Introduction to Java IV

About This Presentation

Title:

Introduction to Java IV

Description:

Patrick Naughton and Herbert Schildt, The Complete Reference Java 2, 3rd ed. ... Merlin Hughes, Michael Shoffner, Derek Hamner, with Umesh Bellur, JAVA Network ... – PowerPoint PPT presentation

Number of Views:651

Avg rating:3.0/5.0

Slides: 128

Provided by: shyhka

Category:

more less

Transcript and Presenter's Notes

Title: Introduction to Java IV

1
Introduction to Java (IV)

Shyh-Kang Jeng
Department of Electrical Engineering/
Graduate Institute of Communication Engineering
National Taiwan University

2
References

Patrick Naughton and Herbert Schildt, The
Complete Reference Java 2, 3rd ed., McGraw-Hill,
1999.
Merlin Hughes, Michael Shoffner, Derek Hamner,
with Umesh Bellur, JAVA Network Programming, 2nd
ed., Manning, 1999.

3
Streams

A stream represents an endpoint of a one-way
communication channel
The connection can take the form of a link
through a network, a memory buffer, a file
Streams provide a uniform data interface for
applications

4
Class OutputStream

Provides the superclass for all concrete output
stream implementation (to a file or to a network
or to a memory buffer)
Methods defined
abstract void write(int b)
void write(byte b, int off, int len)
void write(byte b)
void flush()
void close()

5
Class InputStream

Is the superclass for all input stream
Some methods
abstract int read()
int read(byte b, int off,
int len)
int read(byte b)
int available()
void close()
long skip(long n)

6
Class File (1)

Represents a system-independent file name
Provides methods to determine information about
the actual file of the specified name as well as
methods to modify the files attributes

7
Class File (2)

Constructors
File(String path)
File(String path, String name)
File(File dir, String name)
Some methods
boolean exists()
long length()
String getName()
String getPath()
String list()
boolean delete()

8
Class FileOutputStream (1)

Allows sequential data to be written to a file

9
Class FileOutputStream (2)

Constructors
FileOutputStream(String name)
FileOutputStream(File file)
FileOutputStream(String name, boolean append)

10
Class FileInputStream (1)

Allows one to read sequential data from a file

Readme.txt
FileInputStream
11
Class FileInputStream (2)

Constructors
FileInputStream(String name)
FileInputStream(File file)

12
Class Writer

Is the superclass of all character output stream
Methods defined
void write(int c)
void write(char cbuf)
abstract void write(char cbuf, int off, int
len)
void write(String str)
void write(String str, int off, int len)
abstract void flush()
abstract void close()

13
Class Reader

Is the superclass of all character input streams
Some methods
int read()
int read(char cbuf)
abstract int read(char cbuf, int off, int len)
long skip(long n)
boolean ready()
abstract void close()
void reset()

14
Class OutputStreamWriter (1)

Provides a character-oriented Writer bridge to a
byte-oriented OutputStream channel

15
Class OutputStreamWriter (2)

Constructors
OutputStreamWriter(
OutputStream out )
OutputStreamWriter(
OutputStream out, String enc )

16
Class InputStreamReader (1)

Represents a character-oriented bridge out of a
byte-oriented InputStream

17
Class InputStreamReader (2)

Constructors
InputStreamReader(
InputStream in)
InputStreamReader(
InputStream in, String enc)

18
Class BufferedWriter (1)

Provides write-buffering on the attached stream
All data written to this class are stored in an
internal buffer until either the buffer becomes
full, flush() is called, or close() is called

flush()
Writer
BufferedWriter
19
Class BufferedWriter (2)

Constructors
BufferedWriter( Writer out )
BufferedWriter( Writer out,
int sz )

20
Class BufferedReader (1)

Provides buffering on the attached stream
Data are read in large chunks from the attached
stream into an internal buffer and can then be
efficiently read in small volumes from the buffer

21
Class BufferedReader (2)

Constructors
BufferedReader( Reader in )
BufferedReader( Reader in,
int sz )

22
Object Streams

Object streams allow complete objects to be
written to and read from a communication channel
without much effort on the part of the programmer
Object streams are attached to an underlying
communications channel, such as a file or a
socket
The process to write/read the object status
to/from byte streams is called serialization/deser
ialization

23
Interface ObjectOutput

Some methods
void close()
void flush()
void writeObject(Object obj)

24
Class ObjectOutputStream (1)

Implements the ObjectOutput interface
Attaches to an existing OutputStream

25
Class ObjectOutputStream (2)

Constructor
ObjectOutputStream(
OutputStream outs)
Some methods
void writeChars(String str)
void writeInt(int I)
void writeDouble(double d)
final void writeObject(
Object obj)

26
Interface ObjectInput

Some methods
int available
void close()
Object readObject()
long skip(long numBytes)

27
Class ObjectInputStream (1)

Implements the ObjectInput interface
Attaches to an existing InputStream

readObject
28
Class ObjectInputStream (2)

Constructor
ObjectInputStream(
InputStream inStream)
Some methods
char readChar()
double readDouble()
int readInt()
final Object readObject()

29
Interface Serializable

A marker interface used by classes to indicate
that they may be serialized by the default
serialization mechanism
Defines no methods or data

30
SerializationDemo (1)

import java.io.
public class MyClass implements Serializable
String s
int i
double d
public MyClass( String s, int i, double d )
this.s s
this.i i
this.d d

31
SerializationDemo (2)

public String toString()
return "s " s " i " i " d "
d

32
SerializationDemo (3)

public class MySubclass extends MyClass
int k
public MySubclass(
String s, int i, double d,
int k)
super( s, i, d )
this.k k
public String toString()
return super.toString()
" k " k

33
SerializationDemo (4)

public class SerializationDemo
public static void main(
String args )
try
MyClass object1 new
MyClass( "Hello", -7,
2.7e10)
System.out.println("object1"
object1)
FileOutputStream fos new
FileOutputStream("serial")

34
SerializationDemo (5)

ObjectOutputStream oos new
ObjectOutputStream(fos)
oos.writeObject(object1)
MySubclass subObject new
MySubclass("Hi", 5, 0.3,4)
object1 subObject
System.out.println(
"object1" object1 )
oos.writeObject(object1)
oos.flush()
oos.close()

35
SerializationDemo (6)

catch(Exception e)
System.out.println(
"Exception during serialization
e)
System.exit(0)
try
MyClass object2
FileInputStream fis new
FileInputStream( "serial" )
ObjectInputStream ois new
ObjectInputStream( fis )

36
SerializationDemo (7)

object2 (MyClass)
ois.readObject()
System.out.println(
"object2 " object2 )
object2 (MyClass)
ois.readObject()
System.out.println(
"object2 " object2 )
ois.close()

37
SerializationDemo (8)

catch( Exception e )
System.out.println(
"Exception during deserialization "
e )
System.exit(0)

38
Package java.net

Together, java.io and java.net packages contain
all the tools needed for building complex
networked applications
Encapsulate the socket paradigm

39
Client/Server and Sockets

A server is anything that has some resource that
can be shared
A client is an entity that wants to gain access
to a particular server
Clients and servers communicate with sockets

client
server
40
Connection Ports

A port is a numbered socket on a particular
machine
A server can serve many different clients at
once, as well as serving many different types of
information, through many ports
A server process is said to listen to a port
until a client connects to it
A server is allowed to accept multiple clients
connected to the same port number, although each
session is unique

41
Reserved Ports

Port number is from 1 to 65535
TCP/IP reserves the lower 1024 ports for
specified protocols
Some reserved ports
FTP 21
Telnet 23
Email 25
Finger 79
HTTP 80
Netnews 119

42
Internet Addressing

An IP address is a 32-bit integer, referred to as
a sequence of four numbers between 0 and 255
separated by dots
Examples of IP classes and subnets
Class A 126. xx. xx. xx
Class B 191. 12. xx. xx
Class C 223. 12. 34. xx
Loopback address (localhost)
127. 0. 0. 1
Domain Name
Example www.ntu.edu.tw

43
Class InetAddress

Provides abstracted access to IP addresses
Easily portable to IPv6 (128-bit address)
No constructors
Instantiated by using static methods
InetAddress getByName(
String host)
InetAddress getLocalHost()
Some methods
byte getAddress()
String getHostName()

44
Class URL

Example of Uniform Resource Locator (URL)
http//www.ntu.edu.tw80/index.html
Some Constructors
URL(String urlSpecifier)
URL(String protocolName,
String hostName, int port, String path)
Some method
InputStream openStream()

URL
InputStream
45
GrabbingWebPage (1)

import java.io.
import java.net.
public class GrabbingWebPage
public static void main(
String args)
try
URL url new URL(
"http//www.ntu.edu.tw/index.html")
InputStream in
url.openStream()
Reader reader new
InputStreamReader(in)

46
GrabbingWebPage (2)

BufferedReader bufferedReader
new BufferedReader( reader )
PrintWriter console new PrintWriter(
System.out )
String line
while((line
bufferedReader.readLine()) ! null)
console.println( line )
console.flush()
bufferedReader.close()
catch ( Exception e )
System.out.println( e )

47
Class Socket (1)

Using this class, a client can establish a
stream-based communication channel with a remote
host port which the server is listening to
Constructors
Socket(String host, int port)
Socket(InetAddress address,
int port)

Socket
InputStream
OutputStream
hostport
48
Class Socket (2)

Some methods
InputStream getInputStream()
OutputStream getOutputStream()
void close()
InetAddress getInetAddress()
int getPort()

49
Hypertext Transfer Protocol (HTTP)

Defines the precise manner in which Web clients
communicate with Web servers
HTTP/1.0 is the most popular version today
Stages of a simple web transition

Opens connection
Sends request
client
server
Responds
Close connection
50
HTTP 1.0

Status code category
2xx (successful)
4xx (client error)
5xx (server error)
A GET request
GET index.htm HTTP/1.0
HTTP header
HTTP/1.0 200 OK
Date Fri, 23 Mar 2001 152000 GMT
Content-Length 359
Content-Type text/html

51
HTTPClientDemo (1)

import java.net.
import java.io.
public class HTTPClientDemo
public static void main(
String args)
try
InetAddress address
InetAddress.getLocalHost()
Socket s new Socket(
address, 8080 )
Client client new
Client( s )

52
HTTPClientDemo (2)

client.getFile( "index.htm" )
s.close()
catch (Exception e)
System.out.println(
"Client error " e )

53
HTTPClientDemo (3)

class Client
Socket s
public Client( Socket s )
this.s s
public void getFile( String file ) throws
IOException
int c
OutputStream out
s.getOutputStream()

54
HTTPClientDemo (4)

InputStream in
s.getInputStream()
String str "GET " file
" HTTP\1.0 \n"
byte buf str.getBytes()
out.write(buf)
while( (cin.read())! -1 )
System.out.print((char) c)

55
Class ServerSocket (1)

Creates a Socket for each client connection
The server then can handle these connections in
the usually manner, typically by extracting the
InputStream and an OutputStream and communicating
with the client through the stream interface

ServerSocket
port
Socket
56
Class ServerSocket (2)

Constructors
ServerSocket(int port)
Some methods
Socket accept()
void close()
InetAddress getInetAddress()
int getLocalPort()

57
Class Diagram of HTTPServerDemo
58
HTTPServerDemo (1)

import java.io.
import java.net.
import java.util.StringTokenizer
import java.util.Date
public class HTTPServerDemo
static final int PORT 8080 public static
void main(
String args)
ServerSocket serverConnect
null

59
HTTPServerDemo (2)

try
serverConnect new
ServerSocket(PORT)
System.out.println(
"\nListening for
connections on port
PORT "...\n")
while (true)
HttpServer server new
HttpServer(
serverConnect.accept())

60
HTTPServerDemo (3)

catch (IOException e)
System.out.println(
"Connection error " e )

61
HTTPServerDemo (4)

class HttpServer implements Runnable
static final File WEB_ROOT new
File(".")
static final String DEFAULT_FILE
"index.html"
Socket connect
public HttpServer(Socket connect)
this.connect connect

62
HTTPServerDemo (5)

Thread threadRunner new
Thread(this)
threadRunner.start()
public void run()
try
BufferedReader in new
BufferedReader( new InputStreamReader
(
connect.getInputStream()))

63
HTTPServerDemo (6)

PrintWriter out new
PrintWriter(
connect.getOutputStream())
String input in.readLine()
StringTokenizer parse new
StringTokenizer(input)
String method
parse.nextToken().
toUpperCase()
String fileRequested
parse.nextToken().
toLowerCase()

64
HTTPServerDemo (7)

if (!method.equals("GET"))
sendStatus( out, 501,
"Not Implemented", method )
else
doGet( fileRequested, out )
connect.close()

65
HTTPServerDemo (8)

catch (IOException e)
System.err.println(
"Server Error " e)
private void doGet(
String fileRequested,
PrintWriter out )

66
HTTPServerDemo (9)

if
(fileRequested.endsWith("/"))
fileRequested
DEFAULT_FILE
try
File file new
File(WEB_ROOT, fileRequested)
int fileLength
(int)file.length()

67
HTTPServerDemo (10)

String content
getContentType(fileRequested)
out.println(
"HTTP/1.0 200 OK")
out.println(
"Server HttpServer 1.0")
out.println("Date " new
Date())
out.println(
"Content-type " content)
out.println(
"Content-length " file.length())

68
HTTPServerDemo (11)

out.println()
out.flush()
FileInputStream fileIn
new FileInputStream(file)
byte fileData new
bytefileLength
fileIn.read(fileData)
fileIn.close()
BufferedOutputStream
dataOut new
BufferedOutputStream(
connect.getOutputStream())

69
HTTPServerDemo (12)

dataOut.write(fileData, 0, fileLength)
dataOut.flush()
dataOut.close()
catch (IOException e)
sendStatus(out, 404,
"File Not Found", fileRequested)

70
HTTPServerDemo (13)

private void sendStatus( PrintWriter out,
int code, String status,
String msg )
out.println("HTTP/1.0 " code
" " status )
out.println(
"Server HttpServer 1.0")
out.println("Date "
new Date())
out.println(
"Content-Type text/html")

71
HTTPServerDemo (14)

out.println()
out.println("ltHTMLgt")
out.println("ltHEADgtltTITLEgt"
status "lt/TITLEgtlt/HEADgt")
out.println("ltBODYgt")
out.println("ltH2gt" code " " status
" " msg "lt/H2gt")
out.println("lt/BODYgt")
out.println("lt/HTMLgt")

72
HTTPServerDemo (15)

private String getContentType(
String fileRequested )
if (fileRequested.endsWith(".htm")
fileRequested.endsWith(".html"))
return "text/html"
else
return "text/plain"

73
Class Class (1)

Included in package java.lang
Instances represent classes and interfaces in a
running Java application
No public constructors
Constructed automatically by the Java Virtual
Machine as classes are loaded and by calls to the
defineClass method in the class loader

74
Class Class (2)

Some methods
static Class forName(
String className)
Constructor getConstructor(
Class paramType)
Constructor getConstructors()
Field getField(String name)
Method getMethod(String name, Class paramType)
Method getMethods()
Object newInstance()

75
Package java.lang.reflect

Used to obtain runtime class information
Some classes in the package
Constructor
Field
Method
Modifier
ReflectPermission

76
Class Modifier

Provides static methods and constants to decode
class modifiers
Some static int constants
ABSTRACT
PRIVATE
PROTECTED
PUBLIC
STATIC
FINAL
INTERFACE
SYNCHRONIZED

77
Class Constructor

Provides information about, and access, to, a
single constructor for a class
Some methods
String getName()
int getModifiers()
Class getParameterTypes()
Object newInstance(
Object initArgs )

78
Class Field

Provides information about, and dynamic access
to, a single field of a class or an interface
Some methods
Object get(Object obj)
int getModifiers()
String getName()
Class getType()
void set(Object obj,
Object value)

79
Class Method

Provides information about, and access to, a
single method on a class or an interface
Some methods
int getModifiers()
String getName()
Class getParameterTypes()
Class getReturnType()
Object invoke(Object obj,
Object args)

80
Class ClassLoader (1)

An abstract class
A class loader is responsible for loading classes
Given the name of a class, a class loader should
locate or generate data that constitutes the
definition for the class
A typical strategy is to transform the name into
a file name and read a class file of the name
from a file system
Every Class object contains a reference to the
ClassLoader that defined it

81
Class ClassLoader (2)

Some methods
Class loadClass(String name)
protected Class defineClass(String name,
byte b, int off, int length)
protected Class findClass(String name)
protected Class findLoadedClass(String name)

82
ClassLoaderDemo (1-1)

import java.io.
public class TestClass implements Serializable
int i
public TestClass()
try
System.out.println("Constructor")
i 1
catch (Exception e)
System.out.println(e)

83
ClassLoaderDemo (1-2)

public void Show()
System.out.println("TestClass")
public int getI()
return i
public void increaseI( int inc )
i inc

84
ClassLoaderDemo (2-1)

import java.io.
import java.lang.reflect.Method
class TestLoader extends ClassLoader
public Class findClass(
String name )
byte b loadClassData(name)
System.out.println(
"data loaded")
return defineClass(name,
b, 0, b.length)

85
ClassLoaderDemo (2-2)

private byte loadClassData(String name)
byte code new byte1024
try
File codeFile new File(
"C\\My Documents\\
jbproject\\ClassLoaderDemo\\
classes\\TestClass",
"TestClass.class" )
FileInputStream cis new
FileInputStream( codeFile )
int nBytes cis.read( code )

86
ClassLoaderDemo (2-3)

System.out.println(
"nBytes "nBytes)
catch ( Exception e )
System.out.println( e )
return code

87
ClassLoaderDemo (2-4)

public class ClassLoaderDemo
public static void main(
String args )
try
ClassLoader loader new
TestLoader()
Class testClass
loader.loadClass(
"TestClass.TestClass")
Object test
testClass.newInstance()

88
ClassLoaderDemo (2-5)

Method testMethod
testClass.getMethods()
int nMethods
testMethod.length
System.out.println(
"number of methods "
nMethods )
for(int i0 iltnMethods i)
String name
testMethodi.getName()
System.out.println(
"Method " i " " name )

89
ClassLoaderDemo (2-6)

Method methodShow
testMethod10
Object param null
Object invoke
methodShow.invoke( test,
param )
Method increaseI
testMethod9
Integer incObj new Integer(5)
param new Object1
param0 incObj
Object increaseIInvoke increaseI.invoke(
test, param )

90
ClassLoaderDemo (2-7)

Method methodGetI
testMethod11
param null
Object returnedI methodGetI.invoke( test,
param )
Integer iWrapper (Integer)
returnedI
System.out.println(
"returned i "
iWrapper.intValue() )
catch ( Exception e )
System.out.println( e )

91
ObjectSerializationDemo (1-1)

import testclass.
import java.io.
class MyObjectOutputStream extends
ObjectOutputStream
public MyObjectOutputStream(
OutputStream out )
throws IOException
super( out )

92
ObjectSerializationDemo (1-2)

protected void annotateClass(
Class cl) throws IOException
super.annotateClass(cl)
// Serialize byte code address
String fileName
"C\\My Documents" "\\jbproject"
"\\ObjectSerializationDemo"
"\\classes""\\testclass
"\\TestClass.class"

93
ObjectSerializationDemo (1-3)

int nChar fileName.length()
writeInt( nChar )
System.out.println(nChar)
for(int i0 iltnChar i)
writeChar( fileName.charAt(i) )
System.out.print(
fileName.charAt(i) )

94
ObjectSerializationDemo (1-4)

public class ObjectSerializationDemo
public static void main(
String args )
try
FileOutputStream fos new
FileOutputStream("serial")
MyObjectOutputStream oos
new
MyObjectOutputStream(fos)
TestClass test new
TestClass()

95
ObjectSerializationDemo (1-5)

oos.writeObject(test)
oos.flush()
oos.close()
catch(Exception e)
System.out.println(
"Exception during serialization "e)
System.exit(0)

96
ObjectDeserializationDemo (1-1)

import java.io.
import java.lang.reflect.Method
// load from an address
class MyLoader extends ClassLoader
String fileName
public MyLoader( String fileName )
this.fileName fileName

97
ObjectDeserializationDemo (1-2)

public Class loadClass(
String name )
throws ClassNotFoundException
return super.loadClass( name )
public Class findClass(
String name )
byte b loadClassData(name)
return defineClass(name, b, 0, b.length)

98
ObjectDeserializationDemo (1-3)

private byte loadClassData(
String name)
byte code null
try
File codeFile new
File( fileName )
FileInputStream cis new
FileInputStream( codeFile )
int fileLength (int)
codeFile.length()
code new bytefileLength
int nBytes cis.read( code )

99
ObjectDeserializationDemo (1-4)

System.out.println(
"nBytes "nBytes)
catch ( Exception e )
System.out.println( e )
return code

100
ObjectDeserializationDemo (1-5)

class MyObjectInputStream extends
ObjectInputStream
public MyObjectInputStream(
InputStream in )
throws IOException
super(in)

101
ObjectDeserializationDemo (1-6)

protected Class resolveClass(ObjectStreamClass
v)
throws IOException
int nChar readInt()
System.out.println( nChar )
char fName new charnChar
for(int i0 iltnChar i)
fNamei readChar()
System.out.print( fNamei )
System.out.println()

102
ObjectDeserializationDemo (1-7)

String fileName new
String( fName )
System.out.println( fileName )
MyLoader myLoader new
MyLoader( fileName )
Class myClass null
try
String name v.getName()
myClass
myLoader.loadClass( name )

103
ObjectDeserializationDemo (1-8)

catch ( ClassNotFoundException e )
System.out.println( e )
return myClass

104
ObjectDeserializationDemo (1-9)

public class ObjectDeserializationDemo
public static void main(
String args )
try
FileInputStream fis new
FileInputStream( "serial" )
MyObjectInputStream ois new
MyObjectInputStream( fis )
Object test
ois.readObject()
ois.close()

105
ObjectDeserializationDemo (1-10)

Class testClass test.getClass()
Method testMethod
testClass.getMethods()
int nMethods
testMethod.length
System.out.println(
"number of methods
nMethods )
for(int i0 iltnMethods i)
String name
testMethodi.getName()

106
ObjectDeserializationDemo (1-11)

System.out.println( "Method " i " "
name )
Method methodShow
testMethod10
Object param null
Object invoke
methodShow.invoke( test, param )
Method increaseI
testMethod9
Integer incObj new
Integer(5)

107
ObjectDeserializationDemo (1-12)

param new Object1
param0 incObj
Object increaseIInvoke increaseI.invoke(
test, param )
Method methodGetI
testMethod11
param null
Object returnedI methodGetI.invoke( test,
param )
Integer iWrapper
(Integer) returnedI

108
ObjectDeserializationDemo (1-13)

System.out.println(
"returned i "
iWrapper.intValue() )
catch( Exception e )
System.out.println(
"Exception during deserialization "
e )
System.exit(0)

109
ObjectSerializationDemo (2-1)

class MyObjectOutputStream extends
ObjectOutputStream
public MyObjectOutputStream(
OutputStream out )
throws IOException
super( out )
protected void annotateClass(Class cl) throws
IOException
super.annotateClass(cl)

110
ObjectSerializationDemo (2-2)

// Serialize byte code
byte code null
try
File codeFile new File(
"C\\My Documents"
"\\jbproject"
"\\ObjectSerializationDemo"
"\\classes"
"\\testclass"
"\\TestClass.class" )
int fileLength (int)
codeFile.length()

111
ObjectSerializationDemo (2-3)

writeInt( fileLength )
code new bytefileLength
FileInputStream cis new
FileInputStream( codeFile )
int nBytes cis.read( code )
write( code )
System.out.println(
"nBytes "nBytes)
catch ( Exception e )
System.out.println( e )
write( code )

112
ObjectDeserializationDemo (2-1)

// load from byte code
class MyLoader extends ClassLoader
int codeLength
byte code
public MyLoader( int n,
byte code )
codeLength n
this.code new
bytecodeLength
this.code code

113
ObjectDeserializationDemo (2-2)

public Class loadClass(
String name )
throws ClassNotFoundException
return super.loadClass( name )
public Class findClass( String name )
return defineClass(name, code, 0,
codeLength)

114
ObjectDeserializationDemo (2-3)

class MyObjectInputStream extends
ObjectInputStream
public MyObjectInputStream(
InputStream in )
throws IOException
super(in)
protected Class resolveClass(ObjectStreamClass
v)
throws IOException
int n readInt()

115
ObjectDeserializationDemo (2-4)

System.out.println(
"number of bytes " n )
byte code new byten
read( code )
MyLoader myLoader new
MyLoader( n, code )
Class myClass null
try
String name v.getName()
myClass
myLoader.loadClass( name )

116
ObjectDeserializationDemo (2-5)

catch (
ClassNotFoundException e )
System.out.println( e )
return myClass

117
Package java.rmi

Allows Java objects residing in different virtual
machines to communicate using normal method calls

client JVM
server JVM
Remote
RemoteObject
method()
method()
Internet
stub
stub
118
Interface Remote

To identify interfaces whose methods can be
invoked on a non-local machine
No methods defined
Only methods specified in interfaces that extend
this interface are available remotely

119
Generates Stubs

Stub classes for a class which implements the
Remote interface will be generated with the rmic
tool
Stub classes contain all the code involved in
serializing details of a remote method call,
dynamically invoking the remote method and
serializing the results back to the caller

120
Distributing Codes