用Java实现minio分片上传下载文件

Minio是一个开源的分布式对象存储系统，它允许用户在存储服务上存储和检索数据。它支持S3 API，因此可以与大多数S3兼容的客户端和工具一起使用。

下面是使用Java实现Minio分片上传和下载文件的示例代码：

## 分片上传

import io.minio.MinioClient;
import io.minio.errors.MinioException;
import io.minio.messages.Part;

import java.io.IOException;
import java.io.InputStream;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.security.NoSuchAlgorithmException;
import java.util.ArrayList;
import java.util.List;

public class MinioUploader {
    private MinioClient minioClient;
    private final String bucketName;

    public MinioUploader(MinioClient minioClient, String bucketName) {
        this.minioClient = minioClient;
        this.bucketName = bucketName;
    }

    public void upload(String objectName, Path filePath) throws NoSuchAlgorithmException, IOException, MinioException {
        long fileSize = Files.size(filePath);
        long partSize = 5 * 1024 * 1024; // 5MB
        int partCount = (int) Math.ceil((double) fileSize / partSize);

        List<Part> parts = new ArrayList<>();
        for (int i = 0; i < partCount; i++) {
            int partNumber = i + 1;
            long offset = i * partSize;
            long size = Math.min(partSize, fileSize - offset);

            InputStream inputStream = Files.newInputStream(filePath);
            inputStream.skip(offset);

            String uploadId = minioClient.initiateMultipartUpload(bucketName, objectName);
            Part part = minioClient.uploadPart(bucketName, objectName, uploadId, partNumber, inputStream, size);

            parts.add(part);
        }

        minioClient.completeMultipartUpload(bucketName, objectName, parts);
    }
}

## 分片下载

import io.minio.MinioClient;
import io.minio.errors.MinioException;

import java.io.BufferedOutputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.file.Path;
import java.security.NoSuchAlgorithmException;
import java.util.List;

public class MinioDownloader {
    private MinioClient minioClient;
    private final String bucketName;

    public MinioDownloader(MinioClient minioClient, String bucketName) {
        this.minioClient = minioClient;
        this.bucketName = bucketName;
    }

    public void download(String objectName, Path filePath) throws NoSuchAlgorithmException, IOException, MinioException {
        long partSize = 5 * 1024 * 1024; // 5MB

        List<io.minio.messages.Part> parts = minioClient.listObjectParts(bucketName, objectName, null).getParts();
        try (BufferedOutputStream outputStream = new BufferedOutputStream(new FileOutputStream(filePath.toFile()))) {
            for (io.minio.messages.Part part : parts) {
                InputStream inputStream = minioClient.getObject(bucketName, objectName, part.partNumber(), 0L, partSize);
                byte[] buffer = new byte[1024];
                int bytesRead;
                while ((bytesRead = inputStream.read(buffer)) != -1) {
                    outputStream.write(buffer, 0, bytesRead);
                }
                inputStream.close();
            }
        }
    }
}

这是一个基本的示例，实际使用时需要根据具体需求进行修改。