Java注解实际案例应用（结合工厂设计模式与动态代理和反射机制）

假设现在我们有这样一个场景，有一个电脑用户，需要通过代理类进行网络连接，发送QQ消息，请你提供将对应的真实实现类的信息保存在注解中，通过注解的方式获取service服务类。
代码如下

public class AnnotationFactoryTest {
    public static void main(String[] args) {
        IChannelService iChannelService = new IChannelService();
        iChannelService.send();
    }

}

@Retention(RetentionPolicy.RUNTIME)
@interface IChannelClass{
    Class<?> CLASS();
}

@IChannelClass(CLASS = ComputerUser.class)
class IChannelService{
    private IChannel iChannel=null;
    public IChannelService(){
        Class<?> aClass = IChannelService.class.getAnnotation(IChannelClass.class).CLASS();
        iChannel  = (IChannel) ProxyFactory.getProxyInstance(aClass);
    }
    public void send(){
        iChannel.send();
    }
}

class ProxyFactory{
    private ProxyFactory(){

    }
    public static <T> T getProxyInstance(Class<T> clazz) {
        try {
            return  (T) new IChannelProxy().bind(clazz.getDeclaredConstructor().newInstance());
        } catch ( Exception e) {
            e.printStackTrace();
            return  null;
        }
    }
}

interface IChannel{
    void send();
}

class ComputerUser implements IChannel{

    @Override
    public void send() {
        System.out.println("发送QQ消息~~~~");
    }
}

class IChannelProxy implements InvocationHandler{
    private Object target;
    public Object bind(Object target){
        this.target=target;
        return Proxy.newProxyInstance(this.target.getClass().getClassLoader(),this.target.getClass().getInterfaces(),this);
    }
    public boolean getConnect(){
        System.out.println("【代理类】获取网络连接....");
        return true;
    }
    public void close(){
        System.out.println("断开网络连接。");
    }
    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        Object returnData=null;
        if (getConnect()){
            returnData=method.invoke(this.target,args);
            close();
        }
        return returnData;
    }
}