Pemrograman Jaringan Pengenalan Java

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A R M I N L A W I

P R O G R A M P A S C A S A R A J A N U N H A S

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Pengenalan java

 Menerapkan compiler dan interpreter

public class myCetak {

public static void main(String args[]) {

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Karakteristik Multi-platform

public class myCetak {

System.out.println(“Hello World!”); }

}

compiler

program.java program.class

Windows Linux Solaris MacOS

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Software yang dibutuhkan



Java Standrd Edition (SE) Development Kit (JDK)

Dapat didownload gratis di

http://developers.sun.com/downloads/

 JDK yang digunakan pada MK ini adalah versi terbaru saat ini: JDK1.6.0 update 10



Text Editor:

Notepad, Edit, dll

4

Java IDE:

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OOP dan Java

 Java adalah bahasa pemrograman murni berbasis object-oriented (OO)

 OOP: Program bekerja atas interaksi atau

komunikasi antar obyek (object interprocess)

 OO-program dapat dipandang sebagai sistem tersebar (distributed system)

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Apa itu obyek?

 Segala sesuatu dapat dipandang sbg obyek

 Karateristik obyek

 Memiliki atribut sebagai status (state/variable)

 Memiliki tingkah laku (behavior) atau method

variabel/ state

method/ behavior

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Bagaimana membuat obyek

 Obyek dikonstruksi/dirancang dari prototipe atau

blueprint yang telah ditetapkan (class)

 Contoh:

resep  class

kue  obyek

Bahan:

1 kg gula 2 sdk mentega dan sterusnya.

Cara Membuat: Campur semua lalu panaskan dan seterusnya

Resep Kue 1

Kue 2

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Contoh oop dalam java

class mhs {

private String nama; private String nim; private String ttl; private String agama;

public mhs(String nama, String nim, String m, String agama) { this.nama = nama;

this.nim = nim; this.ttl = ttl;

this.agama = agama; }

public String getNama() { return this.nama; }

public String getNim() { return nim;

}

mhs m = new mhs(“Armin”, “132133693”, “19”, “Islam”); System.out.println(“Nama =“ + m.getNama());

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Ciri-ciri oop

 Abstraksi (abstraction)

Pengabstrakan atau penyembunyian kerumitan dari suatu proses

 Pembungkusan (encapsulation)

Abstraksi dilakukan dengan cara pembungkusan (kapsulasi) semua kode dan data kedalam satu entitas tunggal (obyek)

 Pewarisan (inheritance)

Implementasi khusus dalam OOP yang dapat menurunkan prilaku ke sub-class atau menerima prilaku dari super-class

 Kebanyak-rupaan (polymorphism)

Kemampuan obyek mengungkap banyak hal melalui suatu cara yang sama. Obyek dapat menjalankan prilaku-prilaku atau metode-metode yang diturunkan dari beberapa superclassnya

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Netprog 2000 - Java Network Programming

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Important Java Packages

java.net TCP/IP networking

java.io I/O streams & utilities

java.rmi Remote Method Invocation

java.security Security policies

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Java Sockets Programming

 Java uses BSD-style sockets to interface with TCP/IP services (java.net package)

 Java distinguishes between UDP, TCP server & TCP client sockets

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IP Addresses & Hostnames

 java.net.InetAddress class

 Represents a single IP address

 Factory class – no public constructor

 Performs transparent DNS lookups or reverse lookups

 java.net.UnkownHostException thrown if

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TCP Server Sockets

 java.net.ServerSocket class

 Binds to a local port to listen for initial connections

 Can be bound to a local IP for multi-homed machines

 accept() method returns a java.net.Socket,

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TCP Client Sockets

 java.net.Socket class

 Combines socket with socket options (timeout, linger, keep alive, no delay, etc)

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UDP Sockets

 java.net.DatagramSocket class

 Java makes no distinction between client/server for UDP sockets

 Connected mode UDP supported in Java 2

 Can be bound to both a local port & a local IP address – multi-homed support

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UDP Datagrams

 java.net.DatagramPacket class

 Expects a byte array of data

 Address optional for connected-mode UDP

 This class is final – can’t be extended!

 java.net.DatagramSocket instances can only

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Threading

 Java doesn’t support the notion of forking

processes; how do we support concurrency?

–

Java was designed to support

multi-threading!

–

In server environments we can spawn new

threads

to handle each client

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Java Servlets

 Servlets are the Java analog to CGI

 Advantages of servlets: full access to other Java APIs, persistence between invocations, guaranteed

portability

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HTTP Servlets



javax.servlet.http.HttpServlet

class

 Uses HTTP to receive requests and generate

responses

 Full support for all HTTP methods, cookies, sessions, persistent connections

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Java Applets

 Client-side Java programs that run in a browser

 Applets have special security restrictions called the applet sandbox

 Only applets loaded over the network are subject to the applet sandbox

 The applet sandbox is controlled by a

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Applet Sandbox



Can’t load libraries or define native methods



Can’t access local host filesystem



Can’t open sockets to hosts other than

originating host



Can’t use

Runtime.exec()



Applet windows have a unique appearance

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Escaping the Applet Sandbox

 Browsers can define their own security policy via a new security manager

 Applets can be signed and executed as trusted content

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Remote Method Invocation (RMI)



RMI is the Java analog to RPC



RMI servers use a naming service (rmiregistry) to

register

remote objects



RMI servers use a special security policy

implemented by

RMISecurityManager



The default RMI transport mechanism is via TCP

sockets

–

this is transparent to RMI code!



Any object transferred in an RMI call must

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Java Naming & Directory Interface (JNDI)



JNDI

provides a generic API that can be used to

interface with any naming system



JNDI uses SPIs (service provider interfaces) to

access many different types of naming & directory

services from the JNDI API

