浅谈静态代理和动态代理

1.静态代理，耦合增加，改动较大。

 登录接口

public class CustomerLoginAction implements LoginAction { //执行验证操作 public void execute() throws SQLException, LoginException { } }

用户登录

import java.sql.SQLException; public interface LoginAction { public void execute()throws SQLException, LoginException; }

静态实现

public class ProxyCustomerLoginAction implements LoginAction { private LoginAction customerLogin ; public ProxyCustomerLoginAction(LoginAction customerLogin){ this.customerLogin = customerLogin; } public void execute() throws SQLException, LoginException{ System.out.println("begin the login validate"); customerLogin.execute(); System.out.println("end the login validate"); } }

静态测试

public static void main(String[] args) { CustomerLoginAction customerLoginAction = new CustomerLoginAction(); LoginAction pAction = new ProxyCustomerLoginAction(customerLoginAction); }

2.动态代理，耦合减小，代码改动小

动态代理实现

public class DynaProxyCustomerLoginHandler implements InvocationHandler { private Object realclass; public Object binding(Object realclass) { this.realclass = realclass; //返回一个代理类的实例 return Proxy.newProxyInstance(realclass.getClass().getClassLoader(), realclass.getClass().getInterfaces(), this); } //在被代理类的实例前后增加功能 public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { Object obj = null; //如果被代理类方法的名字包含指定的字符串"execute"，则在被代理类方法执行的前后增加新的功能， //否则直接执行被代理类的方法，而不增加新的功能。 if (method.getName().contains("execute")) { System.out.println("begin the login validate"); try { //执行被代理类的方法 obj = method.invoke(realclass, args); } catch (Exception e) { } System.out.println("end the login validate"); return obj; } else { obj = method.invoke(realclass, args); return obj; } } }

动态代理测试

public static void main(String[] args) { DynaProxyCustomerLoginHandler loginHandler = new DynaProxyCustomerLoginHandler(); CustomerLoginAction customerLoginAction = new CustomerLoginAction(); LoginAction loginAction = (LoginAction)loginHandler.binding(customerLoginAction); loginAction.execute(); }