I need to call 'roslaunch' command on the computer of my robot with my android phone.(There's no keyboard or screen on the computer.)
My solution is using ssh to give command on the shell. Thus, I found the jcraft. When I run the program given on official website(http://www.jcraft.com/jsch/examples/Exec.java.html):
/* -*-mode:java; c-basic-offset:2; indent-tabs-mode:nil -*- */
/**
* This program will demonstrate remote exec.
* $ CLASSPATH=.:../build javac Exec.java
* $ CLASSPATH=.:../build java Exec
* You will be asked username, hostname, displayname, passwd and command.
* If everything works fine, given command will be invoked
* on the remote side and outputs will be printed out.
*
*/
import com.jcraft.jsch.*;
import java.awt.*;
import javax.swing.*;
import java.io.*;
public class Exec{
public static void main(String[] arg){
try{
JSch jsch=new JSch();
String host=null;
if(arg.length>0){
host=arg[0];
}
else{
host=JOptionPane.showInputDialog("Enter username@hostname",
System.getProperty("user.name")+
"@localhost");
}
String user=host.substring(0, host.indexOf('@'));
host=host.substring(host.indexOf('@')+1);
Session session=jsch.getSession(user, host, 22);
/*
String xhost="127.0.0.1";
int xport=0;
String display=JOptionPane.showInputDialog("Enter display name",
xhost+":"+xport);
xhost=display.substring(0, display.indexOf(':'));
xport=Integer.parseInt(display.substring(display.indexOf(':')+1));
session.setX11Host(xhost);
session.setX11Port(xport+6000);
*/
// username and password will be given via UserInfo interface.
UserInfo ui=new MyUserInfo();
session.setUserInfo(ui);
session.connect();
String command=JOptionPane.showInputDialog("Enter command",
"set|grep SSH");
Channel channel=session.openChannel("exec");
((ChannelExec)channel).setCommand(command);
// X Forwarding
// channel.setXForwarding(true);
//channel.setInputStream(System.in);
channel.setInputStream(null);
//channel.setOutputStream(System.out);
//FileOutputStream fos=new FileOutputStream("/tmp/stderr");
//((ChannelExec)channel).setErrStream(fos);
((ChannelExec)channel).setErrStream(System.err);
InputStream in=channel.getInputStream();
channel.connect();
byte[] tmp=new byte[1024];
while(true){
while(in.available()>0){
int i=in.read(tmp, 0, 1024);
if(i<0)break;
System.out.print(new String(tmp, 0, i));
}
if(channel.isClosed()){
if(in.available()>0) continue;
System.out.println("exit-status: "+channel.getExitStatus());
break;
}
try{Thread.sleep(1000);}catch(Exception ee){}
}
channel.disconnect();
session.disconnect();
}
catch(Exception e){
System.out.println(e);
}
}
public static class MyUserInfo implements UserInfo, UIKeyboardInteractive{
public String getPassword(){ return passwd; }
public boolean promptYesNo(String str){
Object[] options={ "yes", "no" };
int foo=JOptionPane.showOptionDialog(null,
str,
"Warning",
JOptionPane.DEFAULT_OPTION,
JOptionPane.WARNING_MESSAGE,
null, options, options[0]);
return foo==0;
}
String passwd;
JTextField passwordField=(JTextField)new JPasswordField(20);
public String getPassphrase(){ return null; }
public boolean promptPassphrase(String message){ return true; }
public boolean promptPassword(String message){
Object[] ob={passwordField};
int result=
JOptionPane.showConfirmDialog(null, ob, message,
JOptionPane.OK_CANCEL_OPTION);
if(result==JOptionPane.OK_OPTION){
passwd=passwordField.getText();
return true;
}
else{
return false;
}
}
public void showMessage(String message){
JOptionPane.showMessageDialog(null, message);
}
final GridBagConstraints gbc =
new GridBagConstraints(0,0,1,1,1,1,
GridBagConstraints.NORTHWEST,
GridBagConstraints.NONE,
new Insets(0,0,0,0),0,0);
private Container panel;
public String[] promptKeyboardInteractive(String destination,
String name,
String instruction,
String[] prompt,
boolean[] echo){
panel = new JPanel();
panel.setLayout(new GridBagLayout());
gbc.weightx = 1.0;
gbc.gridwidth = GridBagConstraints.REMAINDER;
gbc.gridx = 0;
panel.add(new JLabel(instruction), gbc);
gbc.gridy++;
gbc.gridwidth = GridBagConstraints.RELATIVE;
JTextField[] texts=new JTextField[prompt.length];
for(int i=0; i<prompt.length; i++){
gbc.fill = GridBagConstraints.NONE;
gbc.gridx = 0;
gbc.weightx = 1;
panel.add(new JLabel(prompt[i]),gbc);
gbc.gridx = 1;
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.weighty = 1;
if(echo[i]){
texts[i]=new JTextField(20);
}
else{
texts[i]=new JPasswordField(20);
}
panel.add(texts[i], gbc);
gbc.gridy++;
}
if(JOptionPane.showConfirmDialog(null, panel,
destination+": "+name,
JOptionPane.OK_CANCEL_OPTION,
JOptionPane.QUESTION_MESSAGE)
==JOptionPane.OK_OPTION){
String[] response=new String[prompt.length];
for(int i=0; i<prompt.length; i++){
response[i]=texts[i].getText();
}
return response;
}
else{
return null; // cancel
}
}
}
}
I succeed to run command like ls and get the feedback. However, I have problem when run roscore:
zsh:1: command not found: roscore
exit-status: 127
Also, when I run command like 'jupyter notebook', I also get:
zsh:1: command not found: jupyter
exit-status: 127
But actually I can run both roscore and jupyter notebook on the computer.
I expect to know how to change the program to fix the problem? Or how can I run the roslaunch on the computer in another way?
The command not found problem I haven't solved. But I found a new way to do the roslaunch.
By using the other program given by office website: Shell.java, I can type the command via System.in.
If you just want to do one command, you can replace the System.in with an InputStream object:
InputStream stream = new ByteArrayInputStream("roscore\n".getBytes(StandardCharsets.UTF_8));
channel.setInputStream(stream);
By doing this, the roscore command will work immediately.