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<ol class="chapter"><li class="chapter-item expanded affix "><a href="../index.html">Go语言圣经</a></li><li class="chapter-item expanded affix "><a href="../preface-zh.html">译者序</a></li><li class="chapter-item expanded affix "><a href="../preface.html">前言</a></li><li class="chapter-item expanded "><a href="../ch1/ch1.html"><strong aria-hidden="true">1.</strong> 入门</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../ch1/ch1-01.html"><strong aria-hidden="true">1.1.</strong> Hello, World</a></li><li class="chapter-item expanded "><a href="../ch1/ch1-02.html"><strong aria-hidden="true">1.2.</strong> 命令行参数</a></li><li class="chapter-item expanded "><a href="../ch1/ch1-03.html"><strong aria-hidden="true">1.3.</strong> 查找重复的行</a></li><li class="chapter-item expanded "><a href="../ch1/ch1-04.html"><strong aria-hidden="true">1.4.</strong> GIF动画</a></li><li class="chapter-item expanded "><a href="../ch1/ch1-05.html"><strong aria-hidden="true">1.5.</strong> 获取URL</a></li><li class="chapter-item expanded "><a href="../ch1/ch1-06.html"><strong aria-hidden="true">1.6.</strong> 并发获取多个URL</a></li><li class="chapter-item expanded "><a href="../ch1/ch1-07.html"><strong aria-hidden="true">1.7.</strong> Web服务</a></li><li class="chapter-item expanded "><a href="../ch1/ch1-08.html"><strong aria-hidden="true">1.8.</strong> 本章要点</a></li></ol></li><li class="chapter-item expanded "><a href="../ch2/ch2.html"><strong aria-hidden="true">2.</strong> 程序结构</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../ch2/ch2-01.html"><strong aria-hidden="true">2.1.</strong> 命名</a></li><li class="chapter-item expanded "><a href="../ch2/ch2-02.html"><strong aria-hidden="true">2.2.</strong> 声明</a></li><li class="chapter-item expanded "><a href="../ch2/ch2-03.html"><strong aria-hidden="true">2.3.</strong> 变量</a></li><li class="chapter-item expanded "><a href="../ch2/ch2-04.html"><strong aria-hidden="true">2.4.</strong> 赋值</a></li><li class="chapter-item expanded "><a href="../ch2/ch2-05.html"><strong aria-hidden="true">2.5.</strong> 类型</a></li><li class="chapter-item expanded "><a href="../ch2/ch2-06.html"><strong aria-hidden="true">2.6.</strong> 包和文件</a></li><li class="chapter-item expanded "><a href="../ch2/ch2-07.html"><strong aria-hidden="true">2.7.</strong> 作用域</a></li></ol></li><li class="chapter-item expanded "><a href="../ch3/ch3.html"><strong aria-hidden="true">3.</strong> 基础数据类型</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../ch3/ch3-01.html"><strong aria-hidden="true">3.1.</strong> 整型</a></li><li class="chapter-item expanded "><a href="../ch3/ch3-02.html"><strong aria-hidden="true">3.2.</strong> 浮点数</a></li><li class="chapter-item expanded "><a href="../ch3/ch3-03.html"><strong aria-hidden="true">3.3.</strong> 复数</a></li><li class="chapter-item expanded "><a href="../ch3/ch3-04.html"><strong aria-hidden="true">3.4.</strong> 布尔型</a></li><li class="chapter-item expanded "><a href="../ch3/ch3-05.html"><strong aria-hidden="true">3.5.</strong> 字符串</a></li><li class="chapter-item expanded "><a href="../ch3/ch3-06.html"><strong aria-hidden="true">3.6.</strong> 常量</a></li></ol></li><li class="chapter-item expanded "><a href="../ch4/ch4.html"><strong aria-hidden="true">4.</strong> 复合数据类型</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../ch4/ch4-01.html"><strong aria-hidden="true">4.1.</strong> 数组</a></li><li class="chapter-item expanded "><a href="../ch4/ch4-02.html"><strong aria-hidden="true">4.2.</strong> Slice</a></li><li class="chapter-item expanded "><a href="../ch4/ch4-03.html"><strong aria-hidden="true">4.3.</strong> Map</a></li><li class="chapter-item expanded "><a href="../ch4/ch4-04.html"><strong aria-hidden="true">4.4.</strong> 结构体</a></li><li class="chapter-item expanded "><a href="../ch4/ch4-05.html"><strong aria-hidden="true">4.5.</strong> JSON</
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<li><em>Go语言圣经读书笔记(挖坑中...): <a href="https://github.com/chai2010/gopl-notes-zh">https://github.com/chai2010/gopl-notes-zh</a></em></li>
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<h2 id="104-导入声明"><a class="header" href="#104-导入声明">10.4. 导入声明</a></h2>
<p>可以在一个Go语言源文件包声明语句之后其它非导入声明语句之前包含零到多个导入包声明语句。每个导入声明可以单独指定一个导入路径也可以通过圆括号同时导入多个导入路径。下面两个导入形式是等价的但是第二种形式更为常见。</p>
<pre><code class="language-Go">import &quot;fmt&quot;
import &quot;os&quot;
import (
&quot;fmt&quot;
&quot;os&quot;
)
</code></pre>
<p>导入的包之间可以通过添加空行来分组通常将来自不同组织的包独自分组。包的导入顺序无关紧要但是在每个分组中一般会根据字符串顺序排列。gofmt和goimports工具都可以将不同分组导入的包独立排序。</p>
<pre><code class="language-Go">import (
&quot;fmt&quot;
&quot;html/template&quot;
&quot;os&quot;
&quot;golang.org/x/net/html&quot;
&quot;golang.org/x/net/ipv4&quot;
)
</code></pre>
<p>如果我们想同时导入两个有着名字相同的包例如math/rand包和crypto/rand包那么导入声明必须至少为一个同名包指定一个新的包名以避免冲突。这叫做导入包的重命名。</p>
<pre><code class="language-Go">import (
&quot;crypto/rand&quot;
mrand &quot;math/rand&quot; // alternative name mrand avoids conflict
)
</code></pre>
<p>导入包的重命名只影响当前的源文件。其它的源文件如果导入了相同的包,可以用导入包原本默认的名字或重命名为另一个完全不同的名字。</p>
<p>导入包重命名是一个有用的特性它不仅仅只是为了解决名字冲突。如果导入的一个包名很笨重特别是在一些自动生成的代码中这时候用一个简短名称会更方便。选择用简短名称重命名导入包时候最好统一以避免包名混乱。选择另一个包名称还可以帮助避免和本地普通变量名产生冲突。例如如果文件中已经有了一个名为path的变量那么我们可以将“path”标准包重命名为pathpkg。</p>
<p>每个导入声明语句都明确指定了当前包和被导入包之间的依赖关系。如果遇到包循环导入的情况Go语言的构建工具将报告错误。</p>
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