218 lines
8.7 KiB
Plaintext
Generated
218 lines
8.7 KiB
Plaintext
Generated
<!DOCTYPE html>
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<html>
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<head>
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<meta charset="utf-8">
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<title>Go by Example: HTTP Servers</title>
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<link rel=stylesheet href="site.css">
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</head>
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<script>
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onkeydown = (e) => {
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if (e.key == "ArrowLeft") {
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window.location.href = 'http-clients';
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<body>
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<div class="example" id="http-servers">
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<h2><a href="./">Go by Example</a>: HTTP Servers</h2>
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<table>
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<tr>
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<td class="docs">
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<p>Writing a basic HTTP server is easy using the
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<code>net/http</code> package.</p>
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</td>
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<td class="code leading">
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<a href="http://play.golang.org/p/lNuS9ysZmxH"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
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<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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</td>
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<td class="code leading">
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<div class="highlight"><pre><span class="kn">import</span> <span class="p">(</span>
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<span class="s">"fmt"</span>
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<span class="s">"net/http"</span>
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<span class="p">)</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>A fundamental concept in <code>net/http</code> servers is
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<em>handlers</em>. A handler is an object implementing the
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<code>http.Handler</code> interface. A common way to write
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a handler is by using the <code>http.HandlerFunc</code> adapter
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on functions with the appropriate signature.</p>
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</td>
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<td class="code leading">
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<div class="highlight"><pre><span class="kd">func</span> <span class="nx">hello</span><span class="p">(</span><span class="nx">w</span> <span class="nx">http</span><span class="p">.</span><span class="nx">ResponseWriter</span><span class="p">,</span> <span class="nx">req</span> <span class="o">*</span><span class="nx">http</span><span class="p">.</span><span class="nx">Request</span><span class="p">)</span> <span class="p">{</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>Functions serving as handlers take a
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<code>http.ResponseWriter</code> and a <code>http.Request</code> as
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arguments. The response writer is used to fill in the
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HTTP response. Here our simple response is just
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“hello\n”.</p>
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</td>
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<td class="code leading">
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<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Fprintf</span><span class="p">(</span><span class="nx">w</span><span class="p">,</span> <span class="s">"hello\n"</span><span class="p">)</span>
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<span class="p">}</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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</td>
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<td class="code leading">
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<div class="highlight"><pre><span class="kd">func</span> <span class="nx">headers</span><span class="p">(</span><span class="nx">w</span> <span class="nx">http</span><span class="p">.</span><span class="nx">ResponseWriter</span><span class="p">,</span> <span class="nx">req</span> <span class="o">*</span><span class="nx">http</span><span class="p">.</span><span class="nx">Request</span><span class="p">)</span> <span class="p">{</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>This handler does something a little more
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sophisticated by reading all the HTTP request
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headers and echoing them into the response body.</p>
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</td>
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<td class="code leading">
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<div class="highlight"><pre> <span class="k">for</span> <span class="nx">name</span><span class="p">,</span> <span class="nx">headers</span> <span class="o">:=</span> <span class="k">range</span> <span class="nx">req</span><span class="p">.</span><span class="nx">Header</span> <span class="p">{</span>
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<span class="k">for</span> <span class="nx">_</span><span class="p">,</span> <span class="nx">h</span> <span class="o">:=</span> <span class="k">range</span> <span class="nx">headers</span> <span class="p">{</span>
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<span class="nx">fmt</span><span class="p">.</span><span class="nx">Fprintf</span><span class="p">(</span><span class="nx">w</span><span class="p">,</span> <span class="s">"%v: %v\n"</span><span class="p">,</span> <span class="nx">name</span><span class="p">,</span> <span class="nx">h</span><span class="p">)</span>
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<span class="p">}</span>
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<span class="p">}</span>
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<span class="p">}</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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</td>
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<td class="code leading">
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<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>We register our handlers on server routes using the
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<code>http.HandleFunc</code> convenience function. It sets up
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the <em>default router</em> in the <code>net/http</code> package and
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takes a function as an argument.</p>
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</td>
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<td class="code leading">
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<div class="highlight"><pre> <span class="nx">http</span><span class="p">.</span><span class="nx">HandleFunc</span><span class="p">(</span><span class="s">"/hello"</span><span class="p">,</span> <span class="nx">hello</span><span class="p">)</span>
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<span class="nx">http</span><span class="p">.</span><span class="nx">HandleFunc</span><span class="p">(</span><span class="s">"/headers"</span><span class="p">,</span> <span class="nx">headers</span><span class="p">)</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>Finally, we call the <code>ListenAndServe</code> with the port
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and a handler. <code>nil</code> tells it to use the default
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router we’ve just set up.</p>
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</td>
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<td class="code">
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<div class="highlight"><pre> <span class="nx">http</span><span class="p">.</span><span class="nx">ListenAndServe</span><span class="p">(</span><span class="s">":8090"</span><span class="p">,</span> <span class="kc">nil</span><span class="p">)</span>
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<span class="p">}</span>
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</pre></div>
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</td>
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</tr>
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</table>
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<table>
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<tr>
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<td class="docs">
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<p>Run the server in the background.</p>
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</td>
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<td class="code leading">
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<div class="highlight"><pre><span class="gp">$</span> go run http-servers.go <span class="p">&</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>Access the <code>/hello</code> route.</p>
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</td>
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<td class="code">
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<div class="highlight"><pre><span class="gp">$</span> curl localhost:8090/hello
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<span class="go">hello</span>
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</pre></div>
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</td>
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</tr>
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</table>
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<p class="next">
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Next example: <a href="context">Context</a>.
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</p>
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<p class="footer">
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by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/http-servers">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
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</p>
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</div>
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<script>
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var codeLines = [];
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codeLines.push('package main\u000A');codeLines.push('import (\u000A \"fmt\"\u000A \"net/http\"\u000A)\u000A');codeLines.push('func hello(w http.ResponseWriter, req *http.Request) {\u000A');codeLines.push(' fmt.Fprintf(w, \"hello\\n\")\u000A}\u000A');codeLines.push('func headers(w http.ResponseWriter, req *http.Request) {\u000A');codeLines.push(' for name, headers := range req.Header {\u000A for _, h := range headers {\u000A fmt.Fprintf(w, \"%v: %v\\n\", name, h)\u000A }\u000A }\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push(' http.HandleFunc(\"/hello\", hello)\u000A http.HandleFunc(\"/headers\", headers)\u000A');codeLines.push(' http.ListenAndServe(\":8090\", nil)\u000A}\u000A');codeLines.push('');codeLines.push('');
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</script>
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