Việc áp dụng JavaEdge sử dụng các công nghệ sau đây để xây dựng tầng truy cập dữ liệu: Phạt cảnh cáo Vui lòng sử dụng ít nhất OJB phiên bản , trong khi chạy các ứng dụng mã nguồn JavaEdge. Các phiên bản trước của OJB có lỗi gây ra hành vi bất thường với các ứng dụng JavaEdge. | 190 CHAPTER 5 ARCHITECTING THE DATA ACCESS TIER WITH OBJECTRELATIONALBRIDGE OJB is an extremely configurable and tunable product. It is built on a set of pluggable components so that if you find that some feature in OJB does not meet your needs such as its caching model you can easily replace that component with your own implementation. The JavaEdge application uses the following technology to build the data access tier MySQL MaxDB Available at http . Connector J a MySQL JDBC Driver Available at http . Connector J is in development and might be in Generally Available GA release by the time this book is published. OJB Available at http ojb. Caution Please use at least OJB version while running the JavaEdge application source code. Earlier releases of OJB have bugs in them that cause unusual behavior with the JavaEdge application. Now we will walk through some of the key files. The Core OJB Files OJB is very easy to set up. To begin writing the code using OJB you need to first place the following jar files in your classpath. These files are located in the lib directory of the unzipped OJB distribution. The required files are which is the core OJB jar file Several Jakarta Commons jar files including the following Once these jar files are included in your classpath you are ready to begin mapping your Java class files. In the JavaEdge application these will be the MemberVO StoryVO and StoryCommentVO classes mapped to your database tables. Setting Up the Object Relational Mappings Setting up your O R mappings using OJB is a straightforward process that involves creating and editing two files and . The file is used to customize the OJB runtime environment. By modifying the file a developer can control whether OJB is running in single virtual .
