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text-templates.html
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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Go by Example 中文版: 文本模板</title>
<link rel=stylesheet href="site.css">
</head>
<script>
onkeydown = (e) => {
if (e.key == "ArrowLeft") {
window.location.href = 'string-formatting';
}
if (e.key == "ArrowRight") {
window.location.href = 'regular-expressions';
}
}
</script>
<body>
<div class="example" id="text-templates">
<h2><a href="./">Go by Example 中文版</a>: 文本模板</h2>
<table>
<tr>
<td class="docs">
<p>Go 使用 <code>text/template</code> 包为创建动态内容或向用户显示自定义输出提供了内置支持。
一个名为 <code>html/template</code> 的兄弟软件包提供了相同的 API，但具有额外的安全功能，被用于生成 HTML。</p>
</td>
<td class="code empty leading">
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<a href="https://play.studygolang.com/p/a6JSWGUefWK"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
<pre class="chroma"><span class="kn">package</span> <span class="nx">main</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<pre class="chroma"><span class="kn">import</span> <span class="p">(</span>
<span class="s">"os"</span>
<span class="s">"text/template"</span>
<span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<pre class="chroma"><span class="kd">func</span> <span class="nf">main</span><span class="p">()</span> <span class="p">{</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>我们可以创建一个新模板，并从字符串解析其正文。
模板是静态文本和包含在”动作“中用于动态插入内容的混合体。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">t1</span> <span class="o">:=</span> <span class="nx">template</span><span class="p">.</span><span class="nf">New</span><span class="p">(</span><span class="s">"t1"</span><span class="p">)</span>
<span class="nx">t1</span><span class="p">,</span> <span class="nx">err</span> <span class="o">:=</span> <span class="nx">t1</span><span class="p">.</span><span class="nf">Parse</span><span class="p">(</span><span class="s">"Value is {{.}}\n"</span><span class="p">)</span>
<span class="k">if</span> <span class="nx">err</span> <span class="o">!=</span> <span class="kc">nil</span> <span class="p">{</span>
<span class="nb">panic</span><span class="p">(</span><span class="nx">err</span><span class="p">)</span>
<span class="p">}</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>或者，我们可以使用 <code>template.Must</code> 函数，在 <code>Parse</code> 错误时返回 panic。
这对于在全局作用域中初始化的模板非常有用。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">t1</span> <span class="p">=</span> <span class="nx">template</span><span class="p">.</span><span class="nf">Must</span><span class="p">(</span><span class="nx">t1</span><span class="p">.</span><span class="nf">Parse</span><span class="p">(</span><span class="s">"Value: {{.}}\n"</span><span class="p">))</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>通过“执行”模板，我们生成其文本，其中包含其“动作”的具体值。
<code>{{.}}</code> 动作被作为参数传递给 <code>Execute</code> 的值所代替。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">t1</span><span class="p">.</span><span class="nf">Execute</span><span class="p">(</span><span class="nx">os</span><span class="p">.</span><span class="nx">Stdout</span><span class="p">,</span> <span class="s">"some text"</span><span class="p">)</span>
<span class="nx">t1</span><span class="p">.</span><span class="nf">Execute</span><span class="p">(</span><span class="nx">os</span><span class="p">.</span><span class="nx">Stdout</span><span class="p">,</span> <span class="mi">5</span><span class="p">)</span>
<span class="nx">t1</span><span class="p">.</span><span class="nf">Execute</span><span class="p">(</span><span class="nx">os</span><span class="p">.</span><span class="nx">Stdout</span><span class="p">,</span> <span class="p">[]</span><span class="kt">string</span><span class="p">{</span>
<span class="s">"Go"</span><span class="p">,</span>
<span class="s">"Rust"</span><span class="p">,</span>
<span class="s">"C++"</span><span class="p">,</span>
<span class="s">"C#"</span><span class="p">,</span>
<span class="p">})</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>我们将在下面使用辅助函数。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">Create</span> <span class="o">:=</span> <span class="kd">func</span><span class="p">(</span><span class="nx">name</span><span class="p">,</span> <span class="nx">t</span> <span class="kt">string</span><span class="p">)</span> <span class="o">*</span><span class="nx">template</span><span class="p">.</span><span class="nx">Template</span> <span class="p">{</span>
<span class="k">return</span> <span class="nx">template</span><span class="p">.</span><span class="nf">Must</span><span class="p">(</span><span class="nx">template</span><span class="p">.</span><span class="nf">New</span><span class="p">(</span><span class="nx">name</span><span class="p">).</span><span class="nf">Parse</span><span class="p">(</span><span class="nx">t</span><span class="p">))</span>
<span class="p">}</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>如果数据是一个结构体，我们可以使用 <code>{{.FieldName}}</code> 动作来访问其字段。
这些字段应该是导出的，以便在模板执行时可访问。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">t2</span> <span class="o">:=</span> <span class="nf">Create</span><span class="p">(</span><span class="s">"t2"</span><span class="p">,</span> <span class="s">"Name: {{.Name}}\n"</span><span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<pre class="chroma"> <span class="nx">t2</span><span class="p">.</span><span class="nf">Execute</span><span class="p">(</span><span class="nx">os</span><span class="p">.</span><span class="nx">Stdout</span><span class="p">,</span> <span class="kd">struct</span> <span class="p">{</span>
<span class="nx">Name</span> <span class="kt">string</span>
<span class="p">}{</span><span class="s">"Jane Doe"</span><span class="p">})</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>这同样适用于 map；在 map 中没有限制键名的大小写。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">t2</span><span class="p">.</span><span class="nf">Execute</span><span class="p">(</span><span class="nx">os</span><span class="p">.</span><span class="nx">Stdout</span><span class="p">,</span> <span class="kd">map</span><span class="p">[</span><span class="kt">string</span><span class="p">]</span><span class="kt">string</span><span class="p">{</span>
<span class="s">"Name"</span><span class="p">:</span> <span class="s">"Mickey Mouse"</span><span class="p">,</span>
<span class="p">})</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>if/else 提供了条件执行模板。如果一个值是类型的默认值，例如 0、空字符串、空指针等，
则该值被认为是 false。
这个示例演示了另一个模板特性：使用 <code>-</code> 在动作中去除空格。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">t3</span> <span class="o">:=</span> <span class="nf">Create</span><span class="p">(</span><span class="s">"t3"</span><span class="p">,</span>
<span class="s">"{{if . -}} yes {{else -}} no {{end}}\n"</span><span class="p">)</span>
<span class="nx">t3</span><span class="p">.</span><span class="nf">Execute</span><span class="p">(</span><span class="nx">os</span><span class="p">.</span><span class="nx">Stdout</span><span class="p">,</span> <span class="s">"not empty"</span><span class="p">)</span>
<span class="nx">t3</span><span class="p">.</span><span class="nf">Execute</span><span class="p">(</span><span class="nx">os</span><span class="p">.</span><span class="nx">Stdout</span><span class="p">,</span> <span class="s">""</span><span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>range 块允许我们遍历切片，数组，映射或通道。在 range 块内，<code>{{.}}</code> 动作被设置为迭代的当前项。</p>
</td>
<td class="code">
<pre class="chroma">
<span class="nx">t4</span> <span class="o">:=</span> <span class="nf">Create</span><span class="p">(</span><span class="s">"t4"</span><span class="p">,</span>
<span class="s">"Range: {{range .}}{{.}} {{end}}\n"</span><span class="p">)</span>
<span class="nx">t4</span><span class="p">.</span><span class="nf">Execute</span><span class="p">(</span><span class="nx">os</span><span class="p">.</span><span class="nx">Stdout</span><span class="p">,</span>
<span class="p">[]</span><span class="kt">string</span><span class="p">{</span>
<span class="s">"Go"</span><span class="p">,</span>
<span class="s">"Rust"</span><span class="p">,</span>
<span class="s">"C++"</span><span class="p">,</span>
<span class="s">"C#"</span><span class="p">,</span>
<span class="p">})</span>
<span class="p">}</span>
</pre>
</td>
</tr>
</table>
<table>
<tr>
<td class="docs">
</td>
<td class="code">
<pre class="chroma"><span class="gp">$</span> go run templates.go
<span class="go">Value: some text
</span><span class="go">Value: 5
</span><span class="go">Value: [Go Rust C++ C#]
</span><span class="go">Name: Jane Doe
</span><span class="go">Name: Mickey Mouse
</span><span class="go">yes
</span><span class="go">no
</span><span class="go">Range: Go Rust C++ C# </span></pre>
</td>
</tr>
</table>
<p class="next">
下一个例子: <a href="regular-expressions.html">正则表达式</a>
</p>
<p class="footer">
<a href="https://twitter.com/mmcgrana">@mmcgrana</a> 和<a href="https://eli.thegreenplace.net">Eli Bendersky</a>编写 | <a href="https://github.com/gobyexample-cn">gobyexample-cn</a> 翻译 | <a href="https://github.com/gobyexample-cn/gobyexample/issues">反馈</a> | <a href="https://github.com/gobyexample-cn/gobyexample">源码</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> </p>
</p>
</div>
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