InterceptableComponent


1   /* JFox, the OpenSource J2EE Application Server
2    *
3    * Distributable under GNU LGPL license by gun.org
4    * more details please visit http://www.huihoo.org/jfox
5    */
6   package org.jfox.ioc.ext;
7   
8   import java.lang.reflect.Method  ;
9   
10  /**
11   * 可进行方法拦截的组件。实现该接口的组件，在执行器方法的时候，可以在方法执行前后，进行额外的操作
12   * <br><br>
13   * <b>注意：</b>该功能通过Java动态代理技术实现，所以，为了使用该功能，必须首先定义该Component的接口，
14   * 返回的Component实例也只能造型成接口类型：如：
15   * <pre>
16   *      public interface TestComponentInterface extends Component{
17   *          public String getName();
18   *      }
19   *
20   *      public class TestComponent implements TestComponentInterface, InterceptableComponent {
21   *          public String getName() {
22   *              return "getName body";
23   *          }
24   *          public void preInvoke(Method method, Object[] params){
25   *              if(method.getName().equals("getName")) {
26   *                  System.out.println("preInvoke " + method.getName());
27   *              }
28   *          }
29   *          public void postInvoke(Method method, Object result){
30   *              if(method.getName().equals("getName")) {
31   *                  System.out.println("postInvoke " + method.getName());
32   *              }
33   *              return result;
34   *          }
35   *      }
36   *
37   *      Registry registry = Registry.getInstance();
38   *      registry.registerComponent(TestComponent.class);
39   *      TestComponentInterface tc = (TestComponentInterface)registry.getFirstComponentMetabyImplemetation(TestComponent.class);
40   *      system.out.println(tc.getName());
41   *      ...
42   *
43   *      执行结果:
44   *      preInvoke getName
45   *      getName body
46   *      postInvoke getName
47   *
48   * </pre>
49   * @author <a HREF="mailto:young_yy@hotmail.com">Young Yang</a>
50   */
51  
52  public interface InterceptableComponent extends InstantiatedComponent {
53  
54      /**
55       * do something before invoke a method defined in component interface
56       * example: want to log, or repack the params
57       *
58       * @param method
59       * @param params
60       */
61      void preInvoke(Method   method, Object  [] params);
62  
63      /**
64       * do something after invoke a method
65       * example: want to repack the result
66       *
67       * @param method
68       * @param result result return by the method
69       * @return the last object return, may not be the result parameter
70       */
71      Object   postInvoke(Method   method, Object   result);
72  
73  }
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