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2023-06-26 17:30:52 +00:00
< ol class = "chapter" > < li class = "chapter-item expanded affix " > < a href = "../index.html" > Go语言圣经< / a > < / li > < li class = "chapter-item expanded affix " > < a href = "../preface-zh.html" > 译者序< / a > < / li > < li class = "chapter-item expanded affix " > < a href = "../preface.html" > 前言< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch1/ch1.html" > < strong aria-hidden = "true" > 1.< / strong > 入门< / a > < / li > < li > < ol class = "section" > < li class = "chapter-item expanded " > < a href = "../ch1/ch1-01.html" > < strong aria-hidden = "true" > 1.1.< / strong > Hello, World< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch1/ch1-02.html" > < strong aria-hidden = "true" > 1.2.< / strong > 命令行参数< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch1/ch1-03.html" > < strong aria-hidden = "true" > 1.3.< / strong > 查找重复的行< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch1/ch1-04.html" > < strong aria-hidden = "true" > 1.4.< / strong > GIF动画< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch1/ch1-05.html" > < strong aria-hidden = "true" > 1.5.< / strong > 获取URL< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch1/ch1-06.html" > < strong aria-hidden = "true" > 1.6.< / strong > 并发获取多个URL< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch1/ch1-07.html" > < strong aria-hidden = "true" > 1.7.< / strong > Web服务< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch1/ch1-08.html" > < strong aria-hidden = "true" > 1.8.< / strong > 本章要点< / a > < / li > < / ol > < / li > < li class = "chapter-item expanded " > < a href = "../ch2/ch2.html" > < strong aria-hidden = "true" > 2.< / strong > 程序结构< / a > < / li > < li > < ol class = "section" > < li class = "chapter-item expanded " > < a href = "../ch2/ch2-01.html" > < strong aria-hidden = "true" > 2.1.< / strong > 命名< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch2/ch2-02.html" > < strong aria-hidden = "true" > 2.2.< / strong > 声明< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch2/ch2-03.html" > < strong aria-hidden = "true" > 2.3.< / strong > 变量< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch2/ch2-04.html" > < strong aria-hidden = "true" > 2.4.< / strong > 赋值< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch2/ch2-05.html" > < strong aria-hidden = "true" > 2.5.< / strong > 类型< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch2/ch2-06.html" > < strong aria-hidden = "true" > 2.6.< / strong > 包和文件< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch2/ch2-07.html" > < strong aria-hidden = "true" > 2.7.< / strong > 作用域< / a > < / li > < / ol > < / li > < li class = "chapter-item expanded " > < a href = "../ch3/ch3.html" > < strong aria-hidden = "true" > 3.< / strong > 基础数据类型< / a > < / li > < li > < ol class = "section" > < li class = "chapter-item expanded " > < a href = "../ch3/ch3-01.html" > < strong aria-hidden = "true" > 3.1.< / strong > 整型< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch3/ch3-02.html" > < strong aria-hidden = "true" > 3.2.< / strong > 浮点数< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch3/ch3-03.html" > < strong aria-hidden = "true" > 3.3.< / strong > 复数< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch3/ch3-04.html" > < strong aria-hidden = "true" > 3.4.< / strong > 布尔型< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch3/ch3-05.html" > < strong aria-hidden = "true" > 3.5.< / strong > 字符串< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch3/ch3-06.html" > < strong aria-hidden = "true" > 3.6.< / strong > 常量< / a > < / li > < / ol > < / li > < li class = "chapter-item expanded " > < a href = "../ch4/ch4.html" > < strong aria-hidden = "true" > 4.< / strong > 复合数据类型< / a > < / li > < li > < ol class = "section" > < li class = "chapter-item expanded " > < a href = "../ch4/ch4-01.html" > < strong aria-hidden = "true" > 4.1.< / strong > 数组< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch4/ch4-02.html" > < strong aria-hidden = "true" > 4.2.< / strong > Slice< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch4/ch4-03.html" > < strong aria-hidden = "true" > 4.3.< / strong > Map< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch4/ch4-04.html" > < strong aria-hidden = "true" > 4.4.< / strong > 结构体< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch4/ch4-05.html" > < strong aria-hidden = "true" > 4.5.< / strong > JSON< /
2022-08-04 06:59:33 +00:00
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2022-08-24 10:48:15 +00:00
< li > < em > KusonStack一站式可编程配置技术栈(Go): < a href = "https://github.com/KusionStack/kusion" > https://github.com/KusionStack/kusion< / a > < / em > < / li >
< li > < em > KCL 配置编程语言(Rust): < a href = "https://github.com/KusionStack/KCLVM" > https://github.com/KusionStack/KCLVM< / a > < / em > < / li >
< li > < em > 凹语言™: < a href = "https://github.com/wa-lang/wa" > https://github.com/wa-lang/wa< / a > < / em > < / li >
2022-08-04 06:59:33 +00:00
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< h2 id = "46-文本和html模板" > < a class = "header" href = "#46-文本和html模板" > 4.6. 文本和HTML模板< / a > < / h2 >
< p > 前面的例子， ， ， ， < / p >
< p > 一个模板是一个字符串或一个文件，里面包含了一个或多个由双花括号包含的< code > {{action}}< / code > 对象。大部分的字符串只是按字面值打印， ， ， ， ： < / p >
< p > < u > < i > gopl.io/ch4/issuesreport< / i > < / u > < / p >
< pre > < code class = "language-Go" > const templ = `{{.TotalCount}} issues:
{{range .Items}}----------------------------------------
Number: {{.Number}}
User: {{.User.Login}}
Title: {{.Title | printf " %.64s" }}
Age: {{.CreatedAt | daysAgo}} days
{{end}}`
< / code > < / pre >
< p > 这个模板先打印匹配到的issue总数， ， ， ， ， < code > {{.TotalCount}}< / code > 对应action将展开为结构体中TotalCount成员以默认的方式打印的值。模板中< code > {{range .Items}}< / code > 和< code > {{end}}< / code > 对应一个循环action， ， < / p >
< p > 在一个action中， < code > |< / code > 操作符表示将前一个表达式的结果作为后一个函数的输入， ， ， ， ， ， ： < / p >
< pre > < code class = "language-Go" > func daysAgo(t time.Time) int {
return int(time.Since(t).Hours() / 24)
}
< / code > < / pre >
< p > 需要注意的是CreatedAt的参数类型是time.Time， ， （ ） ， < / p >
< p > 生成模板的输出需要两个处理步骤。第一步是要分析模板并转为内部表示， ： ； ， ； < / p >
< pre > < code class = "language-Go" > report, err := template.New(" report" ).
Funcs(template.FuncMap{" daysAgo" : daysAgo}).
Parse(templ)
if err != nil {
log.Fatal(err)
}
< / code > < / pre >
< p > 因为模板通常在编译时就测试好了， ： ， （ ） ， < / p >
< p > 一旦模板已经创建、注册了daysAgo函数、并通过分析和检测， ： < / p >
< pre > < code class = "language-Go" > var report = template.Must(template.New(" issuelist" ).
Funcs(template.FuncMap{" daysAgo" : daysAgo}).
Parse(templ))
func main() {
result, err := github.SearchIssues(os.Args[1:])
if err != nil {
log.Fatal(err)
}
if err := report.Execute(os.Stdout, result); err != nil {
log.Fatal(err)
}
}
< / code > < / pre >
< p > 程序输出一个纯文本报告：< / p >
< pre > < code > $ go build gopl.io/ch4/issuesreport
$ ./issuesreport repo:golang/go is:open json decoder
13 issues:
----------------------------------------
Number: 5680
User: eaigner
Title: encoding/json: set key converter on en/decoder
Age: 750 days
----------------------------------------
Number: 6050
User: gopherbot
Title: encoding/json: provide tokenizer
Age: 695 days
----------------------------------------
...
< / code > < / pre >
< p > 现在让我们转到html/template模板包。它使用和text/template包相同的API和模板语言， ， ， ， ， ， < / p >
< p > 下面的模板以HTML格式输出issue列表。注意import语句的不同： < / p >
< p > < u > < i > gopl.io/ch4/issueshtml< / i > < / u > < / p >
< pre > < code class = "language-Go" > import " html/template"
var issueList = template.Must(template.New(" issuelist" ).Parse(`
< h1> {{.TotalCount}} issues< /h1>
< table>
< tr style='text-align: left'>
< th> #< /th>
< th> State< /th>
< th> User< /th>
< th> Title< /th>
< /tr>
{{range .Items}}
< tr>
< td> < a href='{{.HTMLURL}}'> {{.Number}}< /a> < /td>
< td> {{.State}}< /td>
< td> < a href='{{.User.HTMLURL}}'> {{.User.Login}}< /a> < /td>
< td> < a href='{{.HTMLURL}}'> {{.Title}}< /a> < /td>
< /tr>
{{end}}
< /table>
`))
< / code > < / pre >
< p > 下面的命令将在新的模板上执行一个稍微不同的查询：< / p >
< pre > < code > $ go build gopl.io/ch4/issueshtml
$ ./issueshtml repo:golang/go commenter:gopherbot json encoder > issues.html
< / code > < / pre >
< p > 图4.4显示了在web浏览器中的效果图。每个issue包含到Github对应页面的链接。< / p >
< p > < img src = "../images/ch4-04.png" alt = "" / > < / p >
< p > 图4.4中issue没有包含会对HTML格式产生冲突的特殊字符， < code > & < / code > 和< code > < < / code > 字符的issue。下面的命令选择了两个这样的issue： < / p >
< pre > < code > $ ./issueshtml repo:golang/go 3133 10535 > issues2.html
< / code > < / pre >
< p > 图4.5显示了该查询的结果。注意， ， ， ， & lt;”四个字符将会被当作小于字符“< ”处理，同时“< link> ”字符串将会被当作一个链接元素处理， ， < / p >
< p > 我们也可以通过对信任的HTML字符串使用template.HTML类型来抑制这种自动转义的行为。还有很多采用类型命名的字符串类型分别对应信任的JavaScript、CSS和URL。下面的程序演示了两个使用不同类型的相同字符串产生的不同结果： ， < / p >
< p > < img src = "../images/ch4-05.png" alt = "" / > < / p >
< p > < u > < i > gopl.io/ch4/autoescape< / i > < / u > < / p >
< pre > < code class = "language-Go" > func main() {
const templ = `< p> A: {{.A}}< /p> < p> B: {{.B}}< /p> `
t := template.Must(template.New(" escape" ).Parse(templ))
var data struct {
A string // untrusted plain text
B template.HTML // trusted HTML
}
data.A = " < b> Hello!< /b> "
data.B = " < b> Hello!< /b> "
if err := t.Execute(os.Stdout, data); err != nil {
log.Fatal(err)
}
}
< / code > < / pre >
< p > 图4.6显示了出现在浏览器中的模板输出。我们看到A的黑体标记被转义失效了， < / p >
< p > < img src = "../images/ch4-06.png" alt = "" / > < / p >
< p > 我们这里只讲述了模板系统中最基本的特性。一如既往，如果想了解更多的信息，请自己查看包文档：< / p >
< pre > < code > $ go doc text/template
$ go doc html/template
< / code > < / pre >
< p > < strong > 练习 4.14： < / strong > 创建一个web服务器， ， < / p >
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