使用 JSch 从 SSHD 服务器下载文件：移动端到移动端方案

import com.jcraft.jsch.*;

public class Client {

    private static final String USERNAME = "sftptest"; // 替换为你的用户名
    private static final String PASSWORD = "sftptest"; // 替换为你的密码
    private static final String REMOTE_HOST = "192.168.1.100"; // 替换为你的服务器 IP 地址
    private static final int REMOTE_PORT = 8888; // 替换为你的服务器端口
    private static final int SESSION_TIMEOUT = 10000;
    private static final int CHANNEL_TIMEOUT = 5000;

    public void startClient() {
        String localFile = "/sdcard/download/au.au_1"; // 客户端保存文件的路径，确保有写入权限
        String remoteFile = "/data/user/0/com.open.androidsshd/databases/au.au_1"; // 服务端文件路径

        Session jschSession = null;

        try {
            JSch jsch = new JSch();
            //  jsch.setKnownHosts("/home/mkyong/.ssh/known_hosts"); // 可选：如果需要验证主机密钥

            jschSession = jsch.getSession(USERNAME, REMOTE_HOST, REMOTE_PORT);

            // authenticate using private key
            // jsch.addIdentity("/home/mkyong/.ssh/id_rsa");

            // authenticate using password
            jschSession.setPassword(PASSWORD);

            // 忽略主机密钥检查（仅用于测试环境，生产环境不建议）
            java.util.Properties config = new java.util.Properties();
            config.put("StrictHostKeyChecking", "no");
            jschSession.setConfig(config);

            System.out.println("Establishing connection");
            // 10 seconds session timeout
            jschSession.connect(SESSION_TIMEOUT);

            Channel sftp = jschSession.openChannel("sftp");

            // 5 seconds timeout
            sftp.connect(CHANNEL_TIMEOUT);

            ChannelSftp channelSftp = (ChannelSftp) sftp;

            // transfer file from local to remote server
            //channelSftp.put(localFile, remoteFile);

            // download file from remote server to local
            channelSftp.get(remoteFile, localFile);
            System.out.println("got the file");
            channelSftp.exit();

        } catch (JSchException | SftpException e) {
            e.printStackTrace();
        } finally {
            if (jschSession != null) {
                jschSession.disconnect();
            }
        }
    }

    public static void main(String[] args) {
        Client client = new Client();
        client.startClient();
    }
}

import org.apache.sshd.server.SshServer;
import org.apache.sshd.server.keyprovider.SimpleGeneratorHostKeyProvider;
import org.apache.sshd.server.subsystem.sftp.SftpSubsystemFactory;
import org.apache.sshd.server.command.ScpCommandFactory;
import org.apache.sshd.server.shell.EchoShellFactory;
import org.apache.sshd.server.auth.password.PasswordAuthenticator;
import org.apache.sshd.server.session.ServerSession;
import org.apache.sshd.common.NamedFactory;
import org.apache.sshd.server.command.Command;

import java.io.IOException;
import java.util.Arrays;

public class Server {

    public static void main(String[] args) throws IOException {
        int port = 8888;
        SshServer sshd = SshServer.setUpDefaultServer();
        sshd.setPort(port);
        sshd.setKeyPairProvider(new SimpleGeneratorHostKeyProvider("hostkey.ser")); // 替换为你的密钥文件
        sshd.setSubsystemFactories(Arrays.<NamedFactory<Command>>asList(new SftpSubsystemFactory()));
        sshd.setCommandFactory(new ScpCommandFactory());
        sshd.setShellFactory(new EchoShellFactory()); // necessary if you want to type commands over ssh
        sshd.setPasswordAuthenticator(new PasswordAuthenticator() {

            @Override
            public boolean authenticate(String u, String p, ServerSession s) {
                return ("sftptest".equals(u) && "sftptest".equals(p));
            }
        });

        try {
            sshd.start();
            System.out.println("SSHD Server started on port " + port);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}