Author: move2008 Source: Introduction Section mystery of J2ME overview move2008.com J2ME So far, most people are very familiar with the Java 2 Platform, as well as how the Sun Java Technology is divided into three versions (Standard, Micro Edition and Enterprise Edition), Sun launched Java 2 Pocket (J2ME) in June 1999 to meet the needs of consumer electronics and embedded equipment. J2ME is developed for devices that use limited energy, limited network connections (often wireless connections) and limited graphical user interface capabilities. Its initial goal is 16-bit or 32-bit processor, 16 MHz clock frequencies, 512K or less memory. At first glance, J2ME is like a loose application interface and technical specifications that have not binding obvious themes. We want to describe it by saying that it is not something, it is not a set of desktop Java applications specification, if you look carefully, you will find that all J2ME components around a center, these centers are called For Configuration (configurable, Sun's Marketing Data also known as the Design Center, the design center), each of which is a special class for consumer electronics and embedded devices. Connected Limited Device Configuration (limited connection device configuration, referred to as CLDC) This configuration defines the Java application interface and the technology that supports handheld devices, just as described in Sun's documentation, "Devices That You Hold In your hand" Equipment in your hand) "Palm sequence handheld device may be the best example of equipment in this field, especially it has the function of developing CLDC and the PALM device running period system. Connected Device Configuration (Connection Device Configuration CDC) This configuration definition supports the application interface and technology of the device in the Sun document, "Devices That You Plug INTO PLUG INTO THE WALL) of the device of the device, such a device An example may be a set top box. Different parts of these configurations are the ability of their devices, and the processor capability of the CLDC device is limited (compared to the desktop system), and the memory size is generally only 128 KB to 512 KB. At the same time, at the same time, the CDC system is different, it may have 32-bit or 64-bit processor, and a limited storage capacity, but its lower limit has more than 512K. It follows the principle that every different capabilities Hardware configuration will be supported by different virtual machines. CDC-based systems use a powerful virtual machine, while CLDC systems use KVM (I will introduce each of them). Each configuration represents a low level, Basic application interfaces, on these two similar foundations, for extra application interfaces for special devices. I want to take a chart in the documentation provided by Sun (see Figure 1 To explain the relationship therein. Figure 1 explained that the architecture J2ME of the interpretation configuration and the brief watch is divided into three layers laterally. The configuration includes a virtual machine that controls the core class, the specific brief surface is located Each configuration. J2ME now defines two configurations, Connected Device Configuration, and a restrictive Connected Limited Device Configuration (limited connection device configuration).
