上传文件的三种方式xhr,ajax和iframe及上传预览

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>

    <style>
        .upload {

            display: inline-block;
            background-color: #ef4300;
            cursor: pointer;
            width: 100px;
            height: 35px;
            text-align: center;
            position: absolute;
            line-height: 35px;
            top: 0;
            bottom: 0;
            right: 0;
            left: 0;
            z-index: 99;

        }

        .file {

            width: 100px;
            height: 35px;
            text-align: center;
            position: absolute;
            line-height: 35px;
            top: 0;
            bottom: 0;
            right: 0;
            left: 0;
            z-index: 100;
            opacity: 0;


        }

    </style>
</head>
<body>

<div style="position: relative;width: 100px;height: 35px">
<input type="file" id="i1" name="upload" class="file">
<a class="upload">上传</a>
</div>
<input type="submit" value="xhr提交" onclick="xhrSubmit();">


<input type="submit" value="ajax提交" onclick="ajaxSubmit();">


<script src="/static/jquery-1.12.4.js"></script>
<script src="/static/jquery.cookie.js"></script>


<form action="/xiaoqing/upload_file/" method="post" target="ifm1" enctype="multipart/form-data">
    {% csrf_token %}

    <iframe id="ifm2" name="ifm1"></iframe>
    <input type="file" name="upload">

    <input type="submit" onclick="iframesubmitForm();" value="Form提交" >

</form>






<script>

    var csrftoken = $.cookie('csrftoken');


//第一种上传方式  iframe
      function iframesubmitForm() {

           $('#ifm2').load(function(){

            var text= $('#ifm2').contents().find('body').text();
            var obj= JSON.parse(text);
              console.log(obj);
           })

       }



//第二种上传方法  ajax

    function ajaxSubmit() {
        var fileobj = document.getElementById('i1').files[0];
        console.log(fileobj);


        var fd = new FormData();   //依赖FormData对象
        fd.append('username', 'root');
        fd.append('upload', fileobj);

        $.ajax({

            url: '/xiaoqing/upload_file/',
            type: 'POST',
            data: fd,
            processData: false,
            cententType: false,
            headers: {'X-CSRFtoken': csrftoken},
            success: function(arg,a1,a2){
                console.log(arg);
                console.log(a1);
                console.log(a2);

            }

        })

    }



//第三种上传方法  xhr对象
    function xhrSubmit() {

        var fileobj = document.getElementById('i1').files[0];
        console.log(fileobj);


        var fd = new FormData();   //依赖FormData对象
        fd.append('username','root');
        fd.append('upload',fileobj);


        var xhr= new XMLHttpRequest();   //创建对象

        xhr.open('POST','/xiaoqing/upload_file/',true);

        xhr.setRequestHeader('Content-Type','application/x-www-form-urlencoded; charset-UTF-8'); //POST请求必须设置
        xhr.setRequestHeader('X-CSRFtoken',csrftoken);

        xhr.send(fd);
        xhr.onreadystatechange = function() {

            if(xhr.readyState == 4){
                var obj = JSON.parse(xhr.responseText);   //返回值
                console.log(obj);

            }
        }



    }



</script>

</body>
</html>
三种上传方式