355\u5b9e\u4f8b\uff09\n    static Lazy&lt;ExpensiveObject&gt; lazySafeObj = new Lazy&lt;ExpensiveObject&gt;();\n\n    static void AccessLazyObj()\n    {\n        Console.WriteLine($&quot;\u7ebf\u7a0b{Thread.CurrentThread.ManagedThreadId} \u5c1d\u8bd5\u8bbf\u95eeValue...&quot;);\n        var obj = lazySafeObj.Value;\n        Console.WriteLine($&quot;\u7ebf\u7a0b{Thread.CurrentThread.ManagedThreadId} \u83b7\u53d6\u5bf9\u8c61HashCode\uff1a{obj.GetHashCode()}&quot;);\n    }\n\n    static void Main()\n    {\n        \/\/ \u542f\u52a85\u4e2a\u7ebf\u7a0b\u540c\u65f6\u8bbf\u95ee\n        for (int i = 0; i &lt; 5; i++)\n        {\n            new Thread(AccessLazyObj).Start();\n        }\n        Thread.Sleep(3000); \/\/ \u7b49\u5f85\u6240\u6709\u7ebf\u7a0b\u5b8c\u6210\n    }\n}<\/code><\/pre>\n<p>\u8f93\u51fa\u7ed3\u679c<\/p>\n<p>\u6240\u6709\u7ebf\u7a0b\u6700\u7ec8\u83b7\u53d6\u7684 <code>HashCode<\/code> \u5b8c\u5168\u76f8\u540c\uff0c\u4e14\u4ec5\u89e6\u53d1\u4e00\u6b21\u521d\u59cb\u5316\uff08\u8bc1\u660e\u5355\u5b9e\u4f8b\uff09\uff1a<\/p>\n<pre><code class=\"csharp\">\u7ebf\u7a0b3 \u5c1d\u8bd5\u8bbf\u95eeValue...\nExpensiveObject \u5f00\u59cb\u521d\u59cb\u5316\uff08\u8017\u65f6\u64cd\u4f5c\uff09...\n\u7ebf\u7a0b4 \u5c1d\u8bd5\u8bbf\u95eeValue...\n\u7ebf\u7a0b5 \u5c1d\u8bd5\u8bbf\u95eeValue...\n\u7ebf\u7a0b6 \u5c1d\u8bd5\u8bbf\u95eeValue...\n\u7ebf\u7a0b7 \u5c1d\u8bd5\u8bbf\u95eeValue...\nExpensiveObject \u521d\u59cb\u5316\u5b8c\u6210\uff01\n\u7ebf\u7a0b3 \u83b7\u53d6\u5bf9\u8c61HashCode\uff1a46104728\n\u7ebf\u7a0b4 \u83b7\u53d6\u5bf9\u8c61HashCode\uff1a46104728\n\u7ebf\u7a0b5 \u83b7\u53d6\u5bf9\u8c61HashCode\uff1a46104728\n\u7ebf\u7a0b6 \u83b7\u53d6\u5bf9\u8c61HashCode\uff1a46104728\n\u7ebf\u7a0b7 \u83b7\u53d6\u5bf9\u8c61HashCode\uff1a46104728<\/code><\/pre>\n<h3>\u9ad8\u7ea7\u5e94\u7528\u573a\u666f<\/h3>\n<h4>\u61d2\u52a0\u8f7d\u5355\u4f8b\u6a21\u5f0f<\/h4>\n<p><code>Lazy&lt;T&gt;<\/code> \u662f <code>.NET<\/code> \u4e2d\u5b9e\u73b0\u7ebf\u7a0b\u5b89\u5168\u3001\u61d2\u52a0\u8f7d\u5355\u4f8b\u7684\u6700\u4f18\u65b9\u5f0f\uff1a<\/p>\n<pre><code class=\"csharp\">public sealed class LazySingleton\n{\n    \/\/ \u79c1\u6709\u9759\u6001Lazy\u5b9e\u4f8b\uff1a\u5ef6\u8fdf\u521d\u59cb\u5316\uff0c\u9ed8\u8ba4\u7ebf\u7a0b\u5b89\u5168\n    private static readonly Lazy&lt;LazySingleton&gt; _lazyInstance = new Lazy&lt;LazySingleton&gt;(() =&gt; new LazySingleton());\n\n    \/\/ \u79c1\u6709\u6784\u9020\u51fd\u6570\uff1a\u7981\u6b62\u5916\u90e8\u5b9e\u4f8b\u5316\n    private LazySingleton() \n    {\n        Console.WriteLine(&quot;\u5355\u4f8b\u5bf9\u8c61\u521d\u59cb\u5316...&quot;);\n    }\n\n    \/\/ \u516c\u5171\u5c5e\u6027\uff1a\u9996\u6b21\u8bbf\u95ee\u65f6\u521b\u5efa\u5b9e\u4f8b\n    public static LazySingleton Instance =&gt; _lazyInstance.Value;\n\n    public void DoBusiness() =&gt; Console.WriteLine(&quot;\u5355\u4f8b\u5bf9\u8c61\u6267\u884c\u4e1a\u52a1\u903b\u8f91...&quot;);\n}\n\n\/\/ \u4f7f\u7528\nclass SingletonDemo\n{\n    static void Main()\n    {\n        Console.WriteLine(&quot;\u7a0b\u5e8f\u542f\u52a8\uff0c\u672a\u8bbf\u95ee\u5355\u4f8b...&quot;);\n        \/\/ \u9996\u6b21\u8bbf\u95eeInstance\uff1a\u89e6\u53d1\u5355\u4f8b\u521d\u59cb\u5316\n        LazySingleton.Instance.DoBusiness();\n        \/\/ \u518d\u6b21\u8bbf\u95ee\uff1a\u76f4\u63a5\u8fd4\u56de\u5df2\u521b\u5efa\u7684\u5b9e\u4f8b\n        LazySingleton.Instance.DoBusiness();\n    }\n}<\/code><\/pre>\n<h4>\u5904\u7406\u521d\u59cb\u5316\u5f02\u5e38<\/h4>\n<p>\u82e5 <code>Lazy&lt;T&gt;<\/code> \u7684\u5de5\u5382\u65b9\u6cd5\u629b\u51fa\u5f02\u5e38\uff0c\u540e\u7eed\u8bbf\u95ee <code>Value<\/code> \u4f1a\u7f13\u5b58\u5e76\u91cd\u65b0\u629b\u51fa\u540c\u4e00\u5f02\u5e38<\/p>\n<pre><code class=\"csharp\">Lazy&lt;ExpensiveObject&gt; lazyErrorObj = new Lazy&lt;ExpensiveObject&gt;(() =&gt;\n{\n    throw new InvalidOperationException(&quot;\u521d\u59cb\u5316\u5931\u8d25\uff1a\u914d\u7f6e\u6587\u4ef6\u4e0d\u5b58\u5728\uff01&quot;);\n});\n\ntry\n{\n    \/\/ \u9996\u6b21\u8bbf\u95ee\uff1a\u629b\u51fa\u5f02\u5e38\n    lazyErrorObj.Value.DoWork();\n}\ncatch (AggregateException ex)\n{\n    Console.WriteLine($&quot;\u521d\u59cb\u5316\u5f02\u5e38\uff1a{ex.InnerException.Message}&quot;);\n}\n\ntry\n{\n    \/\/ \u518d\u6b21\u8bbf\u95ee\uff1a\u4ecd\u629b\u51fa\u540c\u4e00\u5f02\u5e38\uff08\u5f02\u5e38\u88ab\u7f13\u5b58\uff09\n    lazyErrorObj.Value.DoWork();\n}\ncatch (AggregateException ex)\n{\n    Console.WriteLine($&quot;\u518d\u6b21\u8bbf\u95ee\u5f02\u5e38\uff1a{ex.InnerException.Message}&quot;);\n}<\/code><\/pre>\n<h4>\u5f02\u6b65\u61d2\u52a0\u8f7d\uff08\u4f2a AsyncLazy\uff09<\/h4>\n<pre><code class=\"csharp\">private readonly Lazy&lt;Task&lt;ExpensiveObject&gt;&gt; _asyncResource = new(async () =&gt;\n{\n    await Task.Delay(2000);\n    return new ExpensiveObject();\n});\n\npublic async Task&lt;ExpensiveObject&gt; GetResourceAsync() =&gt; await _asyncResource.Value;<\/code><\/pre>\n<h4>\u652f\u6301\u5237\u65b0\uff08Reset\uff09\u7684\u81ea\u5b9a\u4e49\u5305\u88c5<\/h4>\n<pre><code class=\"csharp\">public class RefreshableLazy&lt;T&gt;\n{\n    private Lazy&lt;T&gt; _current;\n\n    public RefreshableLazy(Func&lt;T&gt; factory)\n    {\n        _current = new Lazy&lt;T&gt;(factory);\n    }\n\n    public T Value =&gt; _current.Value;\n\n    public void Refresh()\n    {\n        var factory = _current.Value; \/\/ \u4fdd\u7559\u65e7\u5de5\u5382\uff1f\u6216\u4f20\u5165\u65b0\u5de5\u5382\n        _current = new Lazy&lt;T&gt;(_current.Factory); \/\/ \u91cd\u65b0\u521b\u5efa\n    }\n}<\/code><\/pre>\n<h4>\u4e0e\u4f9d\u8d56\u6ce8\u5165\u7ed3\u5408\uff08ASP.NET Core\uff09<\/h4>\n<pre><code class=\"csharp\">services.AddSingleton&lt;ExpensiveService&gt;();\nservices.AddSingleton&lt;Lazy&lt;ExpensiveService&gt;&gt;(provider =&gt; \n    new Lazy&lt;ExpensiveService&gt;(provider.GetRequiredService&lt;ExpensiveService&gt;));<\/code><\/pre>\n<h4>\u914d\u7f6e\u6587\u4ef6\u52a0\u8f7d<\/h4>\n<pre><code class=\"csharp\">public class AppConfig\n{\n    private static readonly Lazy&lt;AppConfig&gt; _instance = \n        new Lazy&lt;AppConfig&gt;(LoadConfiguration);\n    \n    public static AppConfig Instance =&gt; _instance.Value;\n    \n    public string ConnectionString { get; }\n    public int Timeout { get; }\n    \n    private AppConfig(string config)\n    {\n        \/\/ \u89e3\u6790\u914d\u7f6e\n    }\n    \n    private static AppConfig LoadConfiguration()\n    {\n        string configData = File.ReadAllText(&quot;config.json&quot;);\n        return new AppConfig(configData);\n    }\n}<\/code><\/pre>\n<h3><code>Lazy&lt;T&gt;<\/code> vs \u624b\u52a8\u61d2\u52a0\u8f7d<\/h3>\n<p>\u624b\u52a8\u5b9e\u73b0\u7ebf\u7a0b\u5b89\u5168\u7684\u61d2\u52a0\u8f7d\u9700\u8981\u5199\u53cc\u91cd\u68c0\u67e5\u9501\u5b9a\uff08\u6613\u51fa\u9519\uff09\uff0c\u800c <code>Lazy&lt;T&gt;<\/code> \u5df2\u5c01\u88c5\u6240\u6709\u903b\u8f91\uff1a<\/p>\n<pre><code class=\"csharp\">\/\/ \u624b\u52a8\u5b9e\u73b0\uff08\u7ebf\u7a0b\u5b89\u5168\uff0c\u9700\u53cc\u91cd\u68c0\u67e5+volatile\uff09\nprivate volatile ExpensiveObject _manualObj;\nprivate readonly object _lockObj = new object();\npublic ExpensiveObject ManualObj\n{\n    get\n    {\n        if (_manualObj == null)\n        {\n            lock (_lockObj)\n            {\n                if (_manualObj == null)\n                {\n                    _manualObj = new ExpensiveObject();\n                }\n            }\n        }\n        return _manualObj;\n    }\n}\n\n\/\/ Lazy&lt;T&gt;\u5b9e\u73b0\uff08\u4e00\u884c\u641e\u5b9a\uff0c\u7ebf\u7a0b\u5b89\u5168\uff09\nprivate readonly Lazy&lt;ExpensiveObject&gt; _lazyObj = new Lazy&lt;ExpensiveObject&gt;();\npublic ExpensiveObject LazyObj =&gt; _lazyObj.Value;<\/code><\/pre>\n<h3><code>Lazy&lt;T&gt;<\/code> \u5185\u90e8\u5b9e\u73b0\u539f\u7406\uff08\u7b80\u8981\uff09<\/h3>\n<ul>\n<li>\n<p>\u4f7f\u7528\u4e00\u4e2a\u79c1\u6709\u5b57\u6bb5\uff08\u5982 <code>object? _box<\/code>\uff09\u5b58\u50a8\u72b6\u6001\uff1a<\/p>\n<ul>\n<li><code>null<\/code>\uff1a\u672a\u521d\u59cb\u5316<\/li>\n<li><code>Box&lt;T&gt;<\/code>\uff1a\u5df2\u5b8c\u6210\uff08\u5305\u542b\u503c\uff09<\/li>\n<li>\u5f02\u5e38\u5bf9\u8c61\uff1a\u521d\u59cb\u5316\u5931\u8d25<\/li>\n<\/ul>\n<\/li>\n<li>\u521d\u59cb\u5316\u65f6\u4f7f\u7528 <code>Interlocked.CompareExchange<\/code> \u8fdb\u884c\u539f\u5b50\u72b6\u6001\u8f6c\u6362\u3002<\/li>\n<li>\u5185\u90e8\u72b6\u6001\u673a\u7ed3\u5408\u7248\u672c\u673a\u5236\uff0c\u5f7b\u5e95\u9632\u6b62 <code>ABA<\/code> \u95ee\u9898\u3002<\/li>\n<li><code>ExecutionAndPublication<\/code> \u6a21\u5f0f\u4e0b\u4f7f\u7528\u8f7b\u91cf\u81ea\u65cb + \u7b49\u5f85\u673a\u5236\uff0c\u786e\u4fdd\u53ea\u6709\u4e00\u4e2a\u7ebf\u7a0b\u6267\u884c\u5de5\u5382\u65b9\u6cd5\u3002<\/li>\n<\/ul>\n<h3>\u4f18\u70b9\u4e0e\u7f3a\u70b9<\/h3>\n<table>\n<thead>\n<tr>\n<th>\u65b9\u9762<\/th>\n<th>\u4f18\u70b9<\/th>\n<th>\u7f3a\u70b9<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td><strong>\u7ebf\u7a0b\u5b89\u5168<\/strong><\/td>\n<td>\u5185\u7f6e\u5b8c\u7f8e\u652f\u6301\uff0c\u9632 ABA\u3001\u9632\u91cd\u590d\u521d\u59cb\u5316<\/td>\n<td>None \u6a21\u5f0f\u4e0b\u9700\u624b\u52a8\u6ce8\u610f<\/td>\n<\/tr>\n<tr>\n<td><strong>\u6613\u7528\u6027<\/strong><\/td>\n<td>\u4ee3\u7801\u6781\u7b80\uff0c\u4e00\u884c\u641e\u5b9a<\/td>\n<td>\u4e0d\u652f\u6301\u4e3b\u52a8 Reset\uff08\u9700\u81ea\u5b9a\u4e49\u5305\u88c5\uff09<\/td>\n<\/tr>\n<tr>\n<td><strong>\u6027\u80fd<\/strong><\/td>\n<td>\u9ad8\u5ea6\u4f18\u5316\uff0c\u65e0\u9501\u8def\u5f84\u6781\u5feb<\/td>\n<td>\u7b2c\u4e00\u6b21\u8bbf\u95ee\u53ef\u80fd\u963b\u585e\uff08\u4f46\u8fd9\u662f\u5ef6\u8fdf\u521d\u59cb\u5316\u7684\u672c\u8d28\uff09<\/td>\n<\/tr>\n<tr>\n<td><strong>\u529f\u80fd<\/strong><\/td>\n<td>\u5f02\u5e38\u7f13\u5b58\u3001\u503c\u7f13\u5b58\u3001IsValueCreated \u67e5\u8be2<\/td>\n<td>\u4e0d\u652f\u6301\u5f02\u6b65\u521d\u59cb\u5316\uff08\u9700\u7528 Lazy&lt;Task&lt;T&gt;&gt;\uff09<\/td>\n<\/tr>\n<tr>\n<td><strong>\u9002\u7528\u6027<\/strong><\/td>\n<td>\u51e0\u4e4e\u6240\u6709\u61d2\u52a0\u8f7d\u573a\u666f\u7684\u9996\u9009<\/td>\n<td>\u82e5\u9700\u652f\u6301\u5237\u65b0\/\u91cd\u7f6e\uff0c\u9700\u989d\u5916\u5c01\u88c5<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h3>\u6700\u4f73\u5b9e\u8df5<\/h3>\n<ul>\n<li>\u4f18\u5148\u4f7f\u7528 <code>Lazy&lt;T&gt;<\/code> \u66ff\u4ee3\u624b\u52a8\u53cc\u68c0\u67e5\u9501\u3002<\/li>\n<li>\u59cb\u7ec8\u4f7f\u7528\u9ed8\u8ba4\u7ebf\u7a0b\u5b89\u5168\u6a21\u5f0f\uff08\u9664\u975e\u660e\u786e\u9700\u8981 <code>PublicationOnly<\/code>\uff09\u3002<\/li>\n<li>\u5de5\u5382\u65b9\u6cd5\u5e94\u65e0\u526f\u4f5c\u7528\uff08\u5c24\u5176\u5728 <code>PublicationOnly<\/code> \u6a21\u5f0f\u4e0b\uff09\u3002<\/li>\n<li>\u5f02\u5e38\u5904\u7406\uff1a\u6355\u83b7 <code>.Value<\/code> \u629b\u51fa\u7684\u5f02\u5e38\u3002<\/li>\n<li>\u4e0d\u8981\u5728\u5de5\u5382\u65b9\u6cd5\u4e2d\u8bbf\u95ee\u540c\u4e00\u4e2a <code>Lazy<\/code> \u5b9e\u4f8b\uff08\u53ef\u80fd\u6b7b\u9501\uff09\u3002<\/li>\n<\/ul>\n<h3>\u603b\u7ed3<\/h3>\n<ul>\n<li><code>System.Lazy&lt;T&gt;<\/code> \u662f <code>.NET<\/code> \u5b98\u65b9\u7684\u5ef6\u8fdf\u521d\u59cb\u5316\u5de5\u5177\uff0c\u6838\u5fc3\u662f\u9996\u6b21\u8bbf\u95ee <code>Value<\/code> \u65f6\u521b\u5efa\u5bf9\u8c61\uff0c\u63d0\u5347\u7a0b\u5e8f\u542f\u52a8\u901f\u5ea6\u548c\u5185\u5b58\u6548\u7387\uff1b<\/li>\n<li>\u6838\u5fc3\u5c5e\u6027\uff1a<code>Value<\/code>\uff08\u89e6\u53d1\u521d\u59cb\u5316\uff09\u3001<code>IsValueCreated<\/code>\uff08\u5224\u65ad\u662f\u5426\u5df2\u521b\u5efa\uff09\uff1b<\/li>\n<li>\u7ebf\u7a0b\u5b89\u5168\u6a21\u5f0f\u9700\u6309\u9700\u9009\u62e9\uff1a\u5355\u7ebf\u7a0b\u7528 <code>None<\/code>\uff0c\u591a\u7ebf\u7a0b\u9ad8\u6210\u672c\u5bf9\u8c61\u7528\u9ed8\u8ba4\u7684<code>ExecutionAndPublication<\/code>\uff1b<\/li>\n<li>\u6700\u4f18\u573a\u666f\uff1a\u521b\u5efa\u6210\u672c\u9ad8 \/ \u4e0d\u4e00\u5b9a\u4f7f\u7528\u7684\u5bf9\u8c61\u3001\u61d2\u52a0\u8f7d\u5355\u4f8b\u6a21\u5f0f\uff1b<\/li>\n<\/ul>\n<p><a href=\"https:\/\/segmentfault.com\/a\/1190000047521528\">https:\/\/segmentfault.com\/a\/1190000047521528<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4ec0\u4e48\u662f Lazy&lt;T&gt;\uff1f System.Lazy&lt;T&gt; \u662f .NET Framewor [&hellip;]<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[4],"tags":[],"class_list":["post-10021166","post","type-post","status-publish","format-standard","hentry","category-share"],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts\/10021166","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=10021166"}],"version-history":[{"count":0,"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts\/10021166\/revisions"}],"wp:attachment":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=10021166"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=10021166"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=10021166"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}