这是一个很好的方法来做材料/角文件上传。 你可以用bootstrap按钮做同样的事情。

注意，我使用了<a>而不是<button>，这允许点击事件冒泡。

<label>
    <input type="file" (change)="setFile($event)" style="display:none" />

    <a mat-raised-button color="primary">
      <mat-icon>file_upload</mat-icon>
      Upload Document
    </a>

  </label>

更新没关系，这不能工作在IE或它的新兄弟，FF。可以正常工作在其他类型的元素上，但不能工作在文件输入上。更好的方法是创建一个文件输入和一个链接到它的标签。使文件输入显示无和boom，它在IE9+无缝工作。

警告:以下所有内容都是垃圾!

通过使用根据容器定位/调整大小的伪元素，我们可以只使用一个输入文件(不需要额外的标记)，并按通常的方式设置样式。

Demo

<input type="file" class="foo">
<style>
    .foo {
        display: block;
        position: relative;
        width: 300px;
        margin: auto;
        cursor: pointer;
        border: 0;
        height: 60px;
        border-radius: 5px;
        outline: 0;
    }
    .foo:hover:after {
        background: #5978f8;
    }
    .foo:after {
        transition: 200ms all ease;
        border-bottom: 3px solid rgba(0,0,0,.2);
        background: #3c5ff4;
        text-shadow: 0 2px 0 rgba(0,0,0,.2);
        color: #fff;
        font-size: 20px;
        text-align: center;
        position: absolute;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        display: block;
        content: 'Upload Something';
        line-height: 60px;
        border-radius: 5px;
    }
</style>

享受的家伙!

旧的更新

把这个变成了Stylus mixin。应该很容易让你们中的一个酷SCSS猫转换它。

    file-button(button_width = 150px)
      display block
      position relative
      margin auto
      cursor pointer
      border 0
      height 0
      width 0
      outline none
      &:after
        position absolute
        top 0
        text-align center
        display block
        width button_width
        left -(button_width / 2)

用法:

<input type="file">

input[type="file"]
    file-button(200px)

用css隐藏它，并使用$(selector).click()自定义按钮来激活浏览按钮。然后设置检查文件输入类型值的时间间隔。interval可以显示用户的值，这样用户就可以看到上传了什么。当表单提交时，间隔将清除[编辑]对不起，我一直很忙，是想更新这篇文章，这里是一个例子

<form action="uploadScript.php" method="post" enctype="multipart/form-data">
<div>
    <!-- filename to display to the user -->
    <p id="file-name" class="margin-10 bold-10"></p>

    <!-- Hide this from the users view with css display:none; -->
    <input class="display-none" id="file-type" type="file" size="4" name="file"/>

    <!-- Style this button with type image or css whatever you wish -->
    <input id="browse-click" type="button" class="button" value="Browse for files"/>

    <!-- submit button -->
    <input type="submit" class="button" value="Change"/>
</div>

$(window).load(function () {
    var intervalFunc = function () {
        $('#file-name').html($('#file-type').val());
    };
    $('#browse-click').on('click', function () { // use .live() for older versions of jQuery
        $('#file-type').click();
        setInterval(intervalFunc, 1);
        return false;
    });
});

这是一个纯CSS，无javascript，无bootstrap, 100%跨浏览器的解决方案!只需剪切粘贴一个样式块，然后测试您的文件上传控制。

这个解决方案不像其他文章那样试图隐藏然后重新创建原始HTML元素。它使用纯CSS，没有任何马戏团技巧或第三方工具，为所有主要浏览器设置原始文件上传表单控件的样式。你甚至不需要改变你的HTML代码!只需剪切并粘贴下面的代码到你的网页来测试它…

<style>
/* Note: This CSS will style all instances of 
   <input type=file /> controls in your website. */
input[type="file"],
input[type="file"]:visited,
input[type="file"]:hover,
input[type="file"]:focus,
input[type="file"]:active {
    margin:0;
    padding: 0em 0em;/* fallback: older browsers like IE 1-8 need "em" */
    padding: 0rem 0rem;/* older browsers dont know what "rem" is */
    overflow: hidden; /* long file names overflow so just hide the end */
    background: #fff;
    border-radius: .2em;
    border-radius: .2rem;
    outline: none;
    border: 2px solid #bbb;
    cursor: pointer;
    -webkit-appearance: textfield;
    -moz-appearance: textfield;
}

input[type="file"]:hover {
    background: #f9f9ff; /* Optional rollover color: I am using a light blue to indicate an interaction */
    border: 2px solid #999;
}

input[type="file"]:visited,
input[type="file"]:focus,
input[type="file"]:active {
    background: #fff; /* Default back to white when focused. */
    border: 2px solid #999;
}

/* Note: These "disabled" selectors blow up in IE so have to be separated from the same styles above. */
input[type="file"]:disabled {
    margin: 0;
    padding: 0em 0em;
    padding: 0rem 0rem;
    overflow: hidden; /* long file names overflow so just hide the end */
    background: #ddd;
    border-radius: .2em;
    border-radius: .2rem;
    outline: none;
    border: 2px solid #bbb;
    cursor: pointer;
    -webkit-appearance: textfield;
    -moz-appearance: textfield;
}

input[type="file"]:disabled:hover {
    background: #ddd; /* disabled-readonly buttons should be grey */
    border: 2px solid #999;
}

input[type="file"]:disabled:visited,
input[type="file"]:disabled:focus,
input[type="file"]:disabled:active {
    background: #ddd; /* disabled-readonly buttons should be grey */
    border: 2px solid #999;
}

/* IE UPLOAD BUTTON STYLE: This attempts to alter the file upload button style in IE.  Keep in mind IE gives you limited design control but at least you can customize its upload button.*/
::-ms-browse { /* IE */
    display: inline-block;
    margin: 0;
    padding: .2em .5em;
    padding: .2rem .5rem;
    text-align: center;
    outline: none;
    border: none;
    background: #fff;
    white-space: nowrap;
    cursor: pointer;
}
/* FIREFOX UPLOAD BUTTON STYLE */
::file-selector-button {/* firefox */
    display: inline-block;
    margin: 0rem 1rem 0rem 0rem;
    padding: .18em .5em;
    padding: .18rem .5rem;
    -webkit-appearance: button;
    text-align: center;
    border-radius: .1rem 0rem 0rem .1rem;
    outline: none;
    border: none;
    border-right: 2px solid #bbb;
    background: #eee;
    white-space: nowrap;
    cursor: pointer;
}
/* CHROME AND EDGE UPLOAD BUTTON STYLE */
::-webkit-file-upload-button { /* chrome and edge */
    display: inline-block;
    margin: 0rem 1rem 0rem 0rem;
    padding: .19em .5em;
    padding: .19rem .5rem;
    -webkit-appearance: button;
    text-align: center;
    border-radius: .1rem 0rem 0rem .1rem;
    outline: none;
    border: none;
    border-right: 2px solid #bbb;
    background: #eee;
    white-space: nowrap;
    cursor: pointer;
}
</style>

<input type="file" id="fileupload" name="fileupload" 
value="" tabindex="0" enctype="multipart/form-data" 
accept="image/*" autocomplete="off" multiple="multiple" 
aria-multiselectable="true" title="Multiple File Upload" 
aria-label="Multiple File Upload" />

<br /><br />

<input disabled="disabled" type="file" id="fileupload" 
name="fileupload" value="" tabindex="0" 
enctype="multipart/form-data" accept="image/*" 
autocomplete="off" multiple="multiple" 
aria-multiselectable="true" title="Disabled Multiple File Upload" 
aria-label="Disabled Multiple File Upload" />

这是文件上传控件在Firefox、Chrome和Edge中使用下面的CSS的样子。这是一个非常简单干净的设计。你可以把它变成你喜欢的样子:

Internet Explorer为您提供了有限的设计控制，但至少您可以使用CSS操作控件来更改一些东西，包括圆形边框和颜色:

我的解决方案的优点是:

You stick with simple CSS to style the original HTML input control You can see one or more file names in the file input textbox Screen readers and ARIA-friendly devices can interact normally with your file upload control You can set tabindex on your HTML element so its part of the tab order Because you are using plain HTML and CSS, your file input button works perfectly in old and new browsers ZERO JavaScript required! Runs and loads lighting fast in even the oldest of browsers Because your are not using "display:none" to hide the control, its file block stream data is never disabled from reaching the server in any old or new browser version known

你不需要愚蠢的JavaScript技巧，Bootstrap，或尝试隐藏/重新创建你的文件输入控件。这只会破坏所有在线用户的可用性。样式化原始HTML控件意味着你的文件上传控件在25年的新老浏览器中都能很好地工作。

This is why you cannot trust all these scripted hacks here that erase, rewrite, or destroy HTML just to try and recreate some visual experience. That shows that you do not understand how HTML is used or why its been around for 30 years practically unchanged. You should never try and rewrite HTML's native form control functionality. Why? There is more to using natural HTML in websites than just manipulation of markup for some forced visual experience. The trade-offs of limited visual design in these replaced HTML elements was designed that way for a reason.

我的建议是:坚持使用简单的HTML和CSS解决方案，作为web开发人员，你将没有任何问题。

我发现最好的方法是有一个输入类型:文件，然后将其设置为display: none。给它一个id。创建一个按钮或任何您想要打开文件输入的其他元素。

然后在它(按钮)上添加一个事件侦听器，当单击它时，它会模拟对原始文件输入的单击。 比如点击一个名为hello的按钮，但它会打开一个文件窗口。

示例代码

//i am using semantic ui

<button class="ui circular icon button purple send-button" id="send-btn">
      <i class="paper plane icon"></i>
    </button>
  <input type="file" id="file" class="input-file" />

javascript

var attachButton=document.querySelector('.attach-button');
    attachButton.addEventListener('click', e=>{
        $('#file').trigger("click")
    })

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 });