ajax文件异步上传文件，后台request获取上传的文件流

org. apache. commons. fileupload. servlet.ServletFileUpload 组件封装的文件（否则自己处理request.inputStream很麻烦）

ServletFileUpload upload = new ServletFileUpload();
try {
List<?> items = upload.parseRequest(request);
Iterator iter = items.iterator();
while(iter.hasNext()){
FileItem item = (FileItem) iter.next();
if (item.isFormField()) {
//如果是普通表单字段
String name = item.getFieldName();
String value = item.getString();
} else {
String fieldName = item.getFieldName();
String fileName = item.getName();
String contentType = item.getContentType();
boolean isInMemory = item.isInMemory();
long sizeInBytes = item.getSize();
File uploadedFile = new File("E:/Downloads/upload/" + fileName);
try {
item.write(uploadedFile);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

}
} catch (FileUploadException e) {
e.printStackTrace();
}

二、前台的html和js代码

0.html页面引入一个js,些js内容见下面。

1.html页面中要加一个label 控件：<label id="fileup_id" >选择图片</label>。

2.在html页面的onload事件中加如下代码：

asy.init({
url : "/hbnpc/system/activity/activityUpload",//上传的路径
filename : "pic_na",//上传的字段名
target : "fileup_id",//上传按钮的id
complete : afile//回调函数
});

三、引入的js内容

/** *文件异步上传工具 * */ var asy = {}; asy.init = function(args){ asy.args = args; var id = "asy_input_file" + new Date(); var fileinput = document.createElement("input"); asy.fileinput = fileinput; fileinput.type = "file"; fileinput.id = id; fileinput.name = args.filename; fileinput.onchange = asy.upload; fileinput.style.cssText = 'position:absolute; top:-9999px; left:-9999px'; document.body.appendChild(fileinput); var label = document.getElementById(args.target); asy.label = label; label.setAttribute("for",id); //$(label).attr("for",id); //如果要兼容ie7 放开这句 } asy.upload = function(){ var form = document.createElement("form"); asy.form = form; form.action = asy.args.url; form.method = "post"; form.encoding = "multipart/form-data"; form.appendChild(asy.fileinput); var frame = document.createElement("iframe"); frame = document.body.appendChild(frame); asy.frame = frame; frame.src = asy.args.url; //frame.contentWindow.document.body.appendChild(asy.form);//不兼容ie frame.style.cssText = 'position:absolute; top:-9999px; left:-9999px'; setTimeout(function(){ frame.contentWindow.document.body.appendChild(asy.form); frame.onload = function(){ asy.args.complete(this.contentWindow.document.body.outerText);//textContent//不兼容ie asy.clear(); } asy.form.submit(); },100); } asy.clear = function(){ document.body.removeChild(asy.frame); asy.init(asy.args); }