gobyexample/public/http-clients
2019-06-04 07:44:39 -07:00

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<title>Go by Example: HTTP Clients</title>
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<div class="example" id="http-clients">
<h2><a href="./">Go by Example</a>: HTTP Clients</h2>
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<p>The Go standard library comes with excellent support
for HTTP clients and servers in the <code>net/http</code>
package. In this example we&rsquo;ll use it to issue simple
HTTP requests.</p>
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<a href="http://play.golang.org/p/VxYIifr_UuH"><img title="Run code" class="run" src="data:image/png;base64,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" /></a>
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
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<div class="highlight"><pre><span class="kn">import</span> <span class="p">(</span>
<span class="s">&quot;bufio&quot;</span>
<span class="s">&quot;fmt&quot;</span>
<span class="s">&quot;net/http&quot;</span>
<span class="p">)</span>
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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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<p>Issue an HTTP GET request to a server. <code>http.Get</code> is a
convenient shortcut around creating an <code>http.Client</code>
object and calling its <code>Get</code> method; it uses the
<code>http.DefaultClient</code> object which has useful default
settings.</p>
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<div class="highlight"><pre> <span class="nx">resp</span><span class="p">,</span> <span class="nx">err</span> <span class="o">:=</span> <span class="nx">http</span><span class="p">.</span><span class="nx">Get</span><span class="p">(</span><span class="s">&quot;http://gobyexample.com&quot;</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>
<span class="k">defer</span> <span class="nx">resp</span><span class="p">.</span><span class="nx">Body</span><span class="p">.</span><span class="nx">Close</span><span class="p">()</span>
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<p>Print the HTTP response status.</p>
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<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">&quot;Response status:&quot;</span><span class="p">,</span> <span class="nx">resp</span><span class="p">.</span><span class="nx">Status</span><span class="p">)</span>
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<p>Print the first 5 lines of the response body.</p>
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<div class="highlight"><pre> <span class="nx">scanner</span> <span class="o">:=</span> <span class="nx">bufio</span><span class="p">.</span><span class="nx">NewScanner</span><span class="p">(</span><span class="nx">resp</span><span class="p">.</span><span class="nx">Body</span><span class="p">)</span>
<span class="k">for</span> <span class="nx">i</span> <span class="o">:=</span> <span class="mi">0</span><span class="p">;</span> <span class="nx">scanner</span><span class="p">.</span><span class="nx">Scan</span><span class="p">()</span> <span class="o">&amp;&amp;</span> <span class="nx">i</span> <span class="p">&lt;</span> <span class="mi">5</span><span class="p">;</span> <span class="nx">i</span><span class="o">++</span> <span class="p">{</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">scanner</span><span class="p">.</span><span class="nx">Text</span><span class="p">())</span>
<span class="p">}</span>
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<div class="highlight"><pre> <span class="k">if</span> <span class="nx">err</span> <span class="o">:=</span> <span class="nx">scanner</span><span class="p">.</span><span class="nx">Err</span><span class="p">();</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>
<span class="p">}</span>
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<div class="highlight"><pre><span class="gp">$</span> go run http-clients.go
<span class="go">Response status: 200 OK</span>
<span class="go">&lt;!DOCTYPE html&gt;</span>
<span class="go">&lt;html&gt;</span>
<span class="go"> &lt;head&gt;</span>
<span class="go"> &lt;meta charset=&quot;utf-8&quot;&gt;</span>
<span class="go"> &lt;title&gt;Go by Example&lt;/title&gt;</span>
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<p class="next">
Next example: <a href="http-servers">HTTP Servers</a>.
</p>
<p class="footer">
by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/http-clients">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
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