Introduction

1.Oracle 9i 面向对象:

         User-defined data types and objects .

         Support of multimedia and large objects .

2.三层架构

         Browser-based client .

         Application server .

         Database .

3.System Development life cycle

         Strategy and analysis ( Study and analyze the business requirements , draw thebussiness process diagram and DFD = data flow diagram )

         Design ( Design the database , draw the ER diagram )

         Build and Document ( build the prototype system , for example : create tables , develop user documentation , help text  )

         Transition ( Refine the prototype , Somebody start to test the application , Make any modifications required . )

         Production ( Roll out the system to users , monitor its performance , and enhance and refine the system )

4.Entity Relationship model ( ER diagram ) ***

5.SQL statement

         Select Data ( retrieve ) .

         Insert , update , delete , merge (Data manipulation language DML )

         Create , alter , drop , rename , Truncate ( Data definition language DDL )

         Commit , rollback , Savepoint ( Transaction control )

         Grant , revoke ( Date control language DCL )

转载于:https://www.cnblogs.com/moveofgod/archive/2012/09/11/2680131.html

### Aspect Oriented Programming (AOP) Introduction and Basic Principles #### Definition of AOP Aspect-Oriented Programming represents a programming paradigm that aims to increase modularity by allowing the separation of cross-cutting concerns. It creates a new way to think about program structure, beyond objects, procedures or functions. Cross-cutting concerns refer to behaviors that span multiple points in an application, such as logging, transaction management, security checks, caching mechanisms, etc.[^1] #### Core Concepts The core concepts within AOP include aspects, join points, pointcuts, advice, introductions, weaving, and interceptors. - **Aspects**: An aspect defines a particular concern affecting many parts of an application. - **Join Points**: These represent specific points during execution where additional behavior can be inserted—such as method calls, exception handling blocks, field access operations, etc. - **Pointcuts**: Pointcuts define precisely which join points should have extra functionality applied; they match one or more join points based on certain criteria defined through expressions. - **Advice**: Advice encapsulates actions taken around join points matched by associated pointcut definitions—it specifies what action needs performing before/after/before-and-after those moments occur. - **Introductions**: Introducing new methods or fields into existing classes without modifying their source code directly allows adding capabilities not originally present while maintaining original class integrity. - **Weaving**: Weaving refers to combining aspects with other pieces of software to create final woven programs ready for deployment. This process happens either statically at compile-time or dynamically at runtime depending upon implementation strategies chosen. - **Interceptors**: Interceptors act similarly to advices but operate specifically over service layer invocations often found inside enterprise applications built following layered architectures patterns like MVC. ```java @Aspect public class LoggingAspect { @Before("execution(* com.example.service.*.*(..))") public void logMethodEntry(JoinPoint joinPoint){ System.out.println("Entering Method : " + joinPoint.getSignature().getName()); } } ``` This example demonstrates how simple it becomes implementing logging across all services under `com.example.service` package using just few lines thanks to powerful features provided by frameworks supporting this approach natively such as Spring Framework's AOP module. --related questions-- 1. What are some common use cases for applying AOP? 2. How does AOP differ from OOP paradigms concerning design principles? 3. Can you provide examples illustrating different types of advice available in AOP implementations? 4. Explain the concept of 'weaving' in relation to AOP and its significance. 5. Discuss potential drawbacks or challenges faced when adopting AOP practices?
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