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Class TelnetWrapper

java.lang.Object
  |
  +--socket.TelnetWrapper
public class TelnetWrapper
extends java.lang.Object

Wrapper for a Java Telnet call. To use, make a new TelnetWrapper() with the name or IP address of a host. Then, for most uses, the easiest way is to call setPrompt() with the expected prompt, then call login(), and a sequence of sendLine()'s until you get what you want done.

If you don't know the prompt ahead of time, you have to do a sequence of send() and wait() or receiveUntil() calls. send() sends a string across the telnet connection. Add a '\r' to the end if you want to complete a command. wait() waits for an exact string from the other side of the telnet connection, and returns nothing, receiveUntil() also waits for a string, but returns all the data that it received while waiting, including the string itself. Use this if you want the output from a command. Please note that the telnet connection will usually echo the sent command.

sendLine() is generally better, since it adds the '\r' automatically, waits for the prompt before returning, and returns all data received before the prompt, with the prompt itself cut off the end, and the sent command cut off the beginning. login() and sendLine() are implemented using send(), wait() and receiveUntil(). They can be freely mixed and matched.

Here is a simple example of the use of TelnetWrapper: 

 // creates a new file in /tmp, lists the directory to prove it done
 {
   TelnetWrapper telnet = new TelnetWrapper("123.45.78.90");

   // setting the correct prompt ahead of time is very important 
   // if you want to use login and sendLine
   telnet.setPrompt("$ ");
   telnet.login("loginname", "password");

   // this is how you have to do it otherwise
   telnet.send("touch /tmp/TELNET_WRAPPER" + "\r");
   telnet.wait("$ ");

   // sendLine 1: adds the \r automatically, 2: waits for the prompt
   // before returning 3: returns what was printed from the command
   String ls = telnet.sendLine("ls /tmp");
   System.out.println(ls);

   // clean up
   telnet.disconnect();
 }

Version:
0.2 5/15/97 - added comments, replaced String += with StringBuffer.append() in receiveUntil(), added port constructor
Author:
George Ruban 3/4/97
See Also:
TelnetIO

Field Summary
 boolean debug
          Set to true for System.out.println debugging.
 
Constructor Summary
TelnetWrapper(java.lang.String host)
          Connects to the default telnet port on the given host.
TelnetWrapper(java.lang.String host, int port)
          Connects to a specific telnet port on the given host.
 
Method Summary
 int available()
          Returns bytes available to be read.
 void disconnect()
          Ends the telnet connection.
 void finalize()
          Ends the telnet connection.
 void login(java.lang.String loginName, java.lang.String password)
          Logs in as a particular user and password.
static void main(java.lang.String[] args)
          Telnet test driver.
 java.lang.String receive()
          Returns a String from the telnet connection.
 byte[] receiveBytes()
          Returns a byte array.
 java.lang.String receiveUntil(java.lang.String token)
          Returns all data received up until a certain token.
 java.lang.String receiveUntil(java.lang.String token, long timeout)
          Returns all data received up until a certain token.
 void send(byte[] buf)
          Sends bytes over the telnet connection.
 void send(java.lang.String s)
          Sends a String to the remote host.
 java.lang.String sendLine(java.lang.String command)
          Sends a line to the remote host, returns all data before the prompt.
static void setDefaultPrompt(java.lang.String prompt)
          Sets the default prompt used by all TelnetWrappers.
static void setLogin(java.lang.String login, java.lang.String password)
          Sets the default login used by TelnetWrappers.
 void setPrompt(java.lang.String prompt)
          Sets the expected prompt.
static void unsetLogin()
          Turns off the default login of TelnetWrappers.
 void wait(java.lang.String token)
          Skip any received data until the token appears.
 void wait(java.lang.String token, long timeout)
          Wait for a String or a timeout.
 
Methods inherited from class java.lang.Object
clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

debug

public boolean debug
Set to true for System.out.println debugging.
Constructor Detail

TelnetWrapper

public TelnetWrapper(java.lang.String host)
              throws java.io.IOException
Connects to the default telnet port on the given host. If the defaultLogin and defaultPassword are non-null, attempts login.

TelnetWrapper

public TelnetWrapper(java.lang.String host,
                     int port)
              throws java.io.IOException
Connects to a specific telnet port on the given host. If the defaultLogin and defaultPassword are non-null, attempts login.
Method Detail

wait

public void wait(java.lang.String token)
          throws java.io.IOException
Skip any received data until the token appears. More efficient than receiveUntil, but liable to fail on large tokens that can be spread over several "send"s. In that case, consider using receiveUntil and ignoring the return value.
Parameters:
token - String to wait for
Throws:
java.io.IOException - on problems with the socket connection
See Also:
receiveUntil(java.lang.String)

wait

public void wait(java.lang.String token,
                 long timeout)
          throws java.io.IOException,
                 TimedOutException
Wait for a String or a timeout. If time runs out, throws a TimedOutException. Sleeps in intervals of 100 milliseconds until either receiving the token or timeout.

More efficient than receiveUntil, but liable to fail on large tokens that can be spread over several "send"s. In that case, consider using receiveUntil and ignoring the return value.

Parameters:
token - String to wait for
timeout - time in milliseconds to wait (negative means wait forever)
Throws:
java.io.IOException - on problems with the socket connection
TimedOutException - if time runs out before token received
See Also:
receiveUntil(String, long)

available

public int available()
              throws java.io.IOException
Returns bytes available to be read. Since they haven't been negotiated over, this could be misleading...

receive

public java.lang.String receive()
                         throws java.io.IOException
Returns a String from the telnet connection. Blocks until one is available. No guarantees that the string is in any way complete. NOTE: uses Java 1.0.2 style String-bytes conversion.

receiveBytes

public byte[] receiveBytes()
                    throws java.io.IOException
Returns a byte array. Blocks until data is available.

receiveUntil

public java.lang.String receiveUntil(java.lang.String token)
                              throws java.io.IOException
Returns all data received up until a certain token.
Parameters:
token - String to wait for
Throws:
java.io.IOException - on problems with the socket connection
See Also:
wait(java.lang.String)

receiveUntil

public java.lang.String receiveUntil(java.lang.String token,
                                     long timeout)
                              throws java.io.IOException,
                                     TimedOutException
Returns all data received up until a certain token.
Parameters:
token - String to wait for
timeout - time in milliseconds to wait (negative means wait forever)
Throws:
java.io.IOException - on problems with the socket connection
TimedOutException - if time runs out before token received
See Also:
wait(String, long)

send

public void send(java.lang.String s)
          throws java.io.IOException
Sends a String to the remote host. NOTE: uses Java 1.0.2 style String-bytes conversion.
Throws:
java.io.IOException - on problems with the socket connection

sendLine

public java.lang.String sendLine(java.lang.String command)
                          throws java.io.IOException
Sends a line to the remote host, returns all data before the prompt. Since telnet seems to rely on carriage returns ('\r'), one will be appended to the sent string, if necessary.
Parameters:
command - command line to send
Returns:
whatever data the command produced before the prompt.
See Also:
setPrompt(java.lang.String)

send

public void send(byte[] buf)
          throws java.io.IOException
Sends bytes over the telnet connection.

login

public void login(java.lang.String loginName,
                  java.lang.String password)
           throws java.io.IOException
Logs in as a particular user and password. Returns after receiving prompt.

setPrompt

public void setPrompt(java.lang.String prompt)
Sets the expected prompt. If this function is not explicitly called, the default prompt is used.
See Also:
setDefaultPrompt(java.lang.String)

setDefaultPrompt

public static void setDefaultPrompt(java.lang.String prompt)
Sets the default prompt used by all TelnetWrappers. This can be specifically overridden for a specific instance. The default prompt starts out as "$ " until this function is called.
See Also:
setPrompt(java.lang.String)

setLogin

public static void setLogin(java.lang.String login,
                            java.lang.String password)
Sets the default login used by TelnetWrappers. If this method is called with non-null login and password, all TelnetWrappers will attempt to login when first created.
Parameters:
login - login name to use
password - password to use
See Also:
login(java.lang.String, java.lang.String), unsetLogin()

unsetLogin

public static void unsetLogin()
Turns off the default login of TelnetWrappers. After this method is called, TelnetWrappers will not login until that method is explicitly called.
See Also:
setLogin(java.lang.String, java.lang.String), login(java.lang.String, java.lang.String)

disconnect

public void disconnect()
                throws java.io.IOException
Ends the telnet connection.

finalize

public void finalize()
Ends the telnet connection.
Overrides:
finalize in class java.lang.Object

main

public static void main(java.lang.String[] args)
                 throws java.io.IOException
Telnet test driver. Modeled after the IOtest.java example in the Telnet Applet. Logs in to "host", creates a timestamped file in /tmp, lists the /tmp directory to System.out, disconnects. Shows off several TelnetWrapper methods.
Parameters:
args - host login password prompt