微服务架构探索

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微服务介绍

        微服务是一种系统设计模式，是一种架构。传统的项目，一个Project集成了大量的功能和模块，非常臃肿。并且当我们修改了某一个模块，就不得不重启整个项目来让模块生效，白白浪费了其他模块的时间，对系统的效率极不友好。

        微服务通过一组中间件，将这个大的项目按照功能拆分成各个小项目，每个小项目有独立的进程、独立的数据库管理、独立的容器管理。

        核心角色有注册中心、服务提供者和服务消费者。

样例工程

        下面使用eclipse+idea+springcloud+maven来构建微服务样例工程。

         https://github.com/ppr1011/MicroServiceSample

注册中心

        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">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.maven_cloud</groupId>
    <artifactId>exercise</artifactId>
    <version>1.0-SNAPSHOT</version>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.3.7.RELEASE</version>
    </parent>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka-server</artifactId>
        </dependency>
    </dependencies>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Brixton.SR5</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

</project>

        同时创建多个注册中心实例，可以提高并发能力。我们需要多套配置文件application.properties

        现在有peer1和peer2的注册中心实例。

        application-peer1.properties

server.port=1111
spring.application.name=eureka-server
eureka.instance.hostname=peer1
eureka.client.serviceUrl.defaultZone=http://localhost:1112/eureka/
eureka.client.register-with-eureka=true
eureka.client.fetch-registry=true

        application-peer2.properties

server.port=1112
spring.application.name=eureka-server
eureka.instance.hostname=peer2
eureka.client.serviceUrl.defaultZone=http://localhost:1111/eureka/
eureka.client.register-with-eureka=true
eureka.client.fetch-registry=true

        主类：Application.java

package com.exercise;

import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;

@EnableEurekaServer
@SpringBootApplication
public class Application {
    public static void main(String[] args){
        new SpringApplicationBuilder(Application.class).web(true).run(args);
    }
}

运行时需要指定配置文件，使用参数 --spring.profiles.active=peer2（或者peer1）

服务提供者

        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>4.0.0</modelVersion>

  <groupId>com.exercise</groupId>
  <artifactId>providers</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>jar</packaging>

  <name>providers</name>
  <url>http://maven.apache.org</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
    
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
      <version>1.4.0.RELEASE</version>
    </dependency>

    <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-eureka</artifactId>
    </dependency>
  </dependencies>
 
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Brixton.SR5</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
</project>

        application.properties

server.port=8081
spring.application.name=hello-service
eureka.client.serviceUrl.defaultZone=http://localhost:1111/eureka,http://localhost:1112/eureka

        主类App.java

package com.exercise.providers;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

@EnableDiscoveryClient
@SpringBootApplication
public class App 
{
    public static void main( String[] args )
    {
        SpringApplication.run(App.class, args);
    }
}

        api：HelloController.java

package com.exercise.providers.api;


import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.client.discovery.DiscoveryClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
import org.slf4j.LoggerFactory;
import org.slf4j.Logger;

@RestController
public class HelloController {

    private final Logger logger = LoggerFactory.getLogger(HelloController.class);

    @Autowired
    private DiscoveryClient client;

    @RequestMapping(value="/hello",method = RequestMethod.GET)
    public String index() {
        logger.info("test done");
        return "Hello World";
    }

}

可以使用多端口，将多个同一服务的实例注册到注册中心集群当中。运行参数：--server.port=8081(或其他端口号)
 

服务消费者

        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>4.0.0</modelVersion>

  <groupId>com.exercise</groupId>
  <artifactId>consumers</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>jar</packaging>

  <name>consumers</name>
  <url>http://maven.apache.org</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
    
	<!-- https://mvnrepository.com/artifact/org.slf4j/slf4j-api -->
	<dependency>
   		<groupId>org.slf4j</groupId>
    	<artifactId>slf4j-api</artifactId>
    	<version>1.7.12</version>
	</dependency>
    
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-ribbon</artifactId>
    </dependency>
    
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
      <version>1.3.7.RELEASE</version>
    </dependency>

    <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-eureka</artifactId>
    </dependency>
  </dependencies>
 
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Brixton.SR5</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
</project>

        application.properties

spring.application.name=ribbon-consumer
server.port=9000
eureka.client.serviceUrl.defaultZone=http://localhost:1111/eureka,http://localhost:1112/eureka

        主类App.java

        

package com.exercise.consumers;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@EnableDiscoveryClient
@SpringBootApplication
public class App 
{
	@Bean
	@LoadBalanced
	RestTemplate restTemplate() {
		return new RestTemplate();
	}
	
    public static void main(String[] args )
    {
        SpringApplication.run(App.class, args);
    }
}

        api：ConsumerController.java

package com.exercise.consumers.api;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

@RestController
public class ConsumerController {

	@Autowired
	RestTemplate restTemplate;

	@RequestMapping(value="/ribbon-consumer",method=RequestMethod.GET)
	public String helloController() {
		return restTemplate.getForEntity("http://hello-service/hello", String.class).getBody();
	}
}

三个项目都跑起来后，打开注册中心管理页面，大概就是下图。