Java基础之《dubbo（1）—dubbo基础入门》

一、为什么要使用dubbo

1、dubbo是什么
dubbo是一个分布式服务框架，致力于提供高性能和透明化的RPC远程服务调用方案，以及SOA服务治理方案。

2、dubbo有何特点
（1）远程通讯：提供透明化的远程方法调用，提供多协议支持。
（2）集群容错：软负载均衡，失败容错，地址路由，动态配置等集群支持。
（3）自动发现：基于注册中心目录服务，使服务消费方能动态的查找服务提供方，支持平滑减少或增加机器。

3、为什么要使用dubbo
（1）刚起步，技术人员3个，springmvc
一个应用，一个数据库
（2）发展一年，技术人员10个，1个架构师，RPC
将独立的业务抽取出来，形成独立的服务（商品，订单，交易）
多个应用，多个数据库
（3）发展一年半，技术人员80个，服务越来越多，SOA
需要服务自动发现和治理，dubbo、spring cloud、ICE

4、MVC、RPC、SOA的架构如何演进
刚开始直接把系统做出来，推向市场，市场反应好了再改进

5、dubbo与spring cloud、ICE的区别
dubbo2是netty长连接

二、dubbo常用标签

1、application
描述：应用信息，就是当前服务的项目信息配置
特殊说明：无

2、container
描述：服务的运行容器
特殊说明：jetty、log4j、logback、spring

3、provider
描述：服务提供方的一些服务治理、性能调优的一些配置
特殊说明：该标签为当前服务的所有service和protocol标签的缺省值设置

4、service
描述：服务提供者暴露接口配置
特殊说明：无

5、consumer
描述：服务消费方的一些服务治理、性能调优的一些配置
特殊说明：无

6、reference
描述：服务消费者引用接口配置
特殊说明：无

7、registry
描述：注册中心配置
特殊说明：如果有多个不同的注册中心，可以声明多个registry标签，并在service或protocol的registry属性指定使用的注册中心

8、protocol
描述：远程调用协议dubbo、hessian、http、injvm、memcached、redis、rmi、thrift、webservice等
特殊说明：如果需要支持多协议，可以声明多个protocol标签，并在service中通过protocol属性指定使用协议

三、dubbo 3.0入门例子

1、下载官方入门例子
git clone --depth=1 --branch master [e-mail]:apache/dubbo-samples.git

2、eclipse打开，只保留1-basic和tools模块，否则项目太多了

    <modules><module>1-basic</module><!--<module>2-advanced</module>--><!--<module>3-extensions</module>--><!--<module>4-governance</module>--><!--<module>10-task</module>--><!--<module>99-integration</module>--><module>tools</module></modules>

3、启动一个简易zookeeper
运行tools/embedded-zookeeper下的EmbeddedZooKeeper.java

/** Licensed to the Apache Software Foundation (ASF) under one or more* contributor license agreements.  See the NOTICE file distributed with* this work for additional information regarding copyright ownership.* The ASF licenses this file to You 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 org.apache.dubbo.samples;import java.io.File;
import java.util.Properties;
import java.util.UUID;import org.apache.zookeeper.server.ServerConfig;
import org.apache.zookeeper.server.ZooKeeperServerMain;
import org.apache.zookeeper.server.quorum.QuorumPeerConfig;public class EmbeddedZooKeeper {public static void main(String[] args) throws Exception {int port = 2181;if (args.length == 1) {port = Integer.parseInt(args[0]);}Properties properties = new Properties();File file = new File(System.getProperty("java.io.tmpdir")+ File.separator + UUID.randomUUID());file.deleteOnExit();properties.setProperty("dataDir", file.getAbsolutePath());properties.setProperty("clientPort", String.valueOf(port));QuorumPeerConfig quorumPeerConfig = new QuorumPeerConfig();quorumPeerConfig.parseProperties(properties);ZooKeeperServerMain zkServer = new ZooKeeperServerMain();ServerConfig configuration = new ServerConfig();configuration.readFrom(quorumPeerConfig);try {zkServer.runFromConfig(configuration);} catch (Exception e) {e.printStackTrace();System.exit(1);}}
}

4、启动服务提供者
运行1-basic/dubbo-samples-api下的org.apache.dubbo.samples.provider包内的Application.java

/** Licensed to the Apache Software Foundation (ASF) under one or more* contributor license agreements.  See the NOTICE file distributed with* this work for additional information regarding copyright ownership.* The ASF licenses this file to You 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 org.apache.dubbo.samples.provider;import org.apache.dubbo.config.ProtocolConfig;
import org.apache.dubbo.config.RegistryConfig;
import org.apache.dubbo.config.ServiceConfig;
import org.apache.dubbo.config.bootstrap.DubboBootstrap;
import org.apache.dubbo.samples.api.GreetingsService;public class Application {private static final String ZOOKEEPER_HOST = System.getProperty("zookeeper.address", "127.0.0.1");private static final String ZOOKEEPER_PORT = System.getProperty("zookeeper.port", "2181");private static final String ZOOKEEPER_ADDRESS = "zookeeper://" + ZOOKEEPER_HOST + ":" + ZOOKEEPER_PORT;public static void main(String[] args) {ServiceConfig<GreetingsService> service = new ServiceConfig<>();service.setInterface(GreetingsService.class);service.setRef(new GreetingsServiceImpl());DubboBootstrap.getInstance().application("first-dubbo-provider").registry(new RegistryConfig(ZOOKEEPER_ADDRESS)).protocol(new ProtocolConfig("dubbo", -1)).service(service).start().await();}
}

5、启动服务消费者
运行1-basic/dubbo-samples-api下的org.apache.dubbo.samples.client包内的AlwaysApplication.java

/** Licensed to the Apache Software Foundation (ASF) under one or more* contributor license agreements.  See the NOTICE file distributed with* this work for additional information regarding copyright ownership.* The ASF licenses this file to You 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 org.apache.dubbo.samples.client;import java.io.IOException;
import java.util.Date;import org.apache.dubbo.config.ReferenceConfig;
import org.apache.dubbo.config.RegistryConfig;
import org.apache.dubbo.config.bootstrap.DubboBootstrap;
import org.apache.dubbo.samples.api.GreetingsService;public class AlwaysApplication {private static final String ZOOKEEPER_HOST = System.getProperty("zookeeper.address", "127.0.0.1");private static final String ZOOKEEPER_PORT = System.getProperty("zookeeper.port", "2181");private static final String ZOOKEEPER_ADDRESS = "zookeeper://" + ZOOKEEPER_HOST + ":" + ZOOKEEPER_PORT;public static void main(String[] args) throws IOException {ReferenceConfig<GreetingsService> reference = new ReferenceConfig<>();reference.setInterface(GreetingsService.class);DubboBootstrap.getInstance().application("first-dubbo-consumer").registry(new RegistryConfig(ZOOKEEPER_ADDRESS)).reference(reference).start();GreetingsService service = reference.get();while (true) {try {String message = service.sayHi("dubbo");System.out.println(new Date() + " Receive result ======> " + message);Thread.sleep(1000);} catch (Throwable t) {t.printStackTrace();}}}}

6、打印日志

Wed Mar 08 17:05:04 CST 2023 Receive result ======> hi, dubbo
Wed Mar 08 17:05:05 CST 2023 Receive result ======> hi, dubbo
Wed Mar 08 17:05:06 CST 2023 Receive result ======> hi, dubbo
Wed Mar 08 17:05:07 CST 2023 Receive result ======> hi, dubbo
Wed Mar 08 17:05:08 CST 2023 Receive result ======> hi, dubbo
......