Dubbo学习（二）- Dubbo的hello world

项目说明

Dubbo-Demo
dubbo的消费者，负责调用服务

Dubbo-Hello-Api
标准api接口，避免服务提供者和消费者书写重复的代码

Dubbo-Hello-Service
dubbo的服务者，提供服务共其他应用调用

Dubbo-Hello-Api

myeclipse中，右键》new》other》maven project，如下


修改pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0modelVersion>
    <groupId>com.ahutgroupId>
    <artifactId>Dubbo-Hello-ApiartifactId>
    <version>0.0.1-SNAPSHOTversion>
    <build>

        
        <defaultGoal>compiledefaultGoal>

        <plugins>
            <plugin>
                <artifactId>maven-compiler-pluginartifactId>
                <configuration>
                    <source>1.8source>
                    <target>1.8target>
                configuration>
            plugin>
        plugins>
    build>
project>

创建com.ahut.hello.service包，添加如下接口

package com.ahut.hello.service;

/**
 * 
 * @ClassName: HelloService
 * @Description: Hello业务逻辑接口
 * @author cheng
 * @date 2018年4月8日 上午11:25:18
 */
public interface HelloService {

    /**
     * 
     * @Title: sayHello
     * @Description:
     * @param name
     */
    void sayHello(String name);

}

发布项目到maven本地仓库
选中项目》右键，run as》run configuration》maven build

Dubbo-Hello-Service

创建Dubbo-Hello-Service项目，和Dubbo-Hello-Api一样，参考上面
修改pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0modelVersion>
    <groupId>com.ahutgroupId>
    <artifactId>Dubbo-Hello-ServiceartifactId>
    <version>0.0.1-SNAPSHOTversion>
    <dependencies>

        
        <dependency>
            <groupId>com.ahutgroupId>
            <artifactId>Dubbo-Hello-ApiartifactId>
            <version>0.0.1-SNAPSHOTversion>
        dependency>

        
        <dependency>
            <groupId>com.alibabagroupId>
            <artifactId>dubboartifactId>
            <version>2.6.1version>
        dependency>

        
        <dependency>
            <groupId>org.apache.zookeepergroupId>
            <artifactId>zookeeperartifactId>
            <version>3.4.11version>
        dependency>

        
        <dependency>
            <groupId>org.apache.curatorgroupId>
            <artifactId>curator-recipesartifactId>
            <version>4.0.1version>
        dependency>

    dependencies>
    <build>
        <plugins>
            <plugin>
                <artifactId>maven-compiler-pluginartifactId>
                <configuration>
                    <source>1.8source>
                    <target>1.8target>
                configuration>
            plugin>
        plugins>
    build>
project>

创建com.ahut.hello.serviceImpl包，添加如下实现

package com.ahut.hello.serviceImpl;

import com.ahut.hello.service.HelloService;

/**
 * 
 * @ClassName: HelloServiceImpl
 * @Description: Hello业务逻辑实现
 * @author cheng
 * @date 2018年4月8日 上午11:39:48
 */
public class HelloServiceImpl implements HelloService {

    /**
     * 实现
     */
    @Override
    public void sayHello(String name) {
        System.out.println("Hello " + name);
    }

}

添加spring-dubbo.xml配置

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:dubbo="http://code.alibabatech.com/schema/dubbo"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://code.alibabatech.com/schema/dubbo http://code.alibabatech.com/schema/dubbo/dubbo.xsd ">

    <dubbo:application name="dubbo-hello" />

    
    <dubbo:registry address="zookeeper://127.0.0.1:2181" />

    <dubbo:protocol name="dubbo" port="20880" />

    
    <bean id="helloService" class="com.ahut.hello.serviceImpl.HelloServiceImpl" />

    
    <dubbo:service interface="com.ahut.hello.service.HelloService"
        ref="helloService" executes="10" />

beans>  

模拟启动服务，前提要开启zookeeper

package com.ahut;

import java.io.IOException;

import org.springframework.context.support.ClassPathXmlApplicationContext;

/**
 * 
 * @ClassName: ServiceMain
 * @Description:
 * @author cheng
 * @date 2018年4月8日 上午11:45:04
 */
public class ServiceMain {

    public static void main(String[] args) throws IOException {

        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(
                new String[] { "spring-dubbo.xml" });
        context.start();

        System.out.println("输入任意按键退出 ~ ");
        System.in.read();
        context.close();
    }

}

Dubbo-Demo

创建Dubbo-Demo项目，和Dubbo-Hello-Api一样，参考上面
修改pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0modelVersion>
    <groupId>com.ahutgroupId>
    <artifactId>Dubbo-DemoartifactId>
    <version>0.0.1-SNAPSHOTversion>
    <dependencies>

        
        <dependency>
            <groupId>com.ahutgroupId>
            <artifactId>Dubbo-Hello-ApiartifactId>
            <version>0.0.1-SNAPSHOTversion>
        dependency>

        
        <dependency>
            <groupId>com.alibabagroupId>
            <artifactId>dubboartifactId>
            <version>2.6.1version>
        dependency>

        
        <dependency>
            <groupId>org.apache.zookeepergroupId>
            <artifactId>zookeeperartifactId>
            <version>3.4.11version>
        dependency>

        
        <dependency>
            <groupId>org.apache.curatorgroupId>
            <artifactId>curator-recipesartifactId>
            <version>4.0.1version>
        dependency>

    dependencies>
    <build>
        <plugins>
            <plugin>
                <artifactId>maven-compiler-pluginartifactId>
                <configuration>
                    <source>1.8source>
                    <target>1.8target>
                configuration>
            plugin>
        plugins>
    build>
project>

添加spring-dubbo.xml配置

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:dubbo="http://code.alibabatech.com/schema/dubbo"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://code.alibabatech.com/schema/dubbo http://code.alibabatech.com/schema/dubbo/dubbo.xsd ">

    <dubbo:application name="dubbo-demo" />

    
    <dubbo:registry address="zookeeper://127.0.0.1:2181" />

    
    <dubbo:reference id="helloService"
        interface="com.ahut.hello.service.HelloService" />

beans> 

模拟调用服务

package com.ahut;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.ahut.hello.service.HelloService;

/**
 * 
 * @ClassName: DemoMain
 * @Description:
 * @author cheng
 * @date 2018年4月8日 上午11:51:15
 */
public class DemoMain {

    public static void main(String[] args) {
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(
                new String[] { "spring-dubbo.xml" });
        context.start();
        HelloService helloService = (HelloService) context.getBean("helloService");
        helloService.sayHello("world");

        context.close();
    }

}

可能出现的问题

Dubbo-Hello-Api项目打包失败，出现如下错误

[INFO] Scanning for projects...
[WARNING] 
[WARNING] Some problems were encountered while building the effective model for com.ahut:Dubbo-Hello-Api:jar:0.0.1-SNAPSHOT
[WARNING] 'build.plugins.plugin.version' for org.apache.maven.plugins:maven-compiler-plugin is missing. @ line 10, column 12
[WARNING] 
[WARNING] It is highly recommended to fix these problems because they threaten the stability of your build.
[WARNING] 
[WARNING] For this reason, future Maven versions might no longer support building such malformed projects.
[WARNING] 
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 0.096 s
[INFO] Finished at: 2018-04-08T14:32:14+08:00
[INFO] Final Memory: 6M/155M
[INFO] ------------------------------------------------------------------------
[ERROR] No goals have been specified for this build. You must specify a valid lifecycle phase or a goal in the format : or group-id>:[:]:. Available lifecycle phases are: validate, initialize, generate-sources, process-sources, generate-resources, process-resources, compile, process-classes, generate-test-sources, process-test-sources, generate-test-resources, process-test-resources, test-compile, process-test-classes, test, prepare-package, package, pre-integration-test, integration-test, post-integration-test, verify, install, deploy, pre-clean, clean, post-clean, pre-site, site, post-site, site-deploy. -> [Help 1]
[ERROR] 
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] 
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/NoGoalSpecifiedException

解决办法：修改pom.xml文件，添加默认全局

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0modelVersion>
    <groupId>com.ahutgroupId>
    <artifactId>Dubbo-Hello-ApiartifactId>
    <version>0.0.1-SNAPSHOTversion>
    <build>

        
        <defaultGoal>compiledefaultGoal>

        <plugins>
            <plugin>
                <artifactId>maven-compiler-pluginartifactId>
                <configuration>
                    <source>1.8source>
                    <target>1.8target>
                configuration>
            plugin>
        plugins>
    build>
project>

Dubbo-Hello-Service或者Dubbo-Demo模拟启动失败，如下

log4j:WARN No appenders could be found for logger (org.springframework.core.env.StandardEnvironment).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/curator/RetryPolicy
    at com.alibaba.dubbo.remoting.zookeeper.curator.CuratorZookeeperTransporter.connect(CuratorZookeeperTransporter.java:26)
    at com.alibaba.dubbo.remoting.zookeeper.ZookeeperTransporter$Adaptive.connect(ZookeeperTransporter$Adaptive.java)
    at com.alibaba.dubbo.registry.zookeeper.ZookeeperRegistry.(ZookeeperRegistry.java:69)
    at com.alibaba.dubbo.registry.zookeeper.ZookeeperRegistryFactory.createRegistry(ZookeeperRegistryFactory.java:37)
    at com.alibaba.dubbo.registry.support.AbstractRegistryFactory.getRegistry(AbstractRegistryFactory.java:95)
    at com.alibaba.dubbo.registry.RegistryFactory$Adaptive.getRegistry(RegistryFactory$Adaptive.java)
    at com.alibaba.dubbo.registry.integration.RegistryProtocol.getRegistry(RegistryProtocol.java:200)
    at com.alibaba.dubbo.registry.integration.RegistryProtocol.export(RegistryProtocol.java:134)
    at com.alibaba.dubbo.rpc.protocol.ProtocolListenerWrapper.export(ProtocolListenerWrapper.java:54)
    at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper.export(ProtocolFilterWrapper.java:91)
    at com.alibaba.dubbo.qos.protocol.QosProtocolWrapper.export(QosProtocolWrapper.java:54)
    at com.alibaba.dubbo.rpc.Protocol$Adaptive.export(Protocol$Adaptive.java)
    at com.alibaba.dubbo.config.ServiceConfig.doExportUrlsFor1Protocol(ServiceConfig.java:505)
    at com.alibaba.dubbo.config.ServiceConfig.doExportUrls(ServiceConfig.java:357)
    at com.alibaba.dubbo.config.ServiceConfig.doExport(ServiceConfig.java:316)
    at com.alibaba.dubbo.config.ServiceConfig.export(ServiceConfig.java:215)
    at com.alibaba.dubbo.config.spring.ServiceBean.onApplicationEvent(ServiceBean.java:121)
    at com.alibaba.dubbo.config.spring.ServiceBean.onApplicationEvent(ServiceBean.java:50)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:167)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:139)
    at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:393)
    at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:347)
    at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:883)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:546)
    at org.springframework.context.support.ClassPathXmlApplicationContext.(ClassPathXmlApplicationContext.java:139)
    at org.springframework.context.support.ClassPathXmlApplicationContext.(ClassPathXmlApplicationContext.java:93)
    at com.ahut.ServiceMain.main(ServiceMain.java:18)
Caused by: java.lang.ClassNotFoundException: org.apache.curator.RetryPolicy
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 27 more

解决办法：修改pom.xml，引入缺少的jar

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0modelVersion>
    <groupId>com.ahutgroupId>
    <artifactId>Dubbo-Hello-ServiceartifactId>
    <version>0.0.1-SNAPSHOTversion>
    <dependencies>

        
        <dependency>
            <groupId>com.ahutgroupId>
            <artifactId>Dubbo-Hello-ApiartifactId>
            <version>0.0.1-SNAPSHOTversion>
        dependency>

        
        <dependency>
            <groupId>com.alibabagroupId>
            <artifactId>dubboartifactId>
            <version>2.6.1version>
        dependency>

        
        <dependency>
            <groupId>org.apache.zookeepergroupId>
            <artifactId>zookeeperartifactId>
            <version>3.4.11version>
        dependency>

        
        <dependency>
            <groupId>org.apache.curatorgroupId>
            <artifactId>curator-recipesartifactId>
            <version>4.0.1version>
        dependency>

    dependencies>
    <build>
        <plugins>
            <plugin>
                <artifactId>maven-compiler-pluginartifactId>
                <configuration>
                    <source>1.8source>
                    <target>1.8target>
                configuration>
            plugin>
        plugins>
    build>
project>