二、Spring Cloud 的 Eureka 组件

Spring 微服务架构



Spring cloud 微服务解决方案（组件集）, Spring cloud 他不是一蹴而就的，在不同阶段，引用对应组件：

1） 服务变多了，引入注册中心？ Spring Cloud - Eureka

2） 服务间调用的负载均衡？ Spring Cloud - Ribbon 客户端负载均衡

3） 配置如何管理？如何动态更新？ Spring Cloud - Config

4） 服务限流？ Spring Cloud - Hystrix 熔断中心

5） AService -> BService -> CService 调用链路追踪？ Spring Cloud - Sleuth

6） 网关代理（鉴权）? Spring Cloud - Zuul

7） 消息总线？ Spring Cloud - BUS

Zookeeper 与 Eureka 差别

1） Zookeeper 不是专业处理Eureka的工具

2） 和程序的需要定制开发

3） 选举Leader，不能服务

一、Eureka Server

查看 Eureka Server 的Web管理界面 http://localhost:8761 查看 Eureka Server 的服务实例 http://localhost:8761/eureka/apps 1) Maven配置

<?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.itmuch.cloud</groupId>
<artifactId>microservice-eureka-server</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>

<name>eureka-server</name>
<description>Simple for Spring Boot</description>

<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.6.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>

<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
<spring-cloud.version>Dalston.SR3</spring-cloud.version>
</properties>

<dependencies>
<!-- Eureka 服务  -->
<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>${spring-cloud.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>

<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>

</project>

2) yml 文件配置

server:
port: 8761

eureka:
instance:
hostname: localhost
client:
register-with-eureka: false   #表示是否将自己注册到Eureka Server中，默认为true, 由于当前应用就是 Eureka Server， 故而设置为false
fetch-registry: false         #表示是否从 Eureka Server中获取注册信息, 默认为true, 因为这是一个单点的 Eureka Server, 不需要同步其它的 Eureka Server 节点的数据， 故而设置为 false
service-url:
defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/  # 设置与Eureka Server交互的地址， 查询服务和注册服务都需要依赖这个地址. 默认http://localhost:8761/eureka; 多个地址可以使用","分隔

3) 主程序代码

package com.itmuch.cloud;

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

@SpringBootApplication
@EnableEurekaServer    // 开启这是一个 Eureka Server 程序
public class EurekaServerApplication {

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

}

二、生产者程序

1) Maven 配置

<?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.itmuch.cloud</groupId>
<artifactId>microservice-cloud-service</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>

<name>cloud-service</name>
<description>Simple for Spring Boot</description>

<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.6.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>

<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
<spring-cloud.version>Dalston.SR3</spring-cloud.version>
</properties>

<dependencies>
<!-- Spring Eureka 客户端 -->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka</artifactId>
</dependency>

<!-- Spring Cloud -->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter</artifactId>
</dependency>

<!-- Spring Boot Actuator 监控端口 -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>

<!-- JPA依赖包 -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>

<!-- Web项目依赖包 -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>

<!-- MySQL -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>

</dependencies>

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

<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>

</project>

2) yml 文件配置

server:
port: 8080
session:
timeout: 30
tomcat:
max-threads: 0
uri-encoding: UTF-8

spring:
application:
#表示注册到Eureka上的应用名称
name: cloud-service
datasource:
url: jdbc:mysql://localhost:3306/boot
username: root
password: xshdb
driver-class-name: com.mysql.jdbc.Driver

jpa:
# Specify the DBMS
database: MYSQL
# Show or not log for each sql query
show-sql: true
# Hibernate dll auto (create, create-drop, update)
hibernate:
ddl-auto: update

eureka:
client:
service-url:
defaultZone: http://localhost:8761/eureka/ instance:
prefer-ip-address: true     # 表示将自己的IP注册到Eureka Serverk, 如果不配置该属性或将它改为false，则表示注册微服务所在操作系统的hostname到Eureka Server

3) 主程序

package com.itmuch.cloud;

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

@SpringBootApplication
@EnableDiscoveryClient
public class CloudServiceApplication {

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

4) User Entity 类

package com.itmuch.cloud;

import java.io.Serializable;
import java.math.BigDecimal;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;

import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;

@Entity
public class User implements Serializable {

private static final long serialVersionUID = 1L;

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;

@Column
private String username;

@Column
private String name;

@Column
private Integer age;

@Column
private BigDecimal balance;

public Long getId() {
return id;
}

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

public String getUsername() {
return username;
}

public void setUsername(String username) {
this.username = username;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public Integer getAge() {
return age;
}

public void setAge(Integer age) {
this.age = age;
}

public BigDecimal getBalance() {
return balance;
}

public void setBalance(BigDecimal balance) {
this.balance = balance;
}

}

5) Controller 控制台

package com.itmuch.cloud;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class UserController {

@Autowired
private UserRepository userRepository;

@GetMapping("/get/{id}")   // 在Spring 4.3规则中，@GetMapping等价于@RequestMapping(method = RequestMethod.GET), 用于简化， 同理还有@PostMapping, @PutMapping, @DeleteMapping, @PatchMapping等
public User findById(@PathVariable Long id) {
User findOne = this.userRepository.findOne(id);
System.out.println(findOne.toString());
return findOne;
}

}

6) DAO 层

package com.itmuch.cloud;

import org.springframework.data.jpa.repository.JpaRepository;

public interface UserRepository extends JpaRepository<User, Long> {

}

三、 消费者

测试地址: http://localhost:8100/eureka/1 好像有问题, 根据服务名找不到实例
http://localhost:8100/discovery/1
1) Maven 配置

<?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.itmuch.cloud</groupId>
<artifactId>microservice-cloud-consumer</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>

<name>cloud-consumer</name>
<description>Simple for Spring Boot</description>

<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.6.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>

<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
<spring-cloud.version>Dalston.SR3</spring-cloud.version>
</properties>

<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka</artifactId>
</dependency>

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

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

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

</dependencies>

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

<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>

</project>

2） yml 文件配置

server:
port: 8100

spring:
application:
name: cloud-consumer

eureka:
client:
service-url:
defaultZone: http://localhost:8761/eureka/ instance:
prefer-ip-address: true     # 表示将自己的IP注册到Eureka Serverk, 如果不配置该属性或将它改为false，则表示注册微服务所在操作系统的hostname到Eureka Server

user:
userServiceUrl: http://localhost:8080/ userEurekaService: http://cloud-service userEurekaName: cloud-service

3） 主程序

package com.itmuch.cloud;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@SpringBootApplication
@EnableEurekaClient   // 或@EnableDiscoveryClient
public class CloudConsumerApplication {

@Bean  // 等价于 RestTemplate restTemplate = new RestTemplate();
public RestTemplate restTemplate() {
return new RestTemplate();
}

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

}

4） User Entntiy 类

package com.itmuch.cloud;

import java.io.Serializable;
import java.math.BigDecimal;

public class User implements Serializable {

private static final long serialVersionUID = 1L;

private Long id;

private String username;

private String name;

private Integer age;

private BigDecimal balance;

public Long getId() {
return id;
}

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

public String getUsername() {
return username;
}

public void setUsername(String username) {
this.username = username;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public Integer getAge() {
return age;
}

public void setAge(Integer age) {
this.age = age;
}

public BigDecimal getBalance() {
return balance;
}

public void setBalance(BigDecimal balance) {
this.balance = balance;
}

}

5) Controller 控制层

package com.itmuch.cloud;

import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.List;

import org.apache.tomcat.util.http.fileupload.IOUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;

import org.springframework.cloud.client.discovery.DiscoveryClient;
import org.springframework.cloud.client.ServiceInstance;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

@RestController
public class UserController {

@Value("${user.userServiceUrl}")   // 在yml文件中已经配置, 解决它的硬编码问题
private String userServiceUrl;

@Value("${user.userEurekaService}")
private String userEurekaService;

@Value("${user.userEurekaName}")
private String userEurekaName;

@Autowired
private RestTemplate restTemplate;

@Autowired
private DiscoveryClient discoveryClient;

/**
* 基于Spring Boot方式来调用服务
*
* 说明：在Spring 4.3规则中，@GetMapping等价于@RequestMapping(method = RequestMethod.GET), 用于简化， 同理还有@PostMapping, @PutMapping, @DeleteMapping, @PatchMapping等
*
* @param id
* @return
*/
@GetMapping("/user/{id}")
public User findById(@PathVariable Long id) {
return this.restTemplate.getForObject(this.userServiceUrl + id, User.class);
}

/**
* #1 第一种   基于Eureka服务方式来调用
*
* @param id
* @return
*/
@GetMapping("/eureka/{id}")
public User findByIdEureka(@PathVariable Long id) {
User user = this.restTemplate.getForObject("http://cloud-service/get/" + 1, User.class);
return user;
}

/**
* #2 第二种   基于Eureka服务方式来调用
*
* @param id
* @return
* @throws MalformedURLException
*/
@GetMapping("/discovery/{id}")
public Object findByIdDiscovery(@PathVariable Long id) throws Exception {
// 非配置 IP 端口
// 通过服务名获取实例
// Eureka 会缓存, 不是每个请求都会调用 EurekaServer接口
List<ServiceInstance> instances = discoveryClient.getInstances(this.userEurekaName);

// 获取到一个服务器列表,如1.2.3
// 随机、轮询, ribbon客户端负责均衡
// 熔断  Hystrix
ServiceInstance serviceInstance = instances.get(0);

String host = serviceInstance.getHost();
int port = serviceInstance.getPort();

URL url = new URL("http://" + host + ":" + port + "/get/" + id);
byte[] result = new byte[3];
InputStream input = url.openStream();
IOUtils.readFully(input, result);

System.out.println(new String(result));

return new String(result);
}

}