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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Go by Example 中文版: URL 解析</title>
<link rel=stylesheet href="site.css">
</head>
<script>
onkeydown = (e) => {
if (e.key == "ArrowLeft") {
window.location.href = 'number-parsing';
}
if (e.key == "ArrowRight") {
window.location.href = 'sha256-hashes';
}
}
</script>
<body>
<div class="example" id="url-parsing">
<h2><a href="./">Go by Example 中文版</a>: URL 解析</h2>
<table>
<tr>
<td class="docs">
<p>URL 提供了<a href="http://adam.heroku.com/past/2010/3/30/urls_are_the_uniform_way_to_locate_resources/">统一资源定位方式</a>。
这里展示了在 Go 中是如何解析 URL 的。</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/UXUgtMlBACy"><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">"fmt"</span>
<span class="s">"net"</span>
<span class="s">"net/url"</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>我们将解析这个 URL 示例，它包含了一个 scheme、
认证信息、主机名、端口、路径、查询参数以及查询片段。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">s</span> <span class="o">:=</span> <span class="s">"postgres://user:pass@host.com:5432/path?k=v#f"</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>解析这个 URL 并确保解析没有出错。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">u</span><span class="p">,</span> <span class="nx">err</span> <span class="o">:=</span> <span class="nx">url</span><span class="p">.</span><span class="nf">Parse</span><span class="p">(</span><span class="nx">s</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>直接访问 scheme。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">u</span><span class="p">.</span><span class="nx">Scheme</span><span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p><code>User</code> 包含了所有的认证信息，
这里调用 <code>Username</code> 和 <code>Password</code> 来获取单独的值。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">u</span><span class="p">.</span><span class="nx">User</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">u</span><span class="p">.</span><span class="nx">User</span><span class="p">.</span><span class="nf">Username</span><span class="p">())</span>
<span class="nx">p</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">u</span><span class="p">.</span><span class="nx">User</span><span class="p">.</span><span class="nf">Password</span><span class="p">()</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">p</span><span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p><code>Host</code> 包含主机名和端口号（如果存在）。使用 <code>SplitHostPort</code> 提取它们。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">u</span><span class="p">.</span><span class="nx">Host</span><span class="p">)</span>
<span class="nx">host</span><span class="p">,</span> <span class="nx">port</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">net</span><span class="p">.</span><span class="nf">SplitHostPort</span><span class="p">(</span><span class="nx">u</span><span class="p">.</span><span class="nx">Host</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">host</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">port</span><span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>这里我们提取路径和 <code>#</code> 后面的查询片段信息。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">u</span><span class="p">.</span><span class="nx">Path</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">u</span><span class="p">.</span><span class="nx">Fragment</span><span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>要得到字符串中的 <code>k=v</code> 这种格式的查询参数，可以使用 <code>RawQuery</code> 函数。
你也可以将查询参数解析为一个 map。已解析的查询参数 map 以查询字符串为键，
已解析的查询参数会从字符串映射到到字符串的切片，
因此如果您只想要第一个值，则索引为 <code>[0]</code>。</p>
</td>
<td class="code">
<pre class="chroma">
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">u</span><span class="p">.</span><span class="nx">RawQuery</span><span class="p">)</span>
<span class="nx">m</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">url</span><span class="p">.</span><span class="nf">ParseQuery</span><span class="p">(</span><span class="nx">u</span><span class="p">.</span><span class="nx">RawQuery</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">m</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">m</span><span class="p">[</span><span class="s">"k"</span><span class="p">][</span><span class="mi">0</span><span class="p">])</span>
<span class="p">}</span>
</pre>
</td>
</tr>
</table>
<table>
<tr>
<td class="docs">
<p>运行我们的 URL 解析程序，
显示全部我们提取的 URL 的不同数据块。</p>
</td>
<td class="code">
<pre class="chroma">
<span class="gp">$</span> go run url-parsing.go
<span class="go">postgres
</span><span class="go">user:pass
</span><span class="go">user
</span><span class="go">pass
</span><span class="go">host.com:5432
</span><span class="go">host.com
</span><span class="go">5432
</span><span class="go">/path
</span><span class="go">f
</span><span class="go">k=v
</span><span class="go">map[k:[v]]
</span><span class="go">v</span></pre>
</td>
</tr>
</table>
<p class="next">
下一个例子: <a href="sha256-hashes">SHA256 散列</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>
<script>
var codeLines = [];
codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A \"fmt\"\u000A \"net\"\u000A \"net/url\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push(' s :\u003D \"postgres://user:pass@host.com:5432/path?k\u003Dv#f\"\u000A');codeLines.push(' u, err :\u003D url.Parse(s)\u000A if err !\u003D nil {\u000A panic(err)\u000A }\u000A');codeLines.push(' fmt.Println(u.Scheme)\u000A');codeLines.push(' fmt.Println(u.User)\u000A fmt.Println(u.User.Username())\u000A p, _ :\u003D u.User.Password()\u000A fmt.Println(p)\u000A');codeLines.push(' fmt.Println(u.Host)\u000A host, port, _ :\u003D net.SplitHostPort(u.Host)\u000A fmt.Println(host)\u000A fmt.Println(port)\u000A');codeLines.push(' fmt.Println(u.Path)\u000A fmt.Println(u.Fragment)\u000A');codeLines.push(' fmt.Println(u.RawQuery)\u000A m, _ :\u003D url.ParseQuery(u.RawQuery)\u000A fmt.Println(m)\u000A fmt.Println(m[\"k\"][0])\u000A}\u000A');codeLines.push('');
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</body>
</html>