Quick assignment( 2 Questions) need help
jontha11
week6.zipHelloClient.java
HelloClient.java
import
java
.
io
.
*
;
import
java
.
rmi
.
*
;
/**
* This class represents the object client for a distributed
* object of class Hello, which implements the remote interface
* HelloInterface.
*
@author
M. L. Liu
*/
public
class
HelloClient
{
public
static
void
main
(
String
args
[])
{
try
{
int
RMIPort
;
String
hostName
;
InputStreamReader
is
=
new
InputStreamReader
(
System
.
in
);
BufferedReader
br
=
new
BufferedReader
(
is
);
System
.
out
.
println
(
"Enter the RMIRegistry host name:"
);
hostName
=
br
.
readLine
();
System
.
out
.
println
(
"Enter the RMIregistry port number:"
);
String
portNum
=
br
.
readLine
();
RMIPort
=
Integer
.
parseInt
(
portNum
);
String
registryURL
=
"rmi://"
+
hostName
+
":"
+
portNum
+
"/hello"
;
// find the remote object and cast it to an interface object
HelloInterface
h
=
(
HelloInterface
)
Naming
.
lookup
(
registryURL
);
System
.
out
.
println
(
"Lookup completed "
);
// invoke the remote method
String
message
=
h
.
sayHello
(
"Donald Duck"
);
System
.
out
.
println
(
"HelloClient: "
+
message
);
}
// end try
catch
(
Exception
e
)
{
System
.
out
.
println
(
"Exception in HelloClient: "
+
e
);
}
// end catch
}
//end main
}
//end class
HelloImpl.java
HelloImpl.java
import
java
.
rmi
.
*
;
import
java
.
rmi
.
server
.
*
;
/**
* This class implements the remote interface
* HelloInterface.
*
@author
M. L. Liu
*/
public
class
HelloImpl
extends
UnicastRemoteObject
implements
HelloInterface
{
public
HelloImpl
()
throws
RemoteException
{
super
(
);
}
public
String
sayHello
(
String
name
)
throws
RemoteException
{
return
"Hello, World!"
+
name
;
}
}
// end class
HelloInterface.java
HelloInterface.java
// A simple RMI interface file - M. Liu
import
java
.
rmi
.
*
;
/**
* This is a remote interface.
*
@author
M. L. Liu
*/
public
interface
HelloInterface
extends
Remote
{
/**
* This remote method returns a message.
*
@param
name - a String containing a name.
*
@return
a String message.
*/
public
String
sayHello
(
String
name
)
throws
java
.
rmi
.
RemoteException
;
}
//end interface
HelloServer.java
HelloServer.java
import
java
.
rmi
.
*
;
import
java
.
rmi
.
server
.
*
;
import
java
.
rmi
.
registry
.
Registry
;
import
java
.
rmi
.
registry
.
LocateRegistry
;
import
java
.
net
.
*
;
import
java
.
io
.
*
;
/**
* This class represents the object server for a distributed
* object of class Hello, which implements the remote interface
* HelloInterface.
*
@author
M. L. Liu
*/
public
class
HelloServer
{
public
static
void
main
(
String
args
[])
{
InputStreamReader
is
=
new
InputStreamReader
(
System
.
in
);
BufferedReader
br
=
new
BufferedReader
(
is
);
String
portNum
,
registryURL
;
try
{
System
.
out
.
println
(
"Enter the RMIregistry port number:"
);
portNum
=
(
br
.
readLine
()).
trim
();
int
RMIPortNum
=
Integer
.
parseInt
(
portNum
);
startRegistry
(
RMIPortNum
);
HelloImpl
exportedObj
=
new
HelloImpl
();
registryURL
=
"rmi://localhost:"
+
portNum
+
"/hello"
;
Naming
.
rebind
(
registryURL
,
exportedObj
);
/**/
System
.
out
.
println
/**/
(
"Server registered. Registry currently contains:"
);
/**/
// list names currently in the registry
/**/
listRegistry
(
registryURL
);
System
.
out
.
println
(
"Hello Server ready."
);
}
// end try
catch
(
Exception
re
)
{
System
.
out
.
println
(
"Exception in HelloServer.main: "
+
re
);
}
// end catch
}
// end main
// This method starts a RMI registry on the local host, if it
// does not already exists at the specified port number.
private
static
void
startRegistry
(
int
RMIPortNum
)
throws
RemoteException
{
try
{
Registry
registry
=
LocateRegistry
.
getRegistry
(
RMIPortNum
);
registry
.
list
(
);
// This call will throw an exception
// if the registry does not already exist
}
catch
(
RemoteException
e
)
{
// No valid registry at that port.
/**/
System
.
out
.
println
/**/
(
"RMI registry cannot be located at port "
+
RMIPortNum
);
/**/
Registry
registry
=
LocateRegistry
.
createRegistry
(
RMIPortNum
);
/**/
System
.
out
.
println
(
/**/
"RMI registry created at port "
+
RMIPortNum
);
}
}
// end startRegistry
// This method lists the names registered with a Registry object
private
static
void
listRegistry
(
String
registryURL
)
throws
RemoteException
,
MalformedURLException
{
System
.
out
.
println
(
"Registry "
+
registryURL
+
" contains: "
);
String
[
]
names
=
Naming
.
list
(
registryURL
);
for
(
int
i
=
0
;
i
<
names
.
length
;
i
++
)
System
.
out
.
println
(
names
[
i
]);
}
//end listRegistry
}
// end class
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