Implementation of Html5 file asynchronous upload function

This article briefly introduces the use of Html5's FormData to implement asynchronous uploading of files, and can also implement upload progress bars and file size verification. The code is simple and easy to understand, very good, and has reference value. Friends who need it can refer to it

1 Introduction

Developing a file upload function is never a pleasant thing, especially asynchronous upload. I have used iframe and Flash upload solutions. , also felt very awkward. This article briefly introduces the use of Html5's FormData to implement asynchronous uploading of files, and can also implement upload progress bars and file size verification. The server uses the springMVC solution for processing.

2 Html code

<form id="myForm">
    <input type="file" id="u_photo" name="u_photo" />
    <input type="button" id="submit-btn" value="上传" />
</form>

3 JQuery upload

$("#submit-btn").on('click', function() {
    $.ajax({
        url:"/test/upload",
        type:"post",
        data:new FormData($("#myForm").get(0)),
        //十分重要，不能省略
        cache: false,
        processData: false,
        contentType: false,
        success: function () {
            alert("上传成功！");
        }
    });
});

4 JQuery file size verification

File size and corresponding behavior control, You need to handle it yourself as needed. This method is just an example method.

$('#u_photo').on('change', function() {
    var file = this.files[0];
    if (file.size > 1024*1000) {
        alert('文件最大1M！')
    }
});

5 JQuery progress bar

Add xhr to the ajax method to control the upload progress. The progress bar can use HTML5's progress or other progress bars. Displaying and hiding the progress bar needs to be handled by yourself. This method only briefly introduces the basic control of the progress bar.

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

6 springMVC server

6.1 maven dependency

<dependency>
    <groupId>commons-io</groupId>
    <artifactId>commons-io</artifactId>
    <version>2.5</version>
</dependency>
<dependency>
    <groupId>commons-fileupload</groupId>
    <artifactId>commons-fileupload</artifactId>
    <version>1.3.2</version>
</dependency>

6.2 servlet-context.xml

<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver" />

6.3 Controller

The sample program does not provide the corresponding code for file verification, storage and processing.

@RequestMapping(value="/test/upload",method = RequestMethod.POST)
@ResponseBody
public String upload(@RequestParam("u_photo") MultipartFile u_photo) {
    System.out.println("u_photo="+u_photo.getSize());
    return "ok";
}

7 Compatibility

IE 10+, Firefox 4.0+, Chrome 7+, Safari 5+, Opera 12+

8 Recommended reading

If you are not satisfied with the above solution, we recommend the following solution:

JQuery File Uploader

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