基于Servlet和SSM框架的文件上传下载的多种实现方法

今天药忘吃喽~ 2022-05-24 02:05 119阅读 0赞

# 文件上传： #

### Servlet下实现： ###

*  **文件上传**

package TaskSubmit.Servlet;
    
    import java.io.*;
    import java.io.IOException;
    import java.sql.Connection;
    import java.sql.Statement;
    import java.util.List;
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    import org.apache.commons.fileupload.*;
    import org.apache.commons.fileupload.disk.DiskFileItemFactory;
    import org.apache.commons.fileupload.servlet.ServletFileUpload;
    
    import TaskSubmit.JDBCpool.JDBCutils;
    import TaskSubmit.Model.*;
    
    @WebServlet("/UploadServlet")
    public class UploadServlet extends HttpServlet {
    	private static final long serialVersionUID = 1L;
    
    	@SuppressWarnings("unchecked")
    	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    		request.setCharacterEncoding("utf-8");
    		response.setContentType("text/html;charset=utf-8");
    		Task task = (Task) request.getSession().getAttribute("Task");
    		Student student = (Student) request.getSession().getAttribute("user");
    		String Saccount = student.getSaccount(); // 存放用户账号，用来重命名文件
    		String Sname = student.getSname(); // 存放用户姓名，用来重命名文件
    		String ClassName = student.getClassName();// 存放用户班级，用来指定文件夹
    		String TaskName = task.getTaskName(); // 存放作业名字，用来指定文件夹
    		String fileType = null; // 存放文件类型，用来重命名文件
    		try {
    			// 创建工厂
    			DiskFileItemFactory factory = new DiskFileItemFactory();
    			File f = new File("E:\\SubmitFile");
    			if (!f.exists()) {
    				f.mkdirs();
    			}
    			// 设置文件上传的缓存路径
    			factory.setRepository(f);
    			// 创建Fileupload组件
    			ServletFileUpload fileUpload = new ServletFileUpload(factory);
    			fileUpload.setHeaderEncoding("utf-8");
    			// 设置允许上传的最大 1024*1024*10M
    			// fileUpload.setSizeMax(10485760);
    			// 解析request
    			List<FileItem> fileitems = fileUpload.parseRequest(request);
    			// PrintWriter writer = response.getWriter();
    			// 遍历集合
    			for (FileItem fileitem : fileitems) {
    				// 判断是否为普通字段
    				if (fileitem.isFormField()) {
    					// 获得字段名和字段值
    					// String name = fileitem.getFieldName();
    					// String value = fileitem.getString("utf-8");
    					// writer.print("提交者："+value+"<br>");
    				} else {
    					// 上传的文件路径
    					String fileName = fileitem.getName();
    					// 截取出文件名
    					fileName = fileName.substring(fileName.lastIndexOf("\\") + 1);
    					// 截取出文件类型
    					fileType = fileName.substring(fileName.lastIndexOf(".") + 1);
    					// 对上传文件进行重命名
    					fileName = "e:\\SubmitFiles\\" + ClassName + "\\" + TaskName + "\\" + Saccount + "-" + Sname + "." + fileType;
    					// 在服务器创建同名文件
    					File file = new File(fileName);
    					file.getParentFile().mkdirs();
    					file.createNewFile();
    					// 获得上传文件流
    					InputStream in = fileitem.getInputStream();
    					// 获得写入文件流
    					OutputStream out = new FileOutputStream(file);
    					// 流的对拷
    					byte[] buffer = new byte[1024];
    					int len;
    					while ((len = in.read(buffer)) > 0) {
    						out.write(buffer, 0, len);
    					}
    					// 关流
    					in.close();
    					out.close();
    					// 删除临时文件
    					fileitem.delete();
    				}
    			}
    			// 更新提交情况表
    			Connection conn = JDBCutils.getDataSource().getConnection();
    			Statement stmt = conn.createStatement();
    			String sql = "UPDATE taskstu SET Flag=1 WHERE TaskName='" + TaskName + "'AND Saccount='" + Saccount + "'";
    			stmt.executeUpdate(sql);
    			// 提交完成 返回作业列表
    			// response.sendRedirect("/TaskSubmit/StudentView/TaskList.jsp?curPage=1");
    			request.getSession().setAttribute("message", "提交成功！");
    			response.sendRedirect("/TaskSubmit/StudentIndexServlet");
    		} catch (Exception e) {
    			throw new RuntimeException(e);
    		}
    	}
    
    	protected void doPost(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    		doGet(request, response);
    	}
    }

###  ###

#  #

*  **文件下载**

String path = "E:" + File.separator + "hrmUpload";
    		String fileName = documentService.findDocumentById(id).getFileName();
    		// 获取路径，创建文件对象
    		File file = new File(path + File.separator + fileName);// File.separator为分隔符，如'/'
    		// 通知浏览器以下载的方式打开文件
    		response.reset();
    		response.addHeader("Content-Type", "application/octet-stream");
    		response.addHeader("Content-Disposition", "attachment;filename=" + URLEncoder.encode(file.getName(), "utf-8"));
    		// 通过文件对象获取文件相关的输入流
    		InputStream in = new FileInputStream(file);
    		// 获取response对象的输出流
    		OutputStream out = response.getOutputStream();
    		byte[] buffer = new byte[1024];
    		int len;
    		while ((len = in.read(buffer)) != -1) {
    			out.write(buffer, 0, len);
    		}
    		// 关闭流
    		in.close();
    		out.close();

### SSM框架下实现： ###

基于Servlet的文件上传和下载，完全适用于SSM框架下文件上传和下载

*  文件上传

先说一下文件的获取，文件的获取可以通过直接在方法中添加MultipartFile类型的参数进行自动获取，也可以像Servlet中一样通过遍历request进行获取。我这里使用document对象进行接收，其有一个MultipartFile类型的属性file。

首先要配置文件解析器（在Spring的配置文件中）：

<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver"> 
        <property name="defaultEncoding" value="UTF-8"/>
    </bean>

@RequestMapping("/addDocument.do")
    	public String addDocument(Document document, HttpSession session, Model model) throws IllegalStateException, IOException {
    		// 上传文件的路径
    		// String path = session.getServletContext().getRealPath("/upload");
    		String path = "E:" + File.separator + "hrmUpload";
    		File file = new File(path);
    		if (!file.exists()) {
    			file.mkdir();
    		}
    		// 上传的文件名
    		String fileName = document.getFile().getOriginalFilename();
    
    		// 将文件保存到指定路径和名称 document.getFile().transferTo(new File(path + File.separator + fileName));// File.separator分隔符/或者\
    
    		document.setFileName(fileName);
    		document.setUser((User) session.getAttribute("login_user"));
    
    		int rows = documentService.addDocument(document);
    
    		if (rows > 0) {
    			return "redirect:/document/findDocument.do";
    		} else {
    			model.addAttribute("failMSG", "上传文件失败！");
    			return "/jsp/fail.jsp";
    		}
    
    	}

*  文件下载

@RequestMapping("/downLoad.do")
    	public ResponseEntity<byte[]> downLoad(Integer id) throws IOException {
    		String path = "E:" + File.separator + "hrmUpload";
    		String fileName = documentService.findDocumentById(id).getFileName();
    
    		File file = new File(path + File.separator + fileName);
    
    		HttpHeaders headers = new HttpHeaders();
    
    		String downloadFileName = new String(fileName.getBytes("UTF-8"), "iso8859-1");
    
    		// 指定类型，应用程序的字节流
    		headers.setContentType(MediaType.APPLICATION_OCTET_STREAM);
    
    		headers.setContentDispositionFormData("attachment", downloadFileName);
    
    		return new ResponseEntity<byte[]>(FileUtils.readFileToByteArray(file), headers, HttpStatus.OK);
    	}