动态代理

示例代码
  1 package DP;
  2 
  3 import java.lang.reflect.InvocationHandler;
  4 import java.lang.reflect.Method;
  5 import java.lang.reflect.Proxy;
  6 
  7 /**
  8  * 通过动态代理的模式去拓展方法
  9  * 
 10  * @author renguanyu
 11  *
 12  */
 13 public class DynamicProxyDemo {
 14 
 15     public static void main(String[] args) {
 16 
 17         /*
 18         System.getProperties().put("sun.misc.ProxyGenerator.saveGeneratedFiles", "true");
 19         System.getProperties().put("jdk.proxy.ProxyGenerator.saveGeneratedFiles", "true");
 20         */
 21 
 22         // 示例数据
 23         Emp e = new Emp("1", "liubei");
 24         // 业务对象
 25         Dao dao = new DaoImpl();
 26 
 27         // 通过动态代理，拓展方法
 28         InvocationHandler h = null;
 29 
 30         h = new DaoInvocationHandler1(dao);
 31         dao = (Dao) Proxy.newProxyInstance(ClassLoader.getSystemClassLoader(), new Class[] { Dao.class }, h);
 32 
 33         h = new DaoInvocationHandler2(dao);
 34         dao = (Dao) Proxy.newProxyInstance(ClassLoader.getSystemClassLoader(), new Class[] { Dao.class }, h);
 35 
 36         // 业务操作
 37         dao.save(e);
 38     }
 39 
 40 }
 41 
 42 interface Dao {
 43 
 44     void save(Emp e);
 45 
 46 }
 47 
 48 class DaoImpl implements Dao {
 49 
 50     @Override
 51     public void save(Emp e) {
 52 
 53         System.out.println("save -> " + e);
 54 
 55     }
 56 
 57 }
 58 
 59 class DaoInvocationHandler1 implements InvocationHandler {
 60 
 61     Dao dao;
 62 
 63     public DaoInvocationHandler1(Dao dao) {
 64         this.dao = dao;
 65     }
 66 
 67     @Override
 68     public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
 69         System.out.println("DaoInvocationHandler1 - start ");
 70         method.invoke(dao, args);
 71         System.out.println("DaoInvocationHandler1 - end ");
 72         return null;
 73     }
 74 
 75 }
 76 
 77 class DaoInvocationHandler2 implements InvocationHandler {
 78 
 79     Dao dao;
 80 
 81     public DaoInvocationHandler2(Dao dao) {
 82         this.dao = dao;
 83     }
 84 
 85     @Override
 86     public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
 87         System.out.println("DaoInvocationHandler2 - start ");
 88         method.invoke(dao, args);
 89         System.out.println("DaoInvocationHandler2 - end ");
 90         return null;
 91     }
 92 
 93 }
 94 
 95 class Emp {
 96 
 97     String id;
 98     String name;
 99 
100     public Emp(String id, String name) {
101         super();
102         this.id = id;
103         this.name = name;
104     }
105 
106     @Override
107     public String toString() {
108         return "Emp [id=" + id + ", name=" + name + "]";
109     }
110 
111 }