上传文件

1、上传文件

没必要记住，直到流程就行了，用的时候直接copy过来用，嘿嘿

/**
 * @author zhangbingbing
 * @version 1.0
 * @date 2020/5/13 12:58
 */
public class FileServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("进入了我。。。。。");
        //1、判断是否为包含文件上传的表单
        if (!ServletFileUpload.isMultipartContent(request)) {
            return; //如果不是直接结束
        }
        //2、创建上传的保存路径，建议保存在WEB-INF目录下，用户无法直接上传
        String upload = this.getServletContext().getRealPath("/WEB-INF/upload");
        File uploadFile = new File(upload);
        if (!uploadFile.exists()) {
            uploadFile.mkdir();
        }

        //3、创建大文件的缓存路径，为什么？因为服务器存储空间不是无限的,让大文件几天后自动删除
        String temp = this.getServletContext().getRealPath("/WEB-INF/tem");
        File tempFile = new File(upload);
        if (!tempFile.exists()) {
            tempFile.mkdir();   //没有我们就创建
        }

        //4、创建DiskFileItemFactory对象来处理文件上传路径或者大小限制
        try {
            DiskFileItemFactory factory = getDiskFileItemFactory(tempFile);

            //5、用DiskFileItemFactory对象创建文件上传对象：ServletFileUpload对象
            ServletFileUpload fileUpload = getServletFileUpload(factory);

            //6、处理上传的文件
            String msg = uploadParseRequest(request, fileUpload, uploadFile);
            System.out.println(msg);
            request.getRequestDispatcher("success.jsp").forward(request, response);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    //4、获取操作磁盘对象的对象
    private static  DiskFileItemFactory getDiskFileItemFactory(File tempFile) {
        DiskFileItemFactory factory = new DiskFileItemFactory();
        //设置传输速度阈值
        factory.setSizeThreshold(1024*1024);
        factory.setRepository(tempFile);
        return factory;
    }

    //5、获取文件传输对象
    private static ServletFileUpload getServletFileUpload(DiskFileItemFactory factory) {
        ServletFileUpload fileUpload = new ServletFileUpload(factory);
        fileUpload.setHeaderEncoding("utf-8");
        fileUpload.setFileSizeMax(1024*1024*10);
        fileUpload.setSizeMax(1024*1024*10);
        return fileUpload;
    }

    //6、处理上传的文件，因为有的可能不是文件
    private static String uploadParseRequest(HttpServletRequest request, ServletFileUpload upload, File path) throws Exception {
        String msg = "";
        List<FileItem> fileItems = upload.parseRequest(request);
        for (FileItem fileItem : fileItems) {
            //判断是否是上传的文件
            if (fileItem.isFormField()) {      //不是上传的文件
                String fieldName = fileItem.getFieldName();
                String string = fileItem.getString("UTF-8");
                System.out.println("fieldName:"+string);
            } else {
                //是文件
                //处理文件
                String fileName = fileItem.getName();
                System.out.println("fileName:"+fileName);
                if (fileName == null || fileName.trim().equals("")) {
                    continue;
                }
                //是真正要上传的文件
                String substring1 = fileName.substring(fileName.lastIndexOf("/") + 1);
                String substring2 = fileName.substring(fileName.lastIndexOf(".") + 1);
                String UUIDString = UUID.randomUUID().toString();
                String realPath = path + "/" + UUIDString;
                File realPathFile = new File(realPath);
                if (!realPathFile.exists()) {
                    realPathFile.mkdir();
                }

                InputStream inputStream = fileItem.getInputStream();


                FileOutputStream fos = new FileOutputStream(realPath+"/"+substring1);
                byte[] buffer = new byte[1024];
                int len = 0;
                while ((len = inputStream.read(buffer)) > 0) {
                    fos.write(buffer, 0, len);
                }
                inputStream.close();
                fos.close();
                msg = "文件上传成功！";
                fileItem.delete();
            }
        }
        return msg;
    }

流程还是要看一遍的！