使用html5的FormData对象,通过Ajax表单异步提交文件数据

var formData = new FormData();
formData.append('template', that.template);
formData.append('declare', that.declareData.declare);
formData.append('self_intro', that.declareData.self_intro);
formData.append('plan_name', that.declareData.plan_name);
//$("#business_plan") 是一个file类型的input对象
formData.append('business_plan', $("#business_plan")[0].files[0]);
var xhr = new XMLHttpRequest();
xhr.open('POST', url, true);
xhr.setRequestHeader("Accept", "application/json");
xhr.send(formData);
// 指定通信过程中状态改变时的回调函数
xhr.onreadystatechange = function () {
 // 通信成功时，状态值为4
 var completed = 4;
 if (xhr.readyState === completed) {
 if (xhr.status === 200) {
 // 处理服务器发送过来的数据
 var result = JSON.parse(xhr.responseText);
 //这里你可以随意的处理这个result对象了
 //...
 } else {// 处理错误
 alert('连接超时');
 }
 }
};