import org.springframework.stereotype.Component;
import java.io.File;
import java.util.Arrays;
import java.util.List;

@Component
public class FileUtil {
  public static final List<String> IMAGE_EXTENSIONS = Arrays.asList(".jpg", ".jpeg", ".png");
}

import java.util.UUID;

public class CommonUtil {
  public static String getUUID() {
    String uuid = UUID.randomUUID().toString().replaceAll("-", "");
    return uuid;
  }
}

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;

public class DateUtil {
  public static final String HH = "HH";
  public static final String YYYY_MM_DD = "yyyy-MM-dd";
  public static final DateTimeFormatter FORMATTER_HH = DateTimeFormatter.ofPattern(HH);
  public static final DateTimeFormatter FORMATTER_YYYY_MM_DD = DateTimeFormatter.ofPattern(YYYY_MM_DD);
  public static String getHH() {
    return FORMATTER_HH.format(LocalDateTime.now());
  }
  public static String getYYYYMMDD() {
    return FORMATTER_YYYY_MM_DD.format(LocalDateTime.now());
  }
}

@PostMapping("/updateImage.do")
public Map<String, String> updateImage(@RequestParam("image") MultipartFile[] multfiles) {
  	Map<String, String> result = new HashMap<>();
    if (multfiles.length == 0) {
			result.put("message", "請(qǐng)選擇圖片！");
			return result;
    }

    // 源文件名稱
    final String originalFileName = multfiles[0].getOriginalFilename();
    if (StringUtils.isBlank(originalFileName)) {
			result.put("message", "請(qǐng)選擇圖片！");
			return result;
    }

    // 文件后綴[.jpg]
    final String suffix = originalFileName.substring(originalFileName.lastIndexOf(".")).toLowerCase();
    if (!FileUtil.IMAGE_EXTENSIONS.contains(suffix)) {
			result.put("message", "圖片格式錯(cuò)誤！");
			return result;
    }

    String lastFilePath;
    String newFileName = CommonUtil.getUUID() + suffix;
    String folderName = File.separator + "temp" + File.separator;
    String relativePath = folderName + DateUtil.getYYYYMMDD() + File.separator + DateUtil.getHH();
    String filePath = "D:\\file" + relativePath;
    String fileUrl = null;
    File targetFile = new File(filePath);
    if (!targetFile.exists()) {
      targetFile.mkdirs();
    }
    FileOutputStream out = null;
    try {
      lastFilePath = filePath + File.separator + newFileName;
      out = new FileOutputStream(lastFilePath);
      out.write(multfiles[0].getBytes());
      fileUrl = "http://127.0.0.1:9000" + relativePath + File.separator + newFileName;
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
      if (out != null) {
        try {
          out.flush();
        } catch (IOException e) {
          e.printStackTrace();
        }
        try {
          out.close();
        } catch (IOException e) {
          e.printStackTrace();
        }
      }
    }

    if (fileUrl == null) {
			result.put("message", "圖片上傳失敗！");
			return result;
    }

		result.put("message", "上傳成功！");
		result.put("url", fileUrl);
		return result;
  }

url => http://127.0.0.1:9000/temp/2019-09-12/14/0eac00b96f134652b34172e84febe8d1.jpg