SpringCloud系列(五)——Ribbon实现

上篇SpringCloud系列(四)——Ribbon负载均衡介绍了Ribbon负载均衡，都是理论性的东西，接下来用代码实现一下。

• 新建一个简单的Springboot项目——ribbon-service，然后编写一个方法，开启两个端口启动项目。

@RequestMapping(value = "/person", method = RequestMethod.GET, 
            produces = MediaType.APPLICATION_JSON_VALUE)
    public Person getPerson(HttpServletRequest request){
        Person p = new Person();
        p.setId(1);
        p.setName("小米");
        p.setMessage(request.getRequestURL().toString());
        return p;
    }

• 新建一个简单的maven项目，通过简单的main方法访问ribbon-service：

public static void main(String[] args) throws Exception {
        ConfigurationManager.getConfigInstance().setProperty(
                "my-client.ribbon.listOfServers", "localhost:8080,localhost:8081"); 
        RestClient client = (RestClient) ClientFactory.getNamedClient("my-client"); 
        HttpRequest request = HttpRequest.newBuilder().uri(("/person")).build();
        for(int i = 0;i<10;i++){
            HttpResponse response = client.executeWithLoadBalancer(request); 
            String json = response.getEntity(String.class);
            System.out.println(json);
        }

    }

• 输出，可以看到Ribbon的默认策略就是RoundRobinRule（轮换）：

{"id":1,"name":"小米","message":"http://localhost:8081/person"}
{"id":1,"name":"小米","message":"http://localhost:8080/person"}
{"id":1,"name":"小米","message":"http://localhost:8081/person"}
{"id":1,"name":"小米","message":"http://localhost:8080/person"}
{"id":1,"name":"小米","message":"http://localhost:8081/person"}
{"id":1,"name":"小米","message":"http://localhost:8080/person"}
{"id":1,"name":"小米","message":"http://localhost:8081/person"}
{"id":1,"name":"小米","message":"http://localhost:8080/person"}
{"id":1,"name":"小米","message":"http://localhost:8081/person"}
{"id":1,"name":"小米","message":"http://localhost:8080/person"}

• 接下来自定义策略，新建一个类，实现IRule，重写choose():

public class MyRule implements IRule {

    private ILoadBalancer lb;

    public Server choose(Object key) {
        Random r= new Random();
        int num = r.nextInt(10);

        List<Server> servers =  lb.getAllServers();

        if(num > 7){
            return getServerByPost(servers,8081);
        }else{
            return getServerByPost(servers,8080);
        }

    }

    private Server getServerByPost(List<Server> servers,int port){
        for(Server s:servers){
            if(s.getPort() == port){
                return s;
            }
        }
        return null;
    }

    public void setLoadBalancer(ILoadBalancer lb) {
        this.lb=lb;

    }

    public ILoadBalancer getLoadBalancer() {
        return this.lb;
    }

}

• main方法使用MyRule策略：

ConfigurationManager.getConfigInstance().setProperty(
                "my-client.ribbon.NFLoadBalancerRuleClassName", MyRule.class.getName());

• 测试，可以看到，调用8080端口比8081端口的多：

{"id":1,"name":"小米","message":"http://localhost:8080/person"}
{"id":1,"name":"小米","message":"http://localhost:8080/person"}
{"id":1,"name":"小米","message":"http://localhost:8080/person"}
{"id":1,"name":"小米","message":"http://localhost:8081/person"}
{"id":1,"name":"小米","message":"http://localhost:8081/person"}
{"id":1,"name":"小米","message":"http://localhost:8080/person"}
{"id":1,"name":"小米","message":"http://localhost:8080/person"}
{"id":1,"name":"小米","message":"http://localhost:8080/person"}
{"id":1,"name":"小米","message":"http://localhost:8080/person"}
{"id":1,"name":"小米","message":"http://localhost:8081/person"}