Author: Move2008 Source: Move2008.com Section J2ME architecture Now the number of personal computer systems and types have been developed to the point of no control, you think about it, you write the program running scene in the "information appliances" stage Let's include a call, a mobile phone, a mobile phone like a personal digital assistant (PDA) such as Palm, TV set-top box, POS terminal, and other consumer electronics. Nowadays, there are many mobile phone manufacturers, and there are more other household appliances, and each home appliance equipment has different features and interfaces. So, you can think of the ability of the Java application and the ability to solve such many different device programs, making everyone a lot of priority to J2ME. Of course, in order to better develop this information appliance, you will ask Java's essence to enter a very small package, this is J2ME. J2ME is a technique through many components and specifications, which helps J2ME to meet the needs of this many consumer products. Like all Javanese programming, it belongs to a virtual machine in its core. Just like all Java technology, the core of J2ME is also in a virtual machine. Initially, it is known as Kilobyte Virtual Machine or referms KVM for the J2ME application virtual machine. Just like the meaning of its name, KVM is relatively small, usually only 128K or less. This is much smaller than the 32 MB of Java 2 Standard Edition Java Virtual Machine (JVM) we usually knows and used. Used to connect virtual machines is a series of configurations and profiles that provide a class application interface for a specific J2ME environment (see Figure 2). Each configuration and brief mesh is processed in general or specific consumer products, configuration, and briefing specification are developed and established by a variety of equipment manufacturers and users. The configuration is the smallest Java platform for a set of universal devices, often being classified as a horizontal device packet, relatively, transverse packet devices are devices that share the same memory arrangement, communication bandwidth, energy requirements, and user capabilities. It is generally considered that all needs of this numerous equipment can be provided. Figure 2 Explanation: J2ME Hierarchy Java Virtual Machine is the core of J2ME technology, but the configuration and brief mesh provides a special environment class application interface. The configuration is the smallest Java platform for a set of universal devices, while briefings provide more specific capabilities for specific device families or special applications. New developers in J2ME are often confused by these facts. In fact, Sun's first configuration (now only a configuration reference implementation) with virtual machine referred to as KVM, KVM meets the configured virtual machine Necessary condition. However, the Sun's KVM can also be replaced by another virtual machine, and now it is because the configuration and virtual machine combination is a bit tight, so so many confused. On the other hand, the brief watch improves the configuration, providing a higher performance for a particular equipment family or a specific industrial fragment application. In other words, the brief watch provides more performance for specific longitudinal markets such as operational phones. The key here is that the profile must be configured, without configuring and virtual machines providing core type application interfaces and runtime environments, the brief watch will not work. Typically, a brief watch provides a user interface, input method, and persistence mechanism for a given vertical packet device. Such a profile is considered to be a complete toolkit developing these equipment applications. Examples we have seen by the Up to mobile phone briefings and personal digital assistant (PDA) briefs, other briefings provide a very special function or application portability of wide-wide equipment, this aspect It is a brief watch for the remote method to call (RMI) and provide a brief watch for unified banking transactions.
