<script type="text/javascript">
function upload() {
var file1 = document.getElementById("file1");
postFile(file1.files[0]);
}
function postFile(data) {
//1.创建异步对象（小浏览器）
var req = new XMLHttpRequest();
//2.设置参数
req.open("post", "/API/ImgUp.ashx", true);
//3.设置 请求 报文体 的 编码格式（设置为 表单默认编码格式）
req.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
//4.设置回调函数
req.onreadystatechange = function () {
//请求状态readyState=4准备就绪,服务器返回的状态码status=200接收成功
if (req.readyState == 4 && req.status == 200) {
if (req.responseText != "error") {
//changeName(req.responseText);
$("#img").attr("src", req.responseText);
}
}
};
//4.发送异步请求
req.send(data);//post传参在此处
}
</script>
<body>
<input id="file1" type="file" value="选择文件" />
<input id="btnUp" onclick="upload()" type="button" value="上传" />
<img id="img" src="" />
</body>
后台ashx处理
public void ProcessRequest(HttpContext context) { //context.Request["data"] Stream stream = new BufferedStream(context.Request.InputStream); byte[] buffer=new byte[stream.Length]; stream.Read(buffer, 0, buffer.Length); string path = context.Server.MapPath("/ImgUp/") + "1.jpg"; File.WriteAllBytes(path, buffer); context.Response.Write("/ImgUp/1.jpg"); }
原文：http://www.cnblogs.com/yougmi/p/4565589.html