commons-fileupload实现文件上传下载

commons-fileupload是Apache提供的一个实现文件上传下载的简单，有效途径,需要commons-io包的支持，本文是一个简单的示例

上传页面,注意设置响应头

<body><center><h1>文件上传页面</h1><hr><form action="${pageContext.request.contextPath }/servlet/UploadServlet" method="post" enctype="multipart/form-data">选择文件：<input type="file" name="file1"/><br>描述信息:<textarea rows="5" cols="45" name="discription"></textarea><br><input type="submit" value="上传"/></form></center></body>

上传的servlet

//上传文件String upload=this.getServletContext().getRealPath("WEB-INF/upload");String temp=this.getServletContext().getRealPath("WEB-INF/temp");Map pmap=new HashMap();//get client IP addresspmap.put("ip", request.getRemoteAddr());DiskFileItemFactory factory=new DiskFileItemFactory();//设定内存缓冲区大小 Set the memory buffer sizefactory.setSizeThreshold(1024*100);//指定临时文件目录 Specifies the directory for temporary filesfactory.setRepository(new File(temp));ServletFileUpload fileUpload=new ServletFileUpload(factory);fileUpload.setHeaderEncoding("utf-8");fileUpload.setFileSizeMax(1024*1024*100);fileUpload.setSizeMax(1024*1024*200);//set form style enctype="multipart/form-data"if(!fileUpload.isMultipartContent(request)){throw new RuntimeException("请使用正确的表单进行上传");}//解析requesttry {List<FileItem> list= fileUpload.parseRequest(request);//遍历listfor(FileItem item:list){if(item.isFormField()){String name=item.getFieldName();String value=item.getString("utf-8");pmap.put(name, value);}else{String realname=item.getName();String arry[]=realname.split("\\\\");realname=arry[arry.length-1];System.out.println(realname);String uuidName=UUID.randomUUID().toString()+"_"+realname;pmap.put("realname", realname);pmap.put("uuidname", uuidName);InputStream in=item.getInputStream();String hash=Integer.toHexString(uuidName.hashCode());String savepath="/WEB-INF/upload";for(char c:hash.toCharArray()){upload+="/"+c;savepath+="/"+c;}new File(upload).mkdirs();pmap.put("savepath", savepath);OutputStream out=new FileOutputStream(new File(upload,uuidName));IOUtils.In2Out(in, out);IOUtils.close(in, out);item.delete();}}} catch (Exception e) {// TODO 自动生成的 catch 块e.printStackTrace();}//向数据库中插入数据Resourse r=new Resourse(); try {BeanUtils.populate(r, pmap);String sql="insert into netdisk values(null,?,?,?,?,null,?)";QueryRunner runner=new QueryRunner(DaoUtils.getSource());runner.update(sql,r.getUuidname(),r.getRealname(),r.getSavepath(),r.getIp(),r.getDescription());} catch (Exception e) {// TODO 自动生成的 catch 块e.printStackTrace();} //重定向回主页response.sendRedirect(request.getContextPath()+"/index.jsp");

为防止重名，所以使用了UUIDNAME,把文件上传到web-inf/upload文件夹下，并且将路径与文件名保存到数据库中，上传功能完成

下载实现

下载页面

<body><center><h1>下载列表</h1><hr><c:forEach items="${requestScope.list }" var="r"><h2>文件名:${r.realname }<br></h2>上传时间:${r.uploadtime }<br>上传者IP：${r.ip }<br>描述信息：${r.description }<br><a href="${pageContext.request.contextPath }/servlet/DownServlet?id=${r.id}">下载</a><br><hr></c:forEach></center></body>

下载实现

  response.setContentType("text/html;charset=utf-8");//获取IDString id=request.getParameter("id");//根据ID查找资源String sql="select * from netdisk where id=?";Resourse r=null;QueryRunner runner=new QueryRunner(DaoUtils.getSource());try {r= runner.query(sql, new BeanHandler<Resourse>(Resourse.class), id);} catch (SQLException e) {// TODO 自动生成的 catch 块e.printStackTrace();}if(r==null){response.getWriter().write("找不到该资源!!!!");return;}else{//指定响应头response.setHeader("Content-Disposition", "attachment;filename="+URLEncoder.encode(r.getRealname(),"UTF-8"));response.setContentType(this.getServletContext().getMimeType(r.getRealname()));String filePath=this.getServletContext().getRealPath(r.getSavepath()+"/"+r.getUuidname());InputStream in=new FileInputStream(filePath);OutputStream out=response.getOutputStream();IOUtils.In2Out(in, out);IOUtils.close(in, null);}

上传下载完成，注意，下载时一定要指定两个响应头

IO工具类

public class IOUtils {private IOUtils() {}public static void In2Out(InputStream in,OutputStream out) throws IOException{byte [] bs = new byte[1024];int i = 0;while((i=in.read(bs))!=-1){out.write(bs,0,i);}}public static void close(InputStream in,OutputStream out){if(in!=null){try {in.close();} catch (IOException e) {e.printStackTrace();}finally{in = null;}}if(out!=null){try {out.close();} catch (IOException e) {e.printStackTrace();}finally{out = null;}}}
}