SpringCloud之Eureka和Ribbon的使用

何谓Eureka和Ribbon

集群的搭建

• 单机模拟集群

步骤思路

1. 创建父项目导入依赖
2. 创建3个一样结构的数据库
3. 创建一个实体类（pojo）项目（API）
4. 创建3个服务提供者，进行相同的业务处理
5. 创建1个服务消费者
6. 创建3个注册中心
7. 以maven项目创建
8. 修改hosts文件

创建SpringCloud疑问点

• 为什么不直接直接创建springboot项目？ 答：有一个maven依赖叫spring-cloud-dependencies，可以对spring cloud需要用到的组件进行版本控制。因为spring cloud组件的版本对应关系比较严格，一个不注意就会报错。如果全部手动自己导对应版本的依赖会很麻烦。

• 以spring cloud-Hoxton.SR10的spring-cloud-dependencies为例，里面已经指定了常用组件的版本，

• 为什么父pom要用dependencyManagement？ 答：在我们项目顶层的POM文件中，我们会看到dependencyManagement元素。通过它元素来管理jar包的版本，让子项目中引用一个依赖而不用显示的列出版本号。Maven会沿着父子层次向上走，直到找到一个拥有dependencyManagement元素的项目，然后它就会使用在这个dependencyManagement元素中指定的版本号。

• dependencyManagement与dependencies有什么联系呢？

创建父项目导入依赖

<?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>SpringCloud-Project</artifactId>
    <version>1.0-SNAPSHOT</version>
    <properties>
        <junit.version>4.13.2</junit.version>
        <lombok.version>1.18.18</lombok.version>
        <log4j.version>1.2.17</log4j.version>
        <logback.version>1.2.3</logback.version>
        <mybatis-starter.version>2.1.4</mybatis-starter.version>
        <mysql.version>8.0.22</mysql.version>

        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>
    <packaging>pom</packaging>
<!--  项目依赖版本要统一  -->
<dependencyManagement>
    <dependencies>
       <!--  cloud依赖        -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-dependencies</artifactId>
            <version>Hoxton.SR10</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
       <!--    boot依赖   要和cloud版本适应 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-dependencies</artifactId>
            <version>2.3.9.RELEASE</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>${mysql.version}</version>
        </dependency>
        <!--      druid  数据源-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.2.5</version>
        </dependency>
        <dependency>
       <!--    boot启动器-->
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
            <version>2.3.9.RELEASE</version>
        </dependency>
         <!--    日志和偷懒相关    -->
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-core</artifactId>
            <version>${logback.version}</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>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>${lombok.version}</version>
        </dependency>
<!--    mybaties    -->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>${mybatis-starter.version}</version>
        </dependency>
<!--    web依赖    -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <version>2.3.9.RELEASE</version>

        </dependency>
    </dependencies>
</dependencyManagement>
</project>

3个数据库

实体类

@Data
@NoArgsConstructor
@Accessors(chain = true)//链式
public class Dept implements Serializable {//要序列化
    private Integer deptId;
    private String dname;
    private String db_source;

    public Dept(String dname) {
        this.dname = dname;
    }
}

创建服务提供者

• 导入maven依赖，还要导入自己写的实体类依赖

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

    <artifactId>SpringCloud-Provider-8001</artifactId>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>
    <dependencies>
      <!-- 自己写的实体类-->
        <dependency>
            <groupId>org.example</groupId>
            <artifactId>SpringCloud-Api</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
        </dependency>
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-core</artifactId>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        <!--test-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-test</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!--jetty-->
<!--        <dependency>-->
<!--            <groupId>org.springframework.boot</groupId>-->
<!--            <artifactId>spring-boot-starter-jetty</artifactId>-->
<!--        </dependency>-->
        <!--热部署工具-->
<!--        <dependency>-->
<!--            <groupId>org.springframework.boot</groupId>-->
<!--            <artifactId>spring-boot-devtools</artifactId>-->
<!--            <version>2.3.9.RELEASE</version>-->
<!--        </dependency>-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <!--配置服务info的 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
    </dependencies>

</project>

• 创建接口mapper接口

@Mapper
@Repository//spring dao层标记
public interface DeptDao {
    boolean addDept(Dept dept);
    Dept getById(int id);
    List<Dept> getAll();
}

• 创建service层接口

public interface DeptService {
    boolean addDept(Dept dept);
    Dept getById(int id);
    List<Dept> getAll();
}

• 实现service接口

@Service
public class DeptServiceImpl implements DeptService {
    @Autowired
    DeptDao deptDao;
    @Override
    public boolean addDept(Dept dept) {
        return deptDao.addDept(dept);
    }

    @Override
    public Dept getById(int id) {
        return deptDao.getById(id);
    }

    @Override
    public List<Dept> getAll() {
        return deptDao.getAll();
    }
}

• mybatis-config开启二级缓存

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

<configuration>
     <settings>
         <setting name="cacheEnabled" value="ture"/>
     </settings>
</configuration>

• 配置DeptMapper.xml

<?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.cloud.dao.DeptDao">

    <insert id="addDept">
        insert into springcloud.dept (dname, db_source) values (#{dname},DATABASE())
    </insert>
    <select id="getById" resultType="com.cloud.pojo.Dept" parameterType="int">
        select * from springcloud.dept where deptId=#{deptID}
    </select>
    <select id="getAll" resultType="com.cloud.pojo.Dept">
        select * from springcloud.dept
    </select>
</mapper>

• 配置application.yaml,使用druid数据源

server:
  port: 8001

mybatis:
  type-aliases-package: com.cloud.pojo
  config-location: classpath:mybatis/mybatis-config.xml
  mapper-locations: classpath:mybatis/mapper/*.xml
spring:
  application:
    name: springcloud-provider-dept
  datasource:
    username: root
    password: 123456
    url: jdbc:mysql://localhost:3306/springcloud?useUnicode=true&characterEncoding=utf8&useSSL=true&serverTimezone=Asia/Shanghai
    driver-class-name: com.mysql.cj.jdbc.Driver
    # c
    #SpringBoot默认是不注入这些的，需要自己绑定
    #druid数据源专有配置
    type: com.alibaba.druid.pool.DruidDataSource
    initialSize: 5
    minIdle: 5
    maxActive: 20
    maxWait: 60000
    timeBetweenEvictionRunsMillis: 60000
    minEvictableIdleTimeMillis: 300000
    validationQuery: SELECT 1 FROM DUAL
    testWhileIdle: true
    testOnBorrow: false
    testOnReturn: false
    poolPreparedStatements: true

    #配置监控统计拦截的filters，stat：监控统计、log4j：日志记录、wall：防御sql注入
    #如果允许报错，java.lang.ClassNotFoundException: org.apache.Log4j.Properity
    #则导入log4j 依赖就行
    filters: stat,wall,log4j
    maxPoolPreparedStatementPerConnectionSize: 20
    useGlobalDataSourceStat: true
    connectionProperties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=500
#Eureka的配置，服务注册到哪里
eureka:
  client:
    service-url: # 注册地址~
      defaultZone: http://eureka7001.com:7001/eureka/,http://eureka7002.com:7002/eureka/,http://eureka7003.com:7003/eureka/
  instance:
    instance-id: springcloud-provider-dept-8001

# 配置服务信息，其实就是说明一下这个服务是干什么的
info:
  app.name: 它的名字
  company.name: XXX有公司

• druid 参数配置详解
• 创建Controller

//提供restful 服务
@RestController
public class DeptController {
    @Autowired
    private DeptService service;
    @RequestMapping(value = "/add")//用8001端口不行，非要用得post请求。消费服务端ok
    public boolean add(@RequestBody Dept dept){
        System.out.println(dept.getDname());
        return service.addDept(dept);
    }
    @GetMapping("/byId/{id}")
    public Dept getDeptById(@PathVariable int id){
        return service.getById(id);
    }
    @GetMapping("/getAll")
    public List<Dept> getAll(){
        return service.getAll();
    }

}

• 创建启动类

@EnableEurekaClient//让Eureka发现它
@SpringBootApplication
public class DeptProvider_8001{
    public static void main(String[] args) {
        SpringApplication.run(DeptProvider_8001.class,args);
    }
}

• 另外两个就把配置文件中端口号改一下，数据库名称改一下，启动类的名字换成对应端口号即可

创建注册中心

• 导入依赖

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

    <artifactId>SpringCloud-Eurika-7001</artifactId>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        </dependency>
    </dependencies>

</project>

• 创建启动程序

@SpringBootApplication
@EnableEurekaServer//激活Eureka Server相关配置的注释
public class Eureka_7001 {
    public static void main(String[] args) {
        SpringApplication.run(Eureka_7001.class,args);
    }
}

• application.yaml

#server:
#  port: 7001
## Eureka配置
#eureka:
#  instance:
#    hostname: localhost # Eureka服务端的实例名称
#  client:
#    register-with-eureka: false  # 表示是否向eureka注册中心注册自己
#    fetch-registry: false  # fetch-registry如果为false，则表示自己为注册中心
#    service-url: # 监控页面~
#      defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/
spring:
  application:
    name: eureka-server-7001

server:
  port: 7001

eureka:
  instance:
    hostname: eureka7001.com
  client:
    #是否应该向eureka服务器注册其信息，以供其他人发现。由于自身即为eureka服务端，所以设为 false
    register-with-eureka: false
    #是否应该从eureka服务器获取eureka注册表信息。由于自身即为eureka服务端，所以设为 false
    fetch-registry: false
    service-url: # 注册地址~
      defaultZone: http://eureka7002.com:7002/eureka/,http://eureka7003.com:7003/eureka/

• 另外两个一样，改端口号即可

创建服务消费者

• 导入依赖

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

    <artifactId>SpringCloud-Consumer-dept-80</artifactId>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>
     <dependencies>
         <!-- 实体类-->
         <dependency>
             <groupId>org.example</groupId>
             <artifactId>SpringCloud-Api</artifactId>
             <version>1.0-SNAPSHOT</version>
         </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-web</artifactId>
         </dependency>
         <dependency>
             <groupId>org.springframework.cloud</groupId>
             <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
         </dependency>
         <dependency>
             <groupId>org.springframework.cloud</groupId>
             <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
         </dependency>


     </dependencies>
</project>

• 编写Configuration类

@Configuration
public class ConfigBeans {
    //IRule ,定义LoadBalancer的“规则”的接口。 可以将规则视为负载均衡策略。 众所周知的负载平衡策略包括轮询，基于响应时间等
    //默认为轮询
    @Bean
    @LoadBalanced//配置负载均衡实现RestTemplate
    public RestTemplate restTemplate(){
        return new RestTemplate();
    }
}

• 负载均衡的Configuration类（自定义的策略，或自带的策略（轮询，随机，权重。。），）,不要和启动类同级目录,因为如果在一个上下文，会导致所有的服务消费都用同一个负载均衡策略，

@Configuration
public class MyRuleConfiguration {
    @Bean
    public IRule myRule(){
        return new RandomRule();
    }
}

• Controller

@RestController
public class DeptConsumerController {
    //消费者，不应该有service层
    //RestTemplate提供多种便捷访问远程http服务的方法，简单的restful服务模板
    @Autowired
    private RestTemplate restTemplate;
    //private static final String REST_URL_PREFIX="http://localhost:8001";
    private static final String REST_URL_PREFIX="http://SPRINGCLOUD-PROVIDER-DEPT";//通过服务名访问呢
    @GetMapping("/consumer/add/")
    public boolean add(Dept dept){
        System.out.println(dept.getDname());
        return restTemplate.postForObject(REST_URL_PREFIX+"/add",dept,Boolean.class);
    }
    @GetMapping("/consumer/byId/{id}")
    public Dept getDeptById(@PathVariable int id){
        return restTemplate.getForObject(REST_URL_PREFIX+"/byId/"+id,Dept.class);
    }
    @GetMapping("/consumer/getAll")
    public List getAll(){
        return restTemplate.getForObject(REST_URL_PREFIX+"/getAll",List.class);
    }
}

• application.yaml

server:
  port: 80

#eureka配置
eureka:
  client:
    register-with-eureka: false # 不向eureka，注册自己
    service-url:
      defaultZone: http://eureka7001.com:7001/eureka/,http://eureka7003.com:7003/eureka/,http://eureka7002.com:7002/eureka/

• 启动类

@SpringBootApplication
                      //("服务名称"，                     “自定义发负载均衡策略配置类.class”)
@RibbonClient(name="SPRINGCLOUD-PROVIDER-DEPT",configuration= MyRuleConfiguration.class)
public class DeptConsumer_80 {
    public static void main(String[] args) {
        SpringApplication.run(DeptConsumer_80.class,args);
    }
}

修改电脑的hosts文件

• 3个域名代表。3个服务器，模拟一下

127.0.0.1 eureka7001.com
127.0.0.1 eureka7002.com
127.0.0.1 eureka7003.com

小结

项目结构

依赖要导对

配置文件

• 服务提供者的关键配置

==================================

• 注册中心的关键配置

• 服务消费者的关键配置

关键注解和对象

消费者

• • @LoadBalanced，让请求模板进行负载均衡
• • @RibbonClient，使用Ribbon进行负载均衡
• • RestTemplate，在controller中，向服务提供者发出请求
• • IRule，负载均衡策略接口
• • RestTemplate 用法详解

---

============================

注册中心

• • @EnableEurekaServer，激活Eureka Server相关配置的注释，在启动类上

服务提供者

• • @EnableEurekaClient，用于启用Eureka发现配置，在启动类上

最终效果