JSP 页面代码：

        <form action="#" name="uploadForm" method="post" enctype="multipart/form-data">  

        <input type="file" name="upload" id="upload" οnchange="loadImageFile(event)">

                <img id="image" src="" >

                <input type="submit" value="上传">

        </form>  

JS 代码：

        function loadImageFile(event)

        {

                var image = document.getElementById('image');

                image.src = URL.createObjectURL(event.target.files[0]); 

        };