[编织消息框架][JAVA核心技术]动态代理应用3

我们先使用懒处理实现提取接口类上的元信息：

public abstract class QRpcFactory {
 
    public static <T> T loadProxy(Class<T> target, QNode... nodes) 

    public static <T> T loadProxy(Class<T> target, long... ids)  
}

通过工厂类绑定session id 或 node 生成代理实例

RpcContext 是处理临时上下文对象，用来记录发送目标，同处理完返回结果

public class RpcContext {
    private QNode[] nodes;
    private Long[] ids;
    private IQCallback<?> cb;

    public static RpcContext of(QNode... nodes) {
    RpcContext ret = new RpcContext();
    ret.nodes = nodes;
    return ret;
    }
    public static RpcContext of(Long... ids) {
    RpcContext ret = new RpcContext();
    ret.ids = ids;
    return ret;
    }
}

@SuppressWarnings("unchecked")
public abstract class QRpcFactory {
 
    public static <T> T loadProxy(Class<T> target, QNode... nodes) {
    T ret = loadProxy0(target);
    IRpcContext ctx = (IRpcContext) ret;
    ctx.setContext(RpcContext.of(nodes));
    return ret;
    }

    public static <T> T loadProxy(Class<T> target, Long... ids) {
    T ret = loadProxy0(target);
    IRpcContext ctx = (IRpcContext) ret;
    ctx.setContext(RpcContext.of(ids));
    return ret;
    }

    private static <T> T loadProxy0(Class<T> target) {
    T ret = (T) Proxy.newProxyInstance(QRpcFactory.class.getClassLoader(), new Class[] { target, IRpcContext.class }, new InvocationHandler() {
        QModel modelAnno = target.getAnnotation(QModel.class);
        private short model = modelAnno.value();
        private RpcContext ctx;

        @Override
        public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        if (method.getName().equals("setContext")) {
            this.ctx = (RpcContext) args[0];
            System.out.println("setContext");
            return null;
        }
        QCommond commondAnno = method.getAnnotation(QCommond.class);
        // do send

        return null;
        }
    });
    return ret;
    }
    public static void main(String[] args) {
    TestRpcObject obj = QRpcFactory.loadProxy(TestRpcObject.class, 123L);
    }
}

@QModel(1)
public interface TestRpcObject {
    @QCommond(1)
    public void a();
}

每次使用时再处理，是懒处理思想的核心，有的场景加上缓存、double check、ThreadLocal、WeakHashMap技术

由于要解决并发问题，所以这例子缓存用不上，对象不能是单例，而每个实例参数不一，用不了ThreadLocal来记录RpcContext

可以在loadProxy0 创建InvocationHandler 时生成RpcContext 这里为了示例一个接口类如何保存属性的