%@ page contentType="text/html;charset=UTF-8" language="java" %> 
%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %> 
html> 
head> 
 title>文件上傳測試/title> 
/head> 
body> 
form method="POST" enctype="multipart/form-data" action="%=request.getContextPath()%>/UploadServlet"> 
 文件: input type="file" name="upfile">br/> 
 br/> 
 input type="submit" value="上傳"> 
/form> 
c:if test="${not empty errorMessage}"> 
 input type="text" id="errorMessage" value="${errorMessage}" style="color:red;" disabled="disabled"> 
/c:if> 
/body> 
/html> 

package servlet; 
 
import org.apache.commons.fileupload.FileItem; 
import org.apache.commons.fileupload.FileUploadBase; 
import org.apache.commons.fileupload.FileUploadException; 
import org.apache.commons.fileupload.ProgressListener; 
import org.apache.commons.fileupload.disk.DiskFileItemFactory; 
import org.apache.commons.fileupload.servlet.ServletFileUpload; 
 
import javax.servlet.ServletException; 
import javax.servlet.annotation.WebServlet; 
import javax.servlet.http.HttpServlet; 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 
import java.io.File; 
import java.io.FileOutputStream; 
import java.io.IOException; 
import java.io.InputStream; 
import java.util.Calendar; 
import java.util.Iterator; 
import java.util.List; 
import java.util.UUID; 
 
/** 
 * 處理文件上傳 
 * 
 * @author xusucheng 
 * @create 2017-12-27 
 **/ 
@WebServlet("/UploadServlet") 
public class UploadServlet extends HttpServlet { 
 @Override 
 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 
 //設置文件上傳基本路徑 
 String savePath = this.getServletContext().getRealPath("/WEB-INF/uploadFiles"); 
 //設置臨時文件路徑 
 String tempPath = this.getServletContext().getRealPath("/WEB-INF/tempFiles"); 
 File tempFile = new File(tempPath); 
 if (!tempFile.exists()) { 
 tempFile.mkdir(); 
 } 
 
 //定義異常消息 
 String errorMessage = ""; 
 //創建file items工廠 
 DiskFileItemFactory factory = new DiskFileItemFactory(); 
 //設置緩沖區大小 
 factory.setSizeThreshold(1024 * 100); 
 //設置臨時文件路徑 
 factory.setRepository(tempFile); 
 //創建文件上傳處理器 
 ServletFileUpload upload = new ServletFileUpload(factory); 
 //監聽文件上傳進度 
 ProgressListener progressListener = new ProgressListener() { 
 public void update(long pBytesRead, long pContentLength, int pItems) { 
 System.out.println("正在讀取文件： " + pItems); 
 if (pContentLength == -1) { 
  System.out.println("已讀取： " + pBytesRead + " 剩余0"); 
 } else { 
  System.out.println("文件總大小：" + pContentLength + " 已讀取：" + pBytesRead); 
 } 
 } 
 }; 
 upload.setProgressListener(progressListener); 
 
 //解決上傳文件名的中文亂碼 
 upload.setHeaderEncoding("UTF-8"); 
 //判斷提交上來的數據是否是上傳表單的數據 
 if (!ServletFileUpload.isMultipartContent(request)) { 
 //按照傳統方式獲取數據 
 return; 
 } 
 
 //設置上傳單個文件的大小的最大值，目前是設置為1024*1024字節，也就是1MB 
 upload.setFileSizeMax(1024 * 1024); 
 //設置上傳文件總量的最大值，最大值=同時上傳的多個文件的大小的最大值的和，目前設置為10MB 
 upload.setSizeMax(1024 * 1024 * 10); 
 
 try { 
 //使用ServletFileUpload解析器解析上傳數據，解析結果返回的是一個ListFileItem>集合，每一個FileItem對應一個Form表單的輸入項 
 ListFileItem> items = upload.parseRequest(request); 
 IteratorFileItem> iterator = items.iterator(); 
 while (iterator.hasNext()) { 
 FileItem item = iterator.next(); 
 
 //判斷jsp提交過來的是不是文件 
 if (item.isFormField()) { 
  errorMessage = "請提交文件！"; 
  break; 
 } else { 
  //文件名 
  String fileName = item.getName(); 
  if (fileName == null || fileName.trim() == "") { 
  System.out.println("文件名為空！"); 
  } 
  //處理不同瀏覽器提交的文件名帶路徑問題 
  fileName = fileName.substring(fileName.lastIndexOf("\\") + 1); 
  //文件擴展名 
  String fileExtension = fileName.substring(fileName.lastIndexOf(".") + 1); 
  //判斷擴展名是否合法 
  if (!validExtension(fileExtension)) { 
  errorMessage = "上傳文件非法！"; 
  item.delete(); 
  break; 
  } 
  //獲得文件輸入流 
  InputStream in = item.getInputStream(); 
  //得到保存文件的名稱 
  String saveFileName = createFileName(fileName); 
  //得到文件保存路徑 
  String realFilePath = createRealFilePath(savePath, saveFileName); 
  //創建文件輸出流 
  FileOutputStream out = new FileOutputStream(realFilePath); 
  //創建緩沖區 
  byte buffer[] = new byte[1024]; 
  int len = 0; 
  while ((len = in.read(buffer)) > 0) { 
  //寫文件 
  out.write(buffer, 0, len); 
  } 
  //關閉輸入流 
  in.close(); 
  //關閉輸出流 
  out.close(); 
  //刪除臨時文件 TODO 
  item.delete(); 
  //將上傳文件信息保存到附件表中 TODO 
 } 
 
 } 
 
 } catch (FileUploadBase.FileSizeLimitExceededException e) { 
 e.printStackTrace(); 
 request.setAttribute("errorMessage", "單個文件超出最大值！！！"); 
 request.getRequestDispatcher("pages/upload/upload.jsp").forward(request, response); 
 return; 
 } catch (FileUploadBase.SizeLimitExceededException e) { 
 e.printStackTrace(); 
 request.setAttribute("errorMessage", "上傳文件的總的大小超出限制的最大值！！！"); 
 request.getRequestDispatcher("pages/upload/upload.jsp").forward(request, response); 
 return; 
 } catch (FileUploadException e) { 
 e.printStackTrace(); 
 request.setAttribute("errorMessage", "文件上傳失敗！！！"); 
 request.getRequestDispatcher("pages/upload/upload.jsp").forward(request, response); 
 return; 
 } 
 
 request.setAttribute("errorMessage", errorMessage); 
 request.getRequestDispatcher("pages/upload/upload.jsp").forward(request, response); 
 
 
 } 
 
 @Override 
 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 
 doGet(request, response); 
 } 
 
 private boolean validExtension(String fileExtension) { 
 String[] exts = {"jpg", "txt", "doc", "pdf"}; 
 for (int i = 0; i  exts.length; i++) { 
 if (fileExtension.equals(exts[i])) { 
 return true; 
 } 
 
 } 
 
 return false; 
 } 
 
 private String createFileName(String fileName) { 
 return UUID.randomUUID().toString() + "_" + fileName; 
 } 
 
 /** 
 * 根據基本路徑和文件名稱生成真實文件路徑，基本路徑\\年\\月\\fileName 
 * 
 * @param basePath 
 * @param fileName 
 * @return 
 */ 
 private String createRealFilePath(String basePath, String fileName) { 
 Calendar today = Calendar.getInstance(); 
 String year = String.valueOf(today.get(Calendar.YEAR)); 
 String month = String.valueOf(today.get(Calendar.MONTH) + 1); 
 
 
 String upPath = basePath + File.separator + year + File.separator + month + File.separator; 
 File uploadFolder = new File(upPath); 
 if (!uploadFolder.exists()) { 
 uploadFolder.mkdirs(); 
 } 
 
 String realFilePath = upPath + fileName; 
 
 return realFilePath; 
 } 
}