teaching-java/src/main/java/com/teaching/backend/utils/UploadUtils.java

package com.teaching.backend.utils;

import lombok.extern.slf4j.Slf4j;
import org.apache.commons.io.FilenameUtils;
import org.apache.commons.io.FileUtils;
import org.springframework.util.DigestUtils;
import org.springframework.web.multipart.MultipartFile;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.util.*;

import static com.teaching.backend.utils.Constants.UPLOAD_URL;

@Slf4j
//文件上传工具类
public class UploadUtils {

    public static String saveFileByDirectory (MultipartFile file) {
        String url = "";
        try {
            // 将文件保存在服务器目录中
            // 文件名称
            String uuid = UUID.randomUUID().toString();
            // 得到上传文件后缀
            String originalName = file.getOriginalFilename();
            String ext = "." + FilenameUtils.getExtension(originalName);
            // 新生成的文件名称
            String fileName = uuid + ext;
            // 复制文件
            File targetFile = new File(UPLOAD_URL, fileName);
            url = UPLOAD_URL + fileName;
            FileUtils.writeByteArrayToFile(targetFile, file.getBytes());
            System.out.println("保存成功");
        } catch (IOException e) {
            log.error("保存文件到服务器（本地）失败",e);
        }
        return url;
    }

    public static void Chunk(File sourseFile) throws IOException {
//        //源文件
//        File sourseFile = new File("D:/Users/Desktop/image/剪映/7.18/7月20.mp4");
        //分块文件存储路径
        String chunkFilePath = "E:\\workspace\\chunk";
        //分块文件大小
        int chunkSize = 1024 * 1024 * 1;
        //分块文件个数
        int chunkNum = (int) Math.ceil(sourseFile.length() * 1.0 / chunkSize);
        //使用流从源文件读数据，向分块文件中写数据
        RandomAccessFile raf_r = new RandomAccessFile(sourseFile, "r");
        //缓存区
        byte[] bytes = new byte[1024];
        for (int i = 0; i < chunkNum; i++) {
            File chunkFile = new File(chunkFilePath + i);
            //分块文件写入流
            RandomAccessFile raf_rw = new RandomAccessFile(chunkFile, "rw");
            int len = -1;
            while((len=raf_r.read(bytes)) != -1){
                raf_rw.write(bytes, 0, len);
                if (chunkFile.length() >= chunkSize){
                    break;
                }
            }
            raf_rw.close();
        }
        raf_r.close();
    }

    public static void Merge(File sourseFile) throws IOException {
        //块文件目录
        File chunkFolder = new File("E:\\workspace\\chunk");
//        //源文件
//        File sourseFile = new File("D:/Users/Desktop/image/剪映/7.18/7月20.mp4");
        //合并后的文件
        File mergeFile = new File("E:\\workspace\\file\\"+sourseFile.getName());

        //取出所有分块文件
        File[] files = chunkFolder.listFiles();
        //将数组转成list
        List<File> fileList = Arrays.asList(files);
        //对分块文件排序
        Collections.sort(fileList, new Comparator<File>() {
            @Override
            public int compare(File o1, File o2) {
                return Integer.parseInt(o1.getName()) - Integer.parseInt(o2.getName()); //升序
            }
        });
        //向合并文件写的流
        RandomAccessFile raf_rw = new RandomAccessFile(mergeFile, "rw");
        //缓存区
        byte[] bytes = new byte[1024];
        //遍历分块文件，向合并的文件写
        for (File file : fileList) {
            //读分块的流
            RandomAccessFile raf_r = new RandomAccessFile(file, "r");
            int len = -1;
            while((len = raf_r.read(bytes)) != -1){
                raf_rw.write(bytes, 0, len);
            }
            raf_r.close();
        }
        raf_rw.close();
        //合并文件完成后对合并的文件校验
        FileInputStream fileInputStream_merge = new FileInputStream(mergeFile);
        FileInputStream fileInputStream_source = new FileInputStream(sourseFile);
        String md5_merge = DigestUtils.md5DigestAsHex(fileInputStream_merge);
        String md5_source = DigestUtils.md5DigestAsHex(fileInputStream_source);
        if (md5_merge.equals(md5_source)){
            System.out.println("文件合并成功！");
        }
    }
}