如何在android中显示FTP下载的进度条更新

import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.ProgressBar;

import org.apache.commons.net.ftp.FTP;
import org.apache.commons.net.ftp.FTPClient;

import java.io.BufferedOutputStream;
import java.io.FileOutputStream;
import java.io.IOException;

public class FTPDownloadActivity extends AppCompatActivity {

    private ProgressBar progressBar;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_ftp_download);

        progressBar = findViewById(R.id.progressBar);

        // 创建并执行FTP下载任务
        FTPDownloadTask ftpDownloadTask = new FTPDownloadTask();
        ftpDownloadTask.execute();
    }

    private class FTPDownloadTask extends AsyncTask<Void, Integer, Boolean> {

        private static final String FTP_HOST = "ftp.example.com";
        private static final int FTP_PORT = 21;
        private static final String FTP_USERNAME = "username";
        private static final String FTP_PASSWORD = "password";
        private static final String FILE_PATH = "/remote/file/path";
        private static final String LOCAL_FILE_PATH = "/local/file/path";

        @Override
        protected Boolean doInBackground(Void... voids) {
            FTPClient ftpClient = new FTPClient();
            try {
                // 连接FTP服务器
                ftpClient.connect(FTP_HOST, FTP_PORT);
                ftpClient.login(FTP_USERNAME, FTP_PASSWORD);

                // 设置传输模式和字符编码
                ftpClient.setFileType(FTP.BINARY_FILE_TYPE);
                ftpClient.setControlEncoding("UTF-8");

                // 获取文件大小
                long fileSize = ftpClient.mlistFile(FILE_PATH).getSize();

                // 创建本地文件
                BufferedOutputStream outputStream = new BufferedOutputStream(new FileOutputStream(LOCAL_FILE_PATH));

                // 下载文件
                ftpClient.retrieveFile(FILE_PATH, outputStream);
                outputStream.close();

                return true;
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                try {
                    // 断开FTP连接
                    ftpClient.disconnect();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

            return false;
        }

        @Override
        protected void onPostExecute(Boolean result) {
            if (result) {
                // 下载成功
                // 进行其他操作或显示成功信息
            } else {
                // 下载失败
                // 进行其他操作或显示失败信息
            }
        }

        @Override
        protected void onProgressUpdate(Integer... values) {
            int progress = values[0];
            progressBar.setProgress(progress);
        }
    }
}