public class FileUploadServlet extends HttpServlet { private static final long serialVersionUID = 1L; private ServletFileUpload upload; private final long MAXSize = 4194304*2L;//4*2MB private String filedir=null;           /**     * @see HttpServlet#HttpServlet()     */    public FileUploadServlet() {        super();        // TODO Auto-generated constructor stub    } /**  * 设置文件上传的初始化信息  * @see Servlet#init(ServletConfig)  */ public void init(ServletConfig config) throws ServletException {  FileItemFactory factory = new DiskFileItemFactory();// Create a factory for disk-based file items  this.upload = new ServletFileUpload(factory);// Create a new file upload handler  this.upload.setSizeMax(this.MAXSize);// Set overall request size constraint 4194304  filedir=config.getServletContext().getRealPath("images");  System.out.println("filedir="+filedir); } /**  * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)  */ @SuppressWarnings("unchecked") protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {  // TODO Auto-generated method stub  PrintWriter out=response.getWriter();  try {   List
    
      items = this.upload.parseRequest(request);   if(items!=null && !items.isEmpty()){    for (FileItem fileItem : items) {     String filename=fileItem.getName();     String filepath=filedir+File.separator+filename;     System.out.println("文件保存路径为:"+filepath);     File file=new File(filepath);     InputStream inputSteam=fileItem.getInputStream();     BufferedInputStream fis=new BufferedInputStream(inputSteam);        FileOutputStream fos=new FileOutputStream(file);        int f;        while((f=fis.read())!=-1)        {           fos.write(f);        }        fos.flush();        fos.close();        fis.close();     inputSteam.close();     System.out.println("文件："+filename+"上传成功!");    }   }   System.out.println("上传文件成功!");   out.write("上传文件成功!");  } catch (FileUploadException e) {   e.printStackTrace();   out.write("上传文件失败:"+e.getMessage());  } }}