Java - JSCH Library - Run command which expects password

问题

I am writing a java program which runs rsync on local Linux host to copy data to remote host. I am using jsch library. I looked at jsch examples, but I didn't find anything relevant.

I can't setup key authentication, so i was expecting to automated password entry of remote host when rsync command run prompts for the password.

I searched online for some ways of doing it, I don't find any easy way of doing it.

Following function just executes command fed to it, this function is part of a class which has server, username, password

public int executeCommand(String command) throws Exception {
    JSch jsch = new JSch();
    Session session = null;
    Channel channel = null;
    int exitCode;
    try {
        //Initialize session
        session = jsch.getSession(this.username, this.server, 22);
        session.setPassword(this.password);
        session.setConfig("StrictHostKeyChecking", "no");
        session.setConfig("PreferredAuthentications", "publickey,password");
        //Connect
        session.connect();
        //Open a channel for communication
        channel = session.openChannel("shell");

        OutputStream ops = channel.getOutputStream();
        PrintStream ps = new PrintStream(ops, true);

        channel.connect();

        logger.info("Sending command {} ",command);
        ps.println(command);
        ps.flush();

        InputStream inputStream = channel.getInputStream();

        processOutput(inputStream, "password:", timeout);
        logger.info("Sending password.");
        ps.println(this.targetPassword);
        ps.flush();


        processOutput(inputStream, "total size is", timeout);

        //Get the process exit code
        String exitCodeCommand = "echo $?";
        logger.info("Sending command {} ",exitCodeCommand);
        ps.println(exitCodeCommand);
        ps.flush();

        String exitCodeOutput = processOutput(inputStream, "", 0.5);

        String[] outputArray = exitCodeOutput.split(System.lineSeparator());

        if (outputArray.length < 2) {
            String msg = String.format("Exit code of command $1%s is invalid %2$s", exitCodeCommand,
                    exitCodeOutput);
            throw new Exception(msg);
        }

        try {
            exitCode = Integer.parseInt(outputArray[1]);
        } catch (NumberFormatException nfe) {
            logger.error("Exception occurred while parsing {}", outputArray[1], nfe);
            String msg = String.format("Exit code of command $1%s is invalid %2$s. Exit code parsed %3$s is " +
                    "not an integer", exitCodeCommand, exitCodeOutput, outputArray[2]);
            throw new Exception(msg);
        }

        logger.info("Exit code {}", exitCode);

        inputStream.close();
        ps.close();
        channel.disconnect();
        session.disconnect();
    } catch (JSchException e) {
        logger.error("Exception occurred while creating session with {}. Error message {}", this.server, e
                .getMessage(), e);            
    } catch (IOException e) {
        logger.error("Exception occurred while creating performing IO with server {}. Error message {}", this
                .server, e.getMessage(), e);            
    } finally {
        logger.info("Closing channels");
        if (channel != null && !channel.isClosed()) {
            channel.disconnect();
        }
        if (session != null) {
            session.disconnect();
        }
    }
    return exitCode;
}

private String processOutput(InputStream inputStream, String outToFind, double timeout) throws Exception {
    byte[] bt = new byte[1024];

    StringBuilder builder = new StringBuilder();

    double timeoutBeforeExit = timeout * 1000 * 60;

    double timeElapsed = 0;

    while (true) {
        try {
            while (inputStream.available() > 0) {
                int i = inputStream.read(bt, 0, 1024);
                if (i < 0) {
                    break;
                }
                String str = new String(bt, 0, i);
                builder.append(str);
                //displays the output of the command executed for debug purpose.
                logger.info(str);
                if (str.contains(outToFind)) {
                    logger.info("{} output is found.", outToFind);
                    return builder.toString();
                } else {
                    logger.info("{} is not matched", str);
                }
            }
        } catch (IOException e) {
            logger.error("Exception occurred while creating performing IO with server {}. Error message {}", this
                    .server, e.getMessage(), e);
            throw new Exception(e.getMessage());
        }
        timeElapsed = timeElapsed + SLEEP_TIME;

        if (timeElapsed >= timeoutBeforeExit) {
            throw new Exception("Timeout while waiting for output.");
        }

        try {
            Thread.sleep(SLEEP_TIME);
        } catch (InterruptedException e) {
            logger.warn("Benign exception occurred inputStream thread sleep. Continuing.", e);
        }
    }
}

回答1:

You can try the below code. It automatically reads the provided password and continue with running the next commands.

            Properties config = new Properties(); 
            config.put("StrictHostKeyChecking", "no");
            JSch jsch = new JSch();
            Session session=jsch.getSession(user, host, 22);
            session.setPassword(password);
            session.setConfig(config);
            session.connect();
            System.out.println("Connected");

            Channel channel=session.openChannel("exec");
            //write the command, which expects password 
            ((ChannelExec)channel).setCommand("command");
            ((ChannelExec)channel).setErrStream(System.err);
            ((ChannelExec)channel).setPty(true);

            System.out.println("Password taken");
            InputStream in=channel.getInputStream();
            channel.connect();
            OutputStream out=channel.getOutputStream();
            //give the password below
            out.write(("password\n").getBytes());

            out.flush();
            //write your commands
            PrintStream out1= new PrintStream(out);
            out1.println("command1");
            out1.println("command2");
            ...................
            out1.flush();

来源：https://stackoverflow.com/questions/32195464/java-jsch-library-run-command-which-expects-password