通过Ajax方式上传文件，使用FormData进行Ajax请求

Love The Way You Lie 2021-09-14 11:48 472阅读 0赞

[http://m.blog.csdn.net/inuyasha1121/article/details/51915742][http_m.blog.csdn.net_inuyasha1121_article_details_51915742]

# 通过传统的form表单提交的方式上传文件： #

<form id= "uploadForm" action= "http://localhost:8080/cfJAX_RS/rest/file/upload" method= "post" enctype ="multipart/form-data">  
         <h1 >测试通过Rest接口上传文件 </h1>  
         <p >指定文件名： <input type ="text" name="filename" /></p>  
         <p >上传文件： <input type ="file" name="file" /></p>  
         <p >关键字1： <input type ="text" name="keyword" /></p>  
         <p >关键字2： <input type ="text" name="keyword" /></p>  
         <p >关键字3： <input type ="text" name="keyword" /></p>  
         <input type ="submit" value="上传"/>  
    </form>

不过 传统的 form 表单提交会导致页面刷新， 但是在有些情况下，我们不希望页面被刷新，这种时候我们都是使用Ajax的方式进行请求的。

#     #

# Ajax的方式进行请求： #

$.ajax({  
         url : "http://localhost:8080/STS/rest/user",  
         type : "POST",  
         data : $( '#postForm').serialize(),  
         success : function(data) {  
              $( '#serverResponse').html(data);  
         },  
         error : function(data) {  
              $( '#serverResponse').html(data.status + " : " + data.statusText + " : " + data.responseText);  
         }  
    });

通常我们提交（使用submit button）时，会把form中的所有表格元素的name与value组成一个queryString，提交到后台。这用jQuery的方法来说，就是serialize。

通过 $( '\#postForm' ).serialize() 可以对form表单进行序列化，从而将form表单中的所有参数传递到服务端。

但是上述方式，只能传递一般的参数， 上传文件的文件流是无法被序列化并传递的。

不过如今主流浏览器都开始支持一个叫做FormData的对象，有了这个FormData，我们就可以轻松地使用Ajax方式进行文件 上传 了。

# 关于FormData及其用法 #

--------------------

FormData是什么呢？我们来看看Mozilla上的介绍。

<table style="border-collapse:collapse; border-spacing:0px; max-width:650px; word-break:break-all; border:1px solid rgb(204,204,204); color:rgb(0,0,0); font-family:Helvetica,Tahoma,Arial,sans-serif; font-size:14px; line-height:25.2px; table-layout:fixed; min-width:400px"> 
 <tbody style=""> 
  <tr style=""> 
   <td style="border:1px solid rgb(204,204,204); font-size:1em; padding:3px"> 
    <div style="word-break:break-all">
      XMLHttpRequest Level 2添加了一个新的接口 
     <code style="font-family:&quot;Courier New&quot;,Courier,monospace; font-size:1em; padding:2px 4px; color:rgb(199,37,78); white-space:pre; background-color:rgb(249,242,244)">FormData</code>.利用 
     <code style="font-family:&quot;Courier New&quot;,Courier,monospace; font-size:1em; padding:2px 4px; color:rgb(199,37,78); white-space:pre; background-color:rgb(249,242,244)">FormData对象</code>,我们可以通过JavaScript用一些键值对来模拟一系列表单控件,我们还可以使用XMLHttpRequest的 
     <a title="zh-CN/XMLHttpRequest#send()" href="https://developer.mozilla.org/zh-CN/docs/DOM/XMLHttpRequest#send%28%29" style="background:transparent; color:rgb(16,138,198); text-decoration:none; margin:0px; padding:0px; font-family:Arial,&quot;Microsoft YaHei&quot;; outline:none" rel="nofollow"><code style="font-family:&quot;Courier New&quot;,Courier,monospace; font-size:1em; padding:2px 4px; color:rgb(199,37,78); white-space:pre; background-color:rgb(249,242,244)">send()</code></a>方法来异步的提交这个"表单".比起普通的ajax,使用 
     <code style="font-family:&quot;Courier New&quot;,Courier,monospace; font-size:1em; padding:2px 4px; color:rgb(199,37,78); white-space:pre; background-color:rgb(249,242,244)">FormData</code>的最大优点就是我们可以异步上传一个二进制文件.&nbsp; 
    </div> 
    <div style="word-break:break-all">
      &nbsp; 
    </div> 
    <div style="word-break:break-all"> 
     <div style="word-break:break-all"> 
      <span style="margin:0px; padding:0px; font-family:&quot;Microsoft YaHei&quot;">所有主流浏览器的较新版本都已经支持这个对象了，比如Chrome 7+、Firefox 4+、IE 10+、Opera 12+、Safari 5+。</span> 
     </div> 
     <div style="word-break:break-all">
       &nbsp; 
     </div> 
     <span style="margin:0px; padding:0px; font-family:&quot;Microsoft YaHei&quot;">参见：</span> 
     <a href="https://developer.mozilla.org/zh-CN/docs/Web/API/XMLHttpRequest/FormData" style="background:transparent; color:rgb(16,138,198); text-decoration:none; margin:0px; padding:0px; font-family:Arial,&quot;Microsoft YaHei&quot;; outline:none" rel="nofollow">https://developer.mozilla.org/zh-CN/docs/Web/API/XMLHttpRequest/FormData</a> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

Constructor

FormData()

想得到一个FormData对象：

<table style="border-collapse:collapse; border-spacing:0px; max-width:100%; background-color:transparent; word-break:break-all; border:0.05rem solid rgb(238,238,238)"> 
 <tbody style=""> 
  <tr style=""> 
   <td style="border:0.05rem solid rgb(238,238,238)"><code style="font-family:Monaco,Menlo,Consolas,&quot;Courier New&quot;,monospace; font-size:21.6px; padding:2px 4px; color:rgb(199,37,78); white-space:nowrap; background-color:rgb(249,242,244)">var</code><span style="margin:0px; padding:0px; font-family:Arial,&quot;Microsoft YaHei&quot;">&nbsp;</span><code style="font-family:Monaco,Menlo,Consolas,&quot;Courier New&quot;,monospace; font-size:21.6px; padding:2px 4px; color:rgb(199,37,78); white-space:nowrap; background-color:rgb(249,242,244)">formdata =&nbsp;</code><code style="font-family:Monaco,Menlo,Consolas,&quot;Courier New&quot;,monospace; font-size:21.6px; padding:2px 4px; color:rgb(199,37,78); white-space:nowrap; background-color:rgb(249,242,244)">new</code><span style="margin:0px; padding:0px; font-family:Arial,&quot;Microsoft YaHei&quot;">&nbsp;</span><code style="font-family:Monaco,Menlo,Consolas,&quot;Courier New&quot;,monospace; font-size:21.6px; padding:2px 4px; color:rgb(199,37,78); white-space:nowrap; background-color:rgb(249,242,244)">FormData();</code></td> 
  </tr> 
 </tbody> 
</table>

W3c草案提供了三种方案来获取或修改FormData。

方案1：创建一个空的FormData对象，然后再用append方法逐个添加键值对：

<table style="border-collapse:collapse; border-spacing:0px; max-width:100%; background-color:transparent; word-break:break-all; border:0.05rem solid rgb(238,238,238)"> 
 <tbody style=""> 
  <tr style=""> 
   <td style="border:0.05rem solid rgb(238,238,238)"><code style="font-family:Monaco,Menlo,Consolas,&quot;Courier New&quot;,monospace; font-size:21.6px; padding:2px 4px; color:rgb(199,37,78); white-space:nowrap; background-color:rgb(249,242,244)">var</code><span style="margin:0px; padding:0px; font-family:Arial,&quot;Microsoft YaHei&quot;">&nbsp;</span><code style="font-family:Monaco,Menlo,Consolas,&quot;Courier New&quot;,monospace; font-size:21.6px; padding:2px 4px; color:rgb(199,37,78); white-space:nowrap; background-color:rgb(249,242,244)">formdata =&nbsp;</code><code style="font-family:Monaco,Menlo,Consolas,&quot;Courier New&quot;,monospace; font-size:21.6px; padding:2px 4px; color:rgb(199,37,78); white-space:nowrap; background-color:rgb(249,242,244)">new</code><span style="margin:0px; padding:0px; font-family:Arial,&quot;Microsoft YaHei&quot;">&nbsp;</span><code style="font-family:Monaco,Menlo,Consolas,&quot;Courier New&quot;,monospace; font-size:21.6px; padding:2px 4px; color:rgb(199,37,78); white-space:nowrap; background-color:rgb(249,242,244)">FormData();</code></td> 
  </tr> 
 </tbody> 
</table>

<table style="border-collapse:collapse; border-spacing:0px; max-width:100%; background-color:transparent; word-break:break-all; border:0.05rem solid rgb(238,238,238)"> 
 <tbody style=""> 
  <tr style=""> 
   <td style="border:0.05rem solid rgb(238,238,238)"><code style="font-family:Monaco,Menlo,Consolas,&quot;Courier New&quot;,monospace; font-size:21.6px; padding:2px 4px; color:rgb(199,37,78); white-space:nowrap; background-color:rgb(249,242,244)">formdata.append(</code><code style="font-family:Monaco,Menlo,Consolas,&quot;Courier New&quot;,monospace; font-size:21.6px; padding:2px 4px; color:rgb(199,37,78); white-space:nowrap; background-color:rgb(249,242,244)">"name"</code><code style="font-family:Monaco,Menlo,Consolas,&quot;Courier New&quot;,monospace; font-size:21.6px; padding:2px 4px; color:rgb(199,37,78); white-space:nowrap; background-color:rgb(249,242,244)">,&nbsp;</code><code style="font-family:Monaco,Menlo,Consolas,&quot;Courier New&quot;,monospace; font-size:21.6px; padding:2px 4px; color:rgb(199,37,78); white-space:nowrap; background-color:rgb(249,242,244)">"呵呵"</code><code style="font-family:Monaco,Menlo,Consolas,&quot;Courier New&quot;,monospace; font-size:21.6px; padding:2px 4px; color:rgb(199,37,78); white-space:nowrap; background-color:rgb(249,242,244)">);</code></td> 
  </tr> 
 </tbody> 
</table>

<table style="border-collapse:collapse; border-spacing:0px; max-width:100%; background-color:transparent; word-break:break-all; border:0.05rem solid rgb(238,238,238)"> 
 <tbody style=""> 
  <tr style=""> 
   <td style="border:0.05rem solid rgb(238,238,238)"><code style="font-family:Monaco,Menlo,Consolas,&quot;Courier New&quot;,monospace; font-size:21.6px; padding:2px 4px; color:rgb(199,37,78); white-space:nowrap; background-color:rgb(249,242,244)">formdata.append(</code><code style="font-family:Monaco,Menlo,Consolas,&quot;Courier New&quot;,monospace; font-size:21.6px; padding:2px 4px; color:rgb(199,37,78); white-space:nowrap; background-color:rgb(249,242,244)">"url"</code><code style="font-family:Monaco,Menlo,Consolas,&quot;Courier New&quot;,monospace; font-size:21.6px; padding:2px 4px; color:rgb(199,37,78); white-space:nowrap; background-color:rgb(249,242,244)">,&nbsp;</code><code style="font-family:Monaco,Menlo,Consolas,&quot;Courier New&quot;,monospace; font-size:21.6px; padding:2px 4px; color:rgb(199,37,78); white-space:nowrap; background-color:rgb(249,242,244)">"http://www.baidu.com/"</code><code style="font-family:Monaco,Menlo,Consolas,&quot;Courier New&quot;,monospace; font-size:21.6px; padding:2px 4px; color:rgb(199,37,78); white-space:nowrap; background-color:rgb(249,242,244)">);<br style=""> </code></td> 
  </tr> 
 </tbody> 
</table>

方案2：取得form元素对象，将它作为参数传入FormData对象中！

<table style="border-collapse:collapse; border-spacing:0px; max-width:100%; background-color:transparent; word-break:break-all; border:0.05rem solid rgb(238,238,238)"> 
 <tbody style=""> 
  <tr style=""> 
   <td style="border:0.05rem solid rgb(238,238,238)"><code style="font-family:Monaco,Menlo,Consolas,&quot;Courier New&quot;,monospace; font-size:21.6px; padding:2px 4px; color:rgb(199,37,78); white-space:nowrap; background-color:rgb(249,242,244)">var</code><span style="margin:0px; padding:0px; font-family:Arial,&quot;Microsoft YaHei&quot;">&nbsp;</span><code style="font-family:Monaco,Menlo,Consolas,&quot;Courier New&quot;,monospace; font-size:21.6px; padding:2px 4px; color:rgb(199,37,78); white-space:nowrap; background-color:rgb(249,242,244)">formobj =&nbsp; document.getElementById(</code><code style="font-family:Monaco,Menlo,Consolas,&quot;Courier New&quot;,monospace; font-size:21.6px; padding:2px 4px; color:rgb(199,37,78); white-space:nowrap; background-color:rgb(249,242,244)">"form"</code><code style="font-family:Monaco,Menlo,Consolas,&quot;Courier New&quot;,monospace; font-size:21.6px; padding:2px 4px; color:rgb(199,37,78); white-space:nowrap; background-color:rgb(249,242,244)">);</code></td> 
  </tr> 
 </tbody> 
</table>

<table style="border-collapse:collapse; border-spacing:0px; max-width:100%; background-color:transparent; word-break:break-all; border:0.05rem solid rgb(238,238,238)"> 
 <tbody style=""> 
  <tr style=""> 
   <td style="border:0.05rem solid rgb(238,238,238)"><code style="font-family:Monaco,Menlo,Consolas,&quot;Courier New&quot;,monospace; font-size:21.6px; padding:2px 4px; color:rgb(199,37,78); white-space:nowrap; background-color:rgb(249,242,244)">var</code><span style="margin:0px; padding:0px; font-family:Arial,&quot;Microsoft YaHei&quot;">&nbsp;</span><code style="font-family:Monaco,Menlo,Consolas,&quot;Courier New&quot;,monospace; font-size:21.6px; padding:2px 4px; color:rgb(199,37,78); white-space:nowrap; background-color:rgb(249,242,244)">formdata =&nbsp;</code><code style="font-family:Monaco,Menlo,Consolas,&quot;Courier New&quot;,monospace; font-size:21.6px; padding:2px 4px; color:rgb(199,37,78); white-space:nowrap; background-color:rgb(249,242,244)">new</code><span style="margin:0px; padding:0px; font-family:Arial,&quot;Microsoft YaHei&quot;">&nbsp;</span><code style="font-family:Monaco,Menlo,Consolas,&quot;Courier New&quot;,monospace; font-size:21.6px; padding:2px 4px; color:rgb(199,37,78); white-space:nowrap; background-color:rgb(249,242,244)">FormData(formobj);</code></td> 
  </tr> 
 </tbody> 
</table>

方案3：利用form元素对象的getFormData方法生成它！

<table style="border-collapse:collapse; border-spacing:0px; max-width:100%; background-color:transparent; word-break:break-all; border:0.05rem solid rgb(238,238,238)"> 
 <tbody style=""> 
  <tr style=""> 
   <td style="border:0.05rem solid rgb(238,238,238)"><code style="font-family:Monaco,Menlo,Consolas,&quot;Courier New&quot;,monospace; font-size:21.6px; padding:2px 4px; color:rgb(199,37,78); white-space:nowrap; background-color:rgb(249,242,244)">var</code><span style="margin:0px; padding:0px; font-family:Arial,&quot;Microsoft YaHei&quot;">&nbsp;</span><code style="font-family:Monaco,Menlo,Consolas,&quot;Courier New&quot;,monospace; font-size:21.6px; padding:2px 4px; color:rgb(199,37,78); white-space:nowrap; background-color:rgb(249,242,244)">formobj =&nbsp; document.getElementById(</code><code style="font-family:Monaco,Menlo,Consolas,&quot;Courier New&quot;,monospace; font-size:21.6px; padding:2px 4px; color:rgb(199,37,78); white-space:nowrap; background-color:rgb(249,242,244)">"form"</code><code style="font-family:Monaco,Menlo,Consolas,&quot;Courier New&quot;,monospace; font-size:21.6px; padding:2px 4px; color:rgb(199,37,78); white-space:nowrap; background-color:rgb(249,242,244)">);</code></td> 
  </tr> 
 </tbody> 
</table>

<table style="border-collapse:collapse; border-spacing:0px; max-width:100%; background-color:transparent; word-break:break-all; border:0.05rem solid rgb(238,238,238)"> 
 <tbody style=""> 
  <tr style=""> 
   <td style="border:0.05rem solid rgb(238,238,238)"><code style="font-family:Monaco,Menlo,Consolas,&quot;Courier New&quot;,monospace; font-size:21.6px; padding:2px 4px; color:rgb(199,37,78); white-space:nowrap; background-color:rgb(249,242,244)">var</code><span style="margin:0px; padding:0px; font-family:Arial,&quot;Microsoft YaHei&quot;">&nbsp;</span><code style="font-family:Monaco,Menlo,Consolas,&quot;Courier New&quot;,monospace; font-size:21.6px; padding:2px 4px; color:rgb(199,37,78); white-space:nowrap; background-color:rgb(249,242,244)">formdata = formobj.getFormData()</code></td> 
  </tr> 
 </tbody> 
</table>

## Method ##

### FormData.append ###

本方法用于向已存在的键添加新的值，如该键不存在，新建之。

#### 语法 ####

formData.append(name, value);
    formData.append(name, value, filename);

####  ####

#### 注: 通过 [FormData.append()][FormData.append]方法赋给字段的值若是数字会被自动转换为字符(字段的值可以是一个[Blob][]对象,一个[File][]对象,或者一个字符串,剩下其他类型的值都会被自动转换成字符串). ####

#### 参数解释 ####

*  name  
    键 (key)， 对应表单域
 *  value  
    表单域的值
 *  filename (optional)  
    The filename reported to the server (a USVString), when a Blob or File is passed as the second parameter. The default filename for Blob objects is "blob".

### FormData.delete ###

将一对键和值从 FormData 对象中删除。

formData.delete(username);

### FormData.get ###

返回给定键的第一个值

formData.append('username', 'Justin');
    formData.append('username', 'Chris');
    formData.get(username);    // "Justin"

### FormData.getAll ###

返回给定键的所有值

formData.append('username', 'Justin');
    formData.append('username', 'Chris');
    formData.getAll(username);    // ["Justin", "Chris"]

### FormData.has ###

检查是否包含给定键，返回 `true` 或 `false`

formData.has(username);

### FormData.set ###

设置给定键的值

formData.set(name, value);
    formData.set(name, value, filename);

## 浏览器兼容情况 ##

来自 [MDN][]：

Desktop

<table style="border-collapse:collapse; border-spacing:0px; max-width:100%; background-color:transparent; word-break:break-all; border:0.05rem solid rgb(238,238,238); color:rgb(51,51,51); font-family:&quot;Helvetica Neue&quot;,Helvetica,Arial,&quot;PingFang SC&quot;,&quot;Hiragino Sans GB&quot;,&quot;WenQuanYi Micro Hei&quot;,&quot;Microsoft Yahei&quot;,sans-serif; font-size:14px; line-height:1.6; margin:1.5em 0px; width:825px"> 
 <thead style=""> 
  <tr style=""> 
   <th style="text-align:left; border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal; background:rgb(243,243,243)"> Feature</th> 
   <th style="text-align:left; border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal; background:rgb(243,243,243)"> Chrome</th> 
   <th style="text-align:left; border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal; background:rgb(243,243,243)"> Firfox(Gecko)</th> 
   <th style="text-align:left; border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal; background:rgb(243,243,243)"> Intenet Explorer</th> 
   <th style="text-align:left; border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal; background:rgb(243,243,243)"> Opera</th> 
   <th style="text-align:left; border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal; background:rgb(243,243,243)"> Safari</th> 
  </tr> 
 </thead> 
 <tbody style=""> 
  <tr style=""> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> Basic support</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> 7+</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> 4.0(2.0)</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> 10+</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> 12+</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> 5+</td> 
  </tr> 
  <tr style=""> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> append with filename</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> (Yes)</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> 22.0(22.0)</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> ?</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> ?</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> ?</td> 
  </tr> 
  <tr style=""> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> delete, get, getAll, has, set</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> Behind Flag</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> Not supported</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> Not supported</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> (Yes)</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> Not supported</td> 
  </tr> 
 </tbody> 
</table>

Mobile

<table style="border-collapse:collapse; border-spacing:0px; max-width:100%; background-color:transparent; word-break:break-all; border:0.05rem solid rgb(238,238,238); color:rgb(51,51,51); font-family:&quot;Helvetica Neue&quot;,Helvetica,Arial,&quot;PingFang SC&quot;,&quot;Hiragino Sans GB&quot;,&quot;WenQuanYi Micro Hei&quot;,&quot;Microsoft Yahei&quot;,sans-serif; font-size:14px; line-height:1.6; margin:1.5em 0px; width:825px"> 
 <thead style=""> 
  <tr style=""> 
   <th style="text-align:left; border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal; background:rgb(243,243,243)"> Feature</th> 
   <th style="text-align:left; border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal; background:rgb(243,243,243)"> Android</th> 
   <th style="text-align:left; border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal; background:rgb(243,243,243)"> Chrome Android</th> 
   <th style="text-align:left; border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal; background:rgb(243,243,243)"> Firfox Mobile (Gecko)</th> 
   <th style="text-align:left; border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal; background:rgb(243,243,243)"> Firfox OS (Gecko)</th> 
   <th style="text-align:left; border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal; background:rgb(243,243,243)"> IE Mobile</th> 
   <th style="text-align:left; border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal; background:rgb(243,243,243)"> Opera Mobile</th> 
   <th style="text-align:left; border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal; background:rgb(243,243,243)"> Safari Mobile</th> 
  </tr> 
 </thead> 
 <tbody style=""> 
  <tr style=""> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> Basic support</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> 3.0</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> ?</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> 4.0(2.0)</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> 1.0.1</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> ?</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> 12+</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> ?</td> 
  </tr> 
  <tr style=""> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> append with filename</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> ?</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> ?</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> 22.0(22.0)</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> 1.2</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> ?</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> ?</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> ?</td> 
  </tr> 
  <tr style=""> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> delete, get, getAll, has, set</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> (Yes)</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> (Yes)</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> Not supported</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> Not supported</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> Not supported</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> (Yes)</td> 
   <td style="border:1px solid rgb(230,230,230); padding:5px 8px; word-break:normal"> Not supported</td> 
  </tr> 
 </tbody> 
</table>

*  [2015年06月04日发布][2015_06_04]

# Ajax通过FormData上传文件 #

###     ###

### 1.使用<form>表单初始化FormData对象方式上传文件 ###

HTML代码

<form id="uploadForm" enctype="multipart/form-data">
        <input id="file" type="file" name="file"/>
        <button id="upload" type="button">upload</button>
    </form>

javascript代码

$.ajax({ url: '/upload', type: 'POST', cache: false, data: new FormData($('#uploadForm')[0]), processData: false, contentType: false }).done(function(res) { }).fail(function(res) {});

这里要注意几点：

*  `processData`设置为`false`。因为`data`值是`FormData`对象，不需要对数据做处理。
 *  `<form>`标签添加`enctype="multipart/form-data"`属性。
 *  `cache`设置为`false`，上传文件不需要缓存。
 *  `contentType`设置为`false，不设置contentType值，`因为是由`<form>`表单构造的`FormData`对象，且已经声明了属性`enctype="multipart/form-data"`，所以这里设置为false。

上传后，服务器端代码需要使用从查询参数名为`file`获取文件输入流对象，因为`<input>`中声明的是`name="file"`。

如果不是用`<form>`表单构造`FormData`对象又该怎么做呢？

##     ##

###     ###

### 2.使用FormData对象添加字段方式上传文件 ###

HTML代码

<div id="uploadForm">
        <input id="file" type="file"/>
        <button id="upload" type="button">upload</button>
    </div>

这里没有`<form>`标签，也没有`enctype="multipart/form-data"`属性。

javascript代码

这里有几处不一样：

*  `append()`的第二个参数应是文件对象，即`$('#file')[0].files[0]`。
 *  `contentType`也要设置为‘false’。

从代码`$('#file')[0].files[0]`中可以看到一个`<input type="file">`标签能够上传多个文件，  
只需要在`<input type="file">`里添加`multiple`或`multiple="multiple"`属性。

###     ###

### 3.服务器端读文件 ###

从`Servlet 3.0` 开始，可以通过 `request.getPart()` 或 `request.getPars()` 两个接口获取上传的文件。

转载文章：

[http://www.jianshu.com/p/46e6e03a0d53][http_www.jianshu.com_p_46e6e03a0d53]

[https://segmentfault.com/a/1190000002875573][2015_06_04]

[http://my.oschina.net/u/1866405/blog/335987][http_my.oschina.net_u_1866405_blog_335987]

[http://yunzhu.iteye.com/blog/2177923][http_yunzhu.iteye.com_blog_2177923]

[https://developer.mozilla.org/zh-CN/docs/Web/Guide/Using\_FormData\_Objects][https_developer.mozilla.org_zh-CN_docs_Web_Guide_Using_FormData_Objects]

[http_m.blog.csdn.net_inuyasha1121_article_details_51915742]: http://m.blog.csdn.net/inuyasha1121/article/details/51915742
[FormData.append]: https://developer.mozilla.org/zh-CN/DOM/XMLHttpRequest/FormData#append%28%29
[Blob]: https://developer.mozilla.org/zh-CN/docs/Web/API/Blob
[File]: https://developer.mozilla.org/zh-CN/docs/Web/API/File
[MDN]: https://developer.mozilla.org/en/docs/Web/API/FormData
[2015_06_04]: https://segmentfault.com/a/1190000002875573
[http_www.jianshu.com_p_46e6e03a0d53]: http://www.jianshu.com/p/46e6e03a0d53
[http_my.oschina.net_u_1866405_blog_335987]: http://my.oschina.net/u/1866405/blog/335987
[http_yunzhu.iteye.com_blog_2177923]: http://yunzhu.iteye.com/blog/2177923
[https_developer.mozilla.org_zh-CN_docs_Web_Guide_Using_FormData_Objects]: https://developer.mozilla.org/zh-CN/docs/Web/Guide/Using_FormData_Objects