servermanager/src/main/java/de/gurkengewuerz/monitoring/object/SSHManager.java

package de.gurkengewuerz.monitoring.object;

import com.jcraft.jsch.*;

import java.io.IOException;
import java.io.InputStream;
import java.util.logging.Level;
import java.util.logging.Logger;


/*
* SSHManager
*
* @author cabbott
* @version 1.0
*/
public class SSHManager {
    private static final Logger LOGGER =
            Logger.getLogger(SSHManager.class.getName());
    private JSch jschSSHChannel;
    private String strUserName;
    private String strConnectionIP;
    private int intConnectionPort;
    private Session sesConnection;
    private String errorMessage = null;
    private int intTimeOut;

    public SSHManager(String userName, String privateKey, String privateKey_pass, String connectionIP, String knownHostsFileName, int connectionPort) {
        doCommonConstructorActions(userName, privateKey, privateKey_pass, connectionIP, knownHostsFileName);
        intConnectionPort = connectionPort;
        intTimeOut = 60000;
    }

    private void doCommonConstructorActions(String userName, String privateKey, String privateKey_pass, String connectionIP, String knownHostsFileName) {
        jschSSHChannel = new JSch();

        try {
            if (privateKey_pass.isEmpty()) {
                jschSSHChannel.addIdentity(privateKey);
            } else {
                jschSSHChannel.addIdentity(privateKey, privateKey_pass);
            }

            jschSSHChannel.setKnownHosts(knownHostsFileName);
        } catch (JSchException jschX) {
            logError(jschX.getMessage());
        }

        strUserName = userName;
        strConnectionIP = connectionIP;
    }

    public String connect() {
        errorMessage = null;

        try {
            sesConnection = jschSSHChannel.getSession(strUserName,
                    strConnectionIP, intConnectionPort);
            //sesConnection.setPassword(strPassword);
            // UNCOMMENT THIS FOR TESTING PURPOSES, BUT DO NOT USE IN PRODUCTION
            sesConnection.setConfig("StrictHostKeyChecking", "no");
            sesConnection.connect(intTimeOut);
        } catch (JSchException jschX) {
            errorMessage = jschX.getMessage();
        }

        return errorMessage;
    }

    public boolean hasError() {
        return errorMessage != null;
    }

    public String getErrorMessage() {
        return errorMessage;
    }

    private String logError(String errorMessage) {
        if (errorMessage != null) {
            LOGGER.log(Level.SEVERE, "{0}:{1} - {2}",
                    new Object[]{strConnectionIP, intConnectionPort, errorMessage});
        }

        return errorMessage;
    }

    private String logWarning(String warnMessage) {
        if (warnMessage != null) {
            LOGGER.log(Level.WARNING, "{0}:{1} - {2}",
                    new Object[]{strConnectionIP, intConnectionPort, warnMessage});
        }

        return warnMessage;
    }

    public String sendCommand(String command) {
        StringBuilder outputBuffer = new StringBuilder();

        try {
            Channel channel = sesConnection.openChannel("exec");
            ((ChannelExec) channel).setCommand(command);
            InputStream commandOutput = channel.getInputStream();
            channel.connect();
            int readByte = commandOutput.read();

            while (readByte != 0xffffffff) {
                outputBuffer.append((char) readByte);
                readByte = commandOutput.read();
            }

            channel.disconnect();
        } catch (IOException | JSchException ioX) {
            logWarning(ioX.getMessage());
            return null;
        }

        return outputBuffer.toString();
    }

    public void close() {
        sesConnection.disconnect();
    }

}