Java ME(J2ME)

Java ME in the past referred to as J2ME (Java Platform, Micro Edition), is to set-top boxes, mobile phones and PDA embedded consumer electronics devices like the Java language platform to provide, including virtual machines and a standardized set of Java API. It and the Java SE, Java EE technology together constitute the three major versions of Java, and also through the JCP (Java Community Process) developed. Introduction Java ME (Java 2 Micro Edition) is an integral part of Java 2, it is with J2SE, J2EE saying. According to the definition of Sun: Java ME is a highly optimized Java runtime environment, mainly for consumer electronics devices such as cellular phones and video phones, digital set-top boxes, car navigation systems and so on. JAVA ME in the JavaOne Developer Conference 1999 Conference was officially launched, it will be platform-independent Java language features and migrate to small electronic devices that allow mobile wireless devices to share applications. Design specifications J2ME specifications in the design of its time, follow the "For a variety of devices and create a single development system is not meaningful to do," this basic principle. So first of all the embedded JAVA ME devices generally classified into two types: one is the limited computing capabilities, the power supply is also limited embedded devices (for example, PDA, cell phone); another kind of computing power is relatively better and in the power supply is relatively abundant on the embedded device (for example, air conditioners, refrigerators, television set-top boxes (set-top box)). Because these two types of embedded devices, Java has introduced a concept called Configuration, and then the computing function is limited, the definition of embedded devices with limited power in the Connected Limited Device Configuration (CLDC) specification being; and another types of device are standardized for the Connected Device Configuration (CDC) specification. In other words, JAVA ME first of all the concept of embedded devices using Configuration separated into two abstract patterns. In fact, we can put here as a JAVA ME Configuration for the specifications of two types of embedded devices, which defines the specifications of these devices into at least meet the computing power, power supply capacity, memory size and other specifications, but also given a set of running on these devices can use Java class libraries program, the definition of these norms into the Java standard class library for the subset of the core class libraries, and with the type of device characteristics consistent with the expansion of types of libraries. For example, on the CLDC specification, it can support the core class libraries for the java.lang .*, java io .*, java.util .*, and support the expansion of types of libraries as javamicroeditionio .*. Distinguish two main Configuration after, JAVA ME Then define the Profile concept. Profile is a framework on top of the specifications in the Configuration. The reason why the concept of a Profile, in order to more clearly distinguish Java program for embedded devices as well as the how to develop what features they should have. Therefore, the definition of the Profile into embedded devices is associated with a specific expansion of class libraries, and Java programs on a variety of embedded devices to render the user interface is defined in the Profile inside. Profile extend into the defined categories within the library is defined based on the underlying Configuration core class libraries are established. Architecture Description Compared with the J2SE and J2EE, JAVA ME the overall operating environment and target a more diverse, but each of which has more single-use product, and resource constraints are more stringent. In order to achieve the standardization and compatibility at the same time try to meet different needs, JAVA ME framework is divided into Configuration, Profile and Optional Packages (optional package). They choose to form a specific combination of operating environment.
 Configuration is mainly vertical classification of the device, classification based on including the storage and processing capacity, which defines the characteristics of the virtual machine and basic class libraries. Configuration has been standardized - Connected Limited Device Configuration (CLDC) and Connected Device Configuration (CDC). Built on the basis of Profile Configuration, together constitute a complete operating environment. Horizontal classification of its equipment, for specific areas of market segments, including mainly a particular purpose library and API. Profile on the CLDC has been standardized Mobile Information Device Profile (MIDP) and the Information Module Profile (IMP), and the CDC on the standardized Profile with Foundation Profile (FP), Personal Basis Profile (PBP) and Personal Profile (PP).
 Optional packages provide additional independent of the previous two, modular and more diverse functions. The optional package includes the current standard database access, multimedia, Bluetooth and so on.

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