springmvc + VUE大文件分片上传前后端MD5加密

Spring MVC + Vue.js 的大文件分片上传前后端MD5加密流程如下：

1. 前端通过 Vue.js 实现文件的分片上传，同时计算每个分片的MD5值。

<template>
  <div>
    <input type="file" @change="uploadFile"/>
  </div>
</template>

<script>
import SparkMD5 from 'spark-md5'

export default {
  name: 'FileUpload',
  methods: {
    async uploadFile(event) {
      const file = event.target.files[0]
      const chunkSize = 2097152 // 每个分片的大小为2MB
      const chunks = Math.ceil(file.size / chunkSize) // 文件分成的总块数
      const fileReader = new FileReader()
      const spark = new SparkMD5.ArrayBuffer()
      const md5List = []

      for (let i = 0; i < chunks; i++) {
        const start = i * chunkSize
        const end = start + chunkSize > file.size ? file.size : start + chunkSize
        const chunk = file.slice(start, end)
        const chunkReader = new FileReader()

        chunkReader.onload = e => {
          spark.append(e.target.result)
          md5List.push(spark.end())
        }

        chunkReader.readAsArrayBuffer(chunk)
      }

      fileReader.onload = e => {
        const formData = new FormData()
        formData.append('file', file)
        formData.append('md5List', JSON.stringify(md5List))

        // 发送文件分片和MD5值到后端
        this.$axios.post('/uploadFile', formData)
      }

      fileReader.readAsArrayBuffer(file)
    }
  }
}
</script>

2. 后端 Spring MVC 接收到文件分片和 MD5 值，对每个分片进行 MD5 计算，最后将所有分片的 MD5 值进行合并，得到整个文件的 MD5 值，并与前端传过来的 MD5 值进行比较，如果相同，则说明文件传输完整无误。

import org.springframework.web.bind.annotation.*;
import org.springframework.web.multipart.MultipartFile;
import javax.servlet.http.HttpServletRequest;
import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.List;

@RestController
public class FileUploadController {

    @PostMapping("/uploadFile")
    public void uploadFile(@RequestParam("file") MultipartFile file,
                           @RequestParam("md5List") String md5List,
                           HttpServletRequest request) throws IOException, NoSuchAlgorithmException {
        // 将 MD5 值的 JSON 字符串转换成 List
        List<String> md5Array = JSON.parseArray(md5List, String.class);

        // 计算文件的 MD5 值
        MessageDigest md5Digest = MessageDigest.getInstance("MD5");
        byte[] buffer = new byte[1024 * 1024];
        int len;

        try (RandomAccessFile randomAccessFile = new RandomAccessFile(file.getOriginalFilename(), "rw")) {
            for (int i = 0; i < md5Array.size(); i++) {
                randomAccessFile.seek(i * buffer.length);
                len = randomAccessFile.read(buffer, 0, buffer.length);
                md5Digest.update(buffer, 0, len);

                if (!md5Array.get(i).equals(getMD5(buffer, len))) {
                    throw new IOException("文件传输错误");
                }
            }

            randomAccessFile.seek(0);
            while ((len = file.getInputStream().read(buffer)) != -1) {
                randomAccessFile.write(buffer, 0, len);
            }
        }

        // 保存文件
        File newFile = new File("upload/" + file.getOriginalFilename());
        file.transferTo(newFile);
    }

    private String getMD5(byte[] buffer, int len) throws NoSuchAlgorithmException {
        MessageDigest md5Digest = MessageDigest.getInstance("MD5");
        md5Digest.update(buffer, 0, len);
        byte[] md5Bytes = md5Digest.digest();
        StringBuilder stringBuilder = new StringBuilder();

        for (byte md5Byte : md5Bytes) {
            int value = md5Byte & 0xFF;
            if (value < 16) {
                stringBuilder.append("0");
            }

            stringBuilder.append(Integer.toHexString(value));
        }

        return stringBuilder.toString();
    }
}

以上代码仅供参考，实际应用中需要根据具体需求进行修改。