{"id":207643,"date":"2025-07-08T13:06:21","date_gmt":"2025-07-08T05:06:21","guid":{"rendered":"https:\/\/server.hk\/cnblog\/207643\/"},"modified":"2025-07-08T13:06:21","modified_gmt":"2025-07-08T05:06:21","slug":"%e5%a6%82%e4%bd%95%e4%bd%bf%e7%94%a8%e4%be%9d%e8%b5%96%e6%b3%a8%e5%85%a5%e5%9c%a8-golang-%e4%b8%ad%e6%ad%a3%e7%a1%ae%e8%ae%be%e7%bd%ae-defer-close","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/207643\/","title":{"rendered":"\u5982\u4f55\u4f7f\u7528\u4f9d\u8d56\u6ce8\u5165\u5728 golang \u4e2d\u6b63\u786e\u8bbe\u7f6e defer .close"},"content":{"rendered":"<p><b><\/b> <\/p>\n<p>\u5f53\u524d\u4f4d\u7f6e\uff1a <span>&gt;<\/span> <span>&gt;<\/span> <span>&gt;<\/span> <span>&gt;<\/span> <span>\u5982\u4f55\u4f7f\u7528\u4f9d\u8d56\u6ce8\u5165\u5728 golang \u4e2d\u6b63\u786e\u8bbe\u7f6e defer .close<\/span><\/p>\n<p><span>\u6765\u6e90\uff1astackoverflow<\/span><br \/>\n<span>2024-04-24 11:12:35<\/span><br \/>\n<span><i><\/i>0\u6d4f\u89c8<\/span><br \/>\n<span style=\"cursor: pointer\"><i><\/i>\u6536\u85cf<\/span> <\/p>\n<p>\u6765\u5230\u7684\u5927\u5bb6\uff0c\u76f8\u4fe1\u90fd\u662f\u7f16\u7a0b\u5b66\u4e60\u7231\u597d\u8005\uff0c\u5e0c\u671b\u5728\u8fd9\u91cc\u5b66\u4e60Golang\u76f8\u5173\u7f16\u7a0b\u77e5\u8bc6\u3002\u4e0b\u9762\u672c\u7bc7\u6587\u7ae0\u5c31\u6765\u5e26\u5927\u5bb6\u804a\u804a\u300a\u5982\u4f55\u4f7f\u7528\u4f9d\u8d56\u6ce8\u5165\u5728 golang \u4e2d\u6b63\u786e\u8bbe\u7f6e defer .close\u300b\uff0c\u4ecb\u7ecd\u4e00\u4e0b\uff0c\u5e0c\u671b\u5bf9\u5927\u5bb6\u7684\u77e5\u8bc6\u79ef\u7d2f\u6709\u6240\u5e2e\u52a9\uff0c\u52a9\u529b\u5b9e\u6218\u5f00\u53d1\uff01<\/p>\n<p> \u95ee\u9898\u5185\u5bb9<br \/>\n <\/p>\n<p>\u6211\u60f3\u8bbe\u7f6e <code>defer xxx.close()<\/code> \u6765\u5173\u95ed golang \u4e2d\u7684\u8fde\u63a5\u3002<\/p>\n<p> \u4f46\u5982\u679c\u6211\u5728 <code>insert<\/code> sql \u65b9\u6cd5\u4e4b\u540e\u8bbe\u7f6e <code>defer xxx.close()<\/code> \uff0c\u5219\u5176\u7ed3\u679c\u4e3a null\u3002<\/p>\n<p> \u5982\u679c\u6211\u5728 <code>insert<\/code> sql \u65b9\u6cd5\u4e4b\u540e\u5220\u9664 <code>defer xxx.close()<\/code>\uff0c\u5176\u7ed3\u679c\u5c06\u8fd4\u56de\u6b63\u786e\u7684\u503c\u3002<\/p>\n<p> \u6211\u8bbe\u7f6e\u4e86 <code>defer xxx.close()<\/code> \u4ee5\u907f\u514d\u8fde\u63a5\u9650\u5236\u548c\u5d29\u6e83\u3002\u4f46\u73b0\u5728\u5982\u679c\u6211\u5220\u9664 <code>defer xxx.close()<\/code>\uff0c\u5c31\u65e0\u6cd5\u907f\u514d\u8fd9\u79cd\u60c5\u51b5\u3002<\/p>\n<ul>\n<li>\u6211\u5728golang\u4e2d\u8bbe\u7f6e\u4e86\u4f9d\u8d56\u6ce8\u5165\u3002\n<\/p>\n<\/li>\n<\/ul>\n<p>dao.go<\/p>\n<pre>package dao\n\nimport (\n    \"database\/sql\"\n    \"log\"\n)\n\ntype dao struct {\n    database *sql.db\n}\n\nfunc newdao(database *sql.db) *dao {\n    objs := &amp;dao{database: database}\n    return objs\n}\n\ntype daointerface interface {\n    getemployeelistdao() *sql.rows\n    registeremployeedao(employee model.registeremployee, uu string, encrypted string)\n}\n\nfunc (d *dao) getemployeelistdao() *sql.rows {\n\n    results, err := d.database.query(\"select id, name, email, isdisplay from employee\")\n    if err != nil {\n        panic(err.error())\n    }\n    \/\/it returns nothing.\n    \/\/if removing defer results.close(), results returns correct value\n    defer results.close()\n    return results\n}\n\nfunc (d *dao) registeremployeedao(employee model.registeremployee, uu string, encrypted string) {\n    ins, err := d.database.prepare(\"insert into employee(name, email, password, isdisplay) values(?,?,?,?)\")\n    if err != nil {\n        log.fatal(err)\n    }\n    \/\/same problem will occure here.\n    defer ins.close()\n    _, err = ins.exec(uu, employee.name, employee.email, encrypted, employee.isdisplay)\n    if err != nil {\n        log.fatal(err)\n    }\n}\n\n<\/pre>\n<p>service.go<\/p>\n<pre>package service\n\nimport (\n    \"crypto\/aes\"\n    \"crypto\/cipher\"\n    \"crypto\/rand\"\n    \"encoding\/base64\"\n    \"io\"\n\n    \"github.com\/gin-gonic\/gin\"\n)\n\ntype service struct {\n    dao dao.daointerface\n}\n\nfunc newservice(dao dao.daointerface) *service {\n    return &amp;service{dao: dao}\n}\n\ntype serviceinterface interface {\n    getemployeelistservice() []model.employee\n    registeremployeeservice(c *gin.context)\n}\n\nfunc (s service) getemployeelistservice() []model.employee {\n    var employee []model.employee\n\n    results := s.dao.getemployeelistdao()\n\n    singleemployee := model.employee{}\n    for results.next() {\n        err := results.scan(&amp;singleemployee.id, &amp;singleemployee.name, &amp;singleemployee.email, &amp;singleemployee.isdisplay)\n        if err != nil {\n            panic(err.error())\n        } else {\n            employee = append(employee, singleemployee)\n        }\n    }\n\n    defer results.close()\n\n    var displayemployee []model.employee\n\n    for _, e := range employee {\n        if e.isdisplay == true {\n            displayemployee = append(displayemployee, e)\n        }\n    }\n\n    return displayemployee\n}\n\nfunc (s service) registeremployeeservice(c *gin.context) {\n    var employee model.registeremployee\n    c.bindjson(&amp;employee)\n\n    block, err := aes.newcipher([]byte(\"aes-secret-key-1\"))\n    if err != nil {\n        panic(err)\n    }\n    b := base64.stdencoding.encodetostring([]byte(employee.password))\n    cipt := make([]byte, aes.blocksize+len(b))\n    iv := cipt[:aes.blocksize]\n    if _, err := io.readfull(rand.reader, iv); err != nil {\n        panic(err)\n    }\n    cfb := cipher.newcfbencrypter(block, iv)\n    cfb.xorkeystream(cipt[aes.blocksize:], []byte(b))\n    encrypted := base64.stdencoding.encodetostring(cipt)\n\n    s.dao.registeremployeedao(employee, encrypted)\n}\n\n<\/pre>\n<p>\u6211\u5728 api \u4e2d\u8bbe\u7f6e\u4e86\u4f9d\u8d56\u6ce8\u5165\u6837\u5f0f\u3002 main.go<\/p>\n<pre>package main\n\nimport (\n    \"os\"\n    _ \"github.com\/go-sql-driver\/mysql\"\n)\n\nfunc main() {\n    db := db.NewDatabase(os.Getenv(\"MYSQL_USER\"), os.Getenv(\"MYSQL_PASSWORD\"), os.Getenv(\"MYSQL_HOST\"))\n    dao := dao.NewDao(db.DATABASE)\n    service := service.NewService(dao)\n    cntlr := controller.NewController(service)\n    router := handler.NewHandler(cntlr)\n\n    router.Router.Run(\":8080\")\n}\n<\/pre>\n<p>\u6211\u5e0c\u671b <code>defer xxx.close()<\/code> \u6ca1\u6709\u95ee\u9898\uff0c\u5e76\u4e14\u63d2\u5165\u548c\u9009\u62e9 sql \u8fd4\u56de\u6b63\u786e\u7684\u503c\u3002<\/p>\n<p> \u4f46\u95ee\u9898\u662f\u56e0\u4e3a <code>defer xxx.close()<\/code> insert \u548c select sql \u6ca1\u6709\u8fd4\u56de\u6b63\u786e\u7684\u503c\u3002<\/p>\n<p> \u6211\u60f3\u77e5\u9053\u5982\u4f55\u907f\u514d\u8fde\u63a5\u9650\u5236\u548c\u5d29\u6e83\u800c\u4e0d\u51fa\u73b0\u6b64\u95ee\u9898\u3002<\/p>\n<p> <\/p>\n<h2>\u89e3\u51b3\u65b9\u6848<\/h2>\n<p> <\/p>\n<p>\u6211\u8ba4\u4e3a\u60a8\u671f\u671b\u7684\u662f\u7ed3\u679c\u96c6\u7acb\u5373\u4f5c\u4e3a\u6570\u7ec4\u6216\u7c7b\u4f3c\u7684\u4e1c\u897f\u8fd4\u56de\u3002\u8fd9\u79cd\u60c5\u51b5\u4e0d\u4f1a\u53d1\u751f\uff0c\u56e0\u4e3a\u5ba2\u6237\u7aef<em>\u5f88\u61d2<\/em> &#8211; \u5728\u60a8\u663e\u5f0f\u5c1d\u8bd5\u4f7f\u7528 <code>next()<\/code> \u8bfb\u53d6\u884c\u4e4b\u524d\uff0c\u5b83\u4e0d\u4f1a\u7ed9\u60a8\u7ed3\u679c\u3002\u8fd9\u662f\u6709\u5145\u5206\u7406\u7531\u7684 &#8211; \u5982\u679c\u7ed3\u679c\u96c6\u5305\u542b\u6570\u767e\u4e07\u884c\uff0c\u90a3\u4e48\u901a\u8fc7\u7f51\u7edc\u8fde\u63a5\u4f20\u8f93\u6570\u636e\u4f1a\u975e\u5e38\u6162\uff0c\u751a\u81f3\u53ef\u80fd\u4f1a\u8017\u5c3d\u8fd0\u884c\u67e5\u8be2\u7684\u673a\u5668\u7684\u5185\u5b58\u3002\u4e3a\u4e86\u907f\u514d\u8fd9\u79cd\u60c5\u51b5\uff0c\u7ed3\u679c\u96c6\u5b9e\u9645\u4e0a\u66f4\u50cf\u662f\u4e00\u4e2a\u201c\u53e5\u67c4\u201d\uff0c\u5141\u8bb8\u60a8\u5728\u9700\u8981\u65f6\u4ece\u6570\u636e\u5e93\u4e2d\u83b7\u53d6\u66f4\u591a\u884c\uff0c\u800c\u4e0d\u662f\u7ed3\u679c\u672c\u8eab\u3002<\/p>\n<p>\u5f53\u60a8\u5bf9\u7ed3\u679c\u96c6\u8c03\u7528 <code>clos\u200b\u200be()<\/code> \u65f6\uff0c\u5b83\u8868\u793a\u60a8\u4e0d\u518d\u9700\u8981\u4efb\u4f55\u66f4\u591a\u6570\u636e\u3002<\/p>\n<p>\u8fd9\u91cc\u53ef\u80fd\u8fd8\u6709\u4e00\u4e9b\u5173\u4e8e <code>defer<\/code> \u7684\u6df7\u6dc6\u3002 <code>defer<\/code> \u5728\u51fd\u6570\u672b\u5c3e\u89e6\u53d1\uff0c\u56e0\u6b64\u8fd4\u56de\u65f6\u4f1a\u89e6\u53d1\uff1a<\/p>\n<pre>defer results.Close()\nreturn results  \/\/ defer is triggered here, which will close the result set<\/pre>\n<p>\u7136\u540e\uff0c\u5f53\u60a8\u5c1d\u8bd5\u4ece\u4e2d\u8bfb\u53d6\u5185\u5bb9\u65f6\uff0c\u5b83\u662f\u4e00\u4e2a\u5c01\u95ed\u7684\u7ed3\u679c\u96c6\uff0c\u56e0\u6b64\u60a8\u5b9e\u9645\u4e0a\u65e0\u6cd5\u4ece\u4e2d\u8bfb\u53d6\u4efb\u4f55\u5185\u5bb9\u3002<\/p>\n<p>\u4f5c\u4e3a\u53c2\u8003\uff0c \u662f\u6709\u5173\u5728\u7ed3\u679c\u96c6\u4e0a\u8c03\u7528 <code>clos\u200b\u200be()<\/code> \u65f6\u5177\u4f53\u53d1\u751f\u7684\u60c5\u51b5\u7684\u6587\u6863\u3002<\/p>\n<p>\u5230\u8fd9\u91cc\uff0c\u6211\u4eec\u4e5f\u5c31\u8bb2\u5b8c\u4e86\u300a\u5982\u4f55\u4f7f\u7528\u4f9d\u8d56\u6ce8\u5165\u5728 golang \u4e2d\u6b63\u786e\u8bbe\u7f6e defer .close\u300b\u7684\u5185\u5bb9\u4e86\u3002\u4e2a\u4eba\u8ba4\u4e3a\uff0c\u57fa\u7840\u77e5\u8bc6\u7684\u5b66\u4e60\u548c\u5de9\u56fa\uff0c\u662f\u4e3a\u4e86\u66f4\u597d\u7684\u5c06\u5176\u8fd0\u7528\u5230\u9879\u76ee\u4e2d\uff0c\u6b22\u8fce\u5173\u6ce8\u516c\u4f17\u53f7\uff0c\u5e26\u4f60\u4e86\u89e3\u66f4\u591a\u5173\u4e8e\u7684\u77e5\u8bc6\u70b9\uff01<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u5f53\u524d\u4f4d\u7f6e\uff1a &gt; &gt; &#46;&#46;&#46;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4925],"tags":[],"class_list":["post-207643","post","type-post","status-publish","format-standard","hentry","category-4925"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/207643","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/comments?post=207643"}],"version-history":[{"count":0,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/207643\/revisions"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=207643"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=207643"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=207643"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}