方法一: 从HttpServletRequest中获取文件信息

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());
}

//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;
    }
}

1.先debug看request中文件类型

2.强转类型成StandardMultipartHttpServletRequest

StandardMultipartHttpServletRequest standardMultipartHttpServletRequest = (StandardMultipartHttpServletRequest) request;

3.StandardMultipartHttpServletRequest中有一个获取参数的方法getParameterMap，可以直接获取到request中的相关参数

StandardMultipartHttpServletRequest standardMultipartHttpServletRequest = (StandardMultipartHttpServletRequest) request;
Map<String, String[]> parameterMap = standardMultipartHttpServletRequest.getParameterMap();
String[] imageFiles= parameterMap.get("imageFile");//上报的文件的参数名称

 4.还有一个是获取多文件的方法getMultiFileMap返回是MultiValueMap，是StandardMultipartHttpServletRequest继承AbstractMultipartHttpServletRequest中的方法

MultiValueMap<String, MultipartFile> multiFileMap = standardMultipartHttpServletRequest.getMultiFileMap();
//获取文件
MultipartFile multipartFile = multiFileMap.getFirst("xxxFile");
if(multipartFile != null){
    //获取文件名
	String originalFilename = multipartFile.getOriginalFilename();
	//获取流
	InputStream inputStream = multipartFile.getInputStream();
	//上传到oss
	String imageUrl = recvHikVisionUploadImage(inputStream,originalFilename);
}

private static String readInfoStreamToBytes(InputStream is) {
	if (is == null) {
		return null;
	}
	// 字节数组
	byte[] bCache = new byte[2048];
	int readSize = 0;// 每次读取的字节长度
	int totalSize = 0;// 总字节长度
	ByteArrayOutputStream infoStream = new ByteArrayOutputStream();
	try {
		// 一次性读取2048字节
		while ((readSize = is.read(bCache)) > 0) {
			totalSize += readSize;
			if (totalSize > 1024 * 1024 * 10) {
				return null;
			}
			// 将bcache中读取的input数据写入infoStream
			infoStream.write(bCache, 0, readSize);
		}
	} catch (IOException e1) {
		return null;
	} finally {
		try {
			is.close();
		} catch (IOException e) {
		}
	}
	BASE64Encoder encoder = new BASE64Encoder();
	return encoder.encode(infoStream.toByteArray());
}

public String recvHikVisionUploadImage(InputStream inputStream,String originalFilename){
	try {
		String imgStr = readInfoStreamToBytes(inputStream);

		sun.misc.BASE64Decoder decoder = new sun.misc.BASE64Decoder();

		// Base64解码
		byte[] b = decoder.decodeBuffer(imgStr);
		for (int i = 0; i < b.length; ++i) {
			if (b[i] < 0) {// 调整异常数据
				b[i] += 256;
			}
		}
		//上传到oss
		BaseResult<String> result = ossV2Helper.uploadFileInputStream(b, originalFilename +".jpg", "jpg");
		return result.getData();
	}catch (IOException e){
		e.printStackTrace();
	}
	return null;
}

下面是完整代码，有model类和一些判断会删除掉

@RequestMapping("/XXX")
public BaseResult<XXX> XXX(HttpServletRequest request) throws IOException {
	StandardMultipartHttpServletRequest standardMultipartHttpServletRequest = (StandardMultipartHttpServletRequest) request;
	Map<String, String[]> parameterMap = standardMultipartHttpServletRequest.getParameterMap();
	String[] imageFiles= parameterMap.get("imageFile");//上报的文件的参数名称
	if(!StringUtils.isEmpty(mixedTargetDetections) && mixedTargetDetections.length > 0){
		//获取必要的设备信息
		String mixedTargetDetection = mixedTargetDetections[0];
		JSONObject jsonObject = JSONObject.parseObject(mixedTargetDetection);
		if(!StringUtils.isEmpty(jsonObject.get("macAddress"))){
			//mac地址
			String macAddress = jsonObject.get("macAddress").toString();
			String deviceMac = macAddress.replaceAll(":", "");
			MultiValueMap<String, MultipartFile> multiFileMap = standardMultipartHttpServletRequest.getMultiFileMap();
			//获取文件
			MultipartFile multipartFile = multiFileMap.getFirst("xxxFile");
			if(multipartFile != null){
				String originalFilename = multipartFile.getOriginalFilename();
				InputStream inputStream = multipartFile.getInputStream();
				String imageUrl = recvHikVisionUploadImage(inputStream,originalFilename);
				
			}else {
				logger.info("nofaceImage=" +multiFileMap.toString());
			}
		}else{
			logger.info("mixedTargetDetection=" +mixedTargetDetection);
		}
	}else{
		logger.info("parameterMap=" +parameterMap.toString());
	}

	return BaseResult.success();
}

private static String readInfoStreamToBytes(InputStream is) {
	if (is == null) {
		return null;
	}
	// 字节数组
	byte[] bCache = new byte[2048];
	int readSize = 0;// 每次读取的字节长度
	int totalSize = 0;// 总字节长度
	ByteArrayOutputStream infoStream = new ByteArrayOutputStream();
	try {
		// 一次性读取2048字节
		while ((readSize = is.read(bCache)) > 0) {
			totalSize += readSize;
			if (totalSize > 1024 * 1024 * 10) {
				return null;
			}
			// 将bcache中读取的input数据写入infoStream
			infoStream.write(bCache, 0, readSize);
		}
	} catch (IOException e1) {
		return null;
	} finally {
		try {
			is.close();
		} catch (IOException e) {
		}
	}
	BASE64Encoder encoder = new BASE64Encoder();
	return encoder.encode(infoStream.toByteArray());
}

public String recvHikVisionUploadImage(InputStream inputStream,String originalFilename){
	try {
		String imgStr = readInfoStreamToBytes(inputStream);

		sun.misc.BASE64Decoder decoder = new sun.misc.BASE64Decoder();

		// Base64解码
		byte[] b = decoder.decodeBuffer(imgStr);
		for (int i = 0; i < b.length; ++i) {
			if (b[i] < 0) {// 调整异常数据
				b[i] += 256;
			}
		}
		
		BaseResult<String> result = ossV2Helper.uploadFileInputStream(b, originalFilename +".jpg", "jpg");
		return result.getData();
	}catch (IOException e){
		e.printStackTrace();
	}
	return null;
}