在java里实现页面中的上传与下载

    xiaoxiao2021-03-26  9

    一、文件上传

    1.jsp页面中通过form表单上传文件

    <form action="upload.do" method="post" enctype="multipart/form-data"> <input type="file" name="ff"> <input type="submit" value="上传"> </form> //form表单enctype属性一定要改成multipart/form-data,这样才知道submit的是文件

    2.创建UploadServlet

    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setCharacterEncoding("utf-8"); request.setCharacterEncoding("utf-8"); response.setContentType("text/html"); //获得磁盘文件条目工厂 DiskFileItemFactory factory=new DiskFileItemFactory(); //通过调用jar包api,进行文件上传处理 ServletFileUpload upload=new ServletFileUpload(factory); //单个文件最大10M upload.setFileSizeMax(1024*1024*10); //整个request请求的大小,一般比单个文件大小要大,因为包含request的其他请求信息 upload.setSizeMax(1024*1024*11); try { //解析request请求 List<FileItem> items=upload.parseRequest(request); for(FileItem item:items){ //如果不是表单域,则为文件域,开始进行处理 if(!item.isFormField()){ //获取上传文件的名称 String fileName=item.getName(); //根据上传文件的名称,创建对应的文件 String path=request.getRealPath("/upload"); File f=new File(path+"/"+UUID.randomUUID()+"-"+fileName); //写文件,实现上传功能 item.write(f); } } } catch (Exception e) { e.printStackTrace(); } request.getRequestDispatcher("success.jsp").forward(request, response); } //要在WebRoot下建立upload文件夹,并在lib下导入两个包 上传成功后,可以在tomcat下你项目里的upload文件夹中找到上传的文件

    二、下载文件

    1.jsp页面中通过a链接下载

    <a href="down.do?filename=测试.docx">测试.docx</a>

    2.建立DownloadServlet

    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setCharacterEncoding("UTF-8"); response.setCharacterEncoding("utf-8"); response.setContentType("application/x-msdownload;"); String fileName=request.getParameter("filename"); System.out.println("下载的文件为:"+new String(fileName.getBytes("iso8859-1"),"UTF-8")); String filePath=request.getRealPath("/upload"); //浏览器下载时默认保存的文件名称 response.setHeader("Content-disposition", "attachment; filename=\"" + fileName+"\""); InputStream is=new FileInputStream(new File(filePath+"/"+new String(fileName.getBytes("iso8859-1"),"UTF-8"))); //得到浏览器响应的输出流 OutputStream os=response.getOutputStream(); byte data[]=new byte[1024*1024*10]; int length=0; while(is.available()>0){ length=is.read(data); } os.write(data,0,length); os.flush(); } //因为a链接默认使用get方法,所以传过来的fileName要重新编码成utf-8,否则会出现乱码
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