tailieunhanh - Programming java 2 micro edition for symbian os phần 2

Chúng tôi đã vạch ra các gói và các lớp của CLDC và MIDP để hiển thị các chức năng cốt lõi của họ và cũng cho thấy J2ME và Symbian ngồi lại với nhau. Trong chương 2, chúng tôi sẽ kiểm tra MIDP sâu hơn, bắt đầu lập trình ứng dụng MIDP đơn giản và xem xét một số các công cụ khác nhau trên cung cấp. | 22 INTRODUCTION TOJ2ME Summary This chapter has introduced the J2ME architecture in order to indicate the position of MIDP within that structure. We have examined the various configurations and profiles and shown why they are necessary in providing a structure for the various needs and requirements of a J2ME device now and in the future. We have outlined the packages and classes of CLDC and MIDP to show their core functionality and have also shown howJ2ME and Symbian sit together. In Chapter 2 we are going to examine MIDP in more depth start programming a simple MIDP application and look at the some of the various tools on offer. 2 Getting Started Introduction to MIDP In the previous chapter we examined the core MIDP functionality and outlined the CLDC and MIDP classes that form the development environment. Before we start writing our first piece of code we need to look at the basic concepts of MIDP the most commonly used packages and methods and how it all fits together. We ll also look at the various development options what they can do and how they are installed. MIDP allows the execution of multiple MIDP applications known as MIDlets. The model defines how the MIDlet is packaged what runtime environment is available and how it should behave with respect to the sometimes constrained resources of the MIDP device. The model also defines how MIDlets can be packaged together in suites and share one another s resources such as graphics and data stored in the small database facility known as the RMS. Each MIDlet suite also has a descriptor file called the JAD file which allows the application management software on the device to identify what it is about to install prior to installation. The model also defines a lifecycle for a MIDlet which allows for orderly starting stopping and cleanup of a MIDlet. The MIDP Model and Lifecycle The MIDlet forms the application framework that executes on CLDC devices under the Mobile Information .