jsp+servlet实现文件上传与下载

上传：需要导入两个包：commons-fileupload-1.2.1.jar,commons-io-1.4.jarimport java.io.File;import java.io.IOException;import java.util.List;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.apache.commons.fileupload.FileItem;import org.apache.commons.fileupload.disk.DiskFileItemFactory;import org.apache.commons.fileupload.servlet.ServletFileUpload;/** * 上传附件 * @author new * */public class UploadAnnexServlet extends HttpServlet { private static String path = ""; public void doGet(HttpServletRequest request, HttpServletResponse response)   throws ServletException, IOException {  doPost(request, response); } /*  * post处理  * (non-Javadoc)  * @see javax.servlet.http.HttpServlet#doPost(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)  */ public void doPost(HttpServletRequest request, HttpServletResponse response)   throws ServletException, IOException {  path = this.getServletContext().getRealPath("/upload");  try {   DiskFileItemFactory factory = new DiskFileItemFactory();   ServletFileUpload up = new ServletFileUpload(factory);   List<FileItem> ls = up.parseRequest(request);   for (FileItem fileItem : ls) {    if (fileItem.isFormField()) {     String FieldName = fileItem.getFieldName();     //getName()返回的是文件名字 普通域没有文件 返回NULL     //                    String Name = fileItem.getName();     String Content = fileItem.getString("gbk");     request.setAttribute(FieldName, Content);    } else {         String nm = fileItem.getName().substring(       fileItem.getName().lastIndexOf("\\") + 1);     File mkr = new File(path, nm);     if (mkr.createNewFile()) {      fileItem.write(mkr);//非常方便的方法     }     request.setAttribute("result", "上传文件成功！");    }   }  } catch (Exception e) {   e.printStackTrace();   request.setAttribute("result", "上传失败，请查找原因，重新再试！");  }  request.getRequestDispatcher("/pages/admin/annex-manager.jsp").forward(    request, response); }} 下载（i/o流）无需导包：import java.io.IOException;import java.net.URLEncoder;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * 下载文件 * @author * */public class DownloadFilesServlet extends HttpServlet { /**  *   */ private static final long serialVersionUID = 8594448765428224944L; public void doGet(HttpServletRequest request, HttpServletResponse response)   throws ServletException, IOException {  doPost(request, response); } /*  * 处理请求  * (non-Javadoc)  * @see javax.servlet.http.HttpServlet#doPost(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)  */ public void doPost(HttpServletRequest request, HttpServletResponse response)   throws ServletException, IOException {  String name = request.getParameter("fileName");  System.out.print("dddddddddd:" + name);  // web绝对路径  String path = request.getSession().getServletContext().getRealPath("/");  String savePath = path + "upload";  // 设置为下载application/x-download  response.setContentType("application/x-download");  // 即将下载的文件在服务器上的绝对路径  String filenamedownload = savePath + "/" + name;  // 下载文件时显示的文件保存名称  String filenamedisplay = name;  // 中文编码转换  filenamedisplay = URLEncoder.encode(filenamedisplay, "UTF-8");  response.addHeader("Content-Disposition", "attachment;filename="    + filenamedisplay);  try {   java.io.OutputStream os = response.getOutputStream();   java.io.FileInputStream fis = new java.io.FileInputStream(     filenamedownload);   byte[] b = new byte[1024];   int i = 0;   while ((i = fis.read(b)) > 0) {    os.write(b, 0, i);   }   fis.close();   os.flush();   os.close();  } catch (Exception e) {  } }}