springcloud（1）—— eureka本地集群搭建以及实现微服务的负载均衡调用

什么是服务治理?
Spring Cloud 封装了 Netflix 公司开发的 Eureka 模块来实现服务治理
在传统的rpc远程调用框架中，管理每个服务与服务之间依赖关系比较复杂，所以需要使用服务治理，管理服务与服务之间依赖关系，可以实现服务调用、负载均衡、容错等，实现服务发现与注册！

什么是服务注册与发现
Eureka采用了CS的设计架构，Eureka Server 作为服务注册功能的服务器，它是服务注册中心。而系统中的其他微服务，使用 Eureka的客户端连接到 Eureka Server并维持心
跳连接。这样系统的维护人员就可以通过 Eureka Server 来监控系统中各个服务是否正常运行。
在服务注册与发现中，有一个注册中心，当服务器启动的时候，会把当前自己服务器的信息比如服务地址、通讯地址等以别名方式注册到注册中心上。另一方 (消费者|服务提供
者) ，以该别名的方式去注册中心上获取到实际的服务通讯地址，然后再实现本地RPC调用。RPC远程调用框架核心设计思想: 在于注册中心，因为使用注册中心管理每个服务与
服务之间的一个依赖关系(服务治理概念)。在任何rpc远程框架中，都会有一个注册中心(存放服务地址相关信息(接口地址)) 

Eureka包含两个组件: Eureka Server和Eureka Client
Eureka Server提供服务注册服务：
各个微服务节点通过配置启动后，会在EurekaServer中进行注册，这样EurekaServer中的服务注册表中将会存储所有可用服务节点的信息，服务节点的信息可以在界面中直观看到。

EurekaClient通过注册中心进行访问：
是一个Java客户端，用于简化Eureka Server的交互，客户端同时也具备一个内置的、使用轮询(round-robinm)负载算法的负载均衡器。在应用启动后，将会向Eureka Server发送心跳默认周期为30秒。如果Eureka Server在多个心跳周期内没有接收到某个节点的心跳，EurekaServer将会从服务注册表中把这个服务节点移除 (默认90秒)。

我们直接利用eureka搭建一个服务注册与发现的集群，实现一个微服务调用的的功能

1、新建一个maven父工程（springcloud）

<!--统一管理jar包版本-->
  <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>
    <lombok.version>1.18.10</lombok.version>
    <log4j.version>1.2.12</log4j.version>
    <mysql.version>8.0.18</mysql.version>
    <druid.version>1.1.10</druid.version>
    <mybatis.spring.boot.version>1.3.2</mybatis.spring.boot.version>
  </properties>

  <!--子模块继承之后，提供作用：锁定版本+子module不用写groupId和version-->
  <dependencyManagement>
    <dependencies>
      <!--spring boot 2.2.2-->
      <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-dependencies</artifactId>
        <version>2.2.2.RELEASE</version>
        <type>pom</type>
        <scope>import</scope>
      </dependency>
      <!--spring cloud Hoxton.SR1-->
      <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-dependencies</artifactId>
        <version>Hoxton.SR1</version>
        <type>pom</type>
        <scope>import</scope>
      </dependency>
      <!--spring cloud alibaba-->
      <dependency>
        <groupId>com.alibaba.cloud</groupId>
        <artifactId>spring-cloud-alibaba-dependencies</artifactId>
        <version>2.1.0.RELEASE</version>
        <type>pom</type>
        <scope>import</scope>
      </dependency>
      <!--mysql-->
      <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>${mysql.version}</version>
        <scope>runtime</scope>
      </dependency>
      <!-- druid-->
      <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>druid-spring-boot-starter</artifactId>
        <version>${druid.version}</version>
      </dependency>

      <!--mybatis-->
      <dependency>
        <groupId>org.mybatis.spring.boot</groupId>
        <artifactId>mybatis-spring-boot-starter</artifactId>
        <version>${mybatis.spring.boot.version}</version>
      </dependency>
      <!--junit-->
      <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>${junit.version}</version>
      </dependency>
      <!--log4j-->
      <dependency>
        <groupId>log4j</groupId>
        <artifactId>log4j</artifactId>
        <version>${log4j.version}</version>
      </dependency>
    </dependencies>

  </dependencyManagement>

2、创建3个eureka服务

（cloud-eureka-server7001、cloud-eureka-server7002、cloud-eureka-server7003）

主启动类：其他两个就不贴了

@EnableEurekaServer //表示此项目是eureka的服务注册中心
@SpringBootApplication
public class EurekaMain7001 {
    public static void main(String[] args) {
        SpringApplication.run(EurekaMain7001.class, args);
    }
}

pom.xml

<dependencies>
        <!-- eureka-server -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!--监控-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <!-- 一般通用配置 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

application.yml 另外两个就不贴了，改下port和defaultZone

server:
  port: 7001

eureka:
  instance:
    hostname: eureka7001.com  #eureka服务端的实例名称
  client:
    #false表示不向注册中心注册自己（想注册也可以，不过没必要）
    register-with-eureka: false
    #false表示自己端就是注册中心，职责就是维护服务实例，并不需要去检索服务
    fetch-reapplication.ymlgistry: false
    service-url:
      #设置与eurekaServer交互的地址查询服务和注册服务都需要依赖这个地址  单机
      #defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/
      #集群版  相互注册，相互守望
      defaultZone: http://eureka7002.com:7002/eureka/, http://eureka7003.com:7003/eureka/

      #    defaultZone是固定写法，如果想自定义，需要按以下写法才行：
      #    region: eureka-server
      #    availability-zones:
      #      eureka-server: server1,server2
      #    service-url:
      #      server1: http://eureka7002.com:7002/eureka/
      #      server2: http://eureka7003.com:7003/eureka/

  server:
    #关闭自我保护，默认为true
    enable-self-preservation: false
    #心跳的间隔时间，单位毫秒
    eviction-interval-timer-in-ms: 2000

 修改下hosts文件：

 3、搭建消费者和服务者

3.1、创建实体中间件工程

cloud-api-commons

包路径为：

com.cjian.springcloud.bean

public class CommonResult<T> {

    private Integer code;
    private String message;
    private T data;

    public CommonResult(Integer code, String message, T data) {
        this.code = code;
        this.message = message;
        this.data = data;
    }

    public CommonResult(Integer code, String message){
        this(code, message, null);
    }

    public CommonResult() {
    }

    public Integer getCode() {
        return code;
    }

    public void setCode(Integer code) {
        this.code = code;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    public T getData() {
        return data;
    }

    public void setData(T data) {
        this.data = data;
    }
}

public class Payment implements Serializable {

    private Long id;
    private String serial;


    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getSerial() {
        return serial;
    }

    public void setSerial(String serial) {
        this.serial = serial;
    }
}

3.2、搭建两个服务提供者 

cloud-provider-payment8001、cloud-provider-payment8002

<dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>com.cjian.springloud</groupId>
            <artifactId>cloud-api-commons</artifactId>
            <version>${project.version}</version>
        </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>

        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.3.2</version>
        </dependency>

        <!-- alibaba的druid数据库连接池 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.1.10</version>
        </dependency>
        <!--mysql-connector-java-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.18</version>
        </dependency>
        <!--jdbc-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

application.yml

server:
  port: 8001

spring:
  application:
    name: cloud-payment-service
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource      # 当前数据源操作类型
    driver-class-name: com.mysql.cj.jdbc.Driver       # mysql驱动包
    url: jdbc:mysql://127.0.0.1:3306/mysql?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=UTC
    username: root
    password: 123456

mybatis:
  mapperLocations: classpath:mapper/*.xml
  type-aliases-package: com.cjian.springcloud.bean    # 所有Entity别名类所在包


eureka:
  client:
    register-with-eureka: true
    fetch-registry: true
    service-url:
      #defaultZone: http://localhost:7001/eureka
      defaultZone: http://eureka7001.com:7001/eureka,http://eureka7001.com:7002/eureka,http://eureka7001.com:7003/eureka

  instance:
    instance-id: payment8001
    prefer-ip-address: true   #访问路径可以显示ip地址

  #Eureka客户端向服务端发送心跳的时间间隔，单位秒（默认30秒）
  lease-renewal-interval-in-seconds: 1
  #Eureka服务端在收到最后一次心跳后等待的时间上限，单位秒（默认90秒），超时剔除服务
  lease-expiration-duration-in-seconds: 2

包路径：com.cjian.springcloud

@Mapper
public interface PaymentDao {

    public int create(Payment payment);

    public Payment getPaymentById(@Param("id") Long id);
}

public interface  PaymentService {
    public int create(Payment payment);

    public Payment getPaymentById(@Param("id") Long id);
}

@Service
public class PaymentServiceImpl implements PaymentService {
    @Resource
    private PaymentDao paymentDao;

    public int create(Payment payment)
    {
        return paymentDao.create(payment);
    }

    public Payment getPaymentById(Long id)
    {
        return paymentDao.getPaymentById(id);
    }
}

@RestController
public class PaymentController {
    @Resource
    private PaymentService paymentService;

    @Value("${server.port}")
    private String serverPort;

    @PostMapping(value = "/payment/create")
    public CommonResult create(@RequestBody Payment payment)
    {
        int result = paymentService.create(payment);
        System.out.println(("*****插入结果：" + result));

        if(result > 0)
        {
            return new CommonResult(200,"插入数据库成功,serverPort: "+serverPort,result);
        }else{
            return new CommonResult(444,"插入数据库失败",null);
        }
    }

    @GetMapping(value = "/payment/get/{id}")
    public CommonResult<Payment> getPaymentById(@PathVariable("id") Long id)
    {
        Payment payment = paymentService.getPaymentById(id);

        if(payment != null)
        {
            return new CommonResult(200,"查询成功,serverPort:  "+serverPort,payment);
        }else{
            return new CommonResult(444,"没有对应记录,查询ID: "+id,null);
        }
    }
}

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >

<mapper namespace="com.cjian.springcloud.dao.PaymentDao">

    <resultMap id="BaseResultMap" type="com.cjian.springcloud.bean.Payment">
        <id column="id" property="id" jdbcType="BIGINT"/>
        <id column="serial" property="serial" jdbcType="VARCHAR"/>
    </resultMap>

    <insert id="create" parameterType="com.cjian.springcloud.bean.Payment" useGeneratedKeys="true" keyProperty="id">
        insert into payment(serial)  values(#{serial});
    </insert>
    <select id="getPaymentById" parameterType="Long" resultMap="BaseResultMap">
        select * from payment where id=#{id};
    </select>

</mapper>

主启动类：

这里

@SpringBootApplication
//@EnableEurekaClient  不加该注解也是可以的，下面分析eureka原理的时候再说
public class PaymentMain001 {
    public static void main(String[] args) {
        SpringApplication.run(PaymentMain001.class, args);
    }
}

建表sql：

CREATE TABLE `payment`(
	`id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT 'ID',
   `serial` varchar(200) DEFAULT '',
	PRIMARY KEY (id)
)ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8mb4

另一个服务提供者不做赘述~

3.3、搭建一个消费者 

cloud-consumer-order80 

 <dependencies>
        <!-- eureka-client -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>com.cjian.springloud</groupId>
            <artifactId>cloud-api-commons</artifactId>
            <version>1.0-SNAPSHOT</version>
        </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>
        <!--热部署-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

@Configuration
public class ApplicationContextConfig {
    //往容器中添加一个RestTemplate
    //RestTemplate提供了多种便捷访问远程http访问的方法
    @Bean
    @LoadBalanced//开启负载均衡功能
    public RestTemplate restTemplate(){
        return new RestTemplate();
    }
}

@RestController
public class OrderController {

    // public static final String PAYMENT_URL = "http://localhost:8001";
     public static final String PAYMENT_URL = "http://CLOUD-PAYMENT-SERVICE";

    @Resource
    private RestTemplate restTemplate;

    //因为浏览器只支持get请求，为了方便这里就用get
    @GetMapping("/consumer/payment/create")
    public CommonResult<Payment> create(Payment payment){
        System.out.println("********插入的数据：" + payment);
        //postForObject分别有三个参数：请求地址，请求参数，返回的对象类型
        return restTemplate.postForObject(PAYMENT_URL + "/payment/create", payment, CommonResult.class);
    }

    @GetMapping("/consumer/payment/get/{id}")
    public CommonResult<Payment> getPayment(@PathVariable("id") Long id){
        System.out.println("********查询的id：" + id);
        //getForObject两个参数：请求地址，返回的对象类型
        return restTemplate.getForObject(PAYMENT_URL + "/payment/get/" + id, CommonResult.class);
    }

}

 application.yml

#访问一个网站时，默认是80端口，给用户80端口，用户就可以不用加端口直接访问页面
server:
  port: 81

spring:
  application:
    name: cloud-order-service

eureka:
  client:
    register-with-eureka: true
    etch-registry: true
    service-url:
      #defaultZone: http://localhost:7001/eureka
      defaultZone: http://eureka7001.com:7001/eureka,http://eureka7001.com:7002/eureka,http://eureka7001.com:7003/eureka

  instance:
    instance-id: consumer81
    prefer-ip-address: true   #访问路径可以显示ip地址

  #Eureka客户端向服务端发送心跳的时间间隔，单位秒（默认30秒）
  lease-renewal-interval-in-seconds: 1
  #Eureka服务端在收到最后一次心跳后等待的时间上限，单位秒（默认90秒），超时剔除服务
  lease-expiration-duration-in-seconds: 2

主启动类：

@SpringBootApplication
//@EnableDiscoveryClient
public class OrderMain80 {
    public static void main(String[] args) {
        SpringApplication.run(OrderMain80.class, args);
    }
}

4、测试功能

依次启动3个注册中心、消费者和2个服务提供者，访问 localhost:7001

访问  http://localhost:81/consumer/payment/get/3

再次访问：