book

Java Network Programming, Second Edition

Name: Java Network Programming, Second Edition
Author: Elliotte Rusty Harold
ISBN: 9781565928701

by Elliotte Rusty Harold

August 2000

Intermediate to advanced

760 pages

21h

English

O'Reilly Media, Inc.

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Java Network Programming, 2nd Edition
Preface
About the Second Edition
Organization of the Book
Who You Are
Java Versions
Security
About the Examples
Conventions Used in This Book
Request for Comments
Acknowledgments

1. Why Networked Java?
What Can a Network Program Do?Retrieve Data and Display ItRepeatedly Retrieve DataSend DataFile storageMassively parallel computingSmart formsPeer-to-Peer InteractionGamesChatWhiteboardsServersSearching the WebElectronic CommerceApplications of the FutureUbiquitous computingInteractive televisionCollaboration
But Wait!—There’s More!
2. Basic Network Concepts
Networks
The Layers of a Network
The Host-to-Network LayerThe Internet LayerThe Transport LayerThe Application Layer
IP, TCP, and UDP
IP Addresses and Domain NamesPorts
The Internet
Internet Address ClassesFirewallsProxy Servers
The Client/Server Model
Internet Standards
IETF RFCsW3C Recommendations
3. Basic Web Concepts
URIsURNsURLsRelative URLs
HTML, SGML, and XML
HTTP
MIME
CGI
Applets and Security
Where Do Applets and Classes Come from?Security: Who Can an Applet Talk to and What Can It Say?
4. Java I/O
Output Streams
Input Streams
Marking and Resetting
Filter Streams
Chaining Filters TogetherBuffered StreamsPrintStreamPrintStream is evil and network programmers shouldavoid it like the plaguePushbackInputStreamData StreamsCompressing StreamsDigest StreamsEncrypting Streams
Readers and Writers
WritersOutputStreamWriterReadersFilter Readers and WritersBuffered readers and writersLineNumberReaderPushbackReaderPrintWriter
5. Threads
Running ThreadsSubclassing ThreadImplementing the Runnable Interface
Returning Information from a Thread
Race ConditionsPollingCallbacks
Synchronization
Synchronized BlocksSynchronized MethodsAlternatives to Synchronization
Deadlock
Thread Scheduling
PrioritiesPreemptionBlockingYieldingSleepingJoining threadsWaiting on an objectPriority-based preemptionFinish
Thread Pools
6. Looking Up Internet Addresses
DNS, IP Addresses, and All That
The InetAddress Class
Creating New InetAddress Objectspublic static InetAddress InetAddress.getByName(String hostName) throws UnknownHostExceptionpublic static InetAddress[ ] InetAddress.getAllByName (String hostName) throws UnknownHostExceptionpublic static InetAddress InetAddress.getLocalHost( ) throws UnknownHostExceptionSecurity issuesOther sources of InetAddress objectsGetter Methodspublic String getHostName( )public String getHostAddress( )public byte[ ] getAddress( )Object Methodspublic boolean equals(Object o)public int hashCode( )public String toString( )
Some Useful Programs
HostLookupProcessing Web Server Log Files
7. Retrieving Data with URLs
The URL ClassCreating New URLsConstructing a URL from a stringConstructing a URL from its component partsConstructing relative URLsSpecifying a URLStreamHandlerOther sources of URL objectsSplitting a URL into Piecespublic String getProtocol( )public String getHost( )public int getPort( )public String getFile( )public String getPath( ) // Java 1.3public string getRef( )public string getQuery( ) // Java 1.3public string getUserInfo( ) // Java 1.3public string getAuthority( ) // Java 1.3Retrieving Data from a URLpublic final InputStream openStream( ) throws IOExceptionpublic URLConnection openConnection( ) throws IOExceptionpublic final Object getContent( ) throws IOExceptionpublic final Object getContent(Class[ ] classes) throws IOException // Java 1.3Utility Methodspublic boolean sameFile(URL other)public String toExternalForm( )The Object Methodspublic String toString( )public boolean equals(Object o)public int hashCode( )Methods for Protocol Handlerspublic static synchronized void setURLStreamHandlerFactory (URLStreamHandlerFactory factory)protected void set(String protocol, String host, int port, String file, String ref )
The URLEncoder and URLDecoder Classes
URLEncoderURLDecoder
Communicating with CGIs and Servlets Through GET
Accessing Password-Protected Sites
The Authenticator ClassThe PasswordAuthentication ClassThe JPasswordField Class
8. HTML in Swing
HTML on Components
JEditorPane
Constructing HTML User Interfaces on the FlyHandling HyperlinksReading HTML Directly
Parsing HTML
HTMLEditorKit.ParserHTMLEditorKit.ParserCallbackHTML.TagAttributes
9. The Network Methods of java.applet.Applet
Using java.applet.Applet to Download DataFiguring Out Where the Applet Came frompublic URL getDocumentBase( )public URL getCodeBase( )Downloading Imagespublic Image getImage(URL u)public Image getImage(URL path, String filename)Downloading Soundspublic void play(URL u)public void play(URL url, String filename)public AudioClip getAudioClip(URL u)public AudioClip getAudioClip(URL url, String filename)public static final AudioClip newAudioClip(URL url) // Java 1.2
The ImageObserver Interface
The ImageObserver Constants
The MediaTracker Class
The ConstructorAdding Images to MediaTrackerspublic void addImage(Image image, int id)public void addImage(Image image, int id, int width, int height)Checking Whether Media Has Loadedpublic boolean checkID(int id)public boolean checkID(int id, boolean load)public boolean checkAll( )public boolean checkAll(boolean load)Waiting for Media to Loadpublic void waitForID(int id) throws InterruptedExceptionpublic boolean waitForID(int id, long milliseconds) throws InterruptedExceptionpublic boolean waitForAll( ) throws InterruptedExceptionpublic boolean waitForAll(long milliseconds) throws InterruptedExceptionError Checkingpublic boolean isErrorAny( )public Object[ ] getErrorsAny( )public boolean isErrorID(int id)public Object[ ] getErrorsID(int id)Checking the Status of Mediapublic int statusAll(boolean load)public int statusID(int id, boolean load)Removing Images from MediaTrackers
Network Methods of java.applet.AppletContext
10. Sockets for Clients
Socket Basics
Investigating Protocols with Telnet
The Socket Class
The Constructorspublic Socket(String host, int port) throws UnknownHostException, IOExceptionpublic Socket(InetAddress host, int port) throws IOExceptionpublic Socket(String host, int port, InetAddress interface, int localPort) throws IOExceptionpublic Socket(InetAddress host, int port, InetAddress interface, int localPort) throws IOExceptionprotected Socket( )protected Socket(SocketImpl impl)Getting Information About a Socketpublic InetAddress getInetAddress( )public int getPort( )public int getLocalPort( )public InetAddress getLocalAddress( )public InputStream getInputStream( ) throws IOExceptionpublic OutputStream getOutputStream( ) throws IOExceptionClosing the Socketpublic synchronized void close( ) throws IOExceptionHalf-closed sockets // Java 1.3The Object Methodspublic String toString( )Setting Socket OptionsTCP_NODELAYSO_LINGERSO_TIMEOUTSO_RCVBUFSO_SNDBUFSO_KEEPALIVE
Socket Exceptions
Examples
FingerWhois
11. Sockets for Servers
The ServerSocket ClassThe Constructorspublic ServerSocket(int port) throws IOException, BindExceptionpublic ServerSocket(int port, int queueLength) throws IOException, BindExceptionpublic ServerSocket(int port, int queueLength, InetAddress bindAddress) throws BindException, IOExceptionAccepting and Closing Connectionspublic Socket accept( ) throws IOExceptionpublic void close( ) throws IOExceptionThe get Methodspublic InetAddress getInetAddress( )public int getLocalPort( )Socket Optionspublic void setSoTimeout(int timeout) throws SocketExceptionpublic int getSoTimeout( ) throws IOExceptionThe Object Methodspublic String toString( )Implementationpublic static synchronized void setSocketFactory (SocketImpl Factory fac) throws IOExceptionProtected final void implAccept(Socket s) throws IOException
Some Useful Servers
Client TesterHTTP ServersA single-file serverA redirectorA full-fledged HTTP server
12. Secure Sockets
Secure Communications
Creating Secure Client Sockets
Methods of the SSLSocket Class
Choosing the Cipher SuitesEvent HandlersSession ManagementClient Mode
Creating Secure Server Sockets
Methods of the SSLServerSocket Class
Choosing the Cipher SuitesSession ManagementClient Mode
13. UDP Datagrams and Sockets
The UDP Protocol
The DatagramPacket Class
The ConstructorsConstructors for receiving datagramsConstructors for sending datagramsThe get Methodspublic InetAddress getAddress( )public int getPort( )public byte[ ] getData( )public int getLength( )public int getOffset( ) // Java 1.2The set Methodspublic void setData(byte[ ] data)public void setData(byte[ ] data, int offset, int length) // Java 1.2public void setAddress(InetAddress remote)public void setPort(int port)public void setLength(int length)
The DatagramSocket Class
The Constructorspublic DatagramSocket( ) throws SocketExceptionpublic DatagramSocket(int port) throws SocketExceptionpublic DatagramSocket(int port, InetAddress address) throws SocketExceptionSending and Receiving Datagramspublic void send(DatagramPacket dp) throws IOExceptionpublic void receive(DatagramPacket dp) throws IOExceptionpublic void close( )public int getLocalPort( )Managing Connectionspublic void connect(InetAddress host, int port) // Java 1.2public void disconnect( ) // Java 1.2public int getPort( ) // Java 1.2public InetAddress getInetAddress( ) // Java 1.2Socket OptionsSO_TIMEOUTSO_RCVBUFSO_SNDBUF
Some Useful Applications
Simple UDP ClientsUDPServerA UDP Echo Client
14. Multicast Sockets
What Is a Multicast Socket?Multicast Addresses and GroupsClients and ServersRouters and Routing
Working with Multicast Sockets
The Constructorspublic MulticastSocket( ) throws SocketExceptionpublic MulticastSocket(int port) throws SocketExceptionCommunicating with a Multicast Grouppublic void joinGroup(InetAddress address) throws IOExceptionpublic void leaveGroup(InetAddress address) throws IOExceptionpublic void send(DatagramPacket packet, byte ttl) throws IOExceptionpublic void setInterface(InetAddress address) throws SocketExceptionpublic InetAddress getInterface( ) throws SocketExceptionpublic void setTimeToLive(int ttl) throws IOException // Java 1.2public int getTimeToLive( ) throws IOException // Java 1.2
Two Simple Examples
15. The URLConnection Class
Opening URLConnections
Reading Data from a Server
Reading the Header
Retrieving Specific MIME Header Fieldspublic String getContentType( )public int getContentLength( )public String getContentEncoding( )public long getDate( )public long getExpiration( )public long getLastModified( )Retrieving Arbitrary MIME Header Fieldspublic String getHeaderField(String name)public String getHeaderFieldKey(int n)public String getHeaderField(int n)public long getHeaderFieldDate(String name, long default)public int getHeaderFieldInt(String name, int default)
Configuring the Connection
protected URL urlconnectedallowUserInteractiondefaultAllowUserInteractiondoInputdoOutputifModifiedSinceuseCachesdefaultUseCaches
Configuring the Client Request MIME Header
Writing Data to a Server
Content Handlers
Getting Contentpublic Object getContent( ) throws IOExceptionpublic Object getContent(Class[ ] classes) throws IOException // Java 1.3ContentHandlerFactory
The Object Methods
Security Considerations for URLConnections
Guessing MIME Types
HttpURLConnection
The Request MethodHEADOPTIONSDELETEPUTTRACEDisconnecting from the ServerHandling Server ResponsesError conditionsRedirectsProxies
JarURLConnection
16. Protocol Handlers
What Is a Protocol Handler?
The URLStreamHandler Class
The ConstructorMethods for Parsing URLsProtected void parseURL(URL u, String spec, int start, int limit)Protected String toExternalForm(URL u)Protected void setURL(URL u, String protocol, String host, int port, String file, String ref )Protected int getDefaultPort( ) // Java 1.3Protected InetAddress getHostAddress(URL u) // Java 1.3Protected boolean hostsEqual(URL u1, URL u2) // Java 1.3Protected boolean sameFile(URL u1, URL u2) // Java 1.3Protected boolean equals(URL u1, URL u2) // Java 1.3Protected int hashCode(URL u) // Java 1.3A Method for ConnectingProtected abstract URLConnection openConnection(URL u) throws IOException
Writing a Protocol Handler
More Protocol Handler Examples and Techniques
A daytime Protocol HandlerA chargen Protocol Handler
The URLStreamHandlerFactory Interface
17. Content Handlers
What Is a Content Handler?
The ContentHandler Class
A Content Handler for Tab-Separated ValuesUsing Content HandlersChoosing Return Types
The ContentHandlerFactory Interface
The createContentHandler( ) MethodInstalling Content Handler Factories
A Content Handler for an Image Format: image/x-fits
18. Remote Method Invocation
What Is Remote Method Invocation?SecurityObject SerializationUnder the Hood
Implementation
The Server SideThe Client SideCompiling the StubsStarting the ServerRunning the Client
Loading Classes at Runtime
An Applet Client for a Remote ObjectAn Application Client for a Remote Object
The java.rmi Package
The Remote InterfaceThe Naming Classpublic static String[ ] list(String url) throws RemoteException, MalformedURLExceptionpublic static Remote lookup(String url) throws RemoteException, NotBoundException, AccessException, MalformedURLExceptionpublic static void bind(String url, Remote object) throws RemoteException, AlreadyBoundException, MalformedURLException, AccessExceptionpublic static void unbind(String url) throws RemoteException, NotBoundException, AlreadyBoundException, MalformedURLException, AccessException // Java 1.2public static void rebind(String url, Remote object) throws RemoteException, AccessException, MalformedURLExceptionThe RMISecurityManager Classpublic RMISecurityManager( )public Object getSecurityContext( )Checking operationsRemote Exceptions
The java.rmi.registry Package
The Registry InterfaceThe LocateRegistry Class
The java.rmi.server Package
The RemoteObject ClassThe RemoteServer ClassConstructorsGetting information about the clientLoggingThe UnicastRemoteObject ClassExceptions
19. The JavaMail API
What Is the JavaMail API?
Sending Email
Sending Email from an ApplicationSending Email from an Applet
Receiving Mail
Password Authentication
Addresses
The Address ClassThe InternetAddress ClassThe NewsAddress Class
The URLName Class
The ConstructorsParsing Methods
The Message Class
Creating MessagesReplying to messagesGetting messages from foldersBasic Header InfoThe From addressThe Reply-to addressThe recipient addressesThe subject of the messageThe date of the messageSaving changesFlagsFoldersSearching
The Part Interface
AttributesHeadersContentReading the contents of the partWriting the contents of the part
Multipart Messages and File Attachments
MIME Messages
Folders
Opening FoldersBasic Folder InfoManaging FoldersManaging Messages in FoldersSubscriptionsListing the Contents of a FolderChecking for MailGetting Messages from FoldersSearching FoldersFlagsEvent HandlingUtility Methods
Index
Colophon

Content preview from Java Network Programming, Second Edition

Chapter 9. The Network Methods of java.applet.Applet

Undoubtedly you’re familiar with applets, Java programs that can be embedded on a web page and run in a secure environment within a browser. All applets extend the java.applet.Applet class, which includes a number of methods that perform network-related operations. These methods allow an applet to find out where it came from, download images and sounds from a web server, and track the progress of the download. This chapter discusses the interaction between applets and the network. It doesn’t provide an introduction to the Applet class as a whole; for that, see an introductory book such as Niemeyer and Peck’s Learning Java (O’Reilly & Associates, Inc., 2000).

Using java.applet.Applet to Download Data

The methods of the Applet class discussed in this section are really just thin veneers over equivalent methods in the java.applet.AppletStub and java.applet.AppletContext interfaces. These interfaces describe services that the web browser or applet viewer provides to applets. The exact classes that implement these interfaces are undocumented and vary from implementation to implementation. Applets that you instantiate yourself (for example, an applet that also runs as an application by supplying a main( ) method that calls the applet’s init( ) and start( ) methods) will generally have null AppletStub and AppletContext members. Therefore, if you try to use these methods in such an applet, a NullPointerException will be thrown.

Figuring ...

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