用ZooKeeper做为注册中心搭建基于Spring Cloud实现服务注册与发现

前提：

先安装好ZooKeeper的环境，搭建参考：http://www.cnblogs.com/EasonJim/p/7482961.html

说明：

可以再简单的理解为有两方协作，一个是服务提供这，另一个是服务消费者。

搭建实例：

说明：基于Maven的模块工程

父工程POM：

<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.jsoft.testzookeeper</groupId>
    <artifactId>zookeeperdemo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>pom</packaging>
    <name>ZooKeeperDemo</name>
    <description>This is ZookKeeperDemo</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.4.5.RELEASE</version>
    </parent>

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

    <dependencies>
        <!-- 健康监控 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <!-- 断路器 -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-hystrix</artifactId>
        </dependency>
        <!-- 负载均衡 -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-ribbon</artifactId>
        </dependency>
        <!-- ZK依赖 -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-zookeeper-discovery</artifactId>
        </dependency>
        <!-- Web支持 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!-- 测试 -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Camden.SR7</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>

            <dependency>
                <groupId>junit</groupId>
                <artifactId>junit</artifactId>
                <version>3.8.1</version>
                <scope>test</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>    

    <modules>
        <module>zookeeperservice</module>
        <module>zookeeperclient</module>
    </modules>
</project>

服务提供者POM：

<?xml version="1.0"?>
<project
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
    xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>com.jsoft.testzookeeper</groupId>
        <artifactId>zookeeperdemo</artifactId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>
    <groupId>com.jsoft.testzookeeper</groupId>
    <artifactId>zookeeperservice</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>zookeeperservice</name>
    <url>http://maven.apache.org</url>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>
    <dependencies>

    </dependencies>
</project>

application.properties：

server.port=8800
spring.application.name=/service-zookeeper
spring.cloud.zookeeper.discovery.root=/spring-cloud-service
spring.cloud.zookeeper.connect-string=localhost:2181

说明：定义端口，应用的名称，服务在ZK的路径，ZK的服务器地址，其中ZK的服务器地址可以有多个，用逗号隔开。

HelloController：

服务接口

package com.jsoft.testzookeeper.service.controller;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HelloController {

    private static final Logger log = LoggerFactory.getLogger(HelloController.class);

    @RequestMapping(value = "/hello", method = RequestMethod.GET)
    public String sayHello(@RequestParam(name = "name") String name) {
        log.info("param:name->{}", name);
        return "hello: " + name;
    }
}

App：

程序入口

package com.jsoft.testzookeeper.service;

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

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

说明：其中要@EnableDiscoveryClient标注为服务发现注解。

服务消费者POM：

<?xml version="1.0"?>
<project
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
    xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>com.jsoft.testzookeeper</groupId>
        <artifactId>zookeeperdemo</artifactId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>
    <groupId>com.jsoft.testzookeeper</groupId>
    <artifactId>zookeeperclient</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>zookeeperclient</name>
    <url>http://maven.apache.org</url>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>
    <dependencies>
        <!-- Feign客户端 -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-feign</artifactId>
        </dependency>
    </dependencies>
</project>

说明：由于使用了Feign客户端，所以引入Feign依赖。

application.properties：

server.port=8810
spring.application.name=/client-zookeeper
spring.cloud.zookeeper.discovery.register=false
spring.cloud.zookeeper.discovery.root=/spring-cloud-service
spring.cloud.zookeeper.connect-string=localhost:2181
spring.cloud.zookeeper.dependencies.service-zookeeper.required=true
spring.cloud.zookeeper.dependencies.service-zookeeper.path=/service-zookeeper
spring.cloud.zookeeper.dependencies.service-zookeeper.loadBalancerType=ROUND_ROBIN

说明：由于服务提供者的应用名使用了斜杠，所以必须采用依赖关系spring.cloud.zookeeper.dependencies进行别名的选择，注意，使用了这个之后要引入actuator健康监控组件，不然调用时会报错。

App：

程序入口

package com.jsoft.testzookeeper.client;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.netflix.feign.EnableFeignClients;

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

说明：@EnableCircuitBreaker为断路器的支持，@EnableFeignClients为Feign客户端的支持。

Client的实现：

主要有两种，基于RestTemplate和Feign

RestTemplate

package com.jsoft.testzookeeper.client.service;

import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;

@Service
public class HelloService {

    @Autowired
    private RestTemplate restTemplate;

    @HystrixCommand(fallbackMethod = "sayHelloFallback")
    public String sayHello(String name) {
        return restTemplate.getForEntity("http://service-zookeeper/hello?name=" + name, String.class).getBody();
    }

    private String sayHelloFallback(String name) {
        return "service error";
    }
}

说明：@HystrixCommand为断路器写法。

Feign

package com.jsoft.testzookeeper.client.service;

import org.springframework.cloud.netflix.feign.FeignClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;

import com.jsoft.testzookeeper.client.service.fallback.FeignFallback;

@FeignClient(value = "service-zookeeper", fallback = FeignFallback.class)
public interface ServiceFeign {

    @RequestMapping(value = "/hello")
    String sayHello(@RequestParam(name = "name") String name);
}

说明：fallback为断路器回调。

消费服务：

package com.jsoft.testzookeeper.client.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import com.jsoft.testzookeeper.client.service.HelloService;
import com.jsoft.testzookeeper.client.service.ServiceFeign;

@RestController
public class HelloController {

    @Autowired
    private HelloService helloService;

    @Autowired
    private ServiceFeign serviceFeign;

    @RequestMapping(value = "hello")
    public String hello(@RequestParam String name) {
        return helloService.sayHello(name);
    }

    @RequestMapping(value = "hello2")
    public String hello2(@RequestParam String name) {
        return serviceFeign.sayHello(name);
    }
}

总结：

Spring Cloud在服务发现和注册上其实很多坑，上面展示的只是核心代码，最全的还是参考例子代码进行调试。

Maven示例：

https://github.com/easonjim/spring-cloud-demo/tree/master/ZooKeeper

参考：

http://theseus.iteye.com/blog/2366237

http://www.cnblogs.com/skyblog/p/5133752.html

http://blog.csdn.net/mn960mn/article/details/51803703

http://www.jianshu.com/p/775c363d0fda