}

四：文件上传示例：

JSP代码：

<form action="${pageContext.request.contextPath}/servlet/UploadServlet" method="post" enctype="multipart/form-data">
    	用户名:<input type="text" name="username"/><br/>
    	文件1:<input type="file" name="f1"/><br/>
    	文件2:<input type="file" name="f2"/><br/>
    	<input type="submit" value="保存"/>
    </form>

public class UploadServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		request.setCharacterEncoding("UTF-8");
		response.setContentType("text/html;charset=UTF-8");
		PrintWriter pout = response.getWriter();
		try {
			// 得到存放上传文件的真实路径
			String storePath = getServletContext()
					.getRealPath("/WEB-INF/files");

			// 设置环境
			DiskFileItemFactory factory = new DiskFileItemFactory();
			factory.setRepository(new File(getServletContext().getRealPath("/temp")));//设置临时存放目录
			// 判断一下form是否是enctype=multipart/form-data类型的
			boolean isMultipart = ServletFileUpload.isMultipartContent(request);
			if (!isMultipart) {
				System.out.println("大傻鸟");
				return;
			}
			// ServletFileUpload核心类
			ServletFileUpload upload = new ServletFileUpload(factory);
//			upload.setProgressListener(new ProgressListener() {
//				//pBytesRead：当前以读取到的字节数
//				//pContentLength：文件的长度
//				//pItems:第几项
//				public void update(long pBytesRead, long pContentLength,
//						int pItems) {
//					System.out.println("已读取："+pBytesRead+",文件大小："+pContentLength+",第几项："+pItems);
//				}
//				
//			});
			upload.setFileSizeMax(4 * 1024 * 1024);// 设置单个上传文件的大小
			upload.setSizeMax(6 * 1024 * 1024);// 设置总文件大小
			// 解析
			List<FileItem> items = upload.parseRequest(request);
			for (FileItem item : items) {
				if (item.isFormField()) {
					// 普通字段
					String fieldName = item.getFieldName();
					String fieldValue = item.getString("UTF-8");
					System.out.println(fieldName + "=" + fieldValue);
				} else {
					// 得到MIME类型
					String mimeType = item.getContentType();
					// 只允许上传图片
					 if(mimeType.startsWith("image")){
						// 上传字段
						InputStream in = item.getInputStream();
						// 上传的文件名
						String fileName = item.getName();// C:\Documents and
						if(fileName==null||"".equals(fileName.trim())){
							continue;
						}
						// Settings\wzhting\妗岄潰\a.txt
						// a.txt
						fileName = fileName
								.substring(fileName.lastIndexOf("\\") + 1);// a.txt
						fileName = UUID.randomUUID() + "_" + fileName;
						System.out.println(request.getRemoteAddr()+"=============="+fileName);
						// 构建输出流
						// 打散存储目录
						String newStorePath = makeStorePath(storePath, fileName);// 根据
						// /WEB-INF/files和文件名，创建一个新的存储路径
						// /WEB-INF/files/1/12
						String storeFile = newStorePath + "\\" + fileName;// WEB-INF/files/1/2/sldfdslf.txt
	
						OutputStream out = new FileOutputStream(storeFile);
	
						byte b[] = new byte[1024];
						int len = -1;
						while ((len = in.read(b)) != -1) {
							out.write(b, 0, len);
						}
						out.close();
						in.close();
						item.delete();//删除临时文件
					}
				 }
			}
		} catch (org.apache.commons.fileupload.FileUploadBase.FileSizeLimitExceededException e) {
			// 单个文件超出大小时的异常
			pout.write("单个文件大小不能超出4M");
		} catch (org.apache.commons.fileupload.FileUploadBase.SizeLimitExceededException e) {
			// 总文件超出大小时的异常
			pout.write("总文件大小不能超出6M");
		} catch (Exception e) {
			e.printStackTrace();
		}

	}

	// 根据 /WEB-INF/files和文件名，创建一个新的存储路径 /WEB-INF/files/1/12
	private String makeStorePath(String storePath, String fileName) {
		int hashCode = fileName.hashCode();
		int dir1 = hashCode & 0xf;// 0000~1111：整数0~15共16个
		int dir2 = (hashCode & 0xf0) >> 4;// 0000~1111：整数0~15共16个

		String path = storePath + "\\" + dir1 + "\\" + dir2; // WEB-INF/files/1/12
		File file = new File(path);
		if (!file.exists())
			file.mkdirs();

		return path;
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		doGet(request, response);
	}

}

---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

五：文件下载

1.显示上述存储所有的照片信息:

//显示所有上传的文件，封装到域对象中，交给jsp去显示
public class ShowAllFilesServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		Map<String, String> map = new HashMap<String, String>();//key：UUID文件名；value：老文件名
		//得到存储文件的根目录
		String storePath = getServletContext().getRealPath("/WEB-INF/files");
		//递归遍历其中文件
		File file = new File(storePath);
		treeWalk(file,map);
		//交给JSP去显示：如何封装数据.用Map封装。key：UUID文件名；value：老文件名
		request.setAttribute("map", map);
		request.getRequestDispatcher("/listFiles.jsp").forward(request, response);
	}
	//遍历/WEB-INF/files所有文件，把文件名放到map中
	private void treeWalk(File file, Map<String, String> map) {
		if(file.isFile()){
			//是文件
			String uuidName = file.getName();//  UUID_a_a.txt//真实文件名
			String oldName = uuidName.substring(uuidName.indexOf("_")+1);
			map.put(uuidName, oldName);
		}else{
			//是一个目录
			File[] fs = file.listFiles();
			for(File f:fs){
				treeWalk(f,map);
			}
		}
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		doGet(request, response);
	}

}

<body>
    <h1>本站有以下好图片</h1>
    <c:forEach items="${map}" var="me">
    	<c:url value="/servlet/DownloadServlet" var="url">
    		<c:param name="filename" value="${me.key}"></c:param>
    	</c:url>
    	${me.value}  <a href="${url}">下载</a><br/>
    </c:forEach>
  </body>

public class DownloadServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		response.setContentType("text/html;charset=UTF-8");
		OutputStream out = response.getOutputStream();
		
		String filename = request.getParameter("filename");//get请求方式
		filename = new String(filename.getBytes("ISO-8859-1"),"UTF-8");//中文编码
		
		//截取老文件名
		String oldFileName = filename.split("_")[1];
		//得到存储路径
		String storePath = getServletContext().getRealPath("/WEB-INF/files");
		//得到文件的全部路径
		String filePath = makeStorePath(storePath, filename)+"\\"+filename;
		
		//判断文件是否存在
		File file = new File(filePath);
		if(!file.exists()){
			out.write("对比起！你要下载的文件可能已经不存在了".getBytes("UTF-8"));
			return;
		}
		
		InputStream in = new FileInputStream(file);
		//通知客户端以下载的方式打开
		response.setHeader("Content-Disposition", "attachment;filename="+URLEncoder.encode(oldFileName, "UTF-8"));
		
		byte[] b = new byte[1024];
		int len = -1;
		while((len=in.read(b))!=-1){
			out.write(b, 0, len);
		}
		in.close();
		out.write("下载成功".getBytes("UTF-8"));
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		doGet(request, response);
	}
	private String makeStorePath(String storePath, String fileName) {
		int hashCode = fileName.hashCode();
		int dir1 = hashCode & 0xf;// 0000~1111：整数0~15共16个
		int dir2 = (hashCode & 0xf0) >> 4;// 0000~1111：整数0~15共16个

		String path = storePath + "\\" + dir1 + "\\" + dir2; // WEB-INF/files/1/12
		File file = new File(path);
		if (!file.exists())
			file.mkdirs();

		return path;
	}
}

JSP中文件的上传于下载示例,布布扣,bubuko.com

JSP中文件的上传于下载示例