import 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 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);
 }

}

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) {

 }

 }

}