java怎么实现把本地文件通过跳板机登录到服务器1中的然后在重服务器1把本地文件通过传输到服务器二

实现这个功能，可以采用以下步骤：

1. 通过Java程序连接跳板机，可以使用JSch库实现。具体可以参考 https://www.jianshu.com/p/2dcb5a5d6bcb 中的代码。

2. 连接成功后，使用JSch的端口转发功能，在本地建立一个端口，使得通过本地端口可以访问服务器1。

3. 在本地读取文件，使用FTP或者SFTP等协议将文件上传到服务器1上。

4. 在服务器1上执行命令，将文件从服务器1上传到服务器2上。可以使用SCP命令实现，例如：

   scp /path/to/local/file user@server2:/path/to/remote/directory

这个命令会将本地文件上传到服务器2上的指定目录下。

完整的代码实现可以参考以下示例：

import com.jcraft.jsch.*;

import java.io.*;
import java.util.Properties;

public class FileTransfer {
    private static final String JUMP_SERVER_HOST = "jump.server.host";
    private static final String JUMP_SERVER_USERNAME = "jump.server.username";
    private static final String JUMP_SERVER_PASSWORD = "jump.server.password";
    private static final String SERVER1_HOST = "server1.host";
    private static final String SERVER1_USERNAME = "server1.username";
    private static final String SERVER2_HOST = "server2.host";
    private static final String SERVER2_USERNAME = "server2.username";

    public static void main(String[] args) {
        String localFilePath = "/path/to/local/file";
        String remoteDirectory = "/path/to/remote/directory";

        // Connect to jump server
        JSch jsch = new JSch();
        String jumpServerHost = System.getProperty(JUMP_SERVER_HOST);
        String jumpServerUsername = System.getProperty(JUMP_SERVER_USERNAME);
        String jumpServerPassword = System.getProperty(JUMP_SERVER_PASSWORD);
        Session jumpSession;
        try {
            jumpSession = jsch.getSession(jumpServerUsername, jumpServerHost, 22);
            jumpSession.setPassword(jumpServerPassword);
            Properties config = new Properties();
            config.put("StrictHostKeyChecking", "no");
            jumpSession.setConfig(config);
            jumpSession.connect();

            // Forward local port to server1
            int localPort = 12345;
            int server1Port = 22;
            String server1Host = System.getProperty(SERVER1_HOST);
            String server1Username = System.getProperty(SERVER1_USERNAME);
            int assignedPort = jumpSession.setPortForwardingL(localPort, server1Host, server1Port);

            // Connect to server1
            JSch server1Jsch = new JSch();
            Session server1Session = server1Jsch.getSession(server1Username, "127.0.0.1", assignedPort);
            server1Session.setPassword(jumpServerPassword);
            server1Session.setConfig(config);
            server1Session.connect();

            // Upload file to server1
            ChannelSftp sftpChannel = (ChannelSftp) server1Session.openChannel("sftp");
            sftpChannel.connect();
            sftpChannel.put(new FileInputStream(localFilePath), remoteDirectory + "/" + new File(localFilePath).getName());
            sftpChannel.disconnect();

            // Transfer file from server1 to server2
            String server2Host = System.getProperty(SERVER2_HOST);
            String server2Username = System.getProperty(SERVER2_USERNAME);
            String scpCommand = "scp " + remoteDirectory + "/" + new File(localFilePath).getName() + " " + server2Username + "@" + server2Host + ":" + remoteDirectory;
            Channel channel = server1Session.openChannel("exec");
            ((ChannelExec) channel).setCommand(scpCommand);
            channel.connect();
            InputStream in = channel.getInputStream();
            BufferedReader reader = new BufferedReader(new InputStreamReader(in));
            String line;
            while ((line = reader.readLine()) != null) {
                System.out.println(line);
            }
            channel.disconnect();

            // Disconnect from server1
            server1Session.disconnect();
        } catch (JSchException | IOException | SftpException e) {
            e.printStackTrace();
        }
    }
}

注意，上述代码中需要在命令行中传入以下参数：

-Djump.server.host=jump_server_host
-Djump.server.username=jump_server_username
-Djump.server.password=jump_server_password
-Dserver1.host=server1_host
-Dserver1.username=server1_username
-Dserver2.host=server2_host
-Dserver2.username=server2_username

其中，jump_server_host、jump_server_username、jump_server_password分别为跳板机的主机名、用户名和密码；server1_host、server1_username为目标服务器1的主机名和用户名；server2_host、server2_username为目标服务器2的主机名和用户名。