golang实现http表单大文件流式上传服务端代码

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golang的http标准库的上传文件是一次性将文件全部读到内存中，这样上传小文件还可以，但是大文件就无能为力了。
一开始在网上找到一篇gin实现大文件流式上传的文章。大体思路是手动解析form表单的header和body，然后分片读取上传的文件内容。但是代码量有点多且复杂。有兴趣的同学可以自行百度。

后来在github找到一个库
github.com/albrow/forms

可以看到这个库读取上传文件的方法

<pre><code class="lang-go hljs"><span class="token keyword">func</span> <span class="token punctuation">(</span>d Data<span class="token punctuation">)</span> <span class="token function">GetFileBytes</span><span class="token punctuation">(</span>key <span class="token builtin">string</span><span class="token punctuation">)</span> <span class="token punctuation">(</span><span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token builtin">byte</span><span class="token punctuation">,</span> <span class="token builtin">error</span><span class="token punctuation">)</span> <span class="token punctuation">{</span> fileHeader<span class="token punctuation">,</span> found <span class="token operator">:=</span> d<span class="token punctuation">.</span>Files<span class="token punctuation">[</span>key<span class="token punctuation">]</span> <span class="token keyword">if</span> <span class="token operator">!</span>found <span class="token punctuation">{</span> <span class="token keyword">return</span> <span class="token boolean">nil</span><span class="token punctuation">,</span> <span class="token boolean">nil</span> <span class="token punctuation">}</span> <span class="token keyword">else</span> <span class="token punctuation">{</span> file<span class="token punctuation">,</span> err <span class="token operator">:=</span> fileHeader<span class="token punctuation">.</span><span class="token function">Open</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token keyword">if</span> err <span class="token operator">!=</span> <span class="token boolean">nil</span> <span class="token punctuation">{</span> <span class="token keyword">return</span> <span class="token boolean">nil</span><span class="token punctuation">,</span> err <span class="token punctuation">}</span> <span class="token keyword">return</span> ioutil<span class="token punctuation">.</span><span class="token function">ReadAll</span><span class="token punctuation">(</span>file<span class="token punctuation">)</span> <span class="token punctuation">}</span> <span class="token punctuation">}</span> </code></pre>

最后使用的是ioutil.ReadAll，大文件上传的话就会有问题，要实现流式上传，可以在这个包里加一个方法。以下是我自己加的方法

<pre><code class="lang-go hljs"><span class="token keyword">func</span> <span class="token punctuation">(</span>d Data<span class="token punctuation">)</span> <span class="token function">GetFileReader</span><span class="token punctuation">(</span>key <span class="token builtin">string</span><span class="token punctuation">)</span> <span class="token punctuation">(</span>io<span class="token punctuation">.</span>Reader<span class="token punctuation">,</span> <span class="token builtin">error</span><span class="token punctuation">)</span> <span class="token punctuation">{</span> fileHeader<span class="token punctuation">,</span> found <span class="token operator">:=</span> d<span class="token punctuation">.</span>Files<span class="token punctuation">[</span>key<span class="token punctuation">]</span> <span class="token keyword">if</span> <span class="token operator">!</span>found <span class="token punctuation">{</span> <span class="token keyword">return</span> <span class="token boolean">nil</span><span class="token punctuation">,</span> <span class="token boolean">nil</span> <span class="token punctuation">}</span> <span class="token keyword">else</span> <span class="token punctuation">{</span> file<span class="token punctuation">,</span> err <span class="token operator">:=</span> fileHeader<span class="token punctuation">.</span><span class="token function">Open</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token keyword">if</span> err <span class="token operator">!=</span> <span class="token boolean">nil</span> <span class="token punctuation">{</span> <span class="token keyword">return</span> <span class="token boolean">nil</span><span class="token punctuation">,</span> err <span class="token punctuation">}</span> <span class="token keyword">return</span> file<span class="token punctuation">,</span> <span class="token boolean">nil</span> <span class="token punctuation">}</span> <span class="token punctuation">}</span> </code></pre>

得到reader后使用io.Copy即可将文件落盘

<pre><code class="lang-go hljs"> userData<span class="token punctuation">,</span> err <span class="token operator">:=</span> forms<span class="token punctuation">.</span><span class="token function">Parse</span><span class="token punctuation">(</span>c<span class="token punctuation">.</span>Request<span class="token punctuation">)</span> <span class="token keyword">if</span> err <span class="token operator">!=</span> <span class="token boolean">nil</span> <span class="token punctuation">{</span> log<span class="token punctuation">.</span><span class="token function">Printf</span><span class="token punctuation">(</span><span class="token string">"parse错误：%v"</span><span class="token punctuation">,</span> err<span class="token punctuation">)</span> <span class="token keyword">return</span> <span class="token punctuation">}</span> header <span class="token operator">:=</span> userData<span class="token punctuation">.</span><span class="token function">GetFile</span><span class="token punctuation">(</span><span class="token string">"file"</span><span class="token punctuation">)</span> fileReader<span class="token punctuation">,</span> err <span class="token operator">:=</span> userData<span class="token punctuation">.</span><span class="token function">GetFileReader</span><span class="token punctuation">(</span><span class="token string">"file"</span><span class="token punctuation">)</span> <span class="token keyword">if</span> err <span class="token operator">!=</span> <span class="token boolean">nil</span> <span class="token punctuation">{</span> log<span class="token punctuation">.</span><span class="token function">Printf</span><span class="token punctuation">(</span><span class="token string">"获取reader错误：%v"</span><span class="token punctuation">,</span> err<span class="token punctuation">)</span> <span class="token keyword">return</span> <span class="token punctuation">}</span> file<span class="token punctuation">,</span> <span class="token boolean">_</span> <span class="token operator">:=</span> os<span class="token punctuation">.</span><span class="token function">Create</span><span class="token punctuation">(</span>header<span class="token punctuation">.</span>Filename<span class="token punctuation">)</span> io<span class="token punctuation">.</span><span class="token function">Copy</span><span class="token punctuation">(</span>file<span class="token punctuation">,</span> fileReader<span class="token punctuation">)</span> </code></pre> 到此这篇关于“golang实现http表单大文件流式上传服务端代码”的文章就介绍到这了,更多文章或继续浏览下面的相关文章，希望大家以后多多支持JQ教程网！

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