本篇是Dubbo的使用篇，為后續(xù)的源碼分析打基礎(chǔ)。

1. 最簡單的使用

開篇用一個最簡單的例子，來介紹如何用Dubbo搭建一個簡單的例子。

本例包括:

注冊中心(用Zookeeper代替)
服務(wù)提供者(provider)
服務(wù)消費者(consumer)
接口(interface)

1.1 項目結(jié)構(gòu)

創(chuàng)建項目，并創(chuàng)建三個Module，項目結(jié)構(gòu)如下:

項目結(jié)構(gòu)

1.2 項目依賴

整體pom.xml為:

<?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>org.example</groupId>
    <artifactId>Study</artifactId>
    <packaging>pom</packaging>
    <version>1.0-SNAPSHOT</version>
    <modules>
        <module>consumer</module>
        <module>provider</module>
        <module>interface</module>
    </modules>

    <properties>
        <spring-boot.version>2.3.1.RELEASE</spring-boot.version>
        <dubbo.version>2.7.5</dubbo.version>
    </properties>

    <dependencyManagement>
        <dependencies>
            <!-- Spring Boot -->
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>${spring-boot.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>

            <!-- Apache Dubbo  -->
            <dependency>
                <groupId>org.apache.dubbo</groupId>
                <artifactId>dubbo-dependencies-bom</artifactId>
                <version>${dubbo.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>

            <dependency>
                <groupId>org.apache.dubbo</groupId>
                <artifactId>dubbo</artifactId>
                <version>${dubbo.version}</version>
                <exclusions>
                    <exclusion>
                        <groupId>org.springframework</groupId>
                        <artifactId>spring</artifactId>
                    </exclusion>
                    <exclusion>
                        <groupId>javax.servlet</groupId>
                        <artifactId>servlet-api</artifactId>
                    </exclusion>
                    <exclusion>
                        <groupId>log4j</groupId>
                        <artifactId>log4j</artifactId>
                    </exclusion>
                </exclusions>
            </dependency>
        </dependencies>
    </dependencyManagement>

</project>

consumer的依賴為:

<?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>Study</artifactId>
        <groupId>org.example</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>consumer</artifactId>
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>8</source>
                    <target>8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>

    <dependencies>

        <dependency>
            <groupId>org.example</groupId>
            <artifactId>interface</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>

        <!-- Dubbo Spring Boot Starter -->
        <dependency>
            <groupId>org.apache.dubbo</groupId>
            <artifactId>dubbo-spring-boot-starter</artifactId>
            <version>2.7.5</version>
        </dependency>

        <dependency>
            <groupId>org.apache.dubbo</groupId>
            <artifactId>dubbo</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <!-- Zookeeper dependencies -->
        <dependency>
            <groupId>org.apache.dubbo</groupId>
            <artifactId>dubbo-dependencies-zookeeper</artifactId>
            <version>${dubbo.version}</version>
            <type>pom</type>
            <exclusions>
                <exclusion>
                    <groupId>org.slf4j</groupId>
                    <artifactId>slf4j-log4j12</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

        <dependency>
            <groupId>org.apache.dubbo</groupId>
            <artifactId>dubbo-rpc-http</artifactId>
            <version>${dubbo.version}</version>
        </dependency>

    </dependencies>


</project>

interface的依賴為:

<?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>Study</artifactId>
        <groupId>org.example</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>interface</artifactId>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>8</source>
                    <target>8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

provider的依賴為:

<?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>Study</artifactId>
        <groupId>org.example</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>provider</artifactId>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>8</source>
                    <target>8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>

    <dependencies>
        <dependency>
            <groupId>org.example</groupId>
            <artifactId>interface</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>

        <!-- Dubbo Spring Boot Starter -->
        <dependency>
            <groupId>org.apache.dubbo</groupId>
            <artifactId>dubbo-spring-boot-starter</artifactId>
            <version>2.7.5</version>
        </dependency>

        <dependency>
            <groupId>org.jboss.resteasy</groupId>
            <artifactId>resteasy-jaxrs</artifactId>
            <version>3.0.19.Final</version>
        </dependency>

        <dependency>
            <groupId>javax.validation</groupId>
            <artifactId>validation-api</artifactId>
            <version>1.1.0.Final</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.apache.dubbo</groupId>
            <artifactId>dubbo</artifactId>
        </dependency>

        <!-- Zookeeper dependencies -->
        <dependency>
            <groupId>org.apache.dubbo</groupId>
            <artifactId>dubbo-dependencies-zookeeper</artifactId>
            <version>${dubbo.version}</version>
            <type>pom</type>
            <exclusions>
                <exclusion>
                    <groupId>org.slf4j</groupId>
                    <artifactId>slf4j-log4j12</artifactId>
                </exclusion>
            </exclusions>
        </dependency>


        <dependency>
            <groupId>org.apache.dubbo</groupId>
            <artifactId>dubbo-rpc-http</artifactId>
            <version>${dubbo.version}</version>
        </dependency>

        <dependency>
            <groupId>org.apache.dubbo</groupId>
            <artifactId>dubbo-metadata-report-zookeeper</artifactId>
            <version>${dubbo.version}</version>
        </dependency>
    </dependencies>

</project>

1.3 具體代碼

1.3.1 服務(wù)提供者

@Service注解暴露服務(wù)

實現(xiàn)類

package com.zyz.provider.service;

import com.zyz.DemoService;
import org.apache.dubbo.common.URL;
import org.apache.dubbo.config.annotation.Service;
import org.apache.dubbo.rpc.RpcContext;

@Service(version = "default")
public class DefaultDemoService implements DemoService {

    @Override
    public String sayHello(String name) {
        System.out.println("執(zhí)行了服務(wù)" + name);

        URL url = RpcContext.getContext().getUrl();
        return String.format("%s：%s, Hello, %s", url.getProtocol(), url.getPort(), name);  // 正常訪問
    }
}

啟動類

package com.zyz;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class DubboProviderDemo {

    public static void main(String[] args) {
        SpringApplication.run(DubboProviderDemo.class,args);
    }

}

配置文件application.properties:

# Spring boot application
spring.application.name=dubbo-provider-demo
server.port=8081

# Base packages to scan Dubbo Component: @org.apache.dubbo.config.annotation.Service
dubbo.scan.base-packages=com.zyz.provider.service
dubbo.application.name=${spring.application.name}


## Dubbo Registry
dubbo.registry.address=zookeeper://127.0.0.1:2181

# Dubbo Protocol
dubbo.protocol.name=dubbo
dubbo.protocol.port=20880

日志文件log4j.properties:

###set log levels###
log4j.rootLogger=info, stdout
###output to the console###
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.out
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=[%d{dd/MM/yy HH:mm:ss:SSS z}] %t %5p %c{2}: %m%n

1.3.2 接口

接口類DemoService:

package com.zyz;

public interface DemoService {

    String sayHello(String name);

}

1.3.3 服務(wù)消費者

@Reference引入服務(wù)，加入版本表示具體引入哪一個實現(xiàn)類的實例

啟動類:

package com.zyz;

import org.apache.dubbo.config.annotation.Reference;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ConfigurableApplicationContext;

@SpringBootApplication
public class DubboConsumerDemo {

    @Reference(version = "default")
    private DemoService demoService;

    public static void main(String[] args) {
        ConfigurableApplicationContext context = SpringApplication.run(DubboConsumerDemo.class);

        DemoService demoService = context.getBean(DemoService.class);
        System.out.println((demoService.sayHello("zyz")));
    }

}

配置文件application.yml:

spring:
  application:
    name: dubbo-consumer-demo

server:
  port: 8082

dubbo:
  registry:
    address: zookeeper://127.0.0.1:2181

Zookeeper的配置參考

先啟動Zookeeper，再啟動provider的啟動類，最后啟動consumer的啟動類

看到輸出:

dubbo：20880, Hello, zyz

大功告成。

2. 具體應(yīng)用

2.1 負載均衡

Dubbo提供了四種負載均衡策略，也可以自定義。

Random LoadBalance:隨機，按權(quán)重設(shè)置隨機概率。
RoundRobin LoadBalance:輪詢，按公約后的權(quán)重設(shè)置輪詢比率。
LeastActive LoadBalance:最少活躍調(diào)用數(shù)，相同活躍數(shù)的隨機，活躍數(shù)指調(diào)用前后計數(shù)差。
ConsistentHash LoadBalance:一致性 Hash，相同參數(shù)的請求總是發(fā)到同一提供者。

2.2 具體代碼

修改provider的配置文件為:

# Spring boot application
spring.application.name=dubbo-provider-demo
server.port=8081

# Base packages to scan Dubbo Component: @org.apache.dubbo.config.annotation.Service
dubbo.scan.base-packages=com.zyz.provider.service
dubbo.application.name=${spring.application.name}


## Dubbo Registry
dubbo.registry.address=zookeeper://127.0.0.1:2181

# Dubbo Protocol
#dubbo.protocol.name=dubbo
#dubbo.protocol.port=20880

dubbo.protocols.p1.id=dubbo1
dubbo.protocols.p1.name=dubbo
dubbo.protocols.p1.port=20881
dubbo.protocols.p1.host=0.0.0.0

dubbo.protocols.p2.id=dubbo2
dubbo.protocols.p2.name=dubbo
dubbo.protocols.p2.port=20882
dubbo.protocols.p2.host=0.0.0.0

dubbo.protocols.p3.id=dubbo3
dubbo.protocols.p3.name=dubbo
dubbo.protocols.p3.port=20883
dubbo.protocols.p3.host=0.0.0.0

服務(wù)消費端新增類:

package com.zyz.consumer;

import com.zyz.DemoService;
import org.apache.dubbo.config.annotation.Reference;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.context.ConfigurableApplicationContext;

@EnableAutoConfiguration
public class LoadBalanceDubboConsumerDemo {

    @Reference(version = "default", loadbalance = "roundrobin")
    private DemoService demoService;

    public static void main(String[] args) {
        ConfigurableApplicationContext context = SpringApplication.run(LoadBalanceDubboConsumerDemo.class);

        DemoService demoService = context.getBean(DemoService.class);

        roundRobin(demoService);

    }

    /**
     * 負載均衡(輪詢)
     * @param demoService
     */
    public static void roundRobin(DemoService demoService){

        for (int i = 0; i < 1000; i++) {
            System.out.println((demoService.sayHello("zyz")));
            try {
                Thread.sleep(1 * 1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

}

最終輸出為:

dubbo：20882, Hello, zyz
dubbo：20883, Hello, zyz
dubbo：20881, Hello, zyz
dubbo：20882, Hello, zyz
dubbo：20883, Hello, zyz
dubbo：20881, Hello, zyz

2.2 服務(wù)超時

2.2.1 說明

在服務(wù)提供者和服務(wù)消費者上都可以配置服務(wù)超時時間，這兩者是不?樣的。

消費者調(diào)??個服務(wù)，分為三步:

消費者發(fā)送請求（?絡(luò)傳輸）
服務(wù)端執(zhí)?服務(wù)
服務(wù)端返回響應(yīng)（?絡(luò)傳輸）

如果在服務(wù)端和消費端只在其中??配置了timeout，那么沒有歧義，表示消費端調(diào)?服務(wù)的超時時間，消費端如果超過時間還沒有收到響應(yīng)結(jié)果，則消費端會拋超時異常，但，服務(wù)端不會拋異常，服務(wù)端在執(zhí)? 服務(wù)后，會檢查執(zhí)?該服務(wù)的時間，如果超過timeout，則會打印?個超時?志。服務(wù)會正常的執(zhí)?完。

如果在服務(wù)端和消費端各配了?個timeout，那就?較復(fù)雜了，假設(shè)

服務(wù)執(zhí)?為5s
消費端timeout=3s
服務(wù)端timeout=6s

那么消費端調(diào)?服務(wù)時，消費端會收到超時異常（因為消費端超時了），服務(wù)端?切正常（服務(wù)端沒有超時）。

2.2.2 具體代碼

服務(wù)提供方新增兩個類:

package com.zyz.provider.service;


import com.zyz.DemoService;
import org.apache.dubbo.common.URL;
import org.apache.dubbo.config.annotation.Service;
import org.apache.dubbo.rpc.RpcContext;

import java.util.concurrent.TimeUnit;


@Service(version = "timeout", timeout = 6000)
public class TimeoutDemoService implements DemoService {

    @Override
    public String sayHello(String name) {
        System.out.println("執(zhí)行了timeout服務(wù)" + name);

        // 服務(wù)執(zhí)行5秒
        // 服務(wù)超時時間為3秒，但是執(zhí)行了5秒，服務(wù)端會把任務(wù)執(zhí)行完的
        // 服務(wù)的超時時間，是指如果服務(wù)執(zhí)行時間超過了指定的超時時間則會拋一個warn
        try {
            TimeUnit.SECONDS.sleep(5);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        System.out.println("執(zhí)行結(jié)束" + name);

        URL url = RpcContext.getContext().getUrl();
        return String.format("%s：%s, Hello, %s", url.getProtocol(), url.getPort(), name);  // 正常訪問
    }

}

package com.zyz;

import org.apache.dubbo.config.spring.ServiceBean;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.stereotype.Component;

@Component
public class UpdateBeanPostProcessors implements BeanPostProcessor {

    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {

        if (beanName.contains("ServiceBean")) {
            //這里設(shè)置id，否則會造成同一個Service有多個group時，只能注入第一個service
            ServiceBean serviceBean = (ServiceBean) bean;
            serviceBean.setId(beanName);
        }
        return bean;
    }

    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        return bean;
    }
}

消費方新增一個啟動類:

package com.zyz.consumer;

import com.zyz.DemoService;
import org.apache.dubbo.config.annotation.Reference;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.context.ConfigurableApplicationContext;

import java.io.IOException;

@EnableAutoConfiguration
public class TimeoutDubboConsumerDemo {


    @Reference(version = "timeout", timeout = 3000)
    private DemoService demoService;

    public static void main(String[] args) throws IOException {
        ConfigurableApplicationContext context = SpringApplication.run(TimeoutDubboConsumerDemo.class);

        DemoService demoService = context.getBean(DemoService.class);

        // 服務(wù)調(diào)用超時時間為1秒，默認為3秒
        // 如果這1秒內(nèi)沒有收到服務(wù)結(jié)果，則會報錯
        System.out.println((demoService.sayHello("周瑜"))); //xxservestub


    }

}

2.3 集群容錯

集群容錯表示：服務(wù)消費者在調(diào)?某個服務(wù)時，這個服務(wù)有多個服務(wù)提供者，在經(jīng)過負載均衡后選出其中 ?個服務(wù)提供者之后進?調(diào)?，但調(diào)?報錯后，Dubbo所采取的后續(xù)處理策略。

2.3.1 設(shè)置

Failover Cluster:默認配置，重試兩次，一共請求三次
Failfast Cluster:快速失敗，只發(fā)起一次調(diào)用，失敗立即報錯。通常用于非冪等性的寫操作，比如新增記錄
Failsafe Cluster:失敗安全，出現(xiàn)異常時，直接忽略。通常用于寫入審計日志等操作
Failback Cluster:失敗自動恢復(fù)，后臺記錄失敗請求，定時重發(fā)。通常用于消息通知操作
Forking Cluster:并行調(diào)用多個服務(wù)器，只要一個成功即返回。通常用于實時性要求較高的讀操作，但需要浪費更多服務(wù)資源?？赏ㄟ^ forks="2" 來設(shè)置最大并行數(shù)。
Broadcast Cluster:廣播調(diào)用所有提供者，逐個調(diào)用，任意一臺報錯則報錯。通常用于通知所有提供者更新緩存或日志等本地資源信息。

2.3.2 具體代碼

cousumer新增一個類:

package com.zyz.consumer;

import com.zyz.DemoService;
import org.apache.dubbo.config.annotation.Reference;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.context.ConfigurableApplicationContext;

import java.io.IOException;

@EnableAutoConfiguration
public class ClusterDubboConsumerDemo {


    @Reference(version = "cluster", timeout = 1000, cluster = "failfast")
    private DemoService demoService;

    public static void main(String[] args) throws IOException {
        ConfigurableApplicationContext context = SpringApplication.run(ClusterDubboConsumerDemo.class);

        DemoService demoService = context.getBean(DemoService.class);

        System.out.println((demoService.sayHello("zyz")));

    }

}

provider新增一個實現(xiàn)類:

package com.zyz.provider.service;

import com.zyz.DemoService;
import org.apache.dubbo.common.URL;
import org.apache.dubbo.config.annotation.Service;
import org.apache.dubbo.rpc.RpcContext;

import java.util.concurrent.TimeUnit;

@Service(version = "cluster", timeout = 3000)
public class ClusterDemoService implements DemoService {

    @Override
    public String sayHello(String name) {
        System.out.println("執(zhí)行了cluster服務(wù)" + name);

        try {
            TimeUnit.SECONDS.sleep(5);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        System.out.println("執(zhí)行結(jié)束" + name);
        URL url = RpcContext.getContext().getUrl();
        return String.format("%s：%s, Hello, %s", url.getProtocol(), url.getPort(), name);  // 正常訪問
    }
}

2.4 服務(wù)降級

服務(wù)降級表示：服務(wù)消費者在調(diào)?某個服務(wù)提供者時，如果該服務(wù)提供者報錯了，所采取的措施。

集群容錯和服務(wù)降級的區(qū)別在于：

集群容錯是整個集群范圍內(nèi)的容錯
服務(wù)降級是單個服務(wù)提供者的?身容錯

2.4.1 具體代碼

consumer新增一個類:

package com.zyz.consumer;

import com.zyz.DemoService;
import org.apache.dubbo.config.annotation.Reference;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.context.ConfigurableApplicationContext;

import java.io.IOException;

@EnableAutoConfiguration
public class MockDubboConsumerDemo {


    @Reference(version = "timeout", timeout = 1000, mock = "fail: return 123")
    private DemoService demoService;

    public static void main(String[] args) throws IOException {
        ConfigurableApplicationContext context = SpringApplication.run(MockDubboConsumerDemo.class);

        DemoService demoService = context.getBean(DemoService.class);

        System.out.println((demoService.sayHello("zyz")));
    }

}

2.5 本地存根

本地存根就是?段邏輯，這段邏輯是在服務(wù)消費端執(zhí)?的，這段邏輯?般都是由服務(wù)提供者提供，服務(wù)提供者可以利?這種機制在服務(wù)消費者遠程調(diào)?服務(wù)提供者之前或之后再做?些其他事情，?如結(jié)果緩存，請求參數(shù)驗證等等。(AOP功能)

2.5.1 具體代碼

interface新增一個類:

package com.zyz;

public class DemoServiceStub implements DemoService {

    private final DemoService demoService;

    // 構(gòu)造函數(shù)傳入真正的遠程代理對象
    public DemoServiceStub(DemoService demoService){
        this.demoService = demoService;
    }

    @Override
    public String sayHello(String name) {
        // 此代碼在客戶端執(zhí)行, 你可以在客戶端做ThreadLocal本地緩存，或預(yù)先驗證參數(shù)是否合法，等等
        try {
            System.out.println("校驗邏輯");
            return demoService.sayHello(name); // safe  null
        } catch (Exception e) {
            // 你可以容錯，可以做任何AOP攔截事項
            return "容錯數(shù)據(jù)";
        }
    }
}

consumer新增一個類:

package com.zyz.consumer;

import com.zyz.DemoService;
import org.apache.dubbo.config.annotation.Reference;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.context.ConfigurableApplicationContext;

import java.io.IOException;

@EnableAutoConfiguration
public class StubDubboConsumerDemo {


    @Reference(version = "timeout", timeout = 1000, stub = "com.zyz.DemoServiceStub")
    private DemoService demoService;

    public static void main(String[] args) throws IOException {
        ConfigurableApplicationContext context = SpringApplication.run(StubDubboConsumerDemo.class);

        DemoService demoService = context.getBean(DemoService.class);

        System.out.println((demoService.sayHello("周瑜")));


    }

}

2.6 本地偽裝

就是Mock功能，Mock其實就是Dubbo中的服務(wù)容錯的解決?案。

2.7 參數(shù)回調(diào)

?先，如果當前服務(wù)?持參數(shù)回調(diào)，意思就是：對于某個服務(wù)接?中的某個?法，如果想?持消費者在調(diào) ?這個?法時能設(shè)置回調(diào)邏輯，那么該?法就需要提供?個?參?來表示回調(diào)邏輯。

因為Dubbo協(xié)議是基于?連接的，所以消費端在兩次調(diào)?同?個?法時想指定不同的回調(diào)邏輯，那么就需要在調(diào)?時在指定?定key進?區(qū)分。

2.7.1 參數(shù)回調(diào)

consumer新增兩個類

package com.zyz.consumer;


import com.zyz.DemoServiceListener;

public class DemoServiceListenerImpl implements DemoServiceListener {

    @Override
    public void changed(String msg) {
        System.out.println("被回調(diào)了："+msg);
    }
}

package com.zyz.consumer;

import com.zyz.DemoService;
import org.apache.dubbo.config.annotation.Reference;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.context.ConfigurableApplicationContext;

import java.io.IOException;

@EnableAutoConfiguration
public class CallbackDubboConsumerDemo {


    @Reference(version = "callback")
    private DemoService demoService;

    public static void main(String[] args) throws IOException {
        ConfigurableApplicationContext context = SpringApplication.run(CallbackDubboConsumerDemo.class);

        DemoService demoService = context.getBean(DemoService.class);

        // 用來進行callback
        System.out.println(demoService.sayHello("zyz", "d1", new DemoServiceListenerImpl()));
        System.out.println(demoService.sayHello("zyz", "d2", new DemoServiceListenerImpl()));
        System.out.println(demoService.sayHello("zyz", "d3", new DemoServiceListenerImpl()));
    }

}

interface新增一個類，并在DemoService中新增方法:

package com.zyz;

public interface DemoService {

    String sayHello(String name);

    // 添加回調(diào)
    default String sayHello(String name, String key, DemoServiceListener listener) {
        return null;
    };

}

package com.zyz;

public interface DemoServiceListener {
    void changed(String msg);
}

provider新增類:

package com.zyz.provider.service;

import com.zyz.DemoService;
import com.zyz.DemoServiceListener;
import org.apache.dubbo.common.URL;
import org.apache.dubbo.config.annotation.Argument;
import org.apache.dubbo.config.annotation.Method;
import org.apache.dubbo.config.annotation.Service;
import org.apache.dubbo.rpc.RpcContext;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;


// DemoService的sayHello方法的index=1的參數(shù)是回調(diào)對象，服務(wù)消費者可以調(diào)用addListener方法來添加回調(diào)對象，服務(wù)提供者一旦執(zhí)行回調(diào)對象的方法就會通知給服務(wù)消費者

@Service(version = "callback", methods = {@Method(name = "sayHello", arguments = {@Argument(index = 2, callback = true)})}, callbacks = 3)
public class CallBackDemoService implements DemoService {

    private final Map<String, DemoServiceListener> listeners = new ConcurrentHashMap<String, DemoServiceListener>();

    public CallBackDemoService() {
        Thread t = new Thread(new Runnable() {
            @Override
            public void run() {
                while (true) {
                    for (Map.Entry<String, DemoServiceListener> entry : listeners.entrySet()) {
                        entry.getValue().changed(getChanged(entry.getKey()));
                    }
                    try {
                        Thread.sleep(5000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        });

        t.start();

    }


    private String getChanged(String key) {
        return "Changed: " + new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date());
    }

    @Override
    public String sayHello(String name) {
        return null;
    }

    @Override
    public String sayHello(String name, String key, DemoServiceListener callback) {
        System.out.println("執(zhí)行了回調(diào)服務(wù)" + name);

        listeners.put(key, callback);
        URL url = RpcContext.getContext().getUrl();
        return String.format("%s：%s, Hello, %s", url.getProtocol(), url.getPort(), name);  // 正常訪問
    }

}

2.8 異步調(diào)用

從 2.7.0 開始，Dubbo 的所有異步編程接口開始以 CompletableFuture 為基礎(chǔ)

基于 NIO 的非阻塞實現(xiàn)并行調(diào)用，客戶端不需要啟動多線程即可完成并行調(diào)用多個遠程服務(wù)，相對多線程開銷較小。

2.8.1 具體代碼

consumer新增類:

package com.zyz.consumer;

import com.zyz.DemoService;
import org.apache.dubbo.config.annotation.Reference;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.context.ConfigurableApplicationContext;

import java.io.IOException;
import java.util.concurrent.CompletableFuture;

@EnableAutoConfiguration
public class AsyncDubboConsumerDemo {

    @Reference(version = "async")
    private DemoService demoService;

    public static void main(String[] args) throws IOException {
        ConfigurableApplicationContext context = SpringApplication.run(AsyncDubboConsumerDemo.class);

        DemoService demoService = context.getBean(DemoService.class);

        // 調(diào)用直接返回CompletableFuture
        CompletableFuture<String> future = demoService.sayHelloAsync("異步調(diào)用");  // 5

        future.whenComplete((v, t) -> {
            if (t != null) {
                t.printStackTrace();
            } else {
                System.out.println("Response: " + v);
            }
        });

        System.out.println("結(jié)束了");

    }

}

interface中DemoService新增方法:

package com.zyz;

import java.util.concurrent.CompletableFuture;

public interface DemoService {

    String sayHello(String name);

    // 異步調(diào)用方法
    default CompletableFuture<String> sayHelloAsync(String name) {
        return null;
    };

    // 添加回調(diào)
    default String sayHello(String name, String key, DemoServiceListener listener) {
        return null;
    };

}

consumer新增一個類:

package com.zyz.provider.service;

import com.zyz.DemoService;
import org.apache.dubbo.common.URL;
import org.apache.dubbo.config.annotation.Service;
import org.apache.dubbo.rpc.RpcContext;

import java.util.concurrent.CompletableFuture;

@Service(version = "async")
public class AsyncDemoService implements DemoService {

    @Override
    public String sayHello(String name) {
        System.out.println("執(zhí)行了同步服務(wù)" + name);
        URL url = RpcContext.getContext().getUrl();
        return String.format("%s：%s, Hello, %s", url.getProtocol(), url.getPort(), name);  // 正常訪問
    }

    @Override
    public CompletableFuture<String> sayHelloAsync(String name) {
        System.out.println("執(zhí)行了異步服務(wù)" + name);

        return CompletableFuture.supplyAsync(() -> {
            return sayHello(name);
        });
    }
}

2.9 泛化調(diào)用

泛化調(diào)?可以?來做服務(wù)測試。

在Dubbo中，如果某個服務(wù)想要?持泛化調(diào)?，就可以將該服務(wù)的generic屬性設(shè)置為true，那對于服務(wù)消費者來說，就可以不?依賴該服務(wù)的接?，直接利?GenericService接?來進?服務(wù)調(diào)?。

2.9.1 具體代碼

consumer新增一個類:

package com.zyz.consumer;

import org.apache.dubbo.config.annotation.Reference;
import org.apache.dubbo.rpc.service.GenericService;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.context.ConfigurableApplicationContext;

import java.io.IOException;

@EnableAutoConfiguration
public class GenericDubboConsumerDemo {


    @Reference(id = "demoService", version = "default", interfaceName = "com.zyz.DemoService", generic = true)
    private GenericService genericService;

    public static void main(String[] args) throws IOException {
        ConfigurableApplicationContext context = SpringApplication.run(GenericDubboConsumerDemo.class);

        GenericService genericService = (GenericService) context.getBean("demoService");

        Object result = genericService.$invoke("sayHello", new String[]{"java.lang.String"}, new Object[]{"zyz"});
        System.out.println(result);


    }

}

provider新增一個類:

package com.zyz.provider.service;

import org.apache.dubbo.config.annotation.Service;
import org.apache.dubbo.rpc.service.GenericException;
import org.apache.dubbo.rpc.service.GenericService;

@Service(interfaceName = "com.zyz.DemoService", version = "generic")
public class GenericDemoService implements GenericService {
    @Override
    public Object $invoke(String s, String[] strings, Object[] objects) throws GenericException {
        System.out.println("執(zhí)行了generic服務(wù)");

        return "執(zhí)行的方法是" + s;
    }
}

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Dubbo的基本使用與高級應(yīng)用

Dubbo的基本使用與高級應(yīng)用

1. 最簡單的使用

1.1 項目結(jié)構(gòu)

1.2 項目依賴

1.3 具體代碼

1.3.1 服務(wù)提供者

1.3.2 接口

1.3.3 服務(wù)消費者

2. 具體應(yīng)用

2.1 負載均衡

2.2 具體代碼

2.2 服務(wù)超時

2.2.1 說明

2.2.2 具體代碼

2.3 集群容錯

2.3.1 設(shè)置

2.3.2 具體代碼

2.4 服務(wù)降級

2.4.1 具體代碼

2.5 本地存根

2.5.1 具體代碼

2.6 本地偽裝

2.7 參數(shù)回調(diào)

2.7.1 參數(shù)回調(diào)

2.8 異步調(diào)用

2.8.1 具體代碼

2.9 泛化調(diào)用

2.9.1 具體代碼

3. 相關(guān)工具

相關(guān)閱讀更多精彩內(nèi)容

友情鏈接更多精彩內(nèi)容

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Dubbo的基本使用與高級應(yīng)用

1. 最簡單的使用

1.1 項目結(jié)構(gòu)

1.2 項目依賴

1.3 具體代碼

1.3.1 服務(wù)提供者

1.3.2 接口

1.3.3 服務(wù)消費者

2. 具體應(yīng)用

2.1 負載均衡

2.2 具體代碼

2.2 服務(wù)超時

2.2.1 說明

2.2.2 具體代碼

2.3 集群容錯

2.3.1 設(shè)置

2.3.2 具體代碼

2.4 服務(wù)降級

2.4.1 具體代碼

2.5 本地存根

2.5.1 具體代碼

2.6 本地偽裝

2.7 參數(shù)回調(diào)

2.7.1 參數(shù)回調(diào)

2.8 異步調(diào)用

2.8.1 具體代碼

2.9 泛化調(diào)用

2.9.1 具體代碼

3. 相關(guān)工具

相關(guān)閱讀更多精彩內(nèi)容

友情鏈接更多精彩內(nèi)容

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