Analysis of Application of J2SE and J2SE Technologies (1)

Are you familiar with the concepts and usage of the J2SE and J2SE technologies? I 'd like to share with you here. First of all, let's take a look at their concepts, it is used in a variety of consumer electronic products, such as smart cards, mobile phones, PDAs, and TV set-top boxes. J2SE is the Java 2 Standard Edition. It is a development and deployment platform that provides all the necessary functions for writing desktop and workstation applications.

Application of j2-based Technology

J2MEJava2PlatformMicroEdition is designed for the wireless electronics market, including JVM specifications and API specifications. Its API specification is based on J2SEJava2StandardEditon. It defines a set of appropriate class libraries and Virtual Machine technologies. These technologies allow users, service providers, and device manufacturers to use a wide range of applications as needed through physical wired connections or wireless connections.

It is also known as the Java2 micro version. It is used in a variety of consumer electronic products, such as smart cards, mobile phones, PDAs, and TV set-top boxes. Of course, it also provides consistent Java features, that is, cross-platform and secure network transmission. It uses a series of smaller packages, and Javax. microedition. io is a subset of J2SE packages. J2SE and J2EE can be upgraded.

Before the emergence of j2s, we were more exposed to Java card JavaCard, embedded JavaEmbeddedJava) and real-time JavaRealTimeJava. The Java card is the minimum Java subset customized for SIM card, smart card, and other devices, which is smaller than that of j2_, and less portable. Embedded Java configures Java class libraries, VMVirtualMachine, and virtual machines for special users ). It has minimal resource requirements and can run on devices without graphical user interfaces and networks. It can add user-specific APIs, but it cannot be transplanted. Real-Time Java is implemented by the real-time custom Java expert group led by IBM and is still being improved. However, in a strict sense, they are not the real j2s.

Like other versions, Java has many Java technical features, mainly including:

1. It can be run on a variety of devices supporting Java;

2. The code is short;

3. Make full use of the advantages of the Java language;

4. Good security;

5. applications implemented with j2s can be easily upgraded to J2SE and J2EE.

Configuration and framework

To support the flexibility and customization requirements put forward by users and the embedded market, j2s are designed to be more modular and scalable. The third-layer software is built on the original operating system of the device to implement this requirement:

1. On the JVM layer, this layer is based on the host operating system and implements JVM according to a specific j2-based configuration.

2. configuration layer, which has lower user visibility but is very important to the framework layer. It defines the minimum functional set of the Java Virtual Machine and the minimum set of the Java class library to meet the needs of the "horizontal" market. In a sense, the configuration layer defines that developers can use the Java feature and the "minimum public Denominator" of the class library on all devices ".

3. The framework layer is the most common for users and application providers. It defines the minimum functional set of the Java Virtual Machine and the minimum set of the Java class library for the needs of the vertical market. The framework is implemented based on a specific configuration layer. As long as the device supports the same framework layer, applications developed for the specific framework layer can be transplanted to other devices. A device supports multiple frame layers.

The JVM is closely connected to the configuration layer on the j2m‑based devices, which reflect the basic functions of each type of devices. The framework layer specifies additional APIs Based on the configuration layer for different devices. To meet the needs of constantly updated applications, the framework layer can expand new Java library classes. In the near future, with the emergence of new devices, the j2-based technology will provide a wide range of framework layers, configuration layers, and VMS. JCPJavaCommunityProcess) can provide specifications for customers and developers. According to the definition of JCP, one of the current configuration layers of J2EE is ConnectedDeviceConfiguration, which adopts the typical Java virtual machine technology. This full-featured VM includes all the features of virtual machines on the desktop system, suitable for devices with at least a few megabytes of memory. For wireless devices and other devices with insufficient memory, the "connection-oriented limited device configuration" CLDC technology is adopted for the j2_based devices.

KVM is the core feature of j2's. It is a highly portable JVM dedicated to devices with small memory, limited resources, and Internet access, such as cell phones, pagers, and personal organizers. These devices generally contain 16 or 32-bit processors with a minimum memory of kb. KVM can be flexibly applied to various industries and devices, and can adapt to the problems caused by the diversity of these devices, such as power consumption of processors, memory size, special features of devices and applications.