{"id":23,"date":"2017-10-13T15:28:57","date_gmt":"2017-10-13T07:28:57","guid":{"rendered":"http:\/\/www.cloudy.pub\/?p=23"},"modified":"2017-10-13T15:28:57","modified_gmt":"2017-10-13T07:28:57","slug":"c%e7%9a%84using%e8%af%ad%e5%8f%a5%e5%9d%97%e7%9a%84%e8%a7%a3%e9%87%8a%e5%92%8c%e4%bd%bf%e7%94%a8","status":"publish","type":"post","link":"https:\/\/www.0moon.com\/?p=23","title":{"rendered":"c#\u7684using\u8bed\u53e5\u5757\u7684\u89e3\u91ca\u548c\u4f7f\u7528"},"content":{"rendered":"<p>\u4e4b\u524d\u5076\u6709\u673a\u4f1a\u770b\u5230 <a href=\"http:\/\/social.msdn.microsoft.com\/Forums\/zh-TW\/categories\/\">MSDN \u8bba\u575b<\/a>\u4e0a\u6709\u4eba\u63d0\u5230\u5173\u4e8e\u4f7f\u7528 <a href=\"http:\/\/msdn.microsoft.com\/zh-tw\/library\/yh598w02.aspx\">using<\/a> \u8bed\u53e5\u7684\u9519\u8bef\u89c2\u5ff5 (\u770b\u5230\u4e0d\u6b62\u4e00\u6b21)\uff0c\u7531\u4e8e\u81ea\u5df1\u4e5f\u7ecf\u5e38\u5728\u7528\uff0c\u4e0d\u77e5\u9053\u539f\u6765\u6709\u4eba\u4f1a\u8bef\u4ee5\u4e3a\u4f7f\u7528 <a href=\"http:\/\/msdn.microsoft.com\/zh-tw\/library\/yh598w02.aspx\">using<\/a> \u4f1a\u5c06\u6240\u6709\u4f8b\u5916\u72b6\u51b5 (Exception) \u7ed9\u5403\u6389\uff0c\u4f46\u4e8b\u5b9e\u4e0a\u5e76\u975e\u5982\u6b64\uff0c\u8bf7\u8ba9\u6211\u5a13\u5a13\u9053\u6765\u3002<\/p>\n<p><a href=\"http:\/\/msdn.microsoft.com\/zh-tw\/library\/zhdeatwt.aspx\">using<\/a> \u6709\u4e24\u79cd\uff0c\u76f8\u4fe1\u8bb8\u591a\u4eba\u7ecf\u5e38\u4f1a\u7528\u5230\uff1a<\/p>\n<ol>\n<li>\u4e00\u79cd\u662f\u4f5c\u4e3a\u300c\u6307\u793a\u8bcd\u300d\uff0c\u53ef\u7528\u6765\u5efa\u7acb\u547d\u540d\u7a7a\u95f4\u7684\u522b\u540d(Alias)\uff0c\u6216\u7528\u6765\u6c47\u5165\u5728\u5176\u4ed6\u547d\u540d\u7a7a\u95f4\u4e2d\u5b9a\u4e49\u7684\u578b\u522b<br \/>\n2. \u53e6\u4e00\u79cd\u662f\u300c\u8bed\u53e5\u300d\uff0c\u53ef\u7528\u6765\u5b9a\u4e49\u4e00\u4e2a\u8303\u56f4\uff0c\u8be5\u8303\u56f4\u5185\u7684\u5bf9\u8c61\u4f1a\u5728\u6b64\u8303\u56f4\u7ed3\u5c3e\u5904\u6267\u884c Dispose \u65b9\u6cd5\u3002<\/li>\n<\/ol>\n<p><strong>\u7b2c\u4e00\u79cd\uff1ausing \u6307\u793a\u8bcd<\/strong><\/p>\n<p>\u6807\u51c6\u7528\u6cd5\uff1a<\/p>\n<p><em>using System.Text;<\/em><\/p>\n<p>\u522b\u540d\u7528\u6cd5\uff1a<\/p>\n<p><em>using Models = MvcApplication.Models;<\/em><\/p>\n<p><strong>\u7b2c\u4e8c\u79cd\uff1ausing \u8bed\u53e5 ( \u4e5f\u662f\u6211\u4eca\u5929\u60f3\u5f3a\u8c03\u7684\u90e8\u5206 )<\/strong><\/p>\n<p><a href=\"http:\/\/msdn.microsoft.com\/zh-tw\/library\/yh598w02.aspx\">using \u8bed\u53e5<\/a>\u662f\u4e00\u4e2a\u975e\u5e38\u57fa\u672c\u7684 C# \u8bed\u6cd5\uff0c\u76f8\u4fe1\u5728\u5b9e\u52a1\u5f00\u53d1\u4e0a\u7ecf\u5e38\u4f1a\u4f7f\u7528\u5230\uff0c\u5982\u679c\u6ca1\u4f7f\u7528\u8fc7\u7684\u4eba\u53ef\u80fd\u4ee3\u8868\u4f60\u5bf9 .NET \u7684\u5185\u5b58\u7ba1\u7406\u7684 Sense \u4e0d\u592a\u591f\uff0c\u5f88\u6709\u53ef\u80fd\u5199\u51fa\u8d44\u6e90\u8017\u5c3d\u7684 .NET \u7a0b\u5e8f\u4ee3\u7801\u3002<\/p>\n<p>\u867d\u7136 .NET \u6709\u5185\u5efa\u5f3a\u5927\u7684\u5185\u5b58\u7ba1\u7406\u673a\u5236(GC)\uff0c\u4f46\u5f00\u53d1\u4eba\u5458\u8fd8\u662f\u4e0d\u80fd\u5b8c\u5168\u4f9d\u8d56 .NET \u6765\u5904\u7406\u4e00\u4e9b\u65e0\u6cd5\u91ca\u653e\u7684\u8d44\u6e90\uff0c\u4f8b\u5982\uff1aHandles, Unmanaged Resources, \u2026\u3002<\/p>\n<p>\u800c\u4f7f\u7528 <a href=\"http:\/\/msdn.microsoft.com\/zh-tw\/library\/yh598w02.aspx\">using<\/a> \u6700\u4e3b\u8981\u7684\u76ee\u7684\u662f\u4e3a\u4e86\u8ba9\u5bf9\u8c61\u5efa\u7acb\u7684\u540c\u65f6\u80fd\u786e\u4fdd\u8be5\u5bf9\u8c61\u6240\u5360\u7528\u7684\u8d44\u6e90\u4e00\u5b9a\u4f1a\u88ab\u5b8c\u6574\u91ca\u653e\uff0c\u5982\u679c\u6ca1\u6709\u91ca\u653e\u8fd9\u4e9b<strong>\u65e0\u6cd5\u81ea\u52a8\u91ca\u653e<\/strong>\u7684\u8d44\u6e90\uff0c\u5c31\u5f88\u6709\u53ef\u80fd\u8ba9 .NET \u5e94\u7528\u7a0b\u5e8f\u53d1\u751f <strong>\u8d44\u6e90\u8017\u5c3d <\/strong>(Resource Exhausted) \u7684\u72b6\u51b5\u3002<\/p>\n<p>\u4ece MSDN \u4e0a\u8282\u5f55\u4e00\u6bb5\u8303\u4f8b\u7a0b\u5e8f\u5982\u4e0b\uff1a<\/p>\n<p><em>using (System.IO.StreamReader sr =<\/em><\/p>\n<p><em>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 new System.IO.StreamReader(@&#8221;C:\\test.txt&#8221;))<\/em><\/p>\n<p><em>{<\/em><\/p>\n<p><em>\u00a0\u00a0 \u00a0string s = null;<\/em><\/p>\n<p><em>\u00a0\u00a0\u00a0 while((s = sr.ReadLine()) != null)<\/em><\/p>\n<p><em>\u00a0\u00a0\u00a0 {<\/em><\/p>\n<p><em>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Console.WriteLine(s);<\/em><\/p>\n<p><em>\u00a0\u00a0\u00a0 }<\/em><\/p>\n<p><em>}<\/em><\/p>\n<p>\u4f7f\u7528 <a href=\"http:\/\/msdn.microsoft.com\/zh-tw\/library\/yh598w02.aspx\">using<\/a> \u8bed\u53e5\u6709\u4e00\u4e2a\u6700\u57fa\u672c\u7684\u6761\u4ef6\uff0c\u5c31\u662f\u8be5\u5bf9\u8c61\u5fc5\u987b\u6709\u5b9e\u505a <a href=\"http:\/\/msdn.microsoft.com\/zh-tw\/library\/system.idisposable.aspx\">IDisposable<\/a> \u63a5\u53e3\uff0c\u624d\u80fd\u786e\u4fdd\u5728 <a href=\"http:\/\/msdn.microsoft.com\/zh-tw\/library\/yh598w02.aspx\">using<\/a> \u7684\u7ed3\u5c3e\u6570\u65f6\u81ea\u52a8\u6267\u884c <a href=\"http:\/\/msdn.microsoft.com\/zh-tw\/library\/system.idisposable.dispose.aspx\">Dispose() \u65b9\u6cd5<\/a>\u3002<\/p>\n<p>\u4f7f\u7528 <a href=\"http:\/\/msdn.microsoft.com\/zh-tw\/library\/yh598w02.aspx\">using<\/a> \u8bed\u53e5\u7684\u53e6\u4e00\u4e2a<strong>\u5f3a\u70c8\u5efa\u8bae<\/strong>\u7684\u6761\u4ef6\uff0c\u5c31\u662f\u8be5\u5bf9\u8c61\u88ab\u5efa\u7acb\u7684\u8bed\u6cd5\u5fc5\u987b\u5199\u5728 using \u5b50\u53e5\u4e2d\uff0c\u5426\u5219\u5bf9\u8c61\u5f88\u6709\u53ef\u80fd\u5728\u88ab\u91ca\u653e\u540e\u8fd8\u6709\u5176\u4ed6\u5bf9\u8c61\u5b58\u53d6\u7684\u60c5\u51b5\uff0c\u8fdb\u800c\u5f15\u53d1\u4f8b\u5916\u72b6\u51b5\uff01<\/p>\n<p>\u6709\u4e9b\u4eba\u8ba4\u4e3a <a href=\"http:\/\/msdn.microsoft.com\/zh-tw\/library\/yh598w02.aspx\">using<\/a> \u8bed\u53e5\u4f1a\u81ea\u52a8\u88ab\u7ffb\u8bd1\u6210\u4ee5\u4e0b\u7a0b\u5e8f\u4ee3\u7801\uff1a\uff08\u9519\u8bef\u8303\u4f8b\uff09<\/p>\n<p><em>{<\/em><br \/>\n<em> \u00a0\u00a0\u00a0 System.IO.StreamReader sr = new System.IO.StreamReader(@&#8221;C:\\test.txt&#8221;);<\/em><br \/>\n<em> \u00a0\u00a0\u00a0 try<\/em><br \/>\n<em> \u00a0\u00a0\u00a0 {<\/em><br \/>\n<em> \u00a0\u00a0\u00a0\u00a0\u00a0 string s = null;<\/em><br \/>\n<em> \u00a0\u00a0\u00a0\u00a0\u00a0 while((s = sr.ReadLine()) != null)<\/em><br \/>\n<em> \u00a0\u00a0\u00a0\u00a0\u00a0 {<\/em><br \/>\n<em> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Console.WriteLine(s);<\/em><br \/>\n<em> \u00a0\u00a0\u00a0\u00a0\u00a0 }<\/em><br \/>\n<em> \u00a0\u00a0\u00a0 }<\/em><br \/>\n<em> \u00a0\u00a0\u00a0 catch<\/em><br \/>\n<em> \u00a0\u00a0\u00a0 {<\/em><br \/>\n<em> \u00a0\u00a0\u00a0 }<\/em><br \/>\n<em> \u00a0\u00a0\u00a0 finally<\/em><br \/>\n<em> \u00a0\u00a0\u00a0 {<\/em><br \/>\n<em> \u00a0\u00a0\u00a0\u00a0\u00a0 if (sr != null)<\/em><br \/>\n<em> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 ((IDisposable)sr).Dispose();<\/em><br \/>\n<em> \u00a0\u00a0\u00a0 }<\/em><br \/>\n<em> }<\/em><\/p>\n<p>\u4f46\u4e8b\u5b9e\u4e0a\uff0c\u5e94\u8be5\u4e0d\u5305\u542b catch \u7684\u533a\u6bb5\u624d\u662f\uff01<strong>\u6b63\u786e\u7684\u8bed\u6cd5<\/strong>\u5e94\u8be5\u5982\u4e0b\uff1a<\/p>\n<p><em>{<\/em><\/p>\n<p><em>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 System.IO.StreamReader sr = new System.IO.StreamReader(@&#8221;C:\\test.txt&#8221;);<\/em><\/p>\n<p><em>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 try<\/em><\/p>\n<p><em>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 {<\/em><\/p>\n<p><em>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0 string s = null;<\/em><\/p>\n<p><em>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0 while((s = sr.ReadLine()) != null)<\/em><\/p>\n<p><em>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0 {<\/em><\/p>\n<p><em>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0 Console.WriteLine(s);<\/em><\/p>\n<p><em>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0 }<\/em><\/p>\n<p><em>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 }<\/em><\/p>\n<p><em>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 finally<\/em><\/p>\n<p><em>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 {<\/em><\/p>\n<p><em>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0 if (sr != null)<\/em><\/p>\n<p><em>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 ((IDisposable)sr).Dispose();<\/em><\/p>\n<p><em>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 }<\/em><\/p>\n<p><em>}<\/em><\/p>\n<p>\u4e5f\u5c31\u662f\u5728\u4f7f\u7528 <a href=\"http:\/\/msdn.microsoft.com\/zh-tw\/library\/yh598w02.aspx\">using<\/a> \u8bed\u53e5\u65f6\uff0c\u867d\u7136\u6709 <strong>try<\/strong> \u4e0e <strong>finally<\/strong>\uff0c\u4f46\u5e76\u4e0d\u5305\u542b <strong>catch<\/strong> \u7684\u6210\u5206\uff01<\/p>\n<p>\u6362\u53e5\u8bdd\u8bf4\uff0c\u4f7f\u7528 <a href=\"http:\/\/msdn.microsoft.com\/zh-tw\/library\/yh598w02.aspx\">using<\/a> \u8bed\u53e5\u5e76\u4e0d\u4f1a\u5e2e\u4f60\u6355\u6349<strong>\u4f8b\u5916\u72b6\u51b5<\/strong>\uff01\uff01<\/p>\n<p>\u6240\u4ee5\u5c31\u7b97\u4f60\u7528 <a href=\"http:\/\/msdn.microsoft.com\/zh-tw\/library\/yh598w02.aspx\">using<\/a> \u5728\u7a0b\u5e8f\u4e2d\uff0c\u82e5\u8981\u5904\u7406 <a href=\"http:\/\/msdn.microsoft.com\/zh-tw\/library\/0yd65esw.aspx\">try-catch<\/a> \u7684\u72b6\u51b5\u8fd8\u662f\u8981\u81ea\u884c\u64b0\u5199\uff0c\u5426\u5219\u5c31\u4f1a\u9047\u5230\u975e\u9884\u671f\u7684\u4f8b\u5916\u72b6\u51b5\u800c\u5bfc\u81f4\u5e94\u7528\u7a0b\u5e8f\u6302\u6389\uff0c\u8fd9\u70b9\u5fc5\u987b\u7279\u522b\u6ce8\u610f\uff01<\/p>\n<p>&nbsp;<\/p>\n<p>\u4ee5\u4e0a\u5185\u5bb9\u63f4\u5f15\u81ea\uff1ahttps:\/\/blog.miniasp.com\/post\/2009\/10\/12\/About-CSharp-using-Statement-misunderstanding-on-try-catch-finally.aspx<\/p>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e4b\u524d\u5076\u6709\u673a\u4f1a\u770b\u5230 MSDN \u8bba\u575b\u4e0a\u6709\u4eba\u63d0\u5230\u5173\u4e8e\u4f7f\u7528 using \u8bed\u53e5\u7684\u9519\u8bef\u89c2\u5ff5 (\u770b\u5230\u4e0d\u6b62\u4e00\u6b21)\uff0c\u7531\u4e8e\u81ea\u5df1\u4e5f\u7ecf [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[],"class_list":["post-23","post","type-post","status-publish","format-standard","hentry","category-csharp"],"_links":{"self":[{"href":"https:\/\/www.0moon.com\/index.php?rest_route=\/wp\/v2\/posts\/23","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.0moon.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.0moon.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.0moon.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.0moon.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=23"}],"version-history":[{"count":1,"href":"https:\/\/www.0moon.com\/index.php?rest_route=\/wp\/v2\/posts\/23\/revisions"}],"predecessor-version":[{"id":24,"href":"https:\/\/www.0moon.com\/index.php?rest_route=\/wp\/v2\/posts\/23\/revisions\/24"}],"wp:attachment":[{"href":"https:\/\/www.0moon.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=23"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.0moon.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=23"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.0moon.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=23"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}