文件切割合并

超、凢脫俗 2024-03-26 09:56 83阅读 0赞

切割：

@Test
        public void chunk() throws IOException{
            File file = new File("F:\\java学习项目文件夹\\微服务项目(学成在线)\\测试上传文件分块合并\\video.mp4");
            String chunkPath = "F:\\java学习项目文件夹\\微服务项目(学成在线)\\测试上传文件分块合并\\chunk\\";
            File chunkFolder = new File(chunkPath);
    
            chunkFolder.deleteOnExit();
    
    //        int len = 1024;
            long chunkSize = 1024 * 1024 * 1;
            long chunkNum = (long) Math.ceil(file.length() * 1.0 / chunkSize);
    
            //缓冲数组
            byte[] b = new byte[1024];
            //使用randomAccessFile访问文件
            RandomAccessFile raf_read = new RandomAccessFile(file, "r");
    
            for (int i = 0; i < chunkNum; i++) {
                File fileT = new File(chunkPath + i);
                if(fileT.exists()){
                    fileT.delete();
                }
                boolean newFile = fileT.createNewFile();
                if(newFile){
                    RandomAccessFile raf_write
                            = new RandomAccessFile(fileT, "rw");
                    int len = -1;
                    while ((len = raf_read.read(b)) != -1){
                        raf_write.write(b,0,len);
                        if(fileT.length() >= chunkSize){
                            break;
                        }
                    }
                    raf_write.close();
                }
            }
            raf_read.close();
    
        }

合并

@Test
        public void testMerge() throws IOException {
            //块文件目录
            File chunkFolder = new File("F:\\java学习项目文件夹\\微服务项目(学成在线)\\测试上传文件分块合并\\chunk\\");
            //原始文件
            File originalFile = new File("F:\\java学习项目文件夹\\微服务项目(学成在线)\\测试上传文件分块合并\\video.mp4");
            //合并文件
            File mergeFile = new File("F:\\java学习项目文件夹\\微服务项目(学成在线)\\测试上传文件分块合并\\new.mp4");
            if (mergeFile.exists()) {
                mergeFile.delete();
            }
            //创建新的合并文件
            mergeFile.createNewFile();
            //用于写文件
            RandomAccessFile raf_write = new RandomAccessFile(mergeFile, "rw");
            //指针指向文件顶端
            raf_write.seek(0);
            //缓冲区
            byte[] b = new byte[1024];
            //分块列表
            File[] fileArray = chunkFolder.listFiles();
            // 转成集合，便于排序
            List<File> fileList = new ArrayList<File>(Arrays.asList(fileArray));
            // 从小到大排序
            Collections.sort(fileList, new Comparator<File>() {
                @Override
                public int compare(File o1, File o2) {
                    return Integer.parseInt(o1.getName()) - Integer.parseInt(o2.getName());
                }
            });
            //合并文件
            for (File chunkFile : fileList) {
                RandomAccessFile raf_read = new RandomAccessFile(chunkFile, "rw");
                int len = -1;
                while ((len = raf_read.read(b)) != -1) {
                    raf_write.write(b, 0, len);
    
                }
                raf_read.close();
            }
            raf_write.close();
    
            //校验文件
            try (
    
                    FileInputStream fileInputStream = new FileInputStream(originalFile);
                    FileInputStream mergeFileStream = new FileInputStream(mergeFile);
    
    
            ) {
                //取出原始文件的md5
                String originalMd5 = DigestUtils.md5Hex(fileInputStream);
                //取出合并文件的md5进行比较
                String mergeFileMd5 = DigestUtils.md5Hex(mergeFileStream);
                if (originalMd5.equals(mergeFileMd5)) {
                    System.out.println("合并文件成功");
                } else {
                    System.out.println("合并文件失败");
                }
    
            }
    
    
        }