什么是微服务？什么是SpringCloud？
微服务是一种架构的模式，它提倡将一个应用程序划分成很多个微小的服务，服务与服务之间相互协调、相互配合。每个服务运行都是一个独立的进程，服务与服务之间采用轻量级的通讯机制相互沟通。简单的来说就是将一个庞大的复杂的单体应用进行划分成n多个微小的服务（一个服务负责一个业务），各个微服务都被独立的部署。
微服务与集群的区别是，微服务的每一个部署的服务都是不相同的，而集群部署的每一个服务都是相同的。
Spring Cloud是一个微服务框架，相比Dubbo等RPC框架,Spring Cloud提供的全套的分布式系统解决方案。它是在SpringBoot的基础上构建的。SpringCloud的五大神兽分别是Eureka、Ribbon、Feign、Hystrix、Zuul。
环境搭建
版本说明
springboot：2.0.3
springcloud：Finchley
创建一个父工程（maven项目）
选择maven，点击next
然后点击完成
修改父工程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.lzh</groupId> <artifactId>my-springcloud-01</artifactId> <packaging>pom</packaging> <version>1.0-SNAPSHOT</version> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <maven.compiler.source>1.8</maven.compiler.source> <maven.compiler.target>1.8</maven.compiler.target> <junit.version>4.12</junit.version> <log4j.version>1.2.17</log4j.version> <lombok.version>1.16.18</lombok.version> </properties> <dependencyManagement> <dependencies> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-dependencies</artifactId> <version>Finchley.RELEASE</version> <!--<version>Dalston.SR1</version>--> <type>pom</type> <scope>import</scope> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-dependencies</artifactId> <version>2.0.3.RELEASE</version> <type>pom</type> <scope>import</scope> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.0.4</version> </dependency> <dependency> <groupId>com.alibaba</groupId> <artifactId>druid</artifactId> <version>1.0.31</version> </dependency> <dependency> <groupId>org.mybatis.spring.boot</groupId> <artifactId>mybatis-spring-boot-starter</artifactId> <version>1.3.0</version> </dependency> <dependency> <groupId>ch.qos.logback</groupId> <artifactId>logback-core</artifactId> <version>1.2.3</version> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>${junit.version}</version> <scope>test</scope> </dependency> <dependency> <groupId>log4j</groupId> <artifactId>log4j</artifactId> <version>${log4j.version}</version> </dependency> </dependencies> </dependencyManagement> <build> <finalName>microservicecloud</finalName> <resources> <resource> <directory>src/main/resources</directory> <filtering>true</filtering> </resource> </resources> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-resources-plugin</artifactId> <configuration> <delimiters> <delimit>$</delimit> </delimiters> </configuration> </plugin> </plugins> </build> </project>
创建子工程（maven项目）
工程名称：microservice-consumer-80
pom.xml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>my-springcloud-01</artifactId> <groupId>com.lzh</groupId> <version>1.0-SNAPSHOT</version> </parent> <modelVersion>4.0.0</modelVersion> <artifactId>microservice-consumer-80</artifactId> <dependencies> <dependency> <groupId>com.lzh</groupId> <artifactId>microservice-api</artifactId> <version>1.0-SNAPSHOT</version> </dependency> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId> </dependency> <!-- 整合ribbon --> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-ribbon</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-actuator</artifactId> </dependency> </dependencies> </project>
编码实现
在主启动类上加上@EnableDiscoveryClient注解
创建一个配置文件ConfigBean.java，new一个RestTemplate远程调用模板，加入@LoadBalanced注解，开启负载均衡
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;
/**
* @author lzh
* create 2019-11-05-9:58
*/
@Configuration
public class ConfigBean {
@Bean
//加入负载均衡
//Spring Cloud Ribbon是基于Netflix Ribbon实现的一套客户端 负载均衡的工具
@LoadBalanced
public RestTemplate getRestTemplate(){
return new RestTemplate();
}
}
在服务层DeptServiceImpl.java类中用RestTemplate模板工具调用，这里使用服务名称调用，如果服务名称相同，则会进行顺序轮询调用
import com.lzh.cloud.model.Dept;
import com.lzh.cloud.service.DeptService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;
import java.util.List;
/**
* @author lzh
* create 2019-11-05-10:27
*/
@Service
public class DeptServiceImpl implements DeptService {
/**
* 使用restTemplate访问restful接口非常的简单粗暴无脑。
* (url, requestMap, ResponseBean.class)这三个参数分别代表
* REST请求地址、请求参数、HTTP响应转换被转换成的对象类型。
*/
@Autowired
private RestTemplate restTemplate;
//private static final String REST_URL_PREFIX = "http://localhost:8001";
private static final String REST_URL_PREFIX = "http://MICROSERVICECLOUD-DEPT";
@Override
public boolean add(Dept dept) {
return restTemplate.postForObject(REST_URL_PREFIX + "/dept/add", dept, Boolean.class);
}
@Override
public Dept get(Long id) {
return restTemplate.getForObject(REST_URL_PREFIX + "/dept/get/" + id, Dept.class);
}
@Override
public List<Dept> list() {
return restTemplate.getForObject(REST_URL_PREFIX + "/dept/list/", List.class);
}
@Override
public Object discovery() {
return restTemplate.getForObject(REST_URL_PREFIX + "/dept/discovery", Object.class);
}
}
自定义轮询规则
在主启动类的前一个包创建一个配置MySelRule类，注意不要跟主启动类同包或者在主启动类的子包中创建
import com.netflix.loadbalancer.IRule;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
/**
* @author lzh
* create 2019-05-19-17:10
*/
@Configuration
public class MySelfRule {
@Bean
public IRule myRule(){
//return new RandomRule(); //Ribbon默认是轮询，我自定义为随机
//return new RoundRobinRule(); //Ribbon默认是轮询，我自定义为随机
return new RandomRule_LZH(); // 我自定义为每台机器5次
}
}
参照源码，自定义轮询算法RandomRule_LZH.java
import com.netflix.client.config.IClientConfig;
import com.netflix.loadbalancer.AbstractLoadBalancerRule;
import com.netflix.loadbalancer.ILoadBalancer;
import com.netflix.loadbalancer.Server;
import java.util.List;
public class RandomRule_LZH extends AbstractLoadBalancerRule {
// total = 0 // 当total==5以后，我们指针才能往下走，
// index = 0 // 当前对外提供服务的服务器地址，
// total需要重新置为零，但是已经达到过一个5次，我们的index = 1
// 分析：我们5次，但是微服务只有8001 8002 8003 三台，OK？
//
private int total = 0; // 总共被调用的次数，目前要求每台被调用5次
private int currentIndex = 0; // 当前提供服务的机器号
public Server choose(ILoadBalancer lb, Object key) {
if (lb == null) {
return null;
}
Server server = null;
while (server == null) {
if (Thread.interrupted()) {
return null;
}
List<Server> upList = lb.getReachableServers();
List<Server> allList = lb.getAllServers();
int serverCount = allList.size();
if (serverCount == 0) {
/*
* No servers. End regardless of pass, because subsequent passes only get more
* restrictive.
*/
return null;
}
// int index = rand.nextInt(serverCount);// java.util.Random().nextInt(3);
// server = upList.get(index);
// private int total = 0; // 总共被调用的次数，目前要求每台被调用5次
// private int currentIndex = 0; // 当前提供服务的机器号
if (total < 5) {
server = upList.get(currentIndex);
total++;
} else {
total = 0;
currentIndex++;
if (currentIndex >= upList.size()) {
currentIndex = 0;
}
}
if (server == null) {
/*
* The only time this should happen is if the server list were somehow trimmed.
* This is a transient condition. Retry after yielding.
*/
Thread.yield();
continue;
}
if (server.isAlive()) {
return (server);
}
// Shouldn't actually happen.. but must be transient or a bug.
server = null;
Thread.yield();
}
return server;
}
@Override
public Server choose(Object key) {
return choose(getLoadBalancer(), key);
}
@Override
public void initWithNiwsConfig(IClientConfig clientConfig) {
// TODO Auto-generated method stub
}
}
最后不要忘了在主启动类加上注解，使用自定义轮询算法configuration = MySelfRule.class
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
/**
* @author lzh
* create 2019-11-04-22:26
*/
@SpringBootApplication
@EnableEurekaClient
//自定义负载均衡规则
//在启动该为服务的时候就能去加载我们的自定义Ribbon配置类，从而使配置生效
//configuration = MySelfRule.class 把MySelfRule配置类加载进容器
@RibbonClient(name = "MICROSERVICECLOUD-DEPT",configuration = MySelfRule.class)
@EnableDiscoveryClient
public class MyConsumerApplication_80 {
public static void main(String[] args) {
SpringApplication.run(MyConsumerApplication_80.class);
}
}
代码
github：https://github.com/LZHDonald/my-springcloud-01/tree/master/microservice-consumer-80