计算机专业英语4(2)

系统分析,英语

Advice Code that runs after certain conditions are met. Advices allow you to transparently apply things like logging and metrics to an object model..

Concern Some functionality or requirement necessary in a system that may or may not have been implemented in a code structure. Concerns can range from high-level notions like security and quality of service to low-level notions such as caching and buffering. They can be functional, like features or business rules, or systemic, such as synchronization and transaction management.

Crosscutting Two concerns crosscut if the methods related to those

concerns intersect. An aspect crosscuts the traditional class and method boundaries by applying the same code in each.

Interceptor Used to implement an advice in JBoss 4.0, a popular Java application server.

Introduction A way to add methods or fields to an existing class, to bring multiple inheritance to plain Java classes or to attach a new API to an existing object model. Used in JBoss 4.0.

Joinpoints Points, or hooks, in a program’s execution where enhancements can be added or behaviors attached. For example, joinpoints could define calls to specific methods in a class.

Pointcuts Program constructs that designate joinpoints and collect

specific context at those points. In AOP, pointcuts define the points in your model where advice will be applied.

Weave To assemble an individual concern into a process by interlacing different execution-logic fragments according to some supplied criteria. Metadata Additional information that can be attached to a class or a given instance of an object, either statically or at runtime. Metadata helps when writing truly generic aspects that can be applied to any object, but the logic needs to know class-specific information.

面向方面程序设计

面向方面程序设计（AOP）是一种编程方法，允许以程序的整体特性来确定它如何编译成可执行程序。要说明AOP的概念，可以将方面编程类比成织布，这时纱线自动织成布。而没有AOP，程序员必须用手来织布。

AOP是对面向对象程序设计的补充，它允许开发人员动态修改静态的面向对象模型，以生成能成长的系统，来满足新的要求，从而让应用程序在发展过程中适应新的特性。

AOP为把横切代码抽象提供了解决方案，而横切代码在没有与这些代码功能关联性的情况下跨跃了对象的层次。AOP让你将横切代码抽象进入另外的模块（称作方面），来替代将横切代码嵌入类，然后动态地在需要它的地方应用这些代码。通过定义对象模型中应该应用横切代码的具体地方（称作点切），就能获得横切代码的动态应用。在运行时或编译时，依据你的AOP架构，横切代码注入到特定的点切。从本质上讲，AOP允许你将新的功能引入对象，而对象不需要拥有任何有关引入的知识。