fileMD5 (files) {
    // 計(jì)算文件md5
    return new  Promise((resolve,reject) => {
      const fileReader = new FileReader();
      const piece = Math.ceil(files.size / this.pieceSize);
      const nextPiece = () => {
        let start = currentPieces * this.pieceSize;
        let end = start * this.pieceSize >= files.size ? files.size : start + this.pieceSize;
        fileReader.readAsArrayBuffer(files.slice(start,end));
      };
 
      let currentPieces = 0;
      fileReader.onload = (event) => {
        let e = window.event || event;
        this.spark.append(e.target.result);
        currentPieces++
        if (currentPieces < piece) {
          nextPiece()
        } else {
          resolve({fileName: files.name, fileMd5: this.spark.end()})
        }
      }
      // fileReader.onerror = (err => { reject(err) })
      nextPiece()
    })
  }

//創(chuàng)建隨機(jī)存儲(chǔ)文件流，文件屬性由參數(shù)File對(duì)象指定
RandomAccessFile(File file ,  String mode)

//創(chuàng)建隨機(jī)存儲(chǔ)文件流，文件名由參數(shù)name指定
RandomAccessFile(String name ,  String mode)

import java.io.RandomAccessFile;
import java.nio.charset.StandardCharsets;
public class RandomFileTest {
    private static final String filePath = "C:\\Users\\NineSun\\Desktop\\employee.txt";

    public static void main(String[] args) throws Exception {
        Employee e1 = new Employee("zhangsan", 23);
        Employee e2 = new Employee("lisi", 24);
        Employee e3 = new Employee("wangwu", 25);
        RandomAccessFile ra = new RandomAccessFile(filePath, "rw");
        ra.write(e1.name.getBytes(StandardCharsets.UTF_8));//防止寫入文件亂碼
        ra.writeInt(e1.age);
        ra.write(e2.name.getBytes());
        ra.writeInt(e2.age);
        ra.write(e3.name.getBytes());
        ra.writeInt(e3.age);
        ra.close();
        RandomAccessFile raf = new RandomAccessFile(filePath, "r");
        int len = 8;
        raf.skipBytes(12);//跳過第一個(gè)員工的信息，其姓名8字節(jié)，年齡4字節(jié)
        System.out.println("第二個(gè)員工信息：");
        String str = "";
        for (int i = 0; i < len; i++) {
            str = str + (char) raf.readByte();
        }
        System.out.println("name:" + str);
        System.out.println("age:" + raf.readInt());
        System.out.println("第一個(gè)員工信息：");
        raf.seek(0);//將文件指針移動(dòng)到文件開始位置
        str = "";
        for (int i = 0; i < len; i++) {
            str = str + (char) raf.readByte();
        }
        System.out.println("name:" + str);
        System.out.println("age:" + raf.readInt());
        System.out.println("第三個(gè)員工信息：");
        raf.skipBytes(12);//跳過第二個(gè)員工的信息
        str = "";
        for (int i = 0; i < len; i++) {
            str = str + (char) raf.readByte();
        }
        System.out.println("name:" + str);
        System.out.println("age:" + raf.readInt());
        raf.close();
    }
}

class Employee {
    String name;
    int age;
    final static int LEN = 8;

    public Employee(String name, int age) {
        if (name.length() > LEN) {
            name = name.substring(0, 8);
        } else {
            while (name.length() < LEN) {
                name = name + "\u0000";
            }
            this.name = name;
            this.age = age;
        }
    }
}

@UploadMode(mode = UploadModeEnum.RANDOM_ACCESS)
@Slf4j
public class RandomAccessUploadStrategy extends SliceUploadTemplate {

  @Autowired
  private FilePathUtil filePathUtil;

  @Value("${upload.chunkSize}")
  private long defaultChunkSize;

  @Override
  public boolean upload(FileUploadRequestDTO param) {
    RandomAccessFile accessTmpFile = null;
    try {
      String uploadDirPath = filePathUtil.getPath(param);
      File tmpFile = super.createTmpFile(param);
      accessTmpFile = new RandomAccessFile(tmpFile, "rw");
      //這個(gè)必須與前端設(shè)定的值一致
      long chunkSize = Objects.isNull(param.getChunkSize()) ? defaultChunkSize * 1024 * 1024
          : param.getChunkSize();
      long offset = chunkSize * param.getChunk();
      //定位到該分片的偏移量
      accessTmpFile.seek(offset);
      //寫入該分片數(shù)據(jù)
      accessTmpFile.write(param.getFile().getBytes());
      boolean isOk = super.checkAndSetUploadProgress(param, uploadDirPath);
      return isOk;
    } catch (IOException e) {
      log.error(e.getMessage(), e);
    } finally {
      FileUtil.close(accessTmpFile);
    }


    return false;
  }
}

@UploadMode(mode = UploadModeEnum.MAPPED_BYTEBUFFER)
@Slf4j
public class MappedByteBufferUploadStrategy extends SliceUploadTemplate {

  @Autowired
  private FilePathUtil filePathUtil;

  @Value("${upload.chunkSize}")
  private long defaultChunkSize;

  @Override
  public boolean upload(FileUploadRequestDTO param) {

    RandomAccessFile tempRaf = null;
    FileChannel fileChannel = null;
    MappedByteBuffer mappedByteBuffer = null;
    try {
      String uploadDirPath = filePathUtil.getPath(param);
      File tmpFile = super.createTmpFile(param);
      tempRaf = new RandomAccessFile(tmpFile, "rw");
      fileChannel = tempRaf.getChannel();

      long chunkSize = Objects.isNull(param.getChunkSize()) ? defaultChunkSize * 1024 * 1024
          : param.getChunkSize();
      //寫入該分片數(shù)據(jù)
      long offset = chunkSize * param.getChunk();
      byte[] fileData = param.getFile().getBytes();
      mappedByteBuffer = fileChannel
          .map(FileChannel.MapMode.READ_WRITE, offset, fileData.length);
      mappedByteBuffer.put(fileData);
      boolean isOk = super.checkAndSetUploadProgress(param, uploadDirPath);
      return isOk;

    } catch (IOException e) {
      log.error(e.getMessage(), e);
    } finally {

      FileUtil.freedMappedByteBuffer(mappedByteBuffer);
      FileUtil.close(fileChannel);
      FileUtil.close(tempRaf);

    }

    return false;
  }

}

@Slf4j
public abstract class SliceUploadTemplate implements SliceUploadStrategy {

  public abstract boolean upload(FileUploadRequestDTO param);

  protected File createTmpFile(FileUploadRequestDTO param) {

    FilePathUtil filePathUtil = SpringContextHolder.getBean(FilePathUtil.class);
    param.setPath(FileUtil.withoutHeadAndTailDiagonal(param.getPath()));
    String fileName = param.getFile().getOriginalFilename();
    String uploadDirPath = filePathUtil.getPath(param);
    String tempFileName = fileName + "_tmp";
    File tmpDir = new File(uploadDirPath);
    File tmpFile = new File(uploadDirPath, tempFileName);
    if (!tmpDir.exists()) {
      tmpDir.mkdirs();
    }
    return tmpFile;
  }

  @Override
  public FileUploadDTO sliceUpload(FileUploadRequestDTO param) {

    boolean isOk = this.upload(param);
    if (isOk) {
      File tmpFile = this.createTmpFile(param);
      FileUploadDTO fileUploadDTO = this.saveAndFileUploadDTO(param.getFile().getOriginalFilename(), tmpFile);
      return fileUploadDTO;
    }
    String md5 = FileMD5Util.getFileMD5(param.getFile());

    Map<Integer, String> map = new HashMap<>();
    map.put(param.getChunk(), md5);
    return FileUploadDTO.builder().chunkMd5Info(map).build();
  }

  /**
   * 檢查并修改文件上傳進(jìn)度
   */
  public boolean checkAndSetUploadProgress(FileUploadRequestDTO param, String uploadDirPath) {

    String fileName = param.getFile().getOriginalFilename();
    File confFile = new File(uploadDirPath, fileName + ".conf");
    byte isComplete = 0;
    RandomAccessFile accessConfFile = null;
    try {
      accessConfFile = new RandomAccessFile(confFile, "rw");
      //把該分段標(biāo)記為 true 表示完成
      System.out.println("set part " + param.getChunk() + " complete");
      //創(chuàng)建conf文件文件長(zhǎng)度為總分片數(shù)，每上傳一個(gè)分塊即向conf文件中寫入一個(gè)127，那么沒上傳的位置就是默認(rèn)0,已上傳的就是Byte.MAX_VALUE 127
      accessConfFile.setLength(param.getChunks());
      accessConfFile.seek(param.getChunk());
      accessConfFile.write(Byte.MAX_VALUE);

      //completeList 檢查是否全部完成,如果數(shù)組里是否全部都是127(全部分片都成功上傳)
      byte[] completeList = FileUtils.readFileToByteArray(confFile);
      isComplete = Byte.MAX_VALUE;
      for (int i = 0; i < completeList.length && isComplete == Byte.MAX_VALUE; i++) {
        //與運(yùn)算, 如果有部分沒有完成則 isComplete 不是 Byte.MAX_VALUE
        isComplete = (byte) (isComplete & completeList[i]);
        System.out.println("check part " + i + " complete?:" + completeList[i]);
      }

    } catch (IOException e) {
      log.error(e.getMessage(), e);
    } finally {
      FileUtil.close(accessConfFile);
    }
    boolean isOk = setUploadProgress2Redis(param, uploadDirPath, fileName, confFile, isComplete);
    return isOk;
  }

  /**
   * 把上傳進(jìn)度信息存進(jìn)redis
   */
  private boolean setUploadProgress2Redis(FileUploadRequestDTO param, String uploadDirPath,
      String fileName, File confFile, byte isComplete) {

    RedisUtil redisUtil = SpringContextHolder.getBean(RedisUtil.class);
    if (isComplete == Byte.MAX_VALUE) {
      redisUtil.hset(FileConstant.FILE_UPLOAD_STATUS, param.getMd5(), "true");
      redisUtil.del(FileConstant.FILE_MD5_KEY + param.getMd5());
      confFile.delete();
      return true;
    } else {
      if (!redisUtil.hHasKey(FileConstant.FILE_UPLOAD_STATUS, param.getMd5())) {
        redisUtil.hset(FileConstant.FILE_UPLOAD_STATUS, param.getMd5(), "false");
        redisUtil.set(FileConstant.FILE_MD5_KEY + param.getMd5(),
            uploadDirPath + FileConstant.FILE_SEPARATORCHAR + fileName + ".conf");
      }

      return false;
    }
  }

  /**
   * 保存文件操作
   */
  public FileUploadDTO saveAndFileUploadDTO(String fileName, File tmpFile) {

    FileUploadDTO fileUploadDTO = null;

    try {

      fileUploadDTO = renameFile(tmpFile, fileName);
      if (fileUploadDTO.isUploadComplete()) {
        System.out
            .println("upload complete !!" + fileUploadDTO.isUploadComplete() + " name=" + fileName);
        //TODO 保存文件信息到數(shù)據(jù)庫

      }

    } catch (Exception e) {
      log.error(e.getMessage(), e);
    } finally {

    }
    return fileUploadDTO;
  }

  /**
   * 文件重命名
   *
   * @param toBeRenamed 將要修改名字的文件
   * @param toFileNewName 新的名字
   */
  private FileUploadDTO renameFile(File toBeRenamed, String toFileNewName) {
    //檢查要重命名的文件是否存在，是否是文件
    FileUploadDTO fileUploadDTO = new FileUploadDTO();
    if (!toBeRenamed.exists() || toBeRenamed.isDirectory()) {
      log.info("File does not exist: {}", toBeRenamed.getName());
      fileUploadDTO.setUploadComplete(false);
      return fileUploadDTO;
    }
    String ext = FileUtil.getExtension(toFileNewName);
    String p = toBeRenamed.getParent();
    String filePath = p + FileConstant.FILE_SEPARATORCHAR + toFileNewName;
    File newFile = new File(filePath);
    //修改文件名
    boolean uploadFlag = toBeRenamed.renameTo(newFile);

    fileUploadDTO.setMtime(DateUtil.getCurrentTimeStamp());
    fileUploadDTO.setUploadComplete(uploadFlag);
    fileUploadDTO.setPath(filePath);
    fileUploadDTO.setSize(newFile.length());
    fileUploadDTO.setFileExt(ext);
    fileUploadDTO.setFileId(toFileNewName);

    return fileUploadDTO;
  }

}

  @PostMapping(value = "/upload")
  @ResponseBody
  public Result<FileUploadDTO> upload(FileUploadRequestDTO fileUploadRequestDTO) throws IOException {

    boolean isMultipart = ServletFileUpload.isMultipartContent(request);
    FileUploadDTO fileUploadDTO = null;
    if (isMultipart) {

      StopWatch stopWatch = new StopWatch();
      stopWatch.start("upload");
      if (fileUploadRequestDTO.getChunk() != null && fileUploadRequestDTO.getChunks() > 0) {
        fileUploadDTO = fileService.sliceUpload(fileUploadRequestDTO);
      } else {
        fileUploadDTO = fileService.upload(fileUploadRequestDTO);
      }
      stopWatch.stop();
      log.info("{}",stopWatch.prettyPrint());

      return new Result<FileUploadDTO>().setData(fileUploadDTO);
    }

    throw new BizException("上傳失敗", 406);

  }

private boolean setUploadProgress2Redis(FileUploadRequestDTO param, String uploadDirPath,
      String fileName, File confFile, byte isComplete) {

    RedisUtil redisUtil = SpringContextHolder.getBean(RedisUtil.class);
    if (isComplete == Byte.MAX_VALUE) {
      redisUtil.hset(FileConstant.FILE_UPLOAD_STATUS, param.getMd5(), "true");
      redisUtil.del(FileConstant.FILE_MD5_KEY + param.getMd5());
      confFile.delete();
      return true;
    } else {
      if (!redisUtil.hHasKey(FileConstant.FILE_UPLOAD_STATUS, param.getMd5())) {
        redisUtil.hset(FileConstant.FILE_UPLOAD_STATUS, param.getMd5(), "false");
        redisUtil.set(FileConstant.FILE_MD5_KEY + param.getMd5(),
            uploadDirPath + FileConstant.FILE_SEPARATORCHAR + fileName + ".conf");
      }

      return false;
    }
  }