用java生成一个ftp传输，带加载条

您可以使用Apache Commons Net库来实现FTP传输，同时使用Swing库来实现FTP上传进度条。以下是一个简单的示例代码：

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.OutputStream;
import javax.swing.JFrame;
import javax.swing.JProgressBar;
import org.apache.commons.net.ftp.FTP;
import org.apache.commons.net.ftp.FTPClient;

public class FtpTransfer extends JFrame {
    private JProgressBar progressBar;
    private FTPClient ftpClient;

    public FtpTransfer() {
        progressBar = new JProgressBar(0, 100);
        add(progressBar);
        setSize(300, 100);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);
    }

    public void transfer(File file, String server, String user, String password, String remotePath) throws IOException {
        ftpClient = new FTPClient();
        ftpClient.connect(server);
        ftpClient.login(user, password);
        ftpClient.enterLocalPassiveMode();
        ftpClient.setFileType(FTP.BINARY_FILE_TYPE);

        FileInputStream inputStream = new FileInputStream(file);
        OutputStream outputStream = ftpClient.storeFileStream(remotePath + "/" + file.getName());

        long fileSize = file.length();
        long uploadedSize = 0;
        byte[] buffer = new byte[4096];
        int bytesRead = -1;
        while ((bytesRead = inputStream.read(buffer)) != -1) {
            outputStream.write(buffer, 0, bytesRead);
            uploadedSize += bytesRead;
            int progress = (int) (uploadedSize * 100 / fileSize);
            progressBar.setValue(progress);
        }
        inputStream.close();
        outputStream.close();
        ftpClient.completePendingCommand();
        ftpClient.logout();
        ftpClient.disconnect();
    }

    public static void main(String[] args) {
        FtpTransfer ftpTransfer = new FtpTransfer();
        File file = new File("example.txt");
        String server = "ftp.example.com";
        String user = "username";
        String password = "password";
        String remotePath = "/";
        try {
            ftpTransfer.transfer(file, server, user, password, remotePath);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

在这个示例代码中，我们首先创建了一个带有进度条的 Swing 窗口，然后使用 FTPClient 类连接到 FTP 服务器。在文件传输过程中，我们使用 FileInputStream 和 OutputStream 来读写文件，同时更新进度条。在传输完成后，我们关闭输入输出流，完成 FTP 传输过程。