代理模式的运用,AOP日志记录
动态代理可以实现AOP，比如日志记录。可以记录下每个方法的执行时间 ，名称和花费时间。代码如下：
import java.lang.reflect.InvocationHandler; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.lang.reflect.Proxy; import java.util.Date; interface DoAction{ public void ViewAction(); public void AddAction(); } class DoActionImpl implements DoAction { public void ViewAction(){ System.out.println("查看信息！"); } public void AddAction(){ System.out.println("添加信息！"); } } class ProxyAction implements InvocationHandler { private Object action; private User user = new User() ; public ProxyAction(Object action) { this.action = action; } public static Object getInstance(Object action) { return Proxy.newProxyInstance(action.getClass().getClassLoader(), action.getClass().getInterfaces(), new ProxyAction(action)); } public Object invoke(Object proxy, Method m, Object[] args) throws Throwable { Date start = null; Date end; Object result = null; try { // 在委派之前作动作，如权限判断等 start = new Date(); // 进行委派 result = m.invoke(action, args); } catch (InvocationTargetException e) { throw e.getTargetException(); } catch (Exception e) { throw new RuntimeException("unexpected invocation exception: " + e.getMessage()); } finally { // 在委派之后做动作 end = new Date(); System.out.println(start+":"+m.getName()+"方法被执行,花费时间"+(end.getTime() -start.getTime()) ); } return result; } } //用户信息 class User{ private String permission = "ViewAction" ; public String getPermission() { return permission; } public void setPermission(String permission) { this.permission = permission; } } public class proxy { public static void main(String[] args) { DoAction action =(DoAction) ProxyAction.getInstance(new DoActionImpl()); action.AddAction(); } } ?