dubbo学习笔记 十 dubbo-rpc

通过前面的dubbo-common之动态扩展，我们明白了会加载META-INF 目录下的文件。

接着来学习dubbo-rpc吧

Invoker

rpc调用远程实习类叫Invoker

public interface Invoker<T> extends Node {    /**     * get service interface.     *      * @return service interface.     */    Class<T> getInterface();    /**     * invoke.     *      * @param invocation     * @return result     * @throws RpcException     */    Result invoke(Invocation invocation) throws RpcException;}

Exporter

用来获取invoker

public interface Exporter<T> {        /**     * get invoker.     *      * @return invoker     */    Invoker<T> getInvoker();        /**     * unexport.     *      * <code>     *     getInvoker().destroy();     * </code>     */    void unexport();}

Protocol

描述远程协议，定义远程操作

/* * Copyright 1999-2011 Alibaba Group. *   * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at *   *      http://www.apache.org/licenses/LICENSE-2.0 *   * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */package com.alibaba.dubbo.rpc;import com.alibaba.dubbo.common.URL;import com.alibaba.dubbo.common.extension.Adaptive;import com.alibaba.dubbo.common.extension.SPI;/** * Protocol. (API/SPI, Singleton, ThreadSafe) *  * @author william.liangf */@SPI("dubbo")public interface Protocol {        /**     * 获取缺省端口，当用户没有配置端口时使用。     *      * @return 缺省端口     */    int getDefaultPort();    /**     * 暴露远程服务：<br>     * 1. 协议在接收请求时，应记录请求来源方地址信息：RpcContext.getContext().setRemoteAddress();<br>     * 2. export()必须是幂等的，也就是暴露同一个URL的Invoker两次，和暴露一次没有区别。<br>     * 3. export()传入的Invoker由框架实现并传入，协议不需要关心。<br>     *      * @param <T> 服务的类型     * @param invoker 服务的执行体     * @return exporter 暴露服务的引用，用于取消暴露     * @throws RpcException 当暴露服务出错时抛出，比如端口已占用     */    @Adaptive    <T> Exporter<T> export(Invoker<T> invoker) throws RpcException;    /**     * 引用远程服务：<br>     * 1. 当用户调用refer()所返回的Invoker对象的invoke()方法时，协议需相应执行同URL远端export()传入的Invoker对象的invoke()方法。<br>     * 2. refer()返回的Invoker由协议实现，协议通常需要在此Invoker中发送远程请求。<br>     * 3. 当url中有设置check=false时，连接失败不能抛出异常，并内部自动恢复。<br>     *      * @param <T> 服务的类型     * @param type 服务的类型     * @param url 远程服务的URL地址     * @return invoker 服务的本地代理     * @throws RpcException 当连接服务提供方失败时抛出     */    @Adaptive    <T> Invoker<T> refer(Class<T> type, URL url) throws RpcException;    /**     * 释放协议：<br>     * 1. 取消该协议所有已经暴露和引用的服务。<br>     * 2. 释放协议所占用的所有资源，比如连接和端口。<br>     * 3. 协议在释放后，依然能暴露和引用新的服务。<br>     */    void destroy();}

Result

invoke结果

public interface Result {/** * Get invoke result. *  * @return result. if no result return null. */Object getValue();/** * Get exception. *  * @return exception. if no exception return null. */Throwable getException();    /**     * Has exception.     *      * @return has exception.     */    boolean hasException();    /**     * Recreate.     *      * <code>     * if (hasException()) {     *     throw getException();     * } else {     *     return getValue();     * }     * </code>     *      * @return result.     * @throws if has exception throw it.     */    Object recreate() throws Throwable;    /**     * @deprecated Replace to getValue()     * @see com.alibaba.dubbo.rpc.Result#getValue()     */    @Deprecated    Object getResult();    /**     * get attachments.     *     * @return attachments.     */    Map<String, String> getAttachments();    /**     * get attachment by key.     *     * @return attachment value.     */    String getAttachment(String key);    /**     * get attachment by key with default value.     *     * @return attachment value.     */    String getAttachment(String key, String defaultValue);}

Invocation

远程调用入参

public interface Invocation {/** * get method name. *  * @serial * @return method name. */String getMethodName();/** * get parameter types. *  * @serial * @return parameter types. */Class<?>[] getParameterTypes();/** * get arguments. *  * @serial * @return arguments. */Object[] getArguments();/** * get attachments. *  * @serial * @return attachments. */Map<String, String> getAttachments();/**     * get attachment by key.     *      * @serial     * @return attachment value.     */String getAttachment(String key);/**     * get attachment by key with default value.     *      * @serial     * @return attachment value.     */String getAttachment(String key, String defaultValue);    /**     * get the invoker in current context.     *      * @transient     * @return invoker.     */    Invoker<?> getInvoker();}