client side networking

7/27/2019 Client Side Networking

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Client-side networking

14.1 Class InetAddress14.2 An InetAddress example

14.3 Class Socket14.4 Getting Web pages with a socket14.5 Building a PostOutputStream class14.6 Wrapping up


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Package java.netAuthenticatorContentHandlerDatagramPacketDatagramSocket

InetAddressServerSocket

Socket SocketImplURLURLConnectionURLEncoderURLStreamHandlerMalformedURLExceptionProtocolExceptionSocketExceptionUnknownHostExceptionUnknownServiceExceptionContentHandlerFactory

SocketImplFactoryURLStreamHandlerFactory


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Class InetAddress (no constructors)

Listing of Public members of java.net. InetAddress .

public final class InetAddress {public String getHostName()public byte[] getAddress()

public String getHostAddress()public int hashCode()public boolean equals(Object obj)public String toString()

public static synchronized InetAddress getByName(String host) throwsUnknownHostException

public static synchronized InetAddress getAllByName(String host)[] throwsUnknownHostException

public static InetAddress getLocalHost() throws UnknownHostException }


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Static M ethods

public static I netAddress getL ocalH ost() throws UnknownHostException

The getLocalHost() returns an InetAddress objectrepresenting the address of the local host.

public static synchroni zed I netAddress[] getAllByName(Str ing host) throws

UnknownHostException The getAllByName() method returns an array of

InetAddress objects representing all of theaddresses for the specified host .


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Static M ethods

public static synchronized I netAddress getByName(Str ing host) throws

UnknownHostException

The getByName() method returns an InetAddressobject containing the internet address informationfor the specified hostname.

The host is a string object for the specified host.


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I nstance M ethods

public Str ing getH ostName()

The getH ostName() method returns a Stringobject containing the name of the host for this InetAddress.

If the host is null, the returned string willcontain any of the local machine's availablenetwork addresses.


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Instance M ethods

public byte[] getAddress()

The getAddress() method returns an array of bytes containing the raw IP address of thisInetAddress in network byte order.


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Instance M ethods --- JDK1.1

public Str ing getH ostAddress() The getH ostAddress() method returns the IP address

string containing the raw IP address using thestandard format (%d.%d.%d.%d).

public boolean i sM ulticastAddress() The isM ulticastAddress() method checks if the

InetAddress is an IP multicast address and returnsa boolean indicating if the InetAddress is an IPmulticast address.

An IP multicast address is a Class D address i.e thefirst four bits of the address are 1110 (224~239).


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UnknownHostException

java.lang.Object|+--java.lang.Throwable

|

+--java.lang.Exception|+--java.io.IOException

|

+--java.net.UnknownHostExceptionThrown to indicate that the IP address of a hostcould not be determined.


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SecurityException


|

+--java.lang.Exception|+--java.lang.RuntimeException

|

+--java.lang.SecurityException

Thrown by the security manager to indicate asecurity violation.


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An InetAddress Example

A nslookup like example .Class FileReader

java.lang.Object

| || +--java.io.FileDescriptor |+--java.io.Reader

| |

| +--java.io.BufferedReader |

+--java.io.InputStreamReader |+--java.io.FileReader
http://localhost/var/www/apps/conversion/tmp/Hugh's%20Examples/InetExample.javahttp://localhost/var/www/apps/conversion/tmp/Hugh's%20Examples/InetExample.java


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Class Socket

An implementation of a TCP/IP network connection.A client create a Socket to a remote host toestablish a streamed-based communicationchannel.


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Class Socket

Protected members of java.net. Socket .protected Socket()

Creates an unconnected socket, with the system-

default type of SocketImp protected Socket(SocketI mpl impl)

Creates an unconnected Socket with a user-

specified SocketImpl .


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Class SocketListing of Public members of java.net. Socket .

public final class Socket {public Socket (String host, int port) throws UnknownHostException,

IOExceptionpublic Socket (String host, int port, boolean stream) throws IOExceptionpublic Socket (InetAddress address, int port) throws IOException

public Socket (InetAddress address, int port, boolean stream) throwsIOException

public InetAddress getInetAddress()public int getPort()public int getLocalPort()

public InputStream getInputStream() throws IOExceptionpublic OutputStream getOutputStream() throws IOExceptionpublic synchronized void close() throws IOExceptionpublic String toString()public static synchronized void setSocketImplFactory(SocketImplFactory fac)

throws IOException}


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Constructors

public Socket(Str ing host, int por t) throws UnknownH ostException, I OException

This Socket() constructor creates a stream socket tothe specified port on the specified host.

The host is a String object containing the host nameto create the socket on.

The port is an integer (1-65535) value representingthe port to create the socket on.


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Constructors

public Socket(Str ing host, int port, boolean stream) throws I OException --- Deprecated

This Socket() constructor creates a stream socket tothe specified port on the specified host.

The boolean stream value can be used to specify astream socket or a datagram socket.

The stream is a boolean value that is true if a stream socket is to be created, false if a datagram socketis to be created.


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Constructors

public Socket(I netAddress address, int port) thr ows I OException

This Socket() constructor creates a streamsocket to the specified port at the specifiedInetAddress.

The address is an I netAddress specifying theaddress at which to create the socket.


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Constructors

publ ic Socket(I netAddress address, int port,boolean stream) throws I OException

--- Deprecated

This Socket() constructor creates a stream socket tothe specified port at the specified address.

The boolean stream value can be used to specify astream (true ) socket or a datagram (false ) socket.

The address is an InetAddress specifying the addressat which to create the socket.


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Constructors JDK1.1

publ ic Socket(I netAddress address, int port,I netAddress localAddr , int localPort) thr ows

I OException Good for multihomed machine- a machine withmultiple network interface.

This Socket() constructor creates a socket andconnects it to the specified remote address on thespecified remote port.

The Socket will also bind() to the local address and port supplied.


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Constructors JDK1.1

public Socket(Str ing host, int por t, I netAddress localAddr , int localPor t) thr ows I OException

This Socket() constructor creates a socket andconnects it to the specified remote host on the

specified remote port.The Socket will also bind() to the local address and port supplied.

Null - use default local address.

0 - use a random unsed port.


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M ethods

See the JDK1.3 Documentation
http://localhost/Utilities%20Programs/JAVA/jdk1.3/docs/index.htmlhttp://localhost/Utilities%20Programs/JAVA/jdk1.3/docs/index.html


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Related Exceptions

Class SocketException


|+--java.lang.Exception

|+--java.io.IOException

|+--java.net. SocketException

Direct Known Subclasses:BindException , ConnectException ,NoRouteToH ostException


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Related Exceptions

Class SecurityException


|+--java.lang.Exception

|+--java.lang.RuntimeException

|+--java.lang. SecurityException

Direct Known Subclasses:AccessContr olException, RM I Secur i tyException


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Socket I mplementation

Must inherit SocketI mpl abstract class.Create a subclass that implements the necessaryconnection setup and control methods.Create a SocketI mplF actory that returnsinstances of this new SocketI mpl class.Register this SocketI mplF actory with thesocket class through its setSocketI mplF actory()

method.Provide, if necessary, a correspondingimplementation at the server.


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Getting Web pages with a socket

An Example to demonstrate how to download aweb page.This program uses URL class
http://localhost/var/www/apps/conversion/tmp/Hugh's%20Examples/GrabPage.javahttp://localhost/Utilities%20Programs/JAVA/jdk1.3/docs/api/java/net/URL.htmlhttp://localhost/Utilities%20Programs/JAVA/jdk1.3/docs/api/java/net/URL.htmlhttp://localhost/var/www/apps/conversion/tmp/Hugh's%20Examples/GrabPage.java


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Building a PostOutputStream class

Demostrating an OutputStream class that perform an HTTP post operation.Connect to the web server and send:

POST filename HTTP/1.0Content-type: MIME type application/x-www-form-urlencoded Content-length: length


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Building a PostOutputStream class

The body contains:key1=value1&key2=value2.. The Example Program
http://localhost/var/www/apps/conversion/tmp/Hugh's%20Examples/PostOutputStream.javahttp://localhost/var/www/apps/conversion/tmp/Hugh's%20Examples/PostOutputStream.java

client side networking

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