Parse the two types

This article will focus on the configuration of j2's. The j2's configuration provided by Sun is suitable for different levels of market needs-CLDC is suitable for small devices, while CDC is suitable for large devices. Through this article, you can learn that the two configuration types of j2-based architecture are CLDC and CDC.

J2-based Configuration

1. What is the configuration of j2-based architecture?

As previously learned, the configuration defines the basic runtime environment as a set of core classes and a specific JVM running on a specific type of device. You can also learn the two configuration types of j2-based architecture: CLDC and CDC.

Sun's j2-based configuration is suitable for different levels of market needs-CLDC is suitable for small devices, while CDC is suitable for large devices. The j2-based environment can be dynamically configured to provide the environment required to run the application without considering whether the device provides all the Java technical libraries required to run the application. The core platform receives application code and libraries. The server software running on the network performs configuration.

On the following pages, you will learn more about CLDC and CDC and the table associated with them.

2. Connection restriction (CLDC)

CLDC is created by JavaCommunityProcess. As defined by SunMicrosystems's Web site, the standard is: "lightweight, covering the smallest Java build block in the region, suitable for small, resource-limited devices ."

J2MECLDC configuration is prepared for a virtual machine and a core library that will be used in industry-defined summary tables. As mentioned in chapter 2nd, a simple table defines applications for specific devices by providing domain-specific classes at the top of basic j2's configuration. The reference execution of K Virtual Machine (KVM), CLDC of Virtual Machine and Its KJava simple table run on the top of CLDC.

CLDC briefly describes a set of basic library and Java virtual machine features required for each j2-based execution on highly restrictive devices. CLDC is mainly intended for devices with slow network connection speed, limited energy, and often battery power), stable memory greater than or equal to kb, and unstable memory greater than or equal to 32 KB. Unstable memory is not persistent and there is no write protection, which means that if the device is turned off, all content in the memory will be lost. The content in the stable memory is persistent and has write protection. CLDC devices use stable memory to store runtime libraries and KVM, or store another virtual machine created for a special device. The unstable memory is used to allocate the runtime memory.

3. CLDC requirements

CLDC defines the following requirements:

◆ The complete Java language supports not only floating point support, final cases and error handling)

◆ Complete JVM support

◆ Security of CLDC

◆ Limited international support

◆ Inheritance class-all classes not for CLDC must be subclasses of J2SE1.3 class

The classes for CLDC are all in the software package named javax. microedition and its sub-packages.

In addition to the javax. microedition software package, CLDCAPI also consists of a subset of J2SE java. io, java. lang, java. util, and other software packages. In the CLDCAPI chapter, we will learn the relevant details and then use CLDCAPI to develop our drawing application.

4. Connect to the device's j2_configuration (CDC)

The connection device structure (CDC) is defined as a simplified version of Java2 Standard Edition (J2SE) with the CLDC class added. Therefore, CDC is based on CLDC and applications developed for CLDC devices can also run on CDC devices.

CDC is also developed by JavaCommunityProcess, it provides a standardized, lightweight, and fully functional user's electronic and embedded devices, such as smart phones, two-way pagers, PDAs, household appliances, sales network terminals, and vehicle navigation systems. java 2 Virtual Machine build block. These devices run 32-bit microprocessors and exceed 2 MB of memory, which are required to store C virtual machines and libraries. K virtual machines support CLDC, while C virtual machines (CVM) Support CDC. CDC is associated with the basic table, which is not within the scope of this tutorial.