Dubbo学习笔记
Dubbo的设计目的
- 动态注册、发现服务，软负载均衡和服务降级。
- 描述服务依赖关系，描述整体服务架构。
- 统计服务负载，按需扩展容量。
简单实例
该实例参考官方实例，有所修改。
整个项目结构：
dubbo-hello
.
├── dubbo-hello-api
│ ├── pom.xml
│ ├── src
│ │ ├── main
│ │ │ ├── java
│ │ │ │ └── com
│ │ │ │ └── tc
│ │ │ │ └── dubbo
│ │ │ │ └── hello
│ │ │ │ └── HelloService.java
│ │ │ └── resources
│ │ └── test
│ │ └── java
│ └── target
│
├── dubbo-hello-consumer
│ ├── pom.xml
│ ├── src
│ │ ├── main
│ │ │ ├── java
│ │ │ │ └── com
│ │ │ │ └── tc
│ │ │ │ └── dubbo
│ │ │ │ └── hello
│ │ │ │ └── consumer
│ │ │ │ └── Consumer.java
│ │ │ └── resources
│ │ │ ├── META-INF
│ │ │ │ └── spring
│ │ │ │ └── dubbo-hello-consumer.xml
│ │ │ ├── dubbo.properties
│ │ │ └── log4j.properties
│ │ └── test
│ │ └── java
│ └── target
│
├── dubbo-hello-provider
│ ├── pom.xml
│ ├── src
│ │ ├── main
│ │ │ ├── java
│ │ │ │ └── com
│ │ │ │ └── tc
│ │ │ │ └── dubbo
│ │ │ │ └── hello
│ │ │ │ └── provider
│ │ │ │ ├── HelloServiceImpl.java
│ │ │ │ └── Provider.java
│ │ │ └── resources
│ │ │ ├── META-INF
│ │ │ │ └── spring
│ │ │ │ └── dubbo-hello-provider.xml
│ │ │ ├── dubbo.properties
│ │ │ └── log4j.properties
│ │ └── test
│ │ └── java
│ └── target
└── pom.xml整个项目分为三个模块，dubbo-hello-api、dubbo-hello-provider和dubbo-hello-consumer。一下是整个dubbo-hello工程的pom内容：
<?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">
<modelVersion>4.0.0</modelVersion>
<groupId>com.tc</groupId>
<artifactId>dubbo-hello</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>pom</packaging>
<name>${project.artifactId}</name>
<properties>
<skip_maven_deploy>false</skip_maven_deploy>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
</properties>
<modules>
<module>dubbo-hello-api</module>
<module>dubbo-hello-provider</module>
<module>dubbo-hello-consumer</module>
</modules>
</project>公共API定义
一般Provider和Consumer共享的接口应该单独一个包进行定义，方便双方的共享。这里新建了模块dubbo-hello-api来定义公共接口。其pom文件为基本配置，无特殊性，简单定义接口HelloService如下：
package com.tc.dubbo.hello;
/**
* Created by tianchi on 2018/3/14.
*/
public interface HelloService {
String sayHello(String name);
}Provider实现
服务提供者模块dubbo-hello-provider的pom文件内容如下：
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>dubbo-hello</artifactId>
<groupId>com.tc</groupId>
<version>1.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>dubbo-hello-provider</artifactId>
<packaging>jar</packaging>
<name>${project.artifactId}</name>
<description>The demo provider module of dubbo project</description>
<properties>
<skip_maven_deploy>false</skip_maven_deploy>
</properties>
<dependencies>
<dependency>
<groupId>com.tc</groupId>
<artifactId>dubbo-hello-api</artifactId>
<version>${project.parent.version}</version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>dubbo</artifactId>
<version>2.6.0</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<version>2.3</version>
<configuration>
<appendAssemblyId>false</appendAssemblyId>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
<archive>
<manifest>
<mainClass>com.tc.dubbo.hello.provider.Provider</mainClass>
</manifest>
</archive>
</configuration>
<executions>
<execution>
<id>make-assembly</id>
<phase>package</phase>
<goals>
<goal>assembly</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>其中声明了对com.tc:dubbo-hello-api接口的依赖，还有对com.alibaba:dubbo的依赖。插件plugin声明了采用加入依赖的打包方式，这样方便直接运行。
在文件dubbo-hello-provider.xml中声明了要暴露的服务：
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:dubbo="http://code.alibabatech.com/schema/dubbo"
xmlns="http://www.springframework.org/schema/beans"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd
http://code.alibabatech.com/schema/dubbo http://code.alibabatech.com/schema/dubbo/dubbo.xsd">
<!-- provider's application name, used for tracing dependency relationship -->
<dubbo:application name="hello-provider"/>
<!-- use multicast registry center to export service -->
<dubbo:registry address="multicast://224.5.6.7:1234"/>
<!-- use dubbo protocol to export service on port 20880 -->
<dubbo:protocol name="dubbo" port="20880"/>
<!-- service implementation, as same as regular local bean -->
<bean id="helloService" class="com.tc.dubbo.hello.provider.HelloServiceImpl"/>
<!-- declare the service interface to be exported -->
<dubbo:service interface="com.tc.dubbo.hello.HelloService" ref="helloService"/>
</beans>其中说明了注册方式为multicast，也即利用广播，无注册中心的方式。同时声明了协议和端口号。
暴露的服务HelloServiceImpl实现如下：
package com.tc.dubbo.hello.provider;
import com.alibaba.dubbo.rpc.RpcContext;
import com.tc.dubbo.hello.HelloService;
import java.text.SimpleDateFormat;
import java.util.Date;
/**
* Created by tianchi on 2018/3/14.
*/
public class HelloServiceImpl implements HelloService{
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 form provider: " + RpcContext.getContext().getLocalAddress();
}
}入口类Provider的实现如下：
package com.tc.dubbo.hello.provider;
import org.springframework.context.support.ClassPathXmlApplicationContext;
/**
* Created by tianchi on 2018/3/14.
*/
public class Provider {
public static void main(String[] args) throws Exception {
//Prevent to get IPV6 address,this way only work in debug mode
//But you can pass use -Djava.net.preferIPv4Stack=true,then it work well whether in debug mode or not
System.setProperty("java.net.preferIPv4Stack", "true");
ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(new String[]{"META-INF/spring/dubbo-hello-provider.xml"});
context.start();
System.in.read(); // press any key to exit
}
}Consumer实现
其pom文件和Provider类似：
<?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>dubbo-hello</artifactId>
<groupId>com.tc</groupId>
<version>1.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>dubbo-hello-consumer</artifactId>
<packaging>jar</packaging>
<name>${project.artifactId}</name>
<description>The demo consumer module of dubbo project</description>
<dependencies>
<dependency>
<groupId>com.tc</groupId>
<artifactId>dubbo-hello-api</artifactId>
<version>${project.parent.version}</version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>dubbo</artifactId>
<version>2.6.0</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<version>2.3</version>
<configuration>
<appendAssemblyId>false</appendAssemblyId>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
<archive>
<manifest>
<mainClass>com.tc.dubbo.hello.consumer.Consumer</mainClass>
</manifest>
</archive>
</configuration>
<executions>
<execution>
<id>make-assembly</id>
<phase>package</phase>
<goals>
<goal>assembly</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>其dubbo-hello-consumer.xml配置如下，声明了对服务的引用。
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:dubbo="http://code.alibabatech.com/schema/dubbo"
xmlns="http://www.springframework.org/schema/beans"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd
http://code.alibabatech.com/schema/dubbo http://code.alibabatech.com/schema/dubbo/dubbo.xsd">
<!-- consumer's application name, used for tracing dependency relationship (not a matching criterion),
don't set it same as provider -->
<dubbo:application name="hello-consumer"/>
<!-- use multicast registry center to discover service -->
<dubbo:registry address="multicast://224.5.6.7:1234"/>
<!-- generate proxy for the remote service, then demoService can be used in the same way as the
local regular interface -->
<dubbo:reference id="helloService" check="false" interface="com.tc.dubbo.hello.HelloService"/>
</beans>入口类Consumer实现如下：
package com.tc.dubbo.hello.consumer;
import com.tc.dubbo.hello.HelloService;
import org.springframework.context.support.ClassPathXmlApplicationContext;
/**
* Created by tianchi on 2018/3/14.
*/
public class Consumer {
public static void main(String[] args) {
//Prevent to get IPV6 address,this way only work in debug mode
//But you can pass use -Djava.net.preferIPv4Stack=true,then it work well whether in debug mode or not
System.setProperty("java.net.preferIPv4Stack", "true");
ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(new String[]{"META-INF/spring/dubbo-hello-consumer.xml"});
context.start();
HelloService helloService = (HelloService) context.getBean("helloService"); // get remote service proxy
while (true) {
try {
Thread.sleep(1000);
String hello = helloService.sayHello("world"); // call remote method
System.out.println(hello); // get result
} catch (Throwable throwable) {
throwable.printStackTrace();
}
}
}
}
java
**粗体** _斜体_ [链接](http://example.com) `代码` - 列表 > 引用。你还可以使用@来通知其他用户。