<form action="" method="post" enctype="multipart/form-data">
<!--accept=".txt"標簽用來確定上傳的文件默認類型-->
請選擇您要上傳的文件：<input type="file" name="fileName" accept=".txt" ?/> <br/>
確認上傳？<input type="submit" value="確認" /><input type="reset" value="重選" />
</form>

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//1、設置編碼方式為utf-8，獲取字符流
request.setCharacterEncoding("utf-8");
response.setContentType("text/html;charset=utf-8");
PrintWriter write = response.getWriter();
//2、創(chuàng)建DiskFileItemFactory工廠類對象，將文件封裝成單獨的FileItem對象
DiskFileItemFactory diskFileItemFactory = new DiskFileItemFactory();
//3、設置文件緩存目錄
File file = new File("C:\\Cache");
?? ??? ?if(!file.exists()) {
?? ??? ??? ?//如果文件不存在，就創(chuàng)建一個文件
?? ??? ??? ?file.mkdirs();
?? ??? ?}
?? ??? ?diskFileItemFactory.setRepository(file); ? ? ? ? //加載文件緩存目錄
//4、創(chuàng)建ServletFileUpload對象
ServletFileUpload fileUpload = new ServletFileUpload(diskFileItemFactory);
//5、設置文件編碼為utf-8
fileUpload.setHeaderEncoding("utf-8");
//6、解析request請求，得到上傳文件的FileItem對象,得到的也就是所有的表單name --->比如：這里只有一個name="fileName" 拿到的就是這個集合
?? ??? ?List<FileItem> fileItems = null;
?? ??? ?try {
?? ??? ??? ?fileItems = fileUpload.parseRequest(request);
?? ??? ?} catch (FileUploadException e) {
?? ??? ??? ?e.printStackTrace();
?? ??? ?}
//8、遍歷集合
for(FileItem fileItem:fileItems) { ? //文本域
//判斷是否為普通字段
?? ??? ??? ?if(fileItem.isFormField()) {
?? ??? ??? ??? ?//得到字段名、字段值
?? ??? ??? ??? ?String name = fileItem.getFieldName(); ? ? //
?? ??? ??? ?}
? ? //為文件域
?? ??? ??? ?else {
//9、得到所上傳的文件路徑名
String fileName = fileItem.getName();
?//10、截取文件名?
String fiString = fileName.substring(fileName.lastIndexOf("\\")+1);
//11、設置上傳的目標文件夾路徑
File filedir = new File("C:\\NewFile");
? ? ? ? if(!filedir.exists()) {
?? ??? ??? ??? ??? ?filedir.mkdir();
?? ??? ??? ??? ?}
//? ? System.out.println(user.getUserName());
?? ??? ??? ??? ?File filepath = new File(filedir+"\\"+fiString);?
//? ? System.out.println(fiString);
?? ??? ??? ??? ?if(!filepath.exists()) {
?? ??? ??? ??? ??? ?filepath.createNewFile();
?? ??? ??? ??? ?}
?? ??? ??? ??? ?//獲得文件上傳流
?? ??? ??? ??? ?InputStream in = fileItem.getInputStream();
?? ??? ??? ??? ?//使用FileOutStream打開服務器端的上傳文件
?? ??? ??? ??? ?FileOutputStream out = new FileOutputStream(filepath);
?? ??? ??? ??? ?//流的對拷
?? ??? ??? ??? ?byte[] bb = new byte[1024];
?? ??? ??? ??? ?int len ;?
?? ??? ??? ??? ?while((len= in.read(bb))>0) {
?? ??? ??? ??? ??? ?out.write(bb, 0, len);
//?? ??? ??? ??? ??? ?out.close();
//?? ??? ??? ??? ??? ?in.close();
?? ??? ??? ??? ??? ?fileItem.delete(); ? //刪除臨時文件
?? ??? ??? ??? ?}
?? ??? ??? ??? ?write.println("文件上傳成功<br/>");
?? ??? ??? ?}
?? ??? ?}
?? ?}