在bootstrap中，使用fileInput开发文件上传功能。

fileinput是一款非常好用的基于Bootstrap的jQuery插件。

插件地址：http://plugins.krajee.com/file-input

安装

必须在fileinput之前引入jQuery和Bootstrap。

    <!-- bootstrap 4.x is supported. You can also use the bootstrap css 3.3.x versions -->
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta/css/bootstrap.min.css">
    <link href="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-fileinput/4.4.5/css/fileinput.min.css" media="all" rel="stylesheet" type="text/css" />
    <!-- if using RTL (Right-To-Left) orientation, load the RTL CSS file after fileinput.css by uncommenting below -->
    <!-- link href="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-fileinput/4.4.5/css/fileinput-rtl.min.css" media="all" rel="stylesheet" type="text/css" /-->
    <!-- optionally uncomment line below if using a theme or icon set like font awesome (note that default icons used are glyphicons and `fa` theme can override it) -->
    <!-- link https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css media="all" rel="stylesheet" type="text/css" /-->
    <script src="https://code.jquery.com/jquery-3.2.1.min.js"></script>
    <!-- piexif.min.js is only needed for restoring exif data in resized images and when you 
        wish to resize images before upload. This must be loaded before fileinput.min.js -->
    <script src="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-fileinput/4.4.5/js/plugins/piexif.min.js" type="text/javascript"></script>
    <!-- sortable.min.js is only needed if you wish to sort / rearrange files in initial preview. 
        This must be loaded before fileinput.min.js -->
    <script src="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-fileinput/4.4.5/js/plugins/sortable.min.js" type="text/javascript"></script>
    <!-- purify.min.js is only needed if you wish to purify HTML content in your preview for 
        HTML files. This must be loaded before fileinput.min.js -->
    <script src="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-fileinput/4.4.5/js/plugins/purify.min.js" type="text/javascript"></script>
    <!-- popper.min.js below is needed if you use bootstrap 4.x. You can also use the bootstrap js 
       3.3.x versions without popper.min.js. -->
    <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.11.0/umd/popper.min.js"></script>
    <!-- bootstrap.min.js below is needed if you wish to zoom and preview file content in a detail modal
        dialog. bootstrap 4.x is supported. You can also use the bootstrap js 3.3.x versions. -->
    <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta/js/bootstrap.min.js" type="text/javascript"></script>
    <!-- the main fileinput plugin file -->
    <script src="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-fileinput/4.4.5/js/fileinput.min.js"></script>
    <!-- optionally uncomment line below for loading your theme assets for a theme like Font Awesome (`fa`) -->
    <!-- script src="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-fileinput/4.4.5/themes/fa/theme.min.js"></script -->
    <!-- optionally if you need translation for your language then include  locale file as mentioned below -->
    <script src="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-fileinput/4.4.5/js/locales/LANG.js"></script>

 初始化一个file控件

$("#input-id").fileinput();

使用参数初始化

$("#input-id").fileinput({'showUpload':false, 'previewFileType':'any'});

注册监听事件

$('#input-id').on('fileselect', function(event, numFiles, label) {
    console.log("fileselect");
});

调用方法

//支持链式调用
$('#input-id').fileinput('enable').fileinput('disable');

应用场景

单个文件上传