聊聊Dubbo（二）：简单入门
0 准备
- 安装注册中心：Zookeeper、Dubbox自带的dubbo-registry-simple；
- 安装DubboKeeper监控：https://github.com/dubboclub/dubbokeeper；
以上两点准备，不是本文重点，不做详细介绍，安装比较简单，自行查阅相关资料安装学习。
1 服务端
1.2 接口定义
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创建Maven模块：msa-demo-api
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msa-demo-api：配置pom.xml
<dependency><groupId>com.alibabagroupId><artifactId>dubboartifactId><version>2.8.4version> dependency> <dependency><groupId>org.projectlombokgroupId><artifactId>lombokartifactId> dependency> <dependency><groupId>org.jboss.resteasygroupId><artifactId>resteasy-jaxrsartifactId><version>3.0.7.Finalversion> dependency> <dependency><groupId>org.jboss.resteasygroupId><artifactId>resteasy-clientartifactId><version>3.0.7.Finalversion> dependency> <dependency><groupId>javax.validationgroupId><artifactId>validation-apiartifactId><version>1.0.0.GAversion> dependency> <dependency><groupId>org.jboss.resteasygroupId><artifactId>resteasy-jackson-providerartifactId><version>3.0.7.Finalversion> dependency> <dependency><groupId>org.jboss.resteasygroupId><artifactId>resteasy-jaxb-providerartifactId><version>3.0.7.Finalversion> dependency> <dependency><groupId>org.jboss.resteasygroupId><artifactId>resteasy-nettyartifactId><version>3.0.7.Finalversion> dependency> <dependency><groupId>org.jboss.resteasygroupId><artifactId>resteasy-jdk-httpartifactId><version>3.0.7.Finalversion> dependency> <dependency><groupId>org.apache.tomcat.embedgroupId><artifactId>tomcat-embed-coreartifactId><version>8.0.11version> dependency> <dependency><groupId>org.apache.tomcat.embedgroupId><artifactId>tomcat-embed-logging-juliartifactId><version>8.0.11version> dependency> <dependency><groupId>com.esotericsoftware.kryogroupId><artifactId>kryoartifactId><version>2.24.0version> dependency> <dependency><groupId>de.javakaffeegroupId><artifactId>kryo-serializersartifactId><version>0.26version> dependency> <dependency><groupId>de.ruedigermoellergroupId><artifactId>fstartifactId><version>1.55version> dependency> <dependency><groupId>com.fasterxml.jackson.coregroupId><artifactId>jackson-coreartifactId><version>2.3.3version> dependency> <dependency><groupId>com.fasterxml.jackson.coregroupId><artifactId>jackson-databindartifactId><version>2.3.3version> dependency> 复制代码以上POM配置，从dubbox-2.8.4开始，所有依赖库的使用方式将和dubbo原来的一样：即如果要使用REST、Kyro、FST、Jackson等功能，需要用户自行手工添加相关的依赖。
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定义接口：UserService.java
/*** @author TaoBangren* @version 1.0* @since 2017/5/17 上午9:26*/ public interface UserService {User getUser(Long id);Long registerUser(User user); } 复制代码 -
定义REST接口：AnotherUserRestService.java
package com.alibaba.dubbo.demo.user.facade; import com.alibaba.dubbo.demo.user.User; import com.alibaba.dubbo.rpc.protocol.rest.support.ContentType; import javax.validation.constraints.Min; import javax.ws.rs.*; import javax.ws.rs.core.MediaType; /*** @author TaoBangren* @version 1.0* @since 2017/5/17 上午9:26*/ // 在Dubbo中开发REST服务主要都是通过JAX-RS的annotation来完成配置的， // 在上面的示例中，我们都是将annotation放在服务的实现类中。但其实，我 // 们完全也可以将annotation放到服务的接口上，这两种方式是完全等价的. // // 在一般应用中，我们建议将annotation放到服务实现类，这样annotation和 // java实现代码位置更接近，更便于开发和维护。另外更重要的是，我们一般倾向 // 于避免对接口的污染，保持接口的纯净性和广泛适用性。 // 但是，如后文所述，如果我们要用dubbo直接开发的消费端来访问此服务，则annotation必须放到接口上。 // 如果接口和实现类都同时添加了annotation，则实现类的annotation配置会生效，接口上的annotation被直接忽略。 @Path("u") @Consumes({MediaType.APPLICATION_JSON, MediaType.TEXT_XML}) @Produces({ContentType.APPLICATION_JSON_UTF_8, ContentType.TEXT_XML_UTF_8}) public interface AnotherUserRestService {@GET@Path("{id : \\d+}")// 在一个REST服务同时对多种数据格式支持的情况下，根据JAX-RS标准，// 一般是通过HTTP中的MIME header（content-type和accept）来指定当前想用的是哪种格式的数据。// @Produces({ContentType.APPLICATION_JSON_UTF_8, ContentType.TEXT_XML_UTF_8})// 但是在dubbo中，我们还自动支持目前业界普遍使用的方式，即用一个URL后缀（.json和.xml）来指定// 想用的数据格式。例如，在添加上述annotation后，直接访问http://localhost:8888/users/1001.json// 则表示用json格式，直接访问http://localhost:8888/users/1002.xml则表示用xml格式，// 比用HTTP Header更简单直观。Twitter、微博等的REST API都是采用这种方式。// 如果你既不加HTTP header，也不加后缀，则dubbo的REST会优先启用在以上annotation定义中排位最靠前的那种数据格式。// 注意：这里要支持XML格式数据，在annotation中既可以用MediaType.TEXT_XML，也可以用MediaType.APPLICATION_XML，// 但是TEXT_XML是更常用的，并且如果要利用上述的URL后缀方式来指定数据格式，只能配置为TEXT_XML才能生效。User getUser(@PathParam("id") @Min(1L) Long id);@POST@Path("register")RegistrationResult registerUser(User user); } 复制代码 -
定义实体：User.java
package com.alibaba.dubbo.demo.user; import lombok.Data; import org.codehaus.jackson.annotate.JsonProperty; import javax.validation.constraints.Min; import javax.validation.constraints.NotNull; import javax.validation.constraints.Size; import javax.xml.bind.annotation.XmlAccessType; import javax.xml.bind.annotation.XmlAccessorType; import javax.xml.bind.annotation.XmlElement; import javax.xml.bind.annotation.XmlRootElement; import java.io.Serializable; /*** @author TaoBangren* @version 1.0* @since 2017/5/17 上午9:26*/ // 由于JAX-RS的实现一般都用标准的JAXB（Java API for XML Binding）来序列化和反序列化XML格式数据， // 所以我们需要为每一个要用XML传输的对象添加一个类级别的JAXB annotation(@XmlRootElement) ，否则序列化将报错。 @Data @XmlRootElement @XmlAccessorType(XmlAccessType.FIELD) public class User implements Serializable {@NotNull@Min(1L)private Long id;// REST的底层实现会在service的对象和JSON/XML数据格式之间自动做序列化/反序列化。// 但有些场景下，如果觉得这种自动转换不满足要求，可以对其做定制。// Dubbo中的REST实现是用JAXB做XML序列化，用Jackson做JSON序列化，// 所以在对象上添加JAXB或Jackson的annotation即可以定制映射。@JsonProperty("username")@XmlElement(name = "username")@NotNull@Size(min = 6, max = 50)private String name; } 复制代码 -
定义REST响应结果实体：RegistrationResult.java
package com.alibaba.dubbo.demo.user.facade; import lombok.Data; import javax.xml.bind.annotation.XmlRootElement; import java.io.Serializable; /*** @author TaoBangren* @version 1.0* @since 2017/5/17 上午9:26*/ // 此外，如果service方法中的返回值是Java的 primitive类型（如int，long，float，double等）， // 最好为它们添加一层wrapper对象，因为JAXB不能直接序列化primitive类型。这样不但能够解决XML序列化的问题， // 而且使得返回的数据都符合XML和JSON的规范。 // 这种wrapper对象其实利用所谓Data Transfer Object（DTO）模式，采用DTO还能对传输数据做更多有用的定制。 @Data @XmlRootElement public class RegistrationResult implements Serializable {private Long id; } 复制代码
1.3 服务实现
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创建Maven模块：msa-demo-provider
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msa-demo-provider：配置pom.xml
<dependency><groupId>com.alibabagroupId><artifactId>msa-demo-apiartifactId><version>1.0-SNAPSHOTversion> dependency> 复制代码 -
实现UserService接口：UserServiceImpl.java
package com.alibaba.dubbo.demo.user; import lombok.extern.slf4j.Slf4j; import java.util.concurrent.atomic.AtomicLong; /*** @author TaoBangren* @version 1.0* @since 2017/5/17 上午9:26*/ @Slf4j public class UserServiceImpl implements UserService {private final AtomicLong idGen = new AtomicLong();public User getUser(Long id) {User user = new User();user.setId(id);user.setName("username" + id);return user;}public Long registerUser(User user) {// System.out.println("Username is " + user.getName());return idGen.incrementAndGet();} } 复制代码 -
实现REST接口AnotherUserRestService：AnotherUserRestServiceImpl.java
package com.alibaba.dubbo.demo.user.facade; import com.alibaba.dubbo.demo.user.User; import com.alibaba.dubbo.demo.user.UserService; import com.alibaba.dubbo.rpc.RpcContext; import lombok.extern.slf4j.Slf4j; /*** @author TaoBangren* @version 1.0* @since 2017/5/17 上午9:26*/ @Slf4j public class AnotherUserRestServiceImpl implements AnotherUserRestService {private UserService userService;public void setUserService(UserService userService) {this.userService = userService;}public User getUser(Long id) {System.out.println("Client name is " + RpcContext.getContext().getAttachment("clientName"));System.out.println("Client impl is " + RpcContext.getContext().getAttachment("clientImpl"));return userService.getUser(id);}public RegistrationResult registerUser(User user) {Long id = userService.registerUser(user);RegistrationResult registrationResult = new RegistrationResult();registrationResult.setId(id);return registrationResult;} } 复制代码 -
Dubbox与Spring集成配置：msa-demo-provider.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:dubbo="http://code.alibabatech.com/schema/dubbo"xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans-2.5.xsdhttp://code.alibabatech.com/schema/dubbohttp://code.alibabatech.com/schema/dubbo/dubbo.xsd"><dubbo:application name="msa-demo-provider" owner="tbr" organization="tbr"/><dubbo:monitor address="x.x.x.x:20884"/><dubbo:registry protocol="zookeeper" address="x.x.x.x:2181,x.x.x.x:2181,x.x.x.x:2181"/><dubbo:protocol name="dubbo" port="20880" serialization="kryo"/><dubbo:protocol name="rest" port="8888" threads="500" contextpath="services" server="tomcat" accepts="500"extension="com.alibaba.dubbo.demo.extension.TraceInterceptor,com.alibaba.dubbo.demo.extension.TraceFilter,com.alibaba.dubbo.demo.extension.ClientTraceFilter,com.alibaba.dubbo.demo.extension.DynamicTraceBinding,com.alibaba.dubbo.demo.extension.CustomExceptionMapper,com.alibaba.dubbo.rpc.protocol.rest.support.LoggingFilter"/><dubbo:protocol name="http" port="8889"/><dubbo:protocol name="hessian" port="8890"/><dubbo:protocol name="webservice" port="8892"/><dubbo:service interface="com.alibaba.dubbo.demo.user.UserService" ref="userService" protocol="dubbo" group="xmlConfig"/><dubbo:service interface="com.alibaba.dubbo.demo.user.facade.AnotherUserRestService" ref="anotherUserRestService" protocol="rest" timeout="2000" connections="100" validation="true"/><bean id="userService" class="com.alibaba.dubbo.demo.user.UserServiceImpl"/><bean id="anotherUserRestService" class="com.alibaba.dubbo.demo.user.facade.AnotherUserRestServiceImpl"><property name="userService" ref="userService"/>bean> beans> 复制代码 -
配置dubbo.properties
#dubbo.container=log4j,spring #dubbo.application.name=demo-provider #dubbo.application.owner= #dubbo.registry.address=multicast://224.5.6.7:1234 #dubbo.registry.address=zookeeper://127.0.0.1:2181 #dubbo.registry.address=redis://127.0.0.1:6379 #dubbo.registry.address=dubbo://127.0.0.1:9090 #dubbo.monitor.protocol=registry #dubbo.protocol.name=dubbo #dubbo.protocol.port=20880 #dubbo.service.loadbalance=roundrobin #dubbo.log4j.file=logs/msa-demo-provider.log #dubbo.log4j.level=INFO #dubbo.log4j.subdirectory=20880 dubbo.application.logger=slf4j dubbo.spring.config=classpath*:msa-*.xml 复制代码
1.4 服务启动
定义服务启动类
package com.alibaba.dubbo.demo.provider;
/*** @author TaoBangren* @version 1.0* @since 2017/5/17 上午9:26*/
public class DemoProvider {public static void main(String[] args) {com.alibaba.dubbo.container.Main.main(args);}
}
复制代码执行main方法启动，看到以下日志输出时，msa-demo-provider启动成功：
查看DubboKeeper监控大盘，msa-demo-provider发布服务成功，可以看到我们发布的两个接口：
2. 客户端
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创建Maven模块：msa-demo-client
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msa-demo-client：配置pom.xml
<dependency><groupId>com.alibabagroupId><artifactId>msa-demo-apiartifactId><version>1.0-SNAPSHOTversion> dependency> 复制代码 -
Dubbox与Spring集成配置：msa-demo-client.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:dubbo="http://code.alibabatech.com/schema/dubbo"xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans-2.5.xsdhttp://code.alibabatech.com/schema/dubbohttp://code.alibabatech.com/schema/dubbo/dubbo.xsd"><dubbo:reference id="userService" interface="com.alibaba.dubbo.demo.user.UserService" group="xmlConfig"/><dubbo:reference id="anotherUserRestService" interface="com.alibaba.dubbo.demo.user.facade.AnotherUserRestService"/> beans> 复制代码
3. 消费端
3.1 消费端实现
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创建Maven模块：msa-demo-consumer
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msa-demo-consumer：配置pom.xml
<dependency><groupId>com.jeasygroupId><artifactId>msa-demo-clientartifactId><version>1.0-SNAPSHOTversion> dependency> 复制代码 -
创建消费端测试类：DemoAction.java
package com.alibaba.dubbo.demo; import com.alibaba.dubbo.rpc.RpcContext; import com.alibaba.dubbo.demo.user.User; import com.alibaba.dubbo.demo.user.UserService; import com.alibaba.dubbo.demo.user.facade.AnotherUserRestService; /*** @author TaoBangren* @version 1.0* @since 2017/5/17 上午9:26*/ public class DemoAction {private UserService userService;private AnotherUserRestService anotherUserRestService;public void setUserService(final UserService userService) {this.userService = userService;}public void setAnotherUserRestService(final AnotherUserRestService anotherUserRestService) {this.anotherUserRestService = anotherUserRestService;}public void start() throws Exception {User user = new User();user.setId(1L);user.setName("larrypage");System.out.println("SUCCESS: registered user with id by rest" + anotherUserRestService.registerUser(user).getId());System.out.println("SUCCESS: registered user with id " + userService.registerUser(user));RpcContext.getContext().setAttachment("clientName", "demo");RpcContext.getContext().setAttachment("clientImpl", "dubbox rest");System.out.println("SUCCESS: got user by rest" + anotherUserRestService.getUser(1L));System.out.println("SUCCESS: got user " + userService.getUser(1L));} } 复制代码 -
Dubbox与Spring集成配置：msa-demo-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:dubbo="http://code.alibabatech.com/schema/dubbo"xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans-2.5.xsdhttp://code.alibabatech.com/schema/dubbohttp://code.alibabatech.com/schema/dubbo/dubbo.xsd"><dubbo:application name="msa-demo-consumer" owner="tbr" organization="tbr"/><dubbo:registry protocol="zookeeper" address="x.x.x.x:2181,x.x.x.x:2181,x.x.x.x:2181"/><dubbo:monitor address="x.x.x.x:20884"/><bean class="com.alibaba.dubbo.demo.DemoAction" init-method="start"><property name="userService" ref="userService"/><property name="anotherUserRestService" ref="anotherUserRestService"/>bean> beans> 复制代码 -
配置dubbo.properties
#dubbo.container=log4j,spring #dubbo.application.name=demo-consumer #dubbo.application.owner= #dubbo.registry.address=multicast://224.5.6.7:1234 #dubbo.registry.address=zookeeper://127.0.0.1:2181 #dubbo.registry.address=redis://127.0.0.1:6379 #dubbo.registry.address=dubbo://127.0.0.1:9090 #dubbo.monitor.protocol=registry #dubbo.log4j.file=logs/msa-demo-consumer.log #dubbo.log4j.level=INFO dubbo.application.logger=slf4j dubbo.spring.config=classpath*:msa-*.xml 复制代码
3.2 消费端测试
定义消费启动类：
package com.jeasy;
/*** @author TaoBangren* @version 1.0* @since 2017/5/17 上午9:26*/
public class DemoConsumer {public static void main(String[] args) {com.alibaba.dubbo.container.Main.main(args);}
}
复制代码执行main方法启动，看到以下日志输出时，msa-demo-consumer启动成功：
同时服务端会输出服务调用日志信息，并调用成功，如下：
4. 规范使用
| 模块 | 描述 | 是否必须 |
|---|---|---|
| msa-xxx-api | 定义接口&实体 | 必须 |
| msa-xxx-provider | 依赖api模块，实现服务接口，提供服务 | 必须 |
| msa-xxx-client | 依赖api模块，Spring配置文件&测试用例，提供给第三方调用服务使用 | 必须 |
| msa-xxx-consumer | 依赖client模块，建议保留该模块，避免client模块直接与应用方紧耦合 | 可选 |
5. 推荐阅读
5.1 Dubbox相关资源
- 源码地址 : github.com/dangdangdot…
- 在Dubbo中开发REST风格的远程调用 : dangdangdotcom.github.io/dubbox/rest…
- 在Dubbo中使用高效的Java序列化 : dangdangdotcom.github.io/dubbox/seri…
- 使用JavaConfig方式配置dubbox : dangdangdotcom.github.io/dubbox/java…
- Dubbo Jackson序列化使用说明 : dangdangdotcom.github.io/dubbox/jack…
- Demo : dangdangdotcom.github.io/dubbox/demo…
- 当当网开源Dubbox，扩展Dubbo服务框架支持REST风格远程调用 : www.infoq.com/cn/news/201…
- Dubbox Wiki : github.com/dangdangdot…
5.2 Dubbo相关资源
- 源码地址 : github.com/alibaba/dub…
- Dubbo Wiki : github.com/alibaba/dub…
- http://dubbo.io/
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