commons-fileupload实现文件上传下载

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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 address        pmap.put("ip", request.getRemoteAddr());        DiskFileItemFactory factory=new DiskFileItemFactory();        //设定内存缓冲区大小 Set the memory buffer size        factory.setSizeThreshold(1024*100);        //指定临时文件目录 Specifies the directory for temporary files        factory.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request        try {            List<FileItem> list= fileUpload.parseRequest(request);            //遍历list            for(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ID        String 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;            }        }    }}

完成

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