java ftp 复制文件

以下是使用Java实现FTP文件复制的示例代码：

import org.apache.commons.net.ftp.FTP;
import org.apache.commons.net.ftp.FTPClient;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

public class FTPUtil {

    private FTPClient ftpClient;

    /**
     * 连接FTP服务器
     *
     * @param host     FTP服务器地址
     * @param port     FTP服务器端口号
     * @param username FTP登录账号
     * @param password FTP登录密码
     * @throws IOException
     */
    public void connect(String host, int port, String username, String password) throws IOException {
        ftpClient = new FTPClient();
        ftpClient.connect(host, port);
        ftpClient.login(username, password);
        ftpClient.setFileType(FTP.BINARY_FILE_TYPE);
    }

    /**
     * 复制文件
     *
     * @param srcFilePath  源文件路径
     * @param destFilePath 目标文件路径
     * @throws IOException
     */
    public void copyFile(String srcFilePath, String destFilePath) throws IOException {
        InputStream input = ftpClient.retrieveFileStream(srcFilePath);
        OutputStream output = ftpClient.storeFileStream(destFilePath);
        byte[] buffer = new byte[1024];
        int len;
        while ((len = input.read(buffer)) > 0) {
            output.write(buffer, 0, len);
        }
        input.close();
        output.close();
        boolean success = ftpClient.completePendingCommand();
        if (!success) {
            throw new IOException("Failed to copy file: " + srcFilePath);
        }
    }

    /**
     * 关闭FTP连接
     *
     * @throws IOException
     */
    public void disconnect() throws IOException {
        ftpClient.logout();
        ftpClient.disconnect();
    }
}

使用示例：

public class Main {

    public static void main(String[] args) {
        FTPUtil ftpUtil = new FTPUtil();
        try {
            ftpUtil.connect("ftp.example.com", 21, "username", "password");
            ftpUtil.copyFile("/remote/path/file.txt", "/remote/path/copy_of_file.txt");
            ftpUtil.disconnect();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

请将 "ftp.example.com", "username", "password", "/remote/path/file.txt", "/remote/path/copy_of_file.txt" 替换为您自己的FTP服务器信息和文件路径。