Getting started with J2EE (1)

A recent chance to meet a new friendJ2EEIn the hope of help. AlthoughJavaI know little about it, but I still want to help her. Of course I did my best. So it started.J2EE.
First, let's take a lookJ2EEThe architecture of the platform.

Not to mention operating systems and virtual machines.

Let's talk about the configuration first.J2EEThe platform consists of two configurations: Device connection configuration (Connected device configuration, CDC) And the configuration of the connected device.(Connected limited device configuration, cldc). Because mobile phones have relatively limited hardware conditionsCldc,PDACompared with mobile phones, the hardware conditions are better, and most of them should be usedCDC.

Let's take a look at the simple table. Provides complete applications for the target device based on simple table spaces and configurations.ProgramRunning environment. There are severalCldcAndCDCImportant summary:

Mobile Information device simplified table (MIDP) For mobile phones and entry-levelPDADesigned to provide all the core functions required for mobile applications.

Information module summary table (IMP) YesMidp1.0Its target device is a terminal with no display capability or user input capability.

Basic table (Fp) Provides networking capabilities for the running environment.

Personal summary table (PP) Provides complete interfaces for developing user interfaces.AWTComponents are designed for devices with complete graphical user interfaces.

Basic personal table (PbpIs a subset of personal profiles, providing an application environment for networked devices.

Finally, let's take a look at the available packages. You can combine different optional packages on the basis of configuration and related summary tables.J2EEPlatform for expansion.

Next, let's talk aboutCldcAndMIDP.

CldcJustJ2seHas someJ2seFunctions andAPIAll fromCldcTo meet the memory and processor limitations of mobile devices. InCldc1.0The main differences are as follows.

Does not support floating-point operations (Cldc1.1Supported)

Not SupportedFinalizationAnd does not provideObject. Finalize ()

Limited error handling capability

Weak references not supported

MIDPLocated inCldcThe application model, graphic user interface, and persistent data storage are provided.

MIDPA brand new application model --MIDlet.MIDletIs the main class of the application (Application Management System, AMS) Management.

MIDPProvides a graphical user interface.

Record Management System (Record Management System, RMS) YesMIDPA sub-system that provides a persistent data storage solution.

Midp2.0Introduced a dedicated Game Development KitJavax. microedition. lcdui. Game .*.

I talked about someJ2EEOnlyJ2EEHave a rough understanding. Of course, because my current goal is mobile phone programming, I put the focus on the content.CldcAndMIDP. You can try again laterCDCAnd other content.