178 lines
7.7 KiB
Plaintext
178 lines
7.7 KiB
Plaintext
<!DOCTYPE html>
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<html>
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<meta charset="utf-8">
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<title>Go by Example: Base64 Encoding</title>
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<link rel=stylesheet href="site.css">
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</head>
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<body>
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<div class="example" id="base64-encoding">
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<h2><a href="./">Go by Example</a>: Base64 Encoding</h2>
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<table>
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<tr>
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<td class="docs">
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<p>Go provides built-in support for <a href="http://en.wikipedia.org/wiki/Base64">base64
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encoding/decoding</a>.</p>
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</td>
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<td class="code empty leading">
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</td>
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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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<a href="http://play.golang.org/p/y_QTcqdkvZh"><img title="Run code" class="run" src="data:image/png;base64,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" /></a>
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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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<p>This syntax imports the <code>encoding/base64</code> package with
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the <code>b64</code> name instead of the default <code>base64</code>. It’ll
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save us some space below.</p>
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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="nx">b64</span> <span class="s">"encoding/base64"</span>
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<span class="kn">import</span> <span class="s">"fmt"</span>
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</pre></div>
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</td>
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</tr>
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<td class="docs">
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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>Here’s the <code>string</code> we’ll encode/decode.</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">data</span> <span class="o">:=</span> <span class="s">"abc123!?$*&()'-=@~"</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>Go supports both standard and URL-compatible
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base64. Here’s how to encode using the standard
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encoder. The encoder requires a <code>[]byte</code> so we
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convert our <code>string</code> to that type.</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">sEnc</span> <span class="o">:=</span> <span class="nx">b64</span><span class="p">.</span><span class="nx">StdEncoding</span><span class="p">.</span><span class="nx">EncodeToString</span><span class="p">([]</span><span class="nb">byte</span><span class="p">(</span><span class="nx">data</span><span class="p">))</span>
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<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">sEnc</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>Decoding may return an error, which you can check
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if you don’t already know the input to be
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well-formed.</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">sDec</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">b64</span><span class="p">.</span><span class="nx">StdEncoding</span><span class="p">.</span><span class="nx">DecodeString</span><span class="p">(</span><span class="nx">sEnc</span><span class="p">)</span>
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<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nb">string</span><span class="p">(</span><span class="nx">sDec</span><span class="p">))</span>
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<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</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 encodes/decodes using a URL-compatible base64
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format.</p>
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</td>
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<td class="code">
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<div class="highlight"><pre> <span class="nx">uEnc</span> <span class="o">:=</span> <span class="nx">b64</span><span class="p">.</span><span class="nx">URLEncoding</span><span class="p">.</span><span class="nx">EncodeToString</span><span class="p">([]</span><span class="nb">byte</span><span class="p">(</span><span class="nx">data</span><span class="p">))</span>
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<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">uEnc</span><span class="p">)</span>
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<span class="nx">uDec</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">b64</span><span class="p">.</span><span class="nx">URLEncoding</span><span class="p">.</span><span class="nx">DecodeString</span><span class="p">(</span><span class="nx">uEnc</span><span class="p">)</span>
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<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nb">string</span><span class="p">(</span><span class="nx">uDec</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>The string encodes to slightly different values with the
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standard and URL base64 encoders (trailing <code>+</code> vs <code>-</code>)
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but they both decode to the original string as desired.</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 base64-encoding.go
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<span class="go">YWJjMTIzIT8kKiYoKSctPUB+</span>
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<span class="go">abc123!?$*&()'-=@~</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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</td>
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<td class="code">
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<div class="highlight"><pre><span class="go">YWJjMTIzIT8kKiYoKSctPUB-</span>
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<span class="go">abc123!?$*&()'-=@~</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="reading-files">Reading Files</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/base64-encoding">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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</body>
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</html>
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