我能想到的唯一方法是在它被渲染后用javascript找到按钮，并分配一个样式给它

你也可以看看这个记录

按照以下步骤，你就可以为你的文件上传表单创建自定义样式了:

this is the simple HTML form(please read the HTML comments I have written here below) <form action="#type your action here" method="POST" enctype="multipart/form-data"> <div id="yourBtn" style="height: 50px; width: 100px;border: 1px dashed #BBB; cursor:pointer;" onclick="getFile()">Click to upload!</div> <!-- this is your file input tag, so i hide it!--> <div style='height: 0px;width:0px; overflow:hidden;'><input id="upfile" type="file" value="upload"/></div> <!-- here you can have file submit button or you can write a simple script to upload the file automatically--> <input type="submit" value='submit' > </form> then use this simple script to pass the click event to file input tag. function getFile(){ document.getElementById("upfile").click(); } Now you can use any type of styling without worrying about how to change default styles.

我非常清楚这一点，因为我已经尝试更改默认样式一个半月了。相信我，这是非常困难的，因为不同的浏览器有不同的上传输入标签。所以使用这个来构建您的自定义文件上传表单。这里是完整的自动上传代码。

function getFile() { document.getElementById("upfile").click(); } function sub(obj) { var file = obj.value; var fileName = file.split("\\"); document.getElementById("yourBtn").innerHTML = fileName[fileName.length - 1]; document.myForm.submit(); event.preventDefault(); } #yourBtn { position: relative; top: 150px; font-family: calibri; width: 150px; padding: 10px; -webkit-border-radius: 5px; -moz-border-radius: 5px; border: 1px dashed #BBB; text-align: center; background-color: #DDD; cursor: pointer; } <form action="#type your action here" method="POST" enctype="multipart/form-data" name="myForm"> <div id="yourBtn" onclick="getFile()">click to upload a file</div> <!-- this is your file input tag, so i hide it!--> <!-- i used the onchange event to fire the form submission--> <div style='height: 0px;width: 0px; overflow:hidden;'><input id="upfile" type="file" value="upload" onchange="sub(this)" /></div> <!-- here you can have file submit button or you can write a simple script to upload the file automatically--> <!-- <input type="submit" value='submit' > --> </form>

我发现插件解决方案太笨重了，所以我制作了自己的jQuery插件Drolex FileStyle。

This plug-in allows you to style file input fields however you want. Actually, you style div elements to look like a tricked out file input, and the actual file input is automatically overlaid with 0% opacity. No additional HTML is required. Just include the css and js files in the page you want Drolex FileStyle and that's it! Edit the css file to your liking. Don't forget the jQuery library if your page doesn't already have it. If the client does not run JavaScript, then the file input will not be modified by js or css.

测试工作在Chrome 24, Firefox 18, Internet Explorer 9。 预计可以在之前的版本中使用。

下载:http://web.drolex.net/Drolex-FileStyle.zip。

我能想到的唯一方法是在它被渲染后用javascript找到按钮，并分配一个样式给它

你也可以看看这个记录

你不需要JavaScript !下面是一个跨浏览器的解决方案:

请看这个例子!-适用于Chrome/FF/IE - (IE10/9/8/7)

最好的方法是将一个带有for属性的自定义标签元素附加到隐藏的文件输入元素。(标签的for属性必须匹配文件元素的id，这样才能工作)。

<label for="file-upload" class="custom-file-upload">
    Custom Upload
</label>
<input id="file-upload" type="file"/>

作为一种替代方法，你也可以直接用标签包装文件输入元素:

<label class="custom-file-upload">
    <input type="file"/>
    Custom Upload
</label>

在样式方面，只需使用属性选择器隐藏输入元素。

input[type="file"] {
    display: none;
}

然后，您所需要做的就是设置自定义标签元素的样式。(例子)。

.custom-file-upload {
    border: 1px solid #ccc;
    display: inline-block;
    padding: 6px 12px;
    cursor: pointer;
}

1 -值得注意的是，如果你使用display: none隐藏元素，它将在IE8及以下版本中不起作用。还要注意，jQuery验证默认情况下不验证隐藏字段。如果这两种情况对您来说是一个问题，这里有两种不同的方法来隐藏输入(1,2)，在这种情况下可以工作。

我发现这种方法最简单、最轻便。

下面是工作示例:http://codepen.io/c3zar22/pen/QNoYXN

以下是解释:

this would be the markup: <label for="attach-project-file"> <span id="remove-project-file" class="close">x</span> <div class="filename" id="attached-project-file">Click to select a file</div> </label> <input id="attach-project-file" type="file"> hide the input in a hacky way like this: #attach-project-file { width: 0.1px; height: 0.1px; opacity: 0; overflow: hidden; position: absolute; z-index: -1; } style the corresponding label instead [for="attach-project-file"] { /* your styles here */ } style "remove file" button .close { font-size: 16px; padding: 10px; position: absolute; top: 0; right: 0; cursor: pointer; font-style: normal; } .filename element will be used to display the selected file below is the commented JS code needed (using jQuery) to make it work: var $attach = $('#attach-project-file'), $remove = $('#remove-project-file'), $name = $('#attached-project-file'); // initially hide the remove button $remove.hide(); // do this when file input has changed // i.e.: a file has been selected $attach.on('change', function() { var val = $(this).val(); if (val !== '') { // if value different than empty // show the file name as text // hide/text/fadeIn creates a nice effect when changing the text $name .hide() .text(val) .fadeIn(); // show the remove button $remove.fadeIn(); } else { // if value empty, means the file has been removed // show the default text $name .hide() .text('Click to select a file') .fadeIn(); // hide remove button $remove.fadeOut(); } }); // remove selected file when clicking the remove button // prevent click bubbling to the parent label and triggering file selection $remove.on('click', function(e) { e.preventDefault(); e.stopPropagation(); $attach .val('') .change(); // trigger change event });