Jsp+Servlet实现文件上传下载 文件上传（一）

%@ page contentType="text/html;charset=UTF-8" language="java" %> 
%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %> 
html> 
head> 
 title>文件上传测试/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="上传"> 
/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; 
 
/** 
 * 处理文件上传 
 * 
 * @author xusucheng 
 * @create 2017-12-27 
 **/ 
@WebServlet("/UploadServlet") 
public class UploadServlet extends HttpServlet { 
 @Override 
 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 
 //设置文件上传基本路径 
 String savePath = this.getServletContext().getRealPath("/WEB-INF/uploadFiles"); 
 //设置临时文件路径 
 String tempPath = this.getServletContext().getRealPath("/WEB-INF/tempFiles"); 
 File tempFile = new File(tempPath); 
 if (!tempFile.exists()) { 
 tempFile.mkdir(); 
 } 
 
 //定义异常消息 
 String errorMessage = ""; 
 //创建file items工厂 
 DiskFileItemFactory factory = new DiskFileItemFactory(); 
 //设置缓冲区大小 
 factory.setSizeThreshold(1024 * 100); 
 //设置临时文件路径 
 factory.setRepository(tempFile); 
 //创建文件上传处理器 
 ServletFileUpload upload = new ServletFileUpload(factory); 
 //监听文件上传进度 
 ProgressListener progressListener = new ProgressListener() { 
 public void update(long pBytesRead, long pContentLength, int pItems) { 
 System.out.println("正在读取文件： " + pItems); 
 if (pContentLength == -1) { 
  System.out.println("已读取： " + pBytesRead + " 剩余0"); 
 } else { 
  System.out.println("文件总大小：" + pContentLength + " 已读取：" + pBytesRead); 
 } 
 } 
 }; 
 upload.setProgressListener(progressListener); 
 
 //解决上传文件名的中文乱码 
 upload.setHeaderEncoding("UTF-8"); 
 //判断提交上来的数据是否是上传表单的数据 
 if (!ServletFileUpload.isMultipartContent(request)) { 
 //按照传统方式获取数据 
 return; 
 } 
 
 //设置上传单个文件的大小的最大值，目前是设置为1024*1024字节，也就是1MB 
 upload.setFileSizeMax(1024 * 1024); 
 //设置上传文件总量的最大值，最大值=同时上传的多个文件的大小的最大值的和，目前设置为10MB 
 upload.setSizeMax(1024 * 1024 * 10); 
 
 try { 
 //使用ServletFileUpload解析器解析上传数据，解析结果返回的是一个ListFileItem>集合，每一个FileItem对应一个Form表单的输入项 
 ListFileItem> items = upload.parseRequest(request); 
 IteratorFileItem> iterator = items.iterator(); 
 while (iterator.hasNext()) { 
 FileItem item = iterator.next(); 
 
 //判断jsp提交过来的是不是文件 
 if (item.isFormField()) { 
  errorMessage = "请提交文件！"; 
  break; 
 } else { 
  //文件名 
  String fileName = item.getName(); 
  if (fileName == null || fileName.trim() == "") { 
  System.out.println("文件名为空！"); 
  } 
  //处理不同浏览器提交的文件名带路径问题 
  fileName = fileName.substring(fileName.lastIndexOf("\\") + 1); 
  //文件扩展名 
  String fileExtension = fileName.substring(fileName.lastIndexOf(".") + 1); 
  //判断扩展名是否合法 
  if (!validExtension(fileExtension)) { 
  errorMessage = "上传文件非法！"; 
  item.delete(); 
  break; 
  } 
  //获得文件输入流 
  InputStream in = item.getInputStream(); 
  //得到保存文件的名称 
  String saveFileName = createFileName(fileName); 
  //得到文件保存路径 
  String realFilePath = createRealFilePath(savePath, saveFileName); 
  //创建文件输出流 
  FileOutputStream out = new FileOutputStream(realFilePath); 
  //创建缓冲区 
  byte buffer[] = new byte[1024]; 
  int len = 0; 
  while ((len = in.read(buffer)) > 0) { 
  //写文件 
  out.write(buffer, 0, len); 
  } 
  //关闭输入流 
  in.close(); 
  //关闭输出流 
  out.close(); 
  //删除临时文件 TODO 
  item.delete(); 
  //将上传文件信息保存到附件表中 TODO 
 } 
 
 } 
 
 } catch (FileUploadBase.FileSizeLimitExceededException e) { 
 e.printStackTrace(); 
 request.setAttribute("errorMessage", "单个文件超出最大值！！！"); 
 request.getRequestDispatcher("pages/upload/upload.jsp").forward(request, response); 
 return; 
 } catch (FileUploadBase.SizeLimitExceededException e) { 
 e.printStackTrace(); 
 request.setAttribute("errorMessage", "上传文件的总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", "文件上传失败！！！"); 
 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; 
 } 
 
 /** 
 * 根据基本路径和文件名称生成真实文件路径，基本路径\\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; 
 } 
}