Pojo 序列化兼容模式
这篇教程会通过从零构建一个简单的工程来演示如何基于 POJO 方式使用 Dubbo Triple, 在应用不改变已有接口定义的同时升级到 Triple 协议。此模式下 Triple 使用方式与 Dubbo 协议一样。
具体用例可以参考:dubbo-samples-triple/pojo;
前置条件
创建工程
首先创建一个空的 maven 工程
$ mvn archetype:generate \ -DgroupId=org.apache.dubbo \ -DartifactId=tri-pojo-demo \ -DarchetypeArtifactId=maven-archetype-quickstart \ -DarchetypeVersion=1.4 \ -DarchetypeGroupId=org.apache.maven.archetypes \ -Dversion=1.0-SNAPSHOT
切换到工程目录
$ cd tri-pojo-demo
在
pom.xml
中设置 JDK 版本,添加 Dubbo 依赖和插件<properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <maven.compiler.source>1.8</maven.compiler.source> <maven.compiler.target>1.8</maven.compiler.target> </properties> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.13</version> <scope>test</scope> </dependency> <dependency> <groupId>org.apache.dubbo</groupId> <artifactId>dubbo</artifactId> <version>3.0.8</version> </dependency> <dependency> <groupId>org.apache.dubbo</groupId> <artifactId>dubbo-dependencies-zookeeper-curator5</artifactId> <type>pom</type> <version>3.0.8</version> </dependency> <dependency> <groupId>com.google.protobuf</groupId> <artifactId>protobuf-java</artifactId> <version>3.19.4</version> </dependency> </dependencies>
添加接口定义
src/main/java/org/apache/dubbo/Greeter.java
package org.apache.dubbo; public interface Greeter { String sayHello(String name); }
添加服务端接口实现
src/main/java/org/apache/dubbo/GreeterImpl.java
package org.apache.dubbo; public class GreeterImpl implements Greeter { @Override public String sayHello(String name) { return "Hello," + name + "!"; } }
添加服务端启动类
src/main/java/org/apache/dubbo/MyDubboServer.java
package org.apache.dubbo; import org.apache.dubbo.common.constants.CommonConstants; import org.apache.dubbo.config.ApplicationConfig; 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 java.io.IOException; public class MyDubboServer { public static void main(String[] args) throws IOException { ServiceConfig<Greeter> service = new ServiceConfig<>(); service.setInterface(Greeter.class); service.setRef(new GreeterImpl()); DubboBootstrap bootstrap = DubboBootstrap.getInstance(); bootstrap.application(new ApplicationConfig("tri-pojo-server")) .registry(new RegistryConfig("zookeeper://127.0.0.1:2181")) .protocol(new ProtocolConfig(CommonConstants.TRIPLE, 50051)) .service(service) .start(); System.out.println("Dubbo triple pojo server started"); System.in.read(); } }
添加客户端启动类
src/main/java/org/apache/dubbo/MyDubboClient.java
package org.apache.dubbo; import org.apache.dubbo.common.constants.CommonConstants; import org.apache.dubbo.config.ApplicationConfig; import org.apache.dubbo.config.ReferenceConfig; import org.apache.dubbo.config.RegistryConfig; import org.apache.dubbo.config.bootstrap.DubboBootstrap; public class MyDubboClient { public static void main(String[] args) { DubboBootstrap bootstrap = DubboBootstrap.getInstance(); ReferenceConfig<Greeter> ref = new ReferenceConfig<>(); ref.setInterface(Greeter.class); ref.setProtocol(CommonConstants.TRIPLE); ref.setTimeout(3000); bootstrap.application(new ApplicationConfig("tri-pojo-client")) .registry(new RegistryConfig("zookeeper://127.0.0.1:2181")) .reference(ref) .start(); Greeter greeter = ref.get(); String reply = greeter.sayHello("pojo"); System.out.println("Received reply:" + reply); } }
编译代码
$ mvn clean install
启动服务端
$ mvn org.codehaus.mojo:exec-maven-plugin:3.0.0:java -Dexec.mainClass="org.apache.dubbo.MyDubboServer" Dubbo triple pojo server started
打开新的终端,启动客户端
$ mvn org.codehaus.mojo:exec-maven-plugin:3.0.0:java -Dexec.mainClass="org.apache.dubbo.MyDubboClient"
Received reply:message: "Hello,Demo!"
常见问题
- protobuf 类找不到
由于 Triple 协议底层需要依赖 protobuf 协议进行传输,即使定义的服务接口不使用 protobuf 也需要在环境中引入 protobuf 的依赖。
<dependency>
<groupId>com.google.protobuf</groupId>
<artifactId>protobuf-java</artifactId>
<version>3.19.4</version>
</dependency>
最后修改 March 2, 2023: Fix alias forward in docs3-v2 (#2342) (f16c1535592)