At present, Java2 has three versions: J2EE (Enterprise Edition), J2SE (Standard Edition), J2ME (Mini)
1, J2SE (Java2 Standart Edition) Java2 Standard Edition supports the core class function library defined in all Java standard specification and all Java basic categories. J2SE is positioned on the application of the client program.
2, J2EE (Java2 Enterprise Edition) Java2 Enterprise Edition adds support for the internal extension class function library on J2SE, such as supporting servlet / JSP Javax.Servletr. * And Enterprise Java Bean's javax.ejb. * Library. J2EE is located on the application of the server-side program.
3, J2ME (Java 2 Micro Edition) Java2 micro version only supports subset of core class function libraries defined in the Java standard specification. For example, in the J2ME CLDC specification, only java.lang. *, Java.io. *, and java.util. * Class function library. And some extended class functions that support embedded systems are added, such as: javax.meicroedition.io. * Class function library. But do not support all Java basic classes. J2ME is positioned in an embedded system.
4, Smart Card Java Smart Card Java only supports java.lang in the core class function library. *. But there is a dedicated extension class function library, such as Javacard. *, Javacardx. *. Only two BYTE two Java basic classes are supported by Boolean. Positioned on the smart card.
5, KVM (K Virtual Machine) J2ME virtual machine is used to perform a Spotlet or MIDlet. Different versions of Java have different virtual machines to run Java Applet, Java Servlet, or Java Application. And the virtual machine is not only Sun, such as the J9 VM of IBM.
6. Jini is used to connect different versions of Java programs to achieve the purpose of resource sharing.
7. CLDC (Connected Limited Device Configuration) SUN divides the J2ME's application entity into two categories, and proposes the concept of the corresponding Confiution. This specification is applied to the computing power, and the power supply is limited. Such as: PDA, mobile phone. Support java.lang. *, Java.io. *, and java.util. * Class function library, and support the extended class function library javax.meicroedition.io. *.
8, CDC (Connected Device Configuration) This specification is applied to relative calculation capabilities, and the power supply is better. Such as: refrigerator, TV set top box, etc.
9. MIDP (Mobile Information Device Profile) On the basis of Confitration specification, there is a clear zone to divide the Java program development specification for various embedded devices. This specification is very relevant to a particular embedded device, defining the extended class function library associated with specific hardware. Applications / Oem Specific APIS | Profile | Confiuration / VM | Operating System | Hardware 10, STK (SIM Toolkit) Mobile Phone Company cooperates with SIM card manufacturer to write program in the SIM card to achieve value-added services. It is the application of Java on Smart Card. For example, China Mobile's new motion zone is the 64K STK card.
11, OTA (over the air) user directly downloads the information of the telecommunications.
