方法一: 从HttpServletRequest中获取文件信息
参考文档：https://blog.csdn.net/java_newstar/article/details/78053891
Collection<Part> parts = req.getParts();
for (Iterator<Part> iterator = parts.iterator(); iterator.hasNext();) {
    Part part = iterator.next();  
    System.out.println("-----类型名称------->"+part.getName());
    System.out.println("-----类型------->"+part.getContentType());
    System.out.println("-----提交的类型名称------->"+part.getSubmittedFileName());
    System.out.println("----流-------->"+part.getInputStream());
}
方法二: 从MultipartHttpServletRequest中获取文件信息

//将当前上下文初始化给  CommonsMutipartResolver （多部分解析器）
CommonsMultipartResolver multipartResolver=new CommonsMultipartResolver(
                    request.getSession().getServletContext());
// 判断是否是多数据段提交格式
 if (multipartResolver.isMultipart(request)) {
         MultipartHttpServletRequest multiRequest = (MultipartHttpServletRequest)request;
         Iterator<String> iter = multiRequest.getFileNames();
         logger.info("iter.hasNext(): "+iter.hasNext());
         Integer fileCount = 0;
         while (iter.hasNext()) {
                MultipartFile multipartFile = multiRequest.getFile(iter.next());
                String fileName = multipartFile.getOriginalFilename();
                logger.info("upload filename: " + fileName );
                if(fileName == null || fileName.trim().equals("")){
                      continue;
                }
                //20170207 针对IE环境下filename是整个文件路径的情况而做以下处理
                Integer index = fileName.lastIndexOf("\\");
                String newStr = "";
                 if(index>-1){
                       newStr = fileName.substring(index+1);
                  }else{
                       newStr = fileName;
                  }
                 if(!newStr.equals("")){
                        fileName = newStr;
                  }
                  logger.info("new filename: " + fileName );

                  if (multipartFile != null) {
                        HashMap<String,Object> result =  DispatchInterfaceUtil.uploadInputStream(multipartFile.getInputStream(),multipartFile.getSize(),fileName);
                  }
        }
}

import java.io.File;
import java.util.ArrayList;
import java.util.List;

import javax.servlet.http.HttpServletRequest;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

/**
 * 工具类 -从HttpServletRequest中获取文件数据
 * 
 */
public class RequestUtil {

    /**
     * 从HttpServletRequest中获取所有的文件
     * 
     * @param request
     * @return FileItem对象列表
     * @throws FileUploadException
     */
    public static List<FileItem> getFileItemList(HttpServletRequest request) throws FileUploadException {
        List<FileItem> fileItemFromRequestList = getDataFromRequest(request);
        if (fileItemFromRequestList != null && !fileItemFromRequestList.isEmpty()) {
            List<FileItem> fileItemList = new ArrayList<>();
            for (FileItem fileItem : fileItemFromRequestList) {
                if (!fileItem.isFormField()) { // 文件
                    fileItemList.add(fileItem);
                }
            }
            return fileItemList;
        }
        return null;
    }

    /**
     * 从request中获取FileItem对象列表
     * 
     * @param request
     * @return fileItemFromRequestList
     * @throws FileUploadException
     */
    private static List<FileItem> getDataFromRequest(HttpServletRequest request) throws FileUploadException {
        String tempPath = request.getServletContext().getRealPath("/temp");
        File file = new File(tempPath);
        DiskFileItemFactory factory = new DiskFileItemFactory();
        factory.setSizeThreshold(1024 * 1024 * 1024);// 设置缓存大小
        factory.setRepository(file);// 默认情况下 临时文件不会自动删除
        ServletFileUpload servletFileUpload = new ServletFileUpload(factory);
        List<FileItem> fileItemFromRequestList = servletFileUpload.parseRequest(request);
        file.delete(); // 删除临时文件
        return fileItemFromRequestList;
    }
}

/**
	 * 获取当前请求中的文件列表
	 * 
	 * @param request
	 * @return
	 */
	protected List<MultipartFile> getMultipartFileList(
			HttpServletRequest request) {
		List<MultipartFile> files = new ArrayList<MultipartFile>();
		try {
			CommonsMultipartResolver multipartResolver = new CommonsMultipartResolver(
					request.getSession().getServletContext());
			if (request instanceof MultipartHttpServletRequest) {
				// 将request变成多部分request
				MultipartHttpServletRequest multiRequest = (MultipartHttpServletRequest) request;
				Iterator<String> iter = multiRequest.getFileNames();
				// 检查form中是否有enctype="multipart/form-data"
				if (multipartResolver.isMultipart(request) && iter.hasNext()) {
					// 获取multiRequest 中所有的文件名
					while (iter.hasNext()) {
						// 一次遍历所有文件
						// MultipartFile file =
						// multiRequest.getFile(iter.next().toString());
						// if (file != null) {
						// files.add(file);
						// }
						// 适配名字重复的文件
						List<MultipartFile> fileRows = multiRequest
								.getFiles(iter.next().toString());
						if (fileRows != null && fileRows.size() != 0) {
							for (MultipartFile file : fileRows) {
								if (file != null && !file.isEmpty()) {
									files.add(file);
								}
							}
						}
					}
				}
			}
		} catch (Exception ex) {
			log.error("解析MultipartRequest错误", ex);
		}
		return files;
	}

    public static String getFileName(InputStream is) throws IOException {
        StringBuffer sb = new StringBuffer();
        int count = 0;
        while (true) {
            int a = is.read();
            sb.append((char) a);
            if (a == '\r') {
                count++;
            }
            if (count == 4) {
                is.read();
                break;
            }
        }
        String title = sb.toString();
        System.out.println(title);
        String[] titles = title.split("\r\n");
        String fileName = titles[1].split(";")[2].split("=")[1].replace("\"", "");
        return fileName;
    }