Programming Java 2 Micro Edition for Symbian OS 2004 (779882), страница 3
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In contrast, until recently, wireless devices wereas closed as the legendary mainframes of decades past; the only developers of software for the early mobile phones were hidden away in thelaboratories of the large companies who made those phones.Coupled with advances in the raw computational capabilities of thedevices themselves, the development and adoption of the Java 2 MicroEdition (J2ME) platform has changed all that. Within the last few years,wireless devices have emerged as a new, open, networked computingplatform deployed on a massive scale.
Its effectiveness has been in largepart facilitated by the availability of a standard software architecture,xxiiFOREWORDone that reduces the difficulty and cost of developing applications whilesupporting a broad and competitive market for implementations.Symbian has been a key player in the creation of this new ecosystem.The most recent version of Symbian OS incorporates the most currentJ2ME platform targeting mobile devices: MIDP 2.0. Symbian OS andMIDP 2.0 together form an integrated, compelling package spanning thesoftware stack of a wireless device.This book focuses on MIDP programming of Symbian OS phones. Farfrom just reciting a litany of API descriptions, it uses example applicationsto make practical points. It digs into the details that are relevant to goodapplication design and getting good performance. As well as coveringMIDP 2.0 programming, the book also covers programming for MIDP1.0, the platform in many already-deployed devices.
Finally, the bookexplores many of the standard J2ME optional packages that SymbianOS currently supports, or will support in the near future. The examplesare developed completely, through to their installation and execution onreal devices.Although presented in the context of Symbian OS, the worldwideavailability of MIDP on wireless devices means that the lessons of thisbook are not tied to any particular operating system. This book shouldappeal to all developers who want to take better advantage of the wirelessJ2ME platform.Innovation Through OpennessThe success of an open operating system for smartphones is closelylinked to the degree to which the functionality of lower levels of softwareand hardware can be accessed, modified, and augmented by add-onsoftware and hardware.
Java MIDP 1.0 allowed only modest access tounderlying Symbian OS functionality. Java MIDP 2.0 exploits it muchmore fully and this book brings you the most up-to-date informationavailable for programming Java MIDP 2.0 for Symbian OS. As Java MIDP2.0 smartphones begin to ship in volume in 2004, we are witnessing thecoming of a third wave of mobile phones.The first wave was voice-centric mobile phones. Mobile phone manufacturers have performed wonders of optimization on the core featureof these phones – their ability to provide great mobile voice communications. Successive generations of products improved their portability,battery life, reliability, signal handling, voice quality, ergonomics, price,and usability. In the process, mobile phones became the most successfulconsumer electronics product in history.The second wave was rich-experience mobile phones.
Instead of justconveying voice conversations between mouth and ear, these phonesprovided a much richer sensory experience than their predecessors.High-resolution color screens conveyed data vividly and graphically.High-fidelity audio systems played quality music through such thingsas ringtones and audio files. These phones combined multimedia withinformation and communications, to dramatic effect.But the best was still to come. The primary characteristic of the thirdwave of mobile phones is their openness.
Openness is an abstract concept,but one with huge and tangible consequences for developers. The keydriver is that the growing on-board intelligence in modern phones – thesmartness of the hardware and software – can now be readily accessedby add-on hardware and software. The range of applications and servicesthat can be used on a phone is not fixed at the time of manufacture,meaning new applications and services can be added afterwards. ThexxivINNOVATION THROUGH OPENNESSphone can be tailored by an operator to suit its customers and thesecustomers can then add further customizations, reflecting specific needsor interests.The Symbian EcosystemOpen phones allow a much wider array of companies and individualsto contribute to the value and attractiveness of smartphones.
The attractiveness of a phone to an end-user is no longer determined only by thevarious parties involved in the creation of that phone. Over-the-air downloads and other late-binding mechanisms allow additional companiesand individuals to try out new ideas, delivering their applications andservices directly to end-users.
Many of these ideas may not seem viable atthe time of manufacture. However, the advantage of open phones is thatthere is more time and more opportunity for all these new and innovativeideas to mature into advantageous, usable applications that can make auser’s life easier – whether it be over-the-air synchronization with a PC,checking traffic or having fun with 3D games or photo editing.The real power of open phones arises when add-on services on onephone are re-used as add-on services on other phones.
This allows anenormous third-party development ecosystem to flourish. These thirdparties are no longer tied to the fortunes of any one phone, or anyone phone manufacturer. Moreover, applications that start their livesas add-ons for one phone can find themselves incorporated at timeof manufacture in subsequent phones, including phones from othermanufacturers. This depends on the commonality of the underlyingoperating system. Open standards drive a virtuous cycle of researchand development: numerous companies can leverage the prowess, skills,experience and success of the Symbian ecosystem.Symbian OS PhonesSymbian OS phones are currently based on the following user interfacesopen to C++ and Java programmers: the Series 80 Platform (Nokia 9200Communicator series), the Series 90 Platform (Nokia 7700), the Series 60Platform (Nokia 6600, 6620, 7650, 3650, 3660, 3620, N-Gage, SiemensSX1 and Sendo X), and UIQ (Sony Ericsson P800, P900, BenQ P30,Motorola A920 and A925).
The Nokia 6600 was the first smartphone toinclude Java MIDP 2.0. Read on for a brief summary of the user interfacefamilies now available.Mobile Phones with a Numeric KeypadThese phones are designed for one-handed use and require a flexibleUI that is simple to navigate with a joystick, softkeys, jogdial, or anyINNOVATION THROUGH OPENNESSxxvcombination of these. Examples of this come from the Series 60 Platformwhich, in addition to the manufacturers listed above, is also licensed toPanasonic and Samsung. Fujitsu produces a user interface for a rangeof phones including the F2102v, F2051 and F900i for NTT DoCoMo’sFOMA network. Pictured is the Siemens SX1.Mobile Phones with Portrait Touch ScreensThese mobile phones tend to have larger screens than those in theprevious category and can dispense with a numeric keypad altogether.
Alarger screen is ideal for viewing content or working on the move, andpen-based interaction gives new opportunities to users and developers.The best current example of this form factor is UIQ, which is the platformfor the Sony Ericsson P800 and P900, as well as BenQ P30 and Motorola’sA920 and A925. The P800, P900 and P30 actually combine elements offull screen access and more traditional mobile phone use by including anumeric keypad, while the Motorola smartphones dispense with a keypadaltogether.
Pictured is the Sony Ericsson P900.Mobile Phones with Landscape ScreensThese mobile phones have the largest screens of all Symbian OS phonesand can have a full keyboard and may also include a touch screen. Withthis type of mobile phone, developers may find enterprise applicationsparticularly attractive. A current example of the keyboard form factor isthe Series 80 Platform. This is the basis of the Nokia 9200 Communicatorseries, and has been used in the Nokia 9210i and Nokia 9290.
Based onthe Series 90 Platform, the Nokia 7700 is an example of a touch screenmobile phone without keyboard, aimed more at high multimedia usage.xxviINNOVATION THROUGH OPENNESSWhen you’re ready to use the Java programming skills you’ve learnedin this book, you’ll want an up-to-the-minute overview of availablephones, user interfaces and tools.
For the latest information, start atwww.symbian.com/developer for pointers to partner websites, otherbooks, white papers and sample code. If you’re developing technologythat could be used on any Symbian OS phone, you can find more information about partnering with Symbian at www.symbian.com/partners.We wish you an enjoyable experience programming with Symbian OSand lots of commercial success.Section 1J2ME and MIDP1Introduction to J2MEIn order to understand how Java 2 Micro Edition (J2ME) lies within thewider Java landscape it is best to explore the overall Java architecture.J2ME has been developed primarily as a technology for the execution ofapplications on constrained devices.
In this case, constrained devices aremobile phones, PDAs, TV set-top boxes, in-vehicle telemetry, residentialgateways and other embedded devices.J2ME as a whole can be described as the technology that caters for allthese devices. Given that many of them have limited resources, it wouldbe imprudent to expect all of these devices to be able to deliver all of thefunctionality of the few. The Java community therefore decided that thesedevices should be grouped to best reflect their purpose and capabilities.This would provide a lowest common denominator for each devicegroup and arrange them into configurations. To further differentiate thesedevices and to accommodate vertical markets within each configuration,profiles were created, refining the Java APIs for each device type.The following analyzes how J2ME is positioned within the Java architecture and how the J2ME configurations and profiles complement eachother.
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