在网上找了好些，都不是很适合，从以前的工程里找了个，先收藏下，要不下次有的找好长时间！
------------------------upload.jsp-------------------------
<body>
<br>
<h1 align="center">上传文件</h1>
<hr>
<form action="FileUploadServlet" method="post" enctype="multipart/form-data" name="form1">
<div align="center">
<input type="file" name="file">
<input type="submit" name="Submit" value="提交">
</div>
</form>
</body>
---------------------------servlet------------------
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
/* 初始化JSPSmart变量 */
SmartUpload mySmartUpload = new SmartUpload();
Date date = new Date();
//String allowedFilesList = "doc,DOC,pdf,PDF,txt,TXT,html,HTML,htm,HTM";
String allowedFilesList ="mdb";
Files fils = null;
int maxFileSize = 100 * 1024*1024;
Request req = null;
//站点根目录
ServletConfig config = getServletConfig();// 得到servletConfig
mySmartUpload.initialize(config, request, response);
mySmartUpload.setMaxFileSize(maxFileSize); // 上传文件的大小
mySmartUpload.setAllowedFilesList(allowedFilesList);// 允许上传的格式
req = mySmartUpload.getRequest();//得到JspSmart中的Request对象，提取表单中其他数据
String fileName = "";
String fileExt = "";
try {
//mySmartUpload.setDeniedFilesList("reg,jsp,asp,php");
mySmartUpload.upload();// 上传文件
fils = mySmartUpload.getFiles();
com.jspsmart.upload.File file = fils.getFile(0);
if (!file.isMissing()) {
System.out.println(file.getFileName());
fileName = date.toLocaleString().replaceAll("-", "").replaceAll(":", "").replaceAll(" ", "");
fileName += Double.toString(Math.random()).substring(2).substring(0,4);
// 文件路径
String sourceFile = "/upload/km_" + fileName + "."+ file.getFileExt();
fileExt = file.getFileExt();
// 保存源图
file.saveAs(sourceFile, com.jspsmart.upload.File.SAVEAS_VIRTUAL);
}
} catch (SmartUploadException e) {
out.write("失败");
e.printStackTrace();
}
String WEBROOT = request.getRealPath("/");
out.println(WEBROOT+"upload"+"//"+"km_"+ fileName+"."+fileExt+"");
}