多线程实现ftp 多文件下载并且打印文件下载进度Java springboot框架

好的，下面是一个简单的Spring Boot框架的Java代码示例，用于实现FTP多文件下载并打印下载进度：

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import org.apache.commons.net.ftp.FTPClient;
import org.apache.commons.net.ftp.FTPFile;
import org.springframework.stereotype.Component;

@Component
public class FTPDownloadService {
    private static final String FTP_SERVER = "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 FTP_DIRECTORY = "/path/to/files";
    private static final String LOCAL_DIRECTORY = "local_directory/";

    public void downloadFiles(List<String> remoteFilenames) {
        FTPClient ftp = new FTPClient();
        try {
            ftp.connect(FTP_SERVER, FTP_PORT);
            ftp.login(FTP_USERNAME, FTP_PASSWORD);
            ftp.changeWorkingDirectory(FTP_DIRECTORY);

            List<FTPFile> remoteFiles = new ArrayList<FTPFile>();
            for (String remoteFilename : remoteFilenames) {
                FTPFile remoteFile = ftp.listFiles(remoteFilename)[0];
                remoteFiles.add(remoteFile);
            }

            ExecutorService executor = Executors.newFixedThreadPool(remoteFiles.size());
            for (FTPFile remoteFile : remoteFiles) {
                executor.submit(() -> {
                    long remoteFileSize = remoteFile.getSize();
                    String localFilename = LOCAL_DIRECTORY + remoteFile.getName();
                    FileOutputStream fos = new FileOutputStream(new File(localFilename));
                    ProgressMonitorInputStream pmis = new ProgressMonitorInputStream(null, "Downloading " + remoteFile.getName(), ftp.retrieveFileStream(remoteFile.getName()));
                    ProgressMonitor progressMonitor = pmis.getProgressMonitor();
                    progressMonitor.setMaximum((int) remoteFileSize);
                    progressMonitor.setMillisToPopup(1000);
                    progressMonitor.setMillisToDecideToPopup(1000);

                    byte[] buffer = new byte[1024];
                    int bytesRead = 0;
                    while ((bytesRead = pmis.read(buffer)) != -1) {
                        fos.write(buffer, 0, bytesRead);
                        progressMonitor.setProgress(progressMonitor.getProgress() + bytesRead);
                    }
                    fos.close();
                });
            }
            executor.shutdown();
            executor.awaitTermination(Long.MAX_VALUE, TimeUnit.NANOSECONDS);

            ftp.logout();
            ftp.disconnect();
        } catch (IOException | InterruptedException e) {
            e.printStackTrace();
        }
    }
}

在上述代码中，我们首先定义了要连接的FTP服务器的地址、端口号、用户名、密码和文件路径等信息。

然后，我们使用Apache Commons Net库中的FTPClient类来建立FTP连接，并获取要下载的多个文件的大小。

接下来，我们使用Executor框架来启动多个下载线程，并在每个线程中下载一个文件并在屏幕上打印下载进度。

最后，我们下载所有文件并关闭FTP连接。

需要注意的是，在实际应用中，我们需要根据具体的需求来进行代码的修改和优化，以确保代码的可靠性和高效性。