以zookeeper为注册中心搭建spring cloud环境

Java框架

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2019-2-24

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在spring cloud体系中,有多种手段实现注册中心,本例中采用zookeeper作为注册中心的角色。服务提供者向zookeeper注册,服务消费者从zookeeper中发现服务提供者的相关信息,从而远程调用服务提供方

服务提供者

引入相关依赖
<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.4.2.RELEASE</version>
</parent>

<dependencies>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-config</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-zookeeper-discovery</artifactId>
    </dependency>
    
    <!-- 热部署工具 -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-devtools</artifactId>
    </dependency>
</dependencies>

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-dependencies</artifactId>
            <version>Camden.SR2</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

spring cloud与zookeeper的集成主要依赖spring-cloud-starter-zookeeper-discovery模块

定义DTO对象
public class UserDTO {
    
    private Long id;
    private String name;
    private Date birthday;
    
    /*
        省略getter,setter方法
    */
}
定义服务提供接口
@RestController
public class ComputeController {

    @Autowired
    private DiscoveryClient client;
    
    @RequestMapping(value = "/show", method = {RequestMethod.POST})
    @ResponseBody
    public UserDTO show(@RequestParam(value="id") Long id) {
        ServiceInstance instance = client.getLocalServiceInstance();
        UserDTO dto = new UserDTO();
        dto.setId(id);
        dto.setName("scott");
        dto.setBirthday(new Date());
        return dto;
    }

}

在show方法中返回了dto对象。

配置文件

application.properties

server.port=8080
spring.application.name=server

bootstrap.properties

spring.cloud.zookeeper.connectString=192.168.179.200:2181
spring.cloud.zookeeper.discovery.instanceHost=127.0.0.1
spring.cloud.zookeeper.discovery.instancePort=${server.port} 
启动项目
@SpringBootApplication  
@EnableDiscoveryClient
public class AppStart {
    public static void main(String[] args) {
        SpringApplication.run(AppStart.class, args);
    }
}

启动项目后可以在zookeeper中看到新增了/service节点,该节点有一个子节点server

服务消费者

引入与依赖项,这里用feign作为rest调用工具
<dependencies>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-config</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-zookeeper-discovery</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-feign</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-hystrix</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-hystrix-dashboard</artifactId>
    </dependency>
    
    <!-- 热部署工具 -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-devtools</artifactId>
    </dependency>
</dependencies>
定义远程调用代理对象
@Component
@FeignClient(value="server",fallback=FeignConsumerClientHystrix.class)
public interface FeignConsumerClient {
    
    @RequestMapping(method = RequestMethod.POST, value = "/show")
    public String getUser(@RequestParam(value = "id") Long id);
    
}

以POST方式发起远程调用,调用地址根据@FeignClient中value值决定。

通过@FeignClient创建消费端代理对象。value指定服务名,该值与服务提供者的spring.application.name参数值相等,fallback指定异常处理类,异常处理类需实现本接口。

异常处理
@Component
public class FeignConsumerClientHystrix implements FeignConsumerClient{

    @Override
    public String getUser(@RequestParam("id") Long id) {
        return "error";
    }
}

所实现方法即为异常处理代码

注入代理对象,发起远程调用
@RestController
public class ClientController {
    
    @Autowired
    private FeignConsumerClient feignConsumerClient;

    @RequestMapping(value = "/get", method = RequestMethod.GET)
    @ResponseBody
    public String add(@RequestParam(value = "id") Long id) {
        return feignConsumerClient.getUser(id);
    }
}
配置文件

application.properties

server.port=8081
spring.application.name=client

#断路器,断路器跳闸后等待多长时间重试
hystrix.command.default.circuitBreaker.sleepWindowInMilliseconds=1000
#断路器,请求发出后多长时间超时
hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds=5000
#ribbon连接到服务端的超时时间
ribbon.ConnectTimeout=5000
#ribbon连接到服务端后,多长时间没有获取到响应的超时时间
ribbon.ReadTimeout=5000

bootstrap.properties

spring.cloud.zookeeper.connectString=192.168.179.200:2181
#不向zookeeper注册
spring.cloud.zookeeper.discovery.register=false
服务消费者启动项目
@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
@EnableHystrix
@EnableHystrixDashboard
@EnableCircuitBreaker
public class AppStart {
    public static void main(String[] args) {
        SpringApplication.run(AppStart.class, args);
    }
}

启动项目后浏览器访问http://127.0.0.1:8081/get?id=xxx,正常情况即可看到由userDTO对象转换得到的json字符串。

后续补充spring cloud中的异常处理方法,故障转移,负载均衡等。