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Introduction to Java ME
This document provides an introduction to the Java ME platform. It discusses that Java ME is the most widespread mobile application platform, developed by Sun Microsystems and now owned by Oracle. It aims to allow developers to create apps for over 80% of phones worldwide through APIs for GPS, sensors, graphics and touch. The document then covers the different Java platforms of SE, EE and ME. It details the configurations, profiles and APIs that make up the Java ME platform, including CLDC, MIDP and KVM.
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Introduction to Java ME
- 1. Introduc)on to Java ME Jussi Pohjolainen
- 2. INTRO TO JAVA ME PLATFORM
- 3. About Java ME • Java ME (J2ME is older name..) is the world’s most widespread mobile applica>on pla@orm • Developed by Sun Microsystems and bought by Oracle
- 4. Why? • So why? Market reach! • Over 80% of phones worldwide supports Java ME! • It’s possible to create awesome apps with new really powerful APIs: GPS, Sensors, 3D Graphics, Touch etc.. • Hardware geOng more powerful and less expensive
- 5. S40 Touch and Type • Series 40 6th Edi)on, Feature Pack 1 • Touch enabled phone with keyboard • Java ME APIs: Bluetooth, Web Services, Loca)on, Mobile 3D, Wireless Messaging, SVG, Mobile Media API, Gesture API.. • Price in Finland: ~130 euros
- 6. Java Pla[orms • Java Standard Edi>on (Java SE) – Designed for desktop computers – Runs on top of OS X, Linux, Windows … • Java Enterprise Edi>on (Java EE) – Mul)user, enterprise-‐wide applica)ons – Based on J2SE + several APIs for server-‐side compu)ng • Java Micro Edi>on (Java ME) – For )ny, small and resource-‐constrained devices
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- 8. Java Edi)ons Our course concentrates on this Java ME Op)onal Packages Java EE Java SE Personal Profile Op)onal Packages Founda)on Profile MIDP CDC CLDC Java Virtual Machine KVM
- 9. JCP and JSR • Java Community Process, JCP, is a formalized process which creates defini>ons of future versions and features of the Java pla[orm. • These defini)ons are called Java Specifica)on Requests, JSR • JSR is a formal document that describes proposed specifica)on and technology • There are over 300 JSRs. See list of them all.
- 10. Java ME Java Me Op)onal Packages Personal Profile Op)onal Packages Mobile Informa)on Device Profile Founda)on Profile (MIDP) Connected Device Configura)on Connected Limited Device (CLC) Configura)on (CLDC) JVM KVM
- 11. Kilo Virtual Machine • KVM is similar to JVM, runs apps wrifen in Java – language • KVM is used in cell phones, where JVM is used on computers • Op)mized for small size • More info: KVM White Paper
- 12. Java ME Java Me Op)onal Packages Personal Profile Op)onal Packages Mobile Informa)on Device Profile Founda)on Profile (MIDP) Connected Device Configura>on Connected Limited Device (CLC) Configura>on (CLDC) JVM KVM
- 13. Configura)ons: CLDC • CLDC (JSR 139) – Small wireless devices with intermiQent network connec)ons – Low power consump)on – Phones, Pagers, Bar code scanners.. • CDC (JSR 36) – Larger Devices with a robust network connec)on – Set top boxes, Internet appliances
- 14. CDC -‐ CLDC smaller larger Pagers Mobile Phones PDAs Car Naviga)on Systems Internet appliances Set-‐top Boxes Connected Limited Device Configura>on Connected Device Configura>on (CLDC) (CDC)
- 15. CLDC Func)onality • Subset of Java language • Subset of core Java SE libraries • Provides basic input and output • Provides basic networking support • Security
- 16. CLDC Libraries • CLDC has 37 common classes from Java SE – java.lang: Boolean, Byte, Integer, Long, String… – java.u>l: Calendar, Date, Enumera)on, Hashtable.. – java.io: InputStream, OutputStream… • CLDC 1.0 does not have floa)ng point support • CLDC 1.1 supports floa)ng point
- 17. Java ME Java Me Op)onal Packages Personal Profile Op)onal Packages Mobile Informa>on Device Profile Founda)on Profile (MIDP) Connected Device Configura)on Connected Limited Device (CLC) Configura)on (CLDC) JVM KVM
- 18. The Mobile Informa)on Device Profile (MIDP) • Specifica)on for wireless devices • Provides general Java libraries for developing apps for wireless devices • Versions: MIDP 1.0 (JSR 37) and MIDP 2.x (JSR 118) • MIDP 3.0 (JSR 271) under development • Great amount of devices that support MIDP
- 19. MIDP Differences • MIDP 1.0 – Limited graphics and sound – Only HTTP, no Sockets • MIDP 2.X – Game API – Network and Mul)media support • MIDP 3.0 – Background MIDlets, Improved UI, Localisa)on..
- 20. MIDP Sooware Components Device Specific MIDP Java App Java App Op)onal Java Op)onal Device Packages Specific Packages Na)ve Applica)on MIDP CLDC Device Opera)ng System
- 21. Example: Nokia N97 Device Specific MIDP Java App Java App Op)onal Java Nokia UI API Packages Na)ve Symbian App MIDP 2.1 CLDC 1.1 Symbian OS v9.3
- 22. MIDP Func)onality • Applica)on Life Cycle Management • User Interface • Network Connec)vity • Game support
- 23. Java ME Java Me Op)onal Packages Personal Profile Op>onal Packages Mobile Informa)on Device Profile Founda)on Profile (MIDP) Connected Device Configura)on Connected Limited Device (CLC) Configura)on (CLDC) JVM KVM
- 24. Op)onal Packages, JSRs • File Connec)on and PIM • Content Handler API • Bluetooth • SVG 1.0 • Wireless Messaging API (WMA) • Payment API • Mobile Media API (MMAPI) • Advanced Mul)media • Web Services Supplements (AMMS) • Security and Trust Services • Mobile Interna)onaliza)on API • Loca)on API • Java Bindings for the OpenGL ES • SIP API API • Mobile 3D Graphics • Mobile Service Architecture • Mobile Sensor API • Java Technology for the Wireless Industry (JTWI) • SVG 2.0 • Wireless Messaging 2.0 (WMA)
- 25. Problems • Different screen sizes • Bugs in phones • Performance • Fragmenta)on, JSRs
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- 28. How to Build MIDlets? • MIDlet = MIDP Applica)on • If Java SE is familiar, MIDlet development is easy • Part of the API works exactly like Java SE • Building process is different
- 29. Building Process 1. Compile 2. Preverify 3. Compress 4. Create JAD-‐file 5. Upload to client
- 30. 1. Compile • Compile a MIDlet: – javac –bootclasspath midpclasses MyApp.java! • Use now base classes from Java ME! • Aoer the compile, one must preverify the result
- 31. 2. Preverify • It is cheched in the preverifing process that your MIDlet does not harm the client-‐machine. • In Java SE this checking is done by JVM. KVM does not have this kind of security checking! • Security checking is done in two parts – Preverify before sending MIDlet to the client machine – Client machines own check • Command line: – preverify –classpath .; midp classes –d . Midlet!
- 32. 3. Compress • Aoer the MIDlet is compiled and preverified, you must compress all the classes (and resources) into one jar-‐file. • Jar-‐file contains also MANIFEST.MF -‐ file, which describes the contents of the jar-‐file. • Compressing with the jar-‐tool: – jar cvmf manifest.mf MIDlet.jar MIDlet.class!
- 33. Example of Manifest file MIDlet-1: MyMIDlet, MyMIDlet.png, MyMIDlet! MIDlet-Name: MyMIDlet! MIDlet-Vendor: Jussi Pohjolainen! MIDlet-Version: 1.0! MicroEdition-Configuration: CLDC-1.1! MicroEdition-Profile: MIDP-2.1!
- 34. 4. Create JAD -‐ file • Java Applica)on Descriptor file describes the contents of MIDlet. • Together, .jad and .jar are called MIDlet Suite • JAD-‐file is used so that the client machine can have informa)on about the sooware before installing it.
- 35. Example of JAD-‐file MIDlet-1: MyMIDlet, MyMIDlet.png, MyMIDlet! MIDlet-Jar-Size: 1056! MIDlet-Jar-URL: MyMIDlet.jar! MIDlet-Name: MyMIDlet! MIDlet-Vendor: Unknown! MIDlet-Version: 1.0! MicroEdition-Configuration: CLDC-1.1! MicroEdition-Profile: MIDP-2.1!
- 36. Distribu)on Preverified classes Mobile Resource files jar Jar-‐file Phone Manifest file Jad-‐file