Java 快速开始

下载示例代码

示例代码在 dubbo-samples 中

下载源码：$ Git clone -b master https://github.com/apache/dubbo-samples.git
进入示例目录：$ cd dubbo-samples/dubbo-samples-protobuf

快速运行示例

在 dubbo-samples-protobuf 目录

编译并打包示例项目：$ mvn clean package
运行 Provider：$ java -jar ./protobuf-provider/target/protobuf-provider-1.0-SNAPSHOT.jar

运行 consumer

$ java -jar ./protobuf-consumer/target/protobuf-consumer-1.0-SNAPSHOT.jar 
输出以下结果
result: Hello Hello, response from provider: 30.225.20.43:20880

以上就是一个简单的 Dubbo 服务定义、服务调用流程

详细讲解

服务定义

syntax = "proto3";
option java_multiple_files = true;
option java_package = "org.apache.dubbo.demo";
option java_outer_classname = "DemoServiceProto";
option objc_class_prefix = "DEMOSRV";
package demoservice;
// The demo service definition.
service DemoService {
  rpc SayHello (HelloRequest) returns (HelloReply) {}
}
// The request message containing the user's name.
message HelloRequest {
  string name = 1;
}
// The response message containing the greetings
message HelloReply {
  string message = 1;
}

Protobuf Compiler 插件配置

<plugin>
    <groupId>org.xolstice.maven.plugins</groupId>
    <artifactId>protobuf-maven-plugin</artifactId>
    <version>0.5.1</version>
    <configuration>
        <protocArtifact>com.google.protobuf:protoc:3.7.1:exe:${os.detected.classifier}</protocArtifact>
        <outputDirectory>build/generated/source/proto/main/java</outputDirectory>
        <clearOutputDirectory>false</clearOutputDirectory>
        <protocPlugins>
            <protocPlugin>
                <id>dubbo</id>
                <groupId>org.apache.dubbo</groupId>
                <artifactId>dubbo-compiler</artifactId>
                <version>${dubbo.compiler.version}</version>
                <mainClass>org.apache.dubbo.gen.dubbo.Dubbo3Generator</mainClass>
            </protocPlugin>
        </protocPlugins>
    </configuration>
    <executions>
        <execution>
            <goals>
                <goal>compile</goal>
                <goal>test-compile</goal>
            </goals>
        </execution>
    </executions>
</plugin>

编译与stub 运行 mvn clean compile 后，

生成代码路径 dubbo-samples-protobuf/protobuf-provider/build/generated/source/proto/main/java/org/apache/dubbo/demo

生成文件列表

.
├── DemoService.java
├── DemoServiceDubbo.java
├── DemoServiceProto.java
├── HelloReply.java
├── HelloReplyOrBuilder.java
├── HelloRequest.java
└── HelloRequestOrBuilder.java

DemoService.java 定义如下

@javax.annotation.Generated(
value = "by Dubbo generator",
comments = "Source: DemoService.proto")
public interface DemoService {
    static final String JAVA_SERVICE_NAME = "org.apache.dubbo.demo.DemoService";
    static final String SERVICE_NAME = "demoservice.DemoService";
    static final boolean inited = DemoServiceDubbo.init();
    org.apache.dubbo.demo.HelloReply sayHello(org.apache.dubbo.demo.HelloRequest request);
    CompletableFuture<org.apache.dubbo.demo.HelloReply> sayHelloAsync(org.apache.dubbo.demo.HelloRequest request);
}

发布服务

public class DemoServiceImpl implements DemoService {
    private static final Logger logger = LoggerFactory.getLogger(DemoServiceImpl.class);
    @Override
    public HelloReply sayHello(HelloRequest request) {
        logger.info("Hello " + request.getName() + ", request from consumer: " + RpcContext.getContext().getRemoteAddress());
        return HelloReply.newBuilder()
                .setMessage("Hello " + request.getName() + ", response from provider: "
                        + RpcContext.getContext().getLocalAddress())
                .build();
    }
    @Override
    public CompletableFuture<HelloReply> sayHelloAsync(HelloRequest request) {
        return CompletableFuture.completedFuture(sayHello(request));
    }
}

<bean id="demoServiceImpl" class="org.apache.dubbo.demo.provider.DemoServiceImpl"/>
<dubbo:service serialization="protobuf" interface="org.apache.dubbo.demo.DemoService"
               ref="demoServiceImpl"/>

使用服务

<dubbo:reference scope="remote" id="demoService" check="false" interface="org.apache.dubbo.demo.DemoService"/>

public class ConsumerApplication {
    public static void main(String[] args) throws Exception {
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("spring/dubbo-consumer.xml");
        context.start();
        DemoService demoService = context.getBean("demoService", DemoService.class);
        HelloRequest request = HelloRequest.newBuilder().setName("Hello").build();
        HelloReply reply = demoService.sayHello(request);
        System.out.println("result: " + reply.getMessage());
        System.in.read();
    }
}

Java 语言定义服务

示例使用 Spring XML 配置方式进行演示。除此之外，Dubbo Java 还提供了包括注解、API、配置文件、Spring boot等多种启动与接入方式，具体可参见配置章节具体描述。

下载示例代码

示例代码在 dubbo-samples 中

下载源码：$ Git clone -b master https://github.com/apache/dubbo-samples.git
进入示例目录：$ cd dubbo-samples/dubbo-samples-basic

快速运行示例

在 dubbo-samples-basic 目录

编译 Provider：$ mvn clean compile -Pprovider
运行 Provider：$ java -jar ./target/provider.jar
编译 Consumer：$ mvn clean compile -Pconsumer
运行 consumer：$ java -jar ./target/consumer.jar

详细解释

定义服务接口

DemoService.java

package org.apache.dubbo.samples.basic.api;
public interface DemoService {
    String sayHello(String name);
}

在服务提供方实现接口

DemoServiceImpl.java

public class DemoServiceImpl implements DemoService {
    @Override
    public String sayHello(String name) {
        System.out.println("[" + new SimpleDateFormat("HH:mm:ss").format(new Date()) + "] Hello " + name +
                ", request from consumer: " + RpcContext.getContext().getRemoteAddress());
        return "Hello " + name + ", response from provider: " + RpcContext.getContext().getLocalAddress();
    }
}

用 Spring 配置声明暴露服务

provider.xml：

<bean id="demoService" class="org.apache.dubbo.samples.basic.impl.DemoServiceImpl"/>
<dubbo:service interface="org.apache.dubbo.samples.basic.api.DemoService" ref="demoService"/>

服务消费者

引用远程服务

consumer.xml：

<dubbo:reference id="demoService" check="true" interface="org.apache.dubbo.samples.basic.api.DemoService"/>

加载Spring配置，并调用远程服务

Consumer.java

public static void main(String[] args) {
    ...
    DemoService demoService = (DemoService) context.getBean("demoService");
    String hello = demoService.sayHello("world");
    System.out.println(hello);
}

6.3. java

Java 快速开始

下载示例代码

快速运行示例

详细讲解

Java 语言定义服务

下载示例代码

快速运行示例

详细解释

服务消费者