动态代理

目标类和代理类继承统一接口

接口：UserManager

public interface UserManager {
	
	public void addUser(String username,String password);
	
	public void deleteUser(int id);
	
	public void modifyUser(int id,String username,String password);
	
	public String findUserById(int id);

}

目标类：UserManagerImpl

public class UserManagerImpl implements UserManager {

	public void addUser(String username, String password) {
		System.out.println("---------addUser----------");
	}

	public void deleteUser(int id) {
		System.out.println("---------deleteUser----------");
	}

	public String findUserById(int id) {
		System.out.println("---------findUserById----------");
		return null;
	}

	public void modifyUser(int id, String username, String password) {
		System.out.println("---------modifyUser----------");
	}
}

代理类：SecurityHandler

public class SecurityHandler implements InvocationHandler {

	private Object targetObject;
	
	public Object newProxy(Object targetObject){
		this.targetObject = targetObject;
		return Proxy.newProxyInstance(targetObject.getClass().getClassLoader(), 
									  targetObject.getClass().getInterfaces(), 
									  this);
	}
	
	public Object invoke(Object proxy, Method method, Object[] args)
			throws Throwable {
		chechSecurity();
		Object result = null;
		try{
			result = method.invoke(this.targetObject, args);
			
		}catch(Exception e){
			e.printStackTrace();
			throw  new RuntimeException(e);
		}
		return result;
	}
	
	private void chechSecurity(){
		System.out.println("---------chechSecurity----------");
	}

}

客户端：Client

public class Client {
	
	public static void main(String[] args){
		SecurityHandler handler = new SecurityHandler();
		
		UserManager um = (UserManager)handler.newProxy(new UserManagerImpl());
		
		um.addUser("ads", "132");
	}

}