我想用jQuery异步上传文件。

$(文档).ready(函数(){$(“#uploadbutton”).click(函数(){var filename=$(“#file”).val();$.ajax美元({类型:“POST”,url:“addFile.do”,enctype:'多部分/表单数据',数据:{文件:文件名},成功:函数(){alert(“上传的数据:”);}});});});<script src=“https://cdnjs.cloudflare.com/ajax/libs/jquery/2.2.0/jquery.min.js“></script><span>文件</span><input type=“file”id=“file”name=“file”size=“10”/><input id=“uploadbutton”type=“button”value=“Upload”/>

我只得到文件名,而不是上传文件。我可以做什么来解决这个问题?


当前回答

jQueryUploadify是我以前用来上传文件的另一个好插件。JavaScript代码如下所示:code。但是,新版本在Internet Explorer中不起作用。

$('#file_upload').uploadify({
    'swf': '/public/js/uploadify.swf',
    'uploader': '/Upload.ashx?formGuid=' + $('#formGuid').val(),
    'cancelImg': '/public/images/uploadify-cancel.png',
    'multi': true,
    'onQueueComplete': function (queueData) {
        // ...
    },
    'onUploadStart': function (file) {
        // ...
    }
});

我做了大量的搜索,我找到了另一种不用任何插件、只使用ajax上传文件的解决方案。解决方案如下:

$(document).ready(function () {
    $('#btn_Upload').live('click', AjaxFileUpload);
});

function AjaxFileUpload() {
    var fileInput = document.getElementById("#Uploader");
    var file = fileInput.files[0];
    var fd = new FormData();
    fd.append("files", file);
    var xhr = new XMLHttpRequest();
    xhr.open("POST", 'Uploader.ashx');
    xhr.onreadystatechange = function () {
        if (xhr.readyState == 4) {
             alert('success');
        }
        else if (uploadResult == 'success')
            alert('error');
    };
    xhr.send(fd);
}

其他回答

Try

异步函数saveFile(){let formData=新formData();formData.append(“file”,file.files[0]);wait-fetch('addFile.do',{method:“POST”,body:formData});alert(“上传的数据:”);}<span>文件</span><input type=“file”id=“file”name=“file”size=“10”/><input type=“button”value=“Upload”onclick=“saveFile()”/>

content-type='multipart/form-data'由浏览器自动设置,文件名也自动添加到文件名FormData参数中(服务器可以轻松读取)。下面是一个更为成熟的错误处理和json添加示例

异步函数saveFile(inp){让用户={name:'john',年龄:34};let formData=新formData();let photo=inp.files[0];formData.append(“照片”,照片);formData.append(“用户”,JSON.stringify(用户));尝试{let r=等待获取('/upload/image',{method:“POST”,body:formData});console.log('HTTP响应代码:',r.status);警报(“成功”);}捕获(e){console.log('休斯顿我们有问题…:',e);}}<input-type=“file”onchange=“saveFile(this)”><br><br>在选择文件之前,打开chrome控制台>网络选项卡以查看请求详细信息。<br><br><small>因为在本例中,我们将请求发送到https://stacksnippets.net/upload/image响应代码当然是404</小>

你也可以考虑使用类似的https://uppy.io.

它可以在不离开页面的情况下进行文件上传,并提供一些奖励,如拖放、在浏览器崩溃/网络不稳定的情况下恢复上传,以及从例如Instagram导入。它是开源的,不依赖于jQuery/React/Angular/Vue,但可以与它一起使用。免责声明:作为它的创建者,我有偏见;)

我已经在Rails环境中编写了这篇文章。如果您使用轻量级的jQuery表单插件,它只有大约五行JavaScript。

挑战在于如何让AJAX上传工作,因为标准的remote_form_for不理解多部分表单提交。它不会发送Rails通过AJAX请求返回的文件数据。

这就是jQuery表单插件发挥作用的地方。

下面是它的Rails代码:

<% remote_form_for(:image_form, 
                   :url => { :controller => "blogs", :action => :create_asset }, 
                   :html => { :method => :post, 
                              :id => 'uploadForm', :multipart => true }) 
                                                                        do |f| %>
 Upload a file: <%= f.file_field :uploaded_data %>
<% end %>

下面是相关的JavaScript:

$('#uploadForm input').change(function(){
 $(this).parent().ajaxSubmit({
  beforeSubmit: function(a,f,o) {
   o.dataType = 'json';
  },
  complete: function(XMLHttpRequest, textStatus) {
   // XMLHttpRequest.responseText will contain the URL of the uploaded image.
   // Put it in an image element you create, or do with it what you will.
   // For example, if you have an image elemtn with id "my_image", then
   //  $('#my_image').attr('src', XMLHttpRequest.responseText);
   // Will set that image tag to display the uploaded image.
  },
 });
});

这是Rails控制器的动作,非常简单:

 @image = Image.new(params[:image_form])
 @image.save
 render :text => @image.public_filename

在过去的几周里,我一直在Bloggity上使用这个,它的效果就像一个冠军。

对于PHP,请查找https://developer.hyvor.com/php/image-upload-ajax-php-mysql

HTML

<html>
<head>
    <title>Image Upload with AJAX, PHP and MYSQL</title>
</head>
<body>
<form onsubmit="submitForm(event);">
    <input type="file" name="image" id="image-selecter" accept="image/*">
    <input type="submit" name="submit" value="Upload Image">
</form>
<div id="uploading-text" style="display:none;">Uploading...</div>
<img id="preview">
</body>
</html>

JAVASCRIPT语言

var previewImage = document.getElementById("preview"),  
    uploadingText = document.getElementById("uploading-text");

function submitForm(event) {
    // prevent default form submission
    event.preventDefault();
    uploadImage();
}

function uploadImage() {
    var imageSelecter = document.getElementById("image-selecter"),
        file = imageSelecter.files[0];
    if (!file) 
        return alert("Please select a file");
    // clear the previous image
    previewImage.removeAttribute("src");
    // show uploading text
    uploadingText.style.display = "block";
    // create form data and append the file
    var formData = new FormData();
    formData.append("image", file);
    // do the ajax part
    var ajax = new XMLHttpRequest();
    ajax.onreadystatechange = function() {
        if (this.readyState === 4 && this.status === 200) {
            var json = JSON.parse(this.responseText);
            if (!json || json.status !== true) 
                return uploadError(json.error);

            showImage(json.url);
        }
    }
    ajax.open("POST", "upload.php", true);
    ajax.send(formData); // send the form data
}

PHP

<?php
$host = 'localhost';
$user = 'user';
$password = 'password';
$database = 'database';
$mysqli = new mysqli($host, $user, $password, $database);


 try {
    if (empty($_FILES['image'])) {
        throw new Exception('Image file is missing');
    }
    $image = $_FILES['image'];
    // check INI error
    if ($image['error'] !== 0) {
        if ($image['error'] === 1) 
            throw new Exception('Max upload size exceeded');

        throw new Exception('Image uploading error: INI Error');
    }
    // check if the file exists
    if (!file_exists($image['tmp_name']))
        throw new Exception('Image file is missing in the server');
    $maxFileSize = 2 * 10e6; // in bytes
    if ($image['size'] > $maxFileSize)
        throw new Exception('Max size limit exceeded'); 
    // check if uploaded file is an image
    $imageData = getimagesize($image['tmp_name']);
    if (!$imageData) 
        throw new Exception('Invalid image');
    $mimeType = $imageData['mime'];
    // validate mime type
    $allowedMimeTypes = ['image/jpeg', 'image/png', 'image/gif'];
    if (!in_array($mimeType, $allowedMimeTypes)) 
        throw new Exception('Only JPEG, PNG and GIFs are allowed');

    // nice! it's a valid image
    // get file extension (ex: jpg, png) not (.jpg)
    $fileExtention = strtolower(pathinfo($image['name'] ,PATHINFO_EXTENSION));
    // create random name for your image
    $fileName = round(microtime(true)) . mt_rand() . '.' . $fileExtention; // anyfilename.jpg
    // Create the path starting from DOCUMENT ROOT of your website
    $path = '/examples/image-upload/images/' . $fileName;
    // file path in the computer - where to save it 
    $destination = $_SERVER['DOCUMENT_ROOT'] . $path;

    if (!move_uploaded_file($image['tmp_name'], $destination))
        throw new Exception('Error in moving the uploaded file');

    // create the url
    $protocol = stripos($_SERVER['SERVER_PROTOCOL'],'https') === true ? 'https://' : 'http://';
    $domain = $protocol . $_SERVER['SERVER_NAME'];
    $url = $domain . $path;
    $stmt = $mysqli -> prepare('INSERT INTO image_uploads (url) VALUES (?)');
    if (
        $stmt &&
        $stmt -> bind_param('s', $url) &&
        $stmt -> execute()
    ) {
        exit(
            json_encode(
                array(
                    'status' => true,
                    'url' => $url
                )
            )
        );
    } else 
        throw new Exception('Error in saving into the database');

} catch (Exception $e) {
    exit(json_encode(
        array (
            'status' => false,
            'error' => $e -> getMessage()
        )
    ));
}

使用HTML5,您可以使用Ajax和jQuery上传文件。不仅如此,您还可以进行文件验证(名称、大小和MIME类型)或使用HTML5进度标记(或div)处理进度事件。最近我不得不做一个文件上传器,但我不想使用Flash或Iframes或插件,经过一些研究,我想出了解决方案。

HTML:

<form enctype="multipart/form-data">
    <input name="file" type="file" />
    <input type="button" value="Upload" />
</form>
<progress></progress>

首先,如果需要,可以进行一些验证。例如,在文件的.on('change')事件中:

$(':file').on('change', function () {
  var file = this.files[0];

  if (file.size > 1024) {
    alert('max upload size is 1k');
  }

  // Also see .name, .type
});

现在,单击按钮即可提交$.ajax():

$(':button').on('click', function () {
  $.ajax({
    // Your server script to process the upload
    url: 'upload.php',
    type: 'POST',

    // Form data
    data: new FormData($('form')[0]),

    // Tell jQuery not to process data or worry about content-type
    // You *must* include these options!
    cache: false,
    contentType: false,
    processData: false,

    // Custom XMLHttpRequest
    xhr: function () {
      var myXhr = $.ajaxSettings.xhr();
      if (myXhr.upload) {
        // For handling the progress of the upload
        myXhr.upload.addEventListener('progress', function (e) {
          if (e.lengthComputable) {
            $('progress').attr({
              value: e.loaded,
              max: e.total,
            });
          }
        }, false);
      }
      return myXhr;
    }
  });
});

正如你所看到的,通过HTML5(以及一些研究)文件上传不仅变得可能,而且非常容易。尝试使用Google Chrome,因为示例中的一些HTML5组件在每个浏览器中都不可用。