我想我要加上我的三便士价值，只是说一下如何默认的.custom-file-label和custom-file-input BS4文件输入以及如何使用它们。

后一个类在输入组上，是不可见的。而前者是可见标签，并且有一个:后伪元素，看起来像一个按钮。

<div class="custom-file">
<input type="file" class="custom-file-input" id="upload">
<label class="custom-file-label" for="upload">Choose file</label>
</div>

你不能向伪元素中添加类，但是你可以用CSS(或SASS)来设置它们的样式。

.custom-file-label:after {
    color: #fff;
    background-color: #1e7e34;
    border-color: #1c7430;
    pointer: cursor;
}

对我有用:

Bootstrap中漂亮的文件输入字段

更新

jQuery插件风格:

// Based in: http://duckranger.com/2012/06/pretty-file-input-field-in-bootstrap/
// Version: 0.0.3
// Compatibility with: Bootstrap 3.2.0 and jQuery 2.1.1
// Use:
//     <input class="nice_file_field" type="file" data-label="Choose Document">
//     <script> $(".nice_file_field").niceFileField(); </script>
//
(function( $ ) {
  $.fn.niceFileField = function() {
    this.each(function(index, file_field) {
      file_field = $(file_field);
      var label = file_field.attr("data-label") || "Choose File";

      file_field.css({"display": "none"});

      nice_file_block_text  = '<div class="input-group nice_file_block">';
      nice_file_block_text += '  <input type="text" class="form-control">';
      nice_file_block_text += '  <span class="input-group-btn">';
      nice_file_block_text += '   <button class="btn btn-default nice_file_field_button" type="button">' + label + '</button>';
      nice_file_block_text += '  </span>';
      nice_file_block_text += '</div>';

      file_field.after(nice_file_block_text);

      var nice_file_field_button = file_field.parent().find(".nice_file_field_button");
      var nice_file_block_element = file_field.parent().find(".nice_file_block");

      nice_file_field_button.on("click", function(){ console.log("click"); file_field.click() } );
      file_field.change( function(){
        nice_file_block_element.find("input").val(file_field.val());
      });
    });
  };
})( jQuery );

不需要额外的插件，这个bootstrap解决方案非常适合我:

<div style="position:relative;">
        <a class='btn btn-primary' href='javascript:;'>
            Choose File...
            <input type="file" style='position:absolute;z-index:2;top:0;left:0;filter: alpha(opacity=0);-ms-filter:"progid:DXImageTransform.Microsoft.Alpha(Opacity=0)";opacity:0;background-color:transparent;color:transparent;' name="file_source" size="40"  onchange='$("#upload-file-info").html($(this).val());'>
        </a>
        &nbsp;
        <span class='label label-info' id="upload-file-info"></span>
</div>

演示:

http://jsfiddle.net/haisumbhatti/cAXFA/1/ (bootstrap 2)

http://jsfiddle.net/haisumbhatti/y3xyU/ (bootstrap 3)

我已经创建了一个自定义上传按钮，只接受图像，这可以根据您的要求修改。

希望这能有所帮助!!：）

(已使用的Bootstrap框架)

代码笔链接

HTML

<center>
 <br />
 <br />
 <span class="head">Upload Button Re-Imagined</span>
 <br />
 <br />
 <div class="fileUpload blue-btn btn width100">
   <span>Upload your Organizations logo</span>
   <input type="file" class="uploadlogo" />
 </div>
</center>

CSS

 .head {
   font-size: 25px;
   font-weight: 200;
 }

 .blue-btn:hover,
 .blue-btn:active,
 .blue-btn:focus,
 .blue-btn {
   background: transparent;
   border: solid 1px #27a9e0;
   border-radius: 3px;
   color: #27a9e0;
   font-size: 16px;
   margin-bottom: 20px;
   outline: none !important;
   padding: 10px 20px;
 }

 .fileUpload {
   position: relative;
   overflow: hidden;
   height: 43px;
   margin-top: 0;
 }

 .fileUpload input.uploadlogo {
   position: absolute;
   top: 0;
   right: 0;
   margin: 0;
   padding: 0;
   font-size: 20px;
   cursor: pointer;
   opacity: 0;
   filter: alpha(opacity=0);
   width: 100%;
   height: 42px;
 }


 /*Chrome fix*/

 input::-webkit-file-upload-button {
   cursor: pointer !important;
 }

JS

// You can modify the upload files to pdf's, docs etc
//Currently it will upload only images
$(document).ready(function($) {

  // Upload btn
  $(".uploadlogo").change(function() {
    readURL(this);
  });

  function readURL(input) {
    var url = input.value;
    var ext = url.substring(url.lastIndexOf('.') + 1).toLowerCase();
    if (input.files && input.files[0] && (ext == "png" || ext == "jpeg" || ext == "jpg" || ext == "gif" || ext == "svg")) {
      var path = $('.uploadlogo').val();
      var filename = path.replace(/^.*\\/, "");
      $('.fileUpload span').html('Uploaded logo : ' + filename);
      // console.log(filename);
    } else {
      $(".uploadlogo").val("");
      $('.fileUpload span').html('Only Images Are Allowed!');
    }
  }
});

这是另一个技巧，它不是最好的解决方案，但它只是给你一个选择

HTML代码:

<button clss="btn btn-primary" id="btn_upload">Choose File</button>
<input id="fileupload" class="hide" type="file" name="files[]">

Javascript:

$("#btn_upload").click(function(e){
e.preventDefault();
$("#fileupload").trigger('click');
});

从上面的其他文章中得到一些灵感，这里有一个完整的解决方案，它结合了一个看起来像表单控制字段的输入组插件，用于一个干净的文件输入小部件，其中包括到当前文件的链接。

.input-file { position: relative; margin: 60px 60px 0 } /* Remove margin, it is just for stackoverflow viewing */ .input-file .input-group-addon { border: 0px; padding: 0px; } .input-file .input-group-addon .btn { border-radius: 0 4px 4px 0 } .input-file .input-group-addon input { cursor: pointer; position:absolute; width: 72px; z-index:2;top:0;right:0;filter: alpha(opacity=0);-ms-filter:"progid:DXImageTransform.Microsoft.Alpha(Opacity=0)";opacity:0; background-color:transparent; color:transparent; } <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.1/css/bootstrap.min.css"> <div class="input-group input-file"> <div class="form-control"> <a href="/path/to/your/current_file_name.pdf" target="_blank">current_file_name.pdf</a> </div> <span class="input-group-addon"> <a class='btn btn-primary' href='javascript:;'> Browse <input type="file" name="field_name" onchange="$(this).parent().parent().parent().find('.form-control').html($(this).val());"> </a> </span> </div>