Java--文件上传与下载

拼搏现实的明天。 2023-10-17 18:45 53阅读 0赞

一、文件上传

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    		PrintWriter out = response.getWriter();
    		//request.setCharacterEncoding("UTF-8");
    		
    		//执行文件上传的操作
    		//判断表单是否支持文件上传。即enctype="multipart/form-data"
    		boolean isMultipartContent = ServletFileUpload.isMultipartContent(request);
    		if (!isMultipartContent) {
    			throw new RuntimeException("不支持form表单");
    		}
    		
    		//创建一个DiskFileItemFactory工厂类
    		DiskFileItemFactory factory = new DiskFileItemFactory();
    		//创建一个ServletFileUpload核心对象
    		ServletFileUpload sfu = new ServletFileUpload(factory);
    		//解决文件名中文乱码问题
    		sfu.setHeaderEncoding("UTF-8");
    		
    		//解析request对象，并得到一个表单项集合
    		try {
    			sfu.setFileSizeMax(1024*0124*3);//3MB 设置单个文件大小
    			sfu.setSizeMax(1024*1024*12);//12MB  设置总文件大小
    			
    			List<FileItem> fileItems = sfu.parseRequest(new ServletRequestContext(request));
    			
    			//遍历表单项数据
    			for(FileItem fileItem :fileItems) {
    				if (fileItem.isFormField()) {
    					out.println("111aaa");
    					//普通表单项
    					processFormField(fileItem);
    				}else {
    					out.println("222bbb");
    					//上传表单项
    					processUploadField(fileItem);
    				}
    			}
    		}catch (FileUploadBase.FileSizeLimitExceededException e) {
    			System.out.println("文件过大，不能超过3Mb");
    		}catch (FileUploadBase.SizeLimitExceededException e) {
    			System.out.println("总文件过大，不能超过12Mb");
    		}catch (FileUploadException e) {
    			e.printStackTrace();
    		}
    	}
    
    	//上传表单项
    	private void processUploadField(FileItem fileItem) {
    		try {
    			//得到文件输入流
    			InputStream iStream = fileItem.getInputStream();
    			
    			//创建一个文件存盘目录
    			//1、保证服务器的安全,把保存上传文件的目录放在用户直接访问不到的地方*
    			String directoryRealPath = this.getServletContext().getRealPath("/WEB-INF/upload");
    			System.out.println(directoryRealPath);
    			File fileDirectory = new File(directoryRealPath);
    			if (!fileDirectory.exists()) {
    				fileDirectory.mkdir();//创建一个指定目录
    			}
    			
    			//得到上传文件名
    			String fileName = fileItem.getName();
    			if (fileName != null) {
    				fileName = FilenameUtils.getName(fileName);
    			}
    			
    			//2、保证文件名唯一不可重复
    			fileName = UUID.randomUUID()+"_"+fileName;
    			
    			//3、在文件夹下创建子文件夹管理
    			String childDirectory = makeChildDirectory(fileDirectory);//(fileDirectory,fileName);
    			System.out.println(fileDirectory+childDirectory+File.separator+fileName);
    			
    			//在文件夹下，创建完整目录下文件
    			File file = new File(fileDirectory,childDirectory+File.separator+fileName);
    			//通过文件输出流将上传的文件保存到磁盘
    			FileOutputStream fileOutputStream = new FileOutputStream(file);
    			
    			int len = 0;
    			byte[] bs = new byte[1024];
    			while((len=iStream.read(bs))!= -1) {
    				fileOutputStream.write(bs, 0, len);
    			}
    			fileOutputStream.close();
    			iStream.close();
    			fileItem.delete();//清除临时文件
    		} catch (IOException e) {
    			e.printStackTrace();
    		}
    	}
    	
    	//使用日期新建子文件夹
    	private String makeChildDirectory(File fileDirectory) {
    		Date date = new Date();
    		SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
    		String sdate = simpleDateFormat.format(date);
    		File file = new File(fileDirectory,sdate);
    		if (!file.exists()) {
    			file.mkdirs();
    		}
    		return sdate;
    	}
    
    	/*//使用文件名的hashCode新建子文件夹
    	private String makeChildDirectory(File fileDirectory,String fileName) {
    		int hashcode = fileName.hashCode();
    		System.out.println(hashcode);
    		String code = Integer.toHexString(hashcode);
    		System.out.println(code);
    		String childDirectory = code.charAt(0)+File.separator+code.charAt(1);
    		File file = new File(fileDirectory,childDirectory);
    		if (!file.exists()) {
    			file.mkdirs();
    		}
    		return childDirectory;
    	}*/
    
    	//普通表单项
    	private void processFormField(FileItem fileItem) {
    		String fieldName = fileItem.getFieldName();//字段名
    		String fieldValue = fileItem.getString();//字段值
    		System.out.println(fieldName+"="+fieldValue);
    	}

二、文件下载

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    		//设置要下载的文件名
    		String fileName = "销售单.csv";
    		
    		fileName = new String(fileName.getBytes("UTF-8"),"iso-8859-1");
    		//告知浏览器要下载文件
    		response.setHeader("content-disposition", "attachment;fileName="+fileName);
    		//response.setHeader("content-type", "image/jpeg");
    		response.setContentType(this.getServletContext().getMimeType(fileName));
    		
    		response.setCharacterEncoding("UTF-8");//编码方式
    		//创建文件输出流
    		PrintWriter out = response.getWriter();
    		out.write("iphone8 Plus,10yi\n");
    		out.write("iphone8,8yi\n");
    		out.write("iphone7 Plus,6yi\n");
    		out.write("iphone7,5yi\n");
    		out.write("iphone6s,2yi\n");
    	}