用Java写一个ftp分片上传下载的代码

以下是Java实现ftp分片上传下载的示例代码：

FTP上传分片代码：

import org.apache.commons.net.ftp.FTP;
import org.apache.commons.net.ftp.FTPClient;
import java.io.*;

public class FTPUploader {

    private FTPClient ftp;
    private String host;
    private String username;
    private String password;
    private int port;

    public FTPUploader(String host, String username, String password, int port) {
        this.host = host;
        this.username = username;
        this.password = password;
        this.port = port;
        ftp = new FTPClient();
    }

    public void connect() throws Exception {
        ftp.connect(host, port);
        ftp.login(username, password);
        ftp.enterLocalPassiveMode();
        ftp.setFileType(FTP.BINARY_FILE_TYPE);
        ftp.setFileTransferMode(FTP.STREAM_TRANSFER_MODE);
        ftp.setBufferSize(1024 * 1024);
        ftp.setControlEncoding("UTF-8");
    }

    public void uploadFile(String remotePath, String localPath, int chunkSize) throws Exception {
        File localFile = new File(localPath);
        FileInputStream fis = new FileInputStream(localFile);
        ftp.changeWorkingDirectory(remotePath);
        ftp.setFileType(FTP.BINARY_FILE_TYPE);
        String fileName = localFile.getName();
        long fileSize = localFile.length();
        int chunks = (int) Math.ceil((double) fileSize / chunkSize);
        byte[] buffer = new byte[chunkSize];
        for (int i = 0; i < chunks; i++) {
            long startByte = i * chunkSize;
            long endByte = Math.min(fileSize, startByte + chunkSize) - 1;
            int bytesRead = 0;
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            while ((bytesRead = fis.read(buffer)) != -1) {
                baos.write(buffer, 0, bytesRead);
                if (baos.size() == chunkSize) {
                    break;
                }
            }
            ByteArrayInputStream bais = new ByteArrayInputStream(baos.toByteArray());
            ftp.storeFile(fileName + "." + i, bais);
            baos.close();
            bais.close();
        }
        fis.close();
    }

    public void disconnect() throws Exception {
        if (ftp.isConnected()) {
            ftp.logout();
            ftp.disconnect();
        }
    }
}

FTP下载分片代码：

import org.apache.commons.net.ftp.FTP;
import org.apache.commons.net.ftp.FTPClient;
import java.io.*;

public class FTPDownloader {

    private FTPClient ftp;
    private String host;
    private String username;
    private String password;
    private int port;

    public FTPDownloader(String host, String username, String password, int port) {
        this.host = host;
        this.username = username;
        this.password = password;
        this.port = port;
        ftp = new FTPClient();
    }

    public void connect() throws Exception {
        ftp.connect(host, port);
        ftp.login(username, password);
        ftp.enterLocalPassiveMode();
        ftp.setFileType(FTP.BINARY_FILE_TYPE);
        ftp.setFileTransferMode(FTP.STREAM_TRANSFER_MODE);
        ftp.setBufferSize(1024 * 1024);
        ftp.setControlEncoding("UTF-8");
    }

    public void downloadFile(String remotePath, String localPath, int chunkSize) throws Exception {
        File localFile = new File(localPath);
        FileOutputStream fos = new FileOutputStream(localFile);
        ftp.changeWorkingDirectory(remotePath);
        ftp.setFileType(FTP.BINARY_FILE_TYPE);
        String fileName = localFile.getName();
        int i = 0;
        while (true) {
            InputStream is = ftp.retrieveFileStream(fileName + "." + i);
            if (is == null) {
                break;
            }
            byte[] buffer = new byte[chunkSize];
            int bytesRead = 0;
            while ((bytesRead = is.read(buffer)) != -1) {
                fos.write(buffer, 0, bytesRead);
            }
            is.close();
            ftp.completePendingCommand();
            i++;
        }
        fos.close();
    }

    public void disconnect() throws Exception {
        if (ftp.isConnected()) {
            ftp.logout();
            ftp.disconnect();
        }
    }
}

使用示例：

public static void main(String[] args) throws Exception {
    String host = "ftp.example.com";
    String username = "username";
    String password = "password";
    int port = 21;
    String remotePath = "/path/to/remote/file";
    String localPath = "/path/to/local/file";
    int chunkSize = 1024 * 1024; // 1MB
    FTPUploader uploader = new FTPUploader(host, username, password, port);
    uploader.connect();
    uploader.uploadFile(remotePath, localPath, chunkSize);
    uploader.disconnect();
    FTPDownloader downloader = new FTPDownloader(host, username, password, port);
    downloader.connect();
    downloader.downloadFile(remotePath, localPath, chunkSize);
    downloader.disconnect();
}