java fastdfs分片上传，文件重组代码实现

FastDFS是一个开源的分布式文件系统，主要用于解决大容量、高并发的文件存储需求。在FastDFS中，文件通常会被切割成多个小块（分片），每个分片独立存储，然后通过Tracker服务器进行管理。如果需要将文件上传到FastDFS并进行重组，你需要编写客户端程序来完成这个过程。

以下是一个简单的Java代码示例，展示如何分片上传文件，并在接收到所有分片后下载并重组：

import org.apache.commons.io.IOUtils;
import com.github.binarywang.fastdfs.FastDFSClient;

public class FastDFSFileUploader {
    private final FastDFSClient client;
    
    public FastDFSFileUploader(String group) {
        client = new FastDFSClient("localhost", 2111);
        client.setGroup(group);
    }

    // 分片上传文件
    public boolean uploadChunkedFile(String localFilePath, String groupName, String remoteFileName) throws Exception {
        byte[] fileBytes = IOUtils.toByteArray(new File(localFilePath));
        int chunkSize = 1024 * 1024; // 每个分片大小，比如1MB

        for (int i = 0; i < fileBytes.length / chunkSize + (fileBytes.length % chunkSize > 0 ? 1 : 0); i++) {
            byte[] chunk = Arrays.copyOfRange(fileBytes, i * chunkSize, Math.min((i + 1) * chunkSize, fileBytes.length));
            String fileNameWithoutExt = remoteFileName.substring(0, remoteFileName.lastIndexOf('.'));
            String suffix = i == 0 ? "" : "-" + (i + 1);

            String path = "/" + groupName + "/" + fileNameWithoutExt + suffix + ".jpg";
            client.upload(path, chunk);
        }
        return true;
    }

    // 文件接收并重组
    public InputStream downloadAndReconstructFile(String remoteFileName) throws Exception {
        List<LocatedInfo> locatedInfos = client.locateFile(remoteFileName);
        if (locatedInfos.isEmpty()) {
            throw new FileNotFoundException("File not found");
        }

        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        for (LocatedInfo locatedInfo : locatedInfos) {
            byte[] chunk = client.download(locatedInfo.getPath());
            outputStream.write(chunk);
        }
        return new ByteArrayInputStream(outputStream.toByteArray());
    }
}