接口的实际作用（二）-代理设计模式（Proxy）

例子:

interface Subject {        // 操作主题         public void get() ;         // 要银子}class RealSubject implements Subject {   // 真正的要银子         public void get() {                   System.out.println("真实业务主题") ;         }}class ProxySubject implements Subject {         private Subject sub = null ;         public ProxySubject(Subject sub) {                   this.sub = sub ;         }         public void prepare() {                   System.out.println("准备操作。") ;         }         public void destroy() {                   System.out.println("收尾操作。") ;         }         public void get() {                   this.prepare() ;                   this.sub.get() ;                   this.destroy() ;         }}public class Test {         public static void main(String args[]) {                   Subject sub = new ProxySubject(new RealSubject()) ;                   sub.get() ;         }}

运行结果：

准备操作真实业务主题收尾操作

         通过以上的分析就可以得出结论：代理负责完成与真实业务有关的所有辅助性操作。