Dubbo入门

引子

趁着五一的功夫搞了搞Jenkins布署和Dubbo，面试的时候总会问用过Dubbo没

前一家公司是做SpringCloud的微服务，所以就一直没有了解过这个技术，写个基础入门的教程留待备忘

Dubbo是什么？

Dubbo是阿里巴巴开源的一款高性能Java RPC框架 (远程服务调用的分布式框架)。旨在服务拆分后提供服务治理功能，目前已由Apache基金会维护

它提供了三大核心能力：面向接口的远程方法调用，智能容错和负载均衡，以及服务自动注册和发现。

它的架构如图：

了解SpringCloud的注册中心Eureka或Consul就会发现其功能很接近：

  1. 服务提供者将服务地址与方法参数注册到注册中心
  2. 服务消费者启动时订阅服务提供者的服务地址，服务提供者变更时注册中心将服务地址列表发给消费者
  3. 通过得到的地址调用服务接口返回结果，包含负载均衡，失败则调用其它
  4. 异步服务调用计数，用于监控各服务调用情况，如，调用时间/调用次数

其中第3步与Eureka和Consul的Http调用不同，Dubbo底层调用使用的是Netty建立的NIO通道，其高性能就在于此，即没有Http调用频繁开启关闭通道维护session和很多为了标识客户端状态的信息，通过非阻塞（NIO）长连接直接拿到业务数据

HelloWorld 01

以官方推荐Zookeeper注册中心为例，代码在https://github.com/HellxZ/DubboLearn.git 的master分支上

启动Zookeeper注册中心

下载最新的Zookeeper：Download

解压并进入解压缩后的文件夹下的conf目录，复制zoo_sample.cfg，创建新的配置

cd zookeeper-3.4.14/conf
cp zoo_sample.cfg zoo.cfg
vim zoo.cfg

编辑zoo.cfg，按照Zookeeper官方推荐修改dataDir，选择自己想要的路径

保存修改退出

进入可执行文件目录，启动Zookeeper服务端

cd ../bin
./zkServer.sh start #启动服务端

查看启动状态./zkServer.sh status，如下图即正常启动成功

查看Zookeeper日志tail -f zookeeper.out，在bin路径下的zookeeper.out，不要关闭终端方便观察

创建服务提供者

思路：使用两个Spring项目分别代表提供者与消费者，使用Dubbo注册到注册中心，不使用Tomcat以求配置最简化，展示xml全配置方式是如何操作

新建个Maven项目ServiceProvider，pom文件如下：

<?xml version="1.0" encoding="UTF-8"?>
<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">
    <parent>
        <artifactId>XmlConfiguration</artifactId>
        <groupId>com.cnblogs.hellxz</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>ServiceProvider</artifactId>

    <properties>
        <spring.version>4.1.4.RELEASE</spring.version>
        <log4j.version>1.2.17</log4j.version>
        <slf4j.version>1.7.7</slf4j.version>
    </properties>

    <dependencies>
        <!--spring 核心包-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <!--spring上下文包-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context-support</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <!-- 为了方便进行单元测试，添加spring-test包 -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <!--添加spring-web包 -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <!--spring切面包-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aop</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <!--添加aspectjweaver包 -->
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.8.5</version>
        </dependency>
        <!-- 添加servlet3.0核心包 -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.0.1</version>
        </dependency>
        <!--日志包 -->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>${log4j.version}</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>${slf4j.version}</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>${slf4j.version}</version>
        </dependency>
        <!-- 阿里巴巴fastjson包 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.1.41</version>
        </dependency>
        <!--阿里巴巴dubbo-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>dubbo</artifactId>
            <version>2.6.5</version>
        </dependency>
        <dependency>
            <groupId>org.apache.zookeeper</groupId>
            <artifactId>zookeeper</artifactId>
            <version>3.4.6</version>
        </dependency>
        <dependency>
            <groupId>org.apache.curator</groupId>
            <artifactId>curator-recipes</artifactId>
            <version>2.7.0</version>
        </dependency>
        <dependency>
            <groupId>io.netty</groupId>
            <artifactId>netty-all</artifactId>
            <version>4.1.32.Final</version>
        </dependency>

    </dependencies>

    <build>
        <finalName>serviceProvider</finalName>
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.xml</include>
                </includes>
            </resource>
        </resources>

        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

创建个服务接口与实现类

package com.cnblogs.hellxz.service;

public interface IProviderService {
    String call();
}

package com.cnblogs.hellxz.service.impl;

import com.cnblogs.hellxz.service.IProviderService;

public class ProviderServiceImpl implements IProviderService {
    @Override
    public String call() {
        //为了演示清楚，打印红色的输出，并非错误信息
        System.err.println("服务调用成功");
        return "Call service-provider success!";
    }
}

在resources下新建provider.xml，内容如下：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:dubbo="http://code.alibabatech.com/schema/dubbo"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-4.0.xsd
    http://code.alibabatech.com/schema/dubbo
    http://code.alibabatech.com/schema/dubbo/dubbo.xsd"
>
    <!--仅保留核心配置-->

    <!--包扫描-->
    <context:component-scan base-package="com.cnblogs.hellxz"/>

    <!-- 提供方应用信息，用于计算依赖关系，请勿与其他服务名称相同 -->
    <dubbo:application name="service-provider"/>
    <!-- 使用zookeeper注册中心暴露服务地址，地址为zookeeper所在地址 -->
    <dubbo:registry protocol="zookeeper" address="127.0.0.1:2181"/>

    <!--指定要暴露的实现类-->
    <bean id="providerService" class="com.cnblogs.hellxz.service.impl.ProviderServiceImpl"/>
    <!--提供服务实现远程调用，消费者只需要有相同的接口即可调用-->
    <dubbo:service interface="com.cnblogs.hellxz.service.IProviderService" ref="providerService"/>
</beans>

log4j.properties

#日志输出级别
log4j.rootLogger=INFO,stdout
#设置stdout的日志输出控制台
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
#输出日志到控制台的方式，默认为System.out
log4j.appender.stdout.Target=System.out
#设置使用灵活布局
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
#灵活定义输出格式
log4j.appender.stdout.layout.ConversionPattern=[%p][%d{yyyy-MM-dd HH:mm:ss}] %l %m %n

项目启动类ProviderMain

package com.cnblogs.hellxz;

import org.springframework.context.support.ClassPathXmlApplicationContext;
import java.io.IOException;

/**
 * 服务提供者启动类
 */
public class ProviderMain {
    public static void main(String[] args) throws IOException {
        //读取配置文件，初始化Spring容器
        ClassPathXmlApplicationContext ctx = new ClassPathXmlApplicationContext("provider.xml");
        //保持线程存活
        System.in.read();
    }
}

启动项目，我们观察到Zookeeper.out有日志出现了，即注册成功

创建服务消费者

结构如图：

pom文件：

<?xml version="1.0" encoding="UTF-8"?>
<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">
    <parent>
        <artifactId>XmlConfiguration</artifactId>
        <groupId>com.cnblogs.hellxz</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>Consumer</artifactId>

    <properties>
        <spring.version>4.1.4.RELEASE</spring.version>
        <log4j.version>1.2.17</log4j.version>
        <slf4j.version>1.7.7</slf4j.version>
    </properties>

    <dependencies>
        <!--spring 核心包-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <!--spring上下文包-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context-support</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <!-- 为了方便进行单元测试，添加spring-test包 -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <!--添加spring-web包 -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <!--spring切面包-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aop</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <!--添加aspectjweaver包 -->
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.8.5</version>
        </dependency>

        <!-- log4j日志包 -->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>${log4j.version}</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>${slf4j.version}</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>${slf4j.version}</version>
        </dependency>
        <!-- 阿里巴巴fastjson包 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.1.41</version>
        </dependency>
        <!--阿里巴巴dubbo-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>dubbo</artifactId>
            <version>2.6.5</version>
        </dependency>
        <!--解决Caused by: java.lang.ClassNotFoundException: org.apache.curator.framework.api.CuratorWatcher-->
        <dependency>
            <groupId>org.apache.curator</groupId>
            <artifactId>curator-recipes</artifactId>
            <version>2.7.0</version>
        </dependency>
        <!--解决java.lang.NoClassDefFoundError: io/netty/channel/nio/NioEventLoopGroup-->
        <dependency>
            <groupId>io.netty</groupId>
            <artifactId>netty-all</artifactId>
            <version>4.1.32.Final</version>
        </dependency>
    </dependencies>

    <build>
        <finalName>consumer</finalName>
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.xml</include>
                </includes>
            </resource>
        </resources>

        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

pom文件中有些依赖没有会导致一些错误，本人已经将依赖添加的理由写上了，可以去除测试是否如实

log4j配置同提供者项目配置，如下是consumer.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:dubbo="http://code.alibabatech.com/schema/dubbo"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-4.0.xsd
    http://code.alibabatech.com/schema/dubbo
    http://code.alibabatech.com/schema/dubbo/dubbo.xsd"
>
    <!--仅保留核心配置-->

    <!--包扫描-->
    <context:component-scan base-package="com.cnblogs.hellxz"/>

    <!-- 提供方应用信息，用于计算依赖关系，请勿与提供方相同 -->
    <dubbo:application name="service-consumer">
        <dubbo:parameter key="qos.enable" value="true"/>
        <dubbo:parameter key="qos.accept.foreign.ip" value="false"/>
        <!--
        报错java.net.BindException: 地址已在使用
        问题出现的原因：
            consumer启动时qos-server也是使用的默认的22222端口，但是这时候端口已经被provider给占用了，所以才会报错的。
        解决：指定新端口号
        -->
        <dubbo:parameter key="qos.port" value="33333"/>
    </dubbo:application>

    <!-- 
		指定注册中心使用的协议，这里使用zookeeper实现，地址为zookeeper的ip与端口
		如果不指定protocol，address可写为 address="zookeeper://127.0.0.1:2181"
	-->
    <dubbo:registry protocol="zookeeper" address="127.0.0.1:2181"/>

    <!-- 
		引用——通过rpc调用注册服务id为providerService的服务，通过这个设置我们就可以像调用本地方法一样调用
        需要注意的是：接口的包结构与类名，id均要与服务提供者完全相同，本人已测试
     -->
    <dubbo:reference interface="com.cnblogs.hellxz.service.IProviderService" id="providerService"/>
</beans>

调用服务提供者的方法接口的包路径、类名、方法名须与提供者完全相同

创建消费者项目启动类，演示一次调用。启动main方法

package com.cnblogs.hellxz;

import com.cnblogs.hellxz.service.IProviderService;
import org.springframework.context.support.ClassPathXmlApplicationContext;

/**
 * 消费者启动类
 */
public class ConsumerMain {
    public static void main(String[] args) {
        //初始化spring容器
        ClassPathXmlApplicationContext ctx = new ClassPathXmlApplicationContext("consumer.xml");
        //取出容器中的bean
        IProviderService providerService = (IProviderService)ctx.getBean("providerService");
        //打印调用结果 为了演示清楚，打印红色的输出，并非错误信息
        System.err.println(providerService.call());
    }
}

如图，调用成功

这里我们发现：如果我们调用一个方法，必须要写一个重复的接口类，如果服务提供者变更就可能出现不一致的问题，所以在下一个demo中把公共的接口抽取成一个模块，顺便把注解使用写在一起了

Hello World 02

与上一个demo区别：包含注解使用、抽取公共接口模块，代码在https://github.com/HellxZ/DubboLearn.git 的xml-base01分支上

这个分支是从上一个代码中checkout出来的，所以有部分全配置设置，这里只需关心带annotation的xml和启动方法就好

公共接口

与上个demo中服务接口相同，不上代码了，可以参考代码

服务提供者

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<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">
    <parent>
        <artifactId>XmlConfiguration</artifactId>
        <groupId>com.cnblogs.hellxz</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>ServiceProvider</artifactId>

    <properties>
        <spring.version>4.1.4.RELEASE</spring.version>
        <log4j.version>1.2.17</log4j.version>
        <slf4j.version>1.7.7</slf4j.version>
    </properties>

    <dependencies>
        <!--公用接口-->
        <dependency>
            <groupId>com.cnblogs.hellxz</groupId>
            <artifactId>CommonInterface</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
        <!--spring 核心包-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <!--spring上下文包-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context-support</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <!-- 为了方便进行单元测试，添加spring-test包 -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <!--添加spring-web包 -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <!--spring切面包-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aop</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <!--添加aspectjweaver包 -->
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.8.5</version>
        </dependency>
        <!-- 添加servlet3.0核心包 -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.0.1</version>
        </dependency>
        <!--日志包 -->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>${log4j.version}</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>${slf4j.version}</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>${slf4j.version}</version>
        </dependency>
        <!-- 阿里巴巴fastjson包 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.1.41</version>
        </dependency>
        <!--阿里巴巴dubbo-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>dubbo</artifactId>
            <version>2.6.5</version>
        </dependency>
        <!--解决使用注解出现ClassNotFoundException: com.alibaba.spring.beans.factory.annotation.AnnotationInjectedBeanPostProcessor-->
        <dependency>
            <groupId>com.alibaba.spring</groupId>
            <artifactId>spring-context-support</artifactId>
            <version>1.0.2</version>
        </dependency>
        <!--zookeeper包-->
        <dependency>
            <groupId>org.apache.zookeeper</groupId>
            <artifactId>zookeeper</artifactId>
            <version>3.4.6</version>
        </dependency>
        <dependency>
            <groupId>org.apache.curator</groupId>
            <artifactId>curator-recipes</artifactId>
            <version>2.7.0</version>
        </dependency>
        <dependency>
            <groupId>io.netty</groupId>
            <artifactId>netty-all</artifactId>
            <version>4.1.32.Final</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>

    </dependencies>

    <build>
        <finalName>serviceProvider</finalName>
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.xml</include>
                </includes>
            </resource>
        </resources>

        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

provider-annotation-config.xml

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:dubbo="http://code.alibabatech.com/schema/dubbo"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-4.0.xsd
    http://code.alibabatech.com/schema/dubbo
    http://code.alibabatech.com/schema/dubbo/dubbo.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd"
>
    <!--仅保留核心配置-->

    <!--开启切面编程自动代理-->
    <aop:aspectj-autoproxy proxy-target-class="true"/>
    <!--扫描注解生成bean-->
    <context:annotation-config/>
    <!--包扫描-->
    <context:component-scan base-package="com.cnblogs.hellxz"/>

    <!-- 提供方应用信息，用于计算依赖关系，请勿与其他服务名称相同 -->
    <dubbo:application name="service-provider"/>
    <!-- 使用zookeeper注册中心暴露服务地址，地址为zookeeper所在地址 -->
    <dubbo:registry protocol="zookeeper" address="127.0.0.1:2181"/>

    <dubbo:annotation package="com.cnblogs.hellxz"/>
</beans>

log4j日志配置不变，下面是ProviderMain

package com.cnblogs.hellxz;

import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import java.io.IOException;

/**
 * 服务提供者启动类
 */
public class ProviderMain {

    /**
     * 以全配置方式启动spring容器，提供服务
     */
    @Test
    public void testFullXmlConfig() {
        initSpringContextWithConfigXml("provider-full-xml-config.xml");
    }

    /**
     * 使用配置方式开启注解，启动spring容器，提供服务
     */
    @Test
    public void testAnnotation() {
        initSpringContextWithConfigXml("provider-annotation-config.xml");
    }

    /**
     * 使用配置文件启动spring容器
     *
     * @param springConfigXmlName 配置文件在classPath下的路径名称
     */
    private void initSpringContextWithConfigXml(String springConfigXmlName) {
        //读取配置文件，初始化Spring容器
        ApplicationContext ctx = new ClassPathXmlApplicationContext(springConfigXmlName);
        try {
            //保持线程存活，输入任意字符回车停止
            System.in.read();
        } catch (IOException e) {
            //仅作演示不处理
            e.printStackTrace();
        }
    }
}

ProviderServiceImpl相对于Hello World 01中只是加了个@Service注解，但是注意这个注解是dubbo包下的

package com.cnblogs.hellxz.service.impl;

import com.alibaba.dubbo.config.annotation.Service;
import com.cnblogs.hellxz.service.IProviderService;

@Service
public class ProviderServiceImpl implements IProviderService {

    @Override
    public String call() {
        //为了演示清楚，打印红色的输出，并非错误信息
        System.err.println("服务调用成功");
        return "Call service-provider success!";
    }
}

启动testAnnotation方法即可启动服务

请先关掉上个demo中启动的方法

服务消费者

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<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">
    <parent>
        <artifactId>XmlConfiguration</artifactId>
        <groupId>com.cnblogs.hellxz</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>Consumer</artifactId>

    <properties>
        <spring.version>4.1.4.RELEASE</spring.version>
        <log4j.version>1.2.17</log4j.version>
        <slf4j.version>1.7.7</slf4j.version>
    </properties>

    <dependencies>
        <!--spring 核心包-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <!--spring上下文包-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context-support</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <!-- 为了方便进行单元测试，添加spring-test包 -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <!--添加spring-web包 -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <!--spring切面包-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aop</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <!--添加aspectjweaver包 -->
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.8.5</version>
        </dependency>

        <!-- log4j日志包 -->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>${log4j.version}</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>${slf4j.version}</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>${slf4j.version}</version>
        </dependency>
        <!-- 阿里巴巴fastjson包 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.1.41</version>
        </dependency>
        <!--阿里巴巴dubbo-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>dubbo</artifactId>
            <version>2.6.5</version>
        </dependency>
        <!--解决Caused by: java.lang.ClassNotFoundException: org.apache.curator.framework.api.CuratorWatcher-->
        <dependency>
            <groupId>org.apache.curator</groupId>
            <artifactId>curator-recipes</artifactId>
            <version>2.7.0</version>
        </dependency>
        <!--解决java.lang.NoClassDefFoundError: io/netty/channel/nio/NioEventLoopGroup-->
        <dependency>
            <groupId>io.netty</groupId>
            <artifactId>netty-all</artifactId>
            <version>4.1.32.Final</version>
        </dependency>
        <!--添加公用接口模块-->
        <dependency>
            <groupId>com.cnblogs.hellxz</groupId>
            <artifactId>CommonInterface</artifactId>
            <version>1.0-SNAPSHOT</version>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
        <!--解决使用注解出现ClassNotFoundException: com.alibaba.spring.beans.factory.annotation.AnnotationInjectedBeanPostProcessor-->
        <dependency>
            <groupId>com.alibaba.spring</groupId>
            <artifactId>spring-context-support</artifactId>
            <version>1.0.2</version>
        </dependency>
    </dependencies>

    <build>
        <finalName>consumer</finalName>
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.xml</include>
                </includes>
            </resource>
        </resources>

        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

consumer-annotation-config.xml

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:dubbo="http://code.alibabatech.com/schema/dubbo" xmlns:aop="http://www.springframework.org/schema/aop"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-4.0.xsd
    http://code.alibabatech.com/schema/dubbo
    http://code.alibabatech.com/schema/dubbo/dubbo.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd"
>
    <!--仅保留核心配置-->

    <!--开启切面编程自动代理-->
    <aop:aspectj-autoproxy proxy-target-class="true"/>
    <!--包扫描-->
    <context:component-scan base-package="com.cnblogs.hellxz"/>
    <!--扫描注解生成bean-->
    <context:annotation-config/>

    <!-- 提供方应用信息，用于计算依赖关系，请勿与提供方相同 -->
    <dubbo:application name="service-consumer">
        <dubbo:parameter key="qos.enable" value="true"/>
        <dubbo:parameter key="qos.accept.foreign.ip" value="false"/>
        <!--
        报错java.net.BindException: 地址已在使用
        问题出现的原因：
            consumer启动时qos-server也是使用的默认的22222端口，但是这时候端口已经被provider给占用了，所以才会报错的。
        解决：指定新端口号
        -->
        <dubbo:parameter key="qos.port" value="33333"/>
    </dubbo:application>

    <!-- 使用zookeeper注册中心暴露服务地址，地址为zookeeper所在地址 -->
    <dubbo:registry protocol="zookeeper" address="127.0.0.1:2181"/>

    <dubbo:annotation package="com.cnblogs.hellxz"/>
</beans>

需要有一个bean在spring容器中对应Dubbo引用的接口上

package com.cnblogs.hellxz.service.impl;

import com.alibaba.dubbo.config.annotation.Reference;
import com.cnblogs.hellxz.service.IProviderService;
import org.springframework.stereotype.Service;

/**
 * 这个类主要作用就是dubbo引用的接口与providerService这个bean名称作绑定
 * 在全xml配置方式中无需存在，注意这回的@Service注解是spring的
 */
@Service("providerService")
public class ProviderServiceImpl implements IProviderService {

    @Reference
    private IProviderService iProviderService;

    @Override
    public String call() {
        return iProviderService.call();
    }
}

注意事项：

  1. 这回的@Service注解是spring的
  2. 使用Springmvc时无需再包这一层，在@Controller或@RestController的类中直接写@Reference就可以了

贴出启动方法，这次用的是Junit测试的

    @Test
    public void testAnnotationConfig() {
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("consumer-annotation-config.xml");
        IProviderService providerService = (IProviderService) context.getBean("providerService");
        System.err.println(providerService.call());
    }

测试结果与Demo01相同

报错与解决

1.在注册中心找不到对应的服务

java.lang.IllegalStateException: Failed to check the status of the service *.*.*.xxService . No provider available for the service *.*.*.xxService

这个错误原因是服务端没有将xxService服务注册到注册中心，原因无非三种

  1. 没加com.alibaba.dubbo.config.annotation包下的@Service注解或引错包;
  2. 服务端没启动起来，检查服务端状态
  3. 服务端没注册到注册中心，检查服务端测试中心配置

2. 无法连接到注册中心

  1. 检查Zookeeper是否正常运行
  2. 检查报错项目的注册中心地址配置

3. ClassNotFound异常

3.1
Caused by: java.lang.ClassNotFoundException: org.apache.curator.framework.api.CuratorWatcher

添加依赖

        <dependency>
            <groupId>org.apache.curator</groupId>
            <artifactId>curator-recipes</artifactId>
            <version>2.7.0</version>
        </dependency>
3.2
ClassNotFoundException: com.alibaba.spring.beans.factory.annotation.AnnotationInjectedBeanPostProcessor

添加依赖

        <dependency>
            <groupId>com.alibaba.spring</groupId>
            <artifactId>spring-context-support</artifactId>
            <version>1.0.2</version>
        </dependency>

4. NoClassDefFoundError错误

java.lang.NoClassDefFoundError: io/netty/channel/nio/NioEventLoopGroup

添加依赖

        <dependency>
            <groupId>io.netty</groupId>
            <artifactId>netty-all</artifactId>
            <version>4.1.32.Final</version>
        </dependency>

5. java.net.BindException: 地址已在使用

    <!-- 提供方应用信息，用于计算依赖关系，请勿与提供方相同 -->
    <dubbo:application name="service-consumer">
        <dubbo:parameter key="qos.enable" value="true"/>
        <dubbo:parameter key="qos.accept.foreign.ip" value="false"/>
        <!--
        报错java.net.BindException: 地址已在使用
        问题出现的原因：
            consumer启动时qos-server也是使用的默认的22222端口，但是这时候端口已经被provider给占用了，所以才会报错的。
        解决：指定新端口号
        -->
        <dubbo:parameter key="qos.port" value="33333"/>
    </dubbo:application>

最后

与SpringBoot的集成的版本后续会开发到新分支下，本文仅介绍Dubbo的架构与基础用法

欢迎关注点赞评论转载，比B站多一连 😃，您的支持就是我的动力

本文为实操笔记，转载请注明出处

posted @ 2019-05-04 16:13  东北小狐狸  阅读(1313)  评论(0)  编辑  收藏  举报