在spring cloud體系中，有多種手段實(shí)現(xiàn)注冊中心，本例中采用zookeeper作為注冊中心的角色。服務(wù)提供者向zookeeper注冊，服務(wù)消費(fèi)者從zookeeper中發(fā)現(xiàn)服務(wù)提供者的相關(guān)信息，從而遠(yuǎn)程調(diào)用服務(wù)提供方。

服務(wù)提供者

引入相關(guān)依賴

<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>
    
    <!-- 熱部署工具 -->
    <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與zookeeper的集成主要依賴spring-cloud-starter-zookeeper-discovery模塊

定義DTO對象

public class UserDTO {
    
    private Long id;
    private String name;
    private Date birthday;
    
    /*
        省略getter,setter方法
    */
}

定義服務(wù)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對象。

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} 

啟動(dòng)項(xiàng)目

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

啟動(dòng)項(xiàng)目后可以在zookeeper中看到新增了/service節(jié)點(diǎn)，該節(jié)點(diǎn)有一個(gè)子節(jié)點(diǎn)server

服務(wù)消費(fèi)者

引入與依賴項(xiàng)，這里用feign作為rest調(diào)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>
    
    <!-- 熱部署工具 -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-devtools</artifactId>
    </dependency>
</dependencies>

定義遠(yuǎn)程調(diào)用代理對象

@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方式發(fā)起遠(yuǎn)程調(diào)用，調(diào)用地址根據(jù)@FeignClient中value值決定。

通過@FeignClient創(chuàng)建消費(fèi)端代理對象。value指定服務(wù)名,該值與服務(wù)提供者的spring.application.name參數(shù)值相等，fallback指定異常處理類，異常處理類需實(shí)現(xiàn)本接口。

異常處理

@Component
public class FeignConsumerClientHystrix implements FeignConsumerClient{

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

所實(shí)現(xiàn)方法即為異常處理代碼

注入代理對象，發(fā)起遠(yuǎn)程調(diào)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

#斷路器，斷路器跳閘后等待多長時(shí)間重試
hystrix.command.default.circuitBreaker.sleepWindowInMilliseconds=1000
#斷路器，請求發(fā)出后多長時(shí)間超時(shí)
hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds=5000
#ribbon連接到服務(wù)端的超時(shí)時(shí)間
ribbon.ConnectTimeout=5000
#ribbon連接到服務(wù)端后，多長時(shí)間沒有獲取到響應(yīng)的超時(shí)時(shí)間
ribbon.ReadTimeout=5000

bootstrap.properties

spring.cloud.zookeeper.connectString=192.168.179.200:2181
#不向zookeeper注冊
spring.cloud.zookeeper.discovery.register=false

服務(wù)消費(fèi)者啟動(dòng)項(xiàng)目

@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
@EnableHystrix
@EnableHystrixDashboard
@EnableCircuitBreaker
public class AppStart {
    public static void main(String[] args) {
        SpringApplication.run(AppStart.class, args);
    }
}

啟動(dòng)項(xiàng)目后瀏覽器訪問http://127.0.0.1:8081/get?id=xxx，正常情況即可看到由userDTO對象轉(zhuǎn)換得到的json字符串。

后續(xù)補(bǔ)充spring cloud中的異常處理方法，故障轉(zhuǎn)移，負(fù)載均衡等。