��空的map。返回的map映射小写字母的属性和对应的属性值。</p>
    <h3 id="TypeByExtension">func <a title="View Source" href="https://github.com/golang/go/blob/master/src/mime/type.go?name=release#45">TypeByExtension</a> <a class="permalink" href="#pkg-index">&para;</a></h3>
    <pre class="funcdecl">func TypeByExtension(ext <a href="builtin.htm#string">string</a>) <a href="builtin.htm#string">string</a></pre>
    <p align="left">函数返回与扩展名偶联的MIME类型。扩展名应�