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Spring Cloud Netflix Ribbon 源码分析

利用 RibbonLoadBalancerClient

新建一个工程

三个模块：

  • user-api：公用 API
  • user-robbon-client：客户端应用
  • user-service-provider：服务端应用

实现 user-robbon-client

配置信息

application.properties:

## 用户 Ribbon 客户端应用
spring.application.name = user-ribbon-client

## 服务端口
server.port = 8080

## 提供方服务名称
provider.service.name = user-service-provider
## 提供方服务主机
provider.service.host = localhost
## 提供方服务端口
provider.service.port = 9090

## 关闭 Eureka Client，显示地通过配置方式注册 Ribbon 服务地址
eureka.client.enabled = false

## 定义 user-service-provider Ribbon 的服务器地址
## 为 RibbonLoadBalancerClient 提供服务列表
user-service-provider.ribbon.listOfServers = \
  http://${provider.service.host}:${provider.service.port}
编写客户端调用
package com.springclouid.lesson7.user.ribbon.client.web.controller;

import com.springclouid.lesson7.domain.User;
import com.sun.org.apache.regexp.internal.RE;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.loadbalancer.LoadBalancerClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

import java.io.IOException;

@RestController
public class UserRibbonController {

//    @Autowired
//    private RestTemplate restTemplate;

    /**
     * 负载均衡器客户端
     */
    @Autowired
    private LoadBalancerClient loadBalancerClient;

    @Value("${provider.service.name}")
    private String providerServiceName;

    @GetMapping("")
    public String index() throws IOException {
        User user = new User();
        user.setId(1L);
        user.setName("xiaoming");

        //选择服务
       ServiceInstance serviceInstance = loadBalancerClient.choose(providerServiceName);
       return loadBalancerClient.execute(providerServiceName, serviceInstance, instance -> {
           // 服务器实例
           String host = instance.getHost();
           int port = instance.getPort();
           String url = "http://" + host + ":" + port + "/user/save";
           RestTemplate restTemplate = new RestTemplate();
           return restTemplate.postForObject(url, user, String.class);
       });
    }
}
编写引导类
package com.springclouid.lesson7.user.ribbon.client;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.ribbon.RibbonClient;

@SpringBootApplication
@RibbonClient("user-service-provider") // 指定目标应用名称
public class UserRibbonClientApplication {
    public static void main(String[] args) {
        SpringApplication.run(UserRibbonClientApplication.class, args);
    }
}

实现 user-service-provider

配置信息

application.properties:

## 用户服务提供方应用信息
spring.application.name = user-service-provider

## 服务端口
server.port = 9090

## 关闭 Eureka Client，显示地通过配置方式注册 Ribbon 服务地址
eureka.client.enabled = false
实现 UserService
package com.springclouid.lesson7.service;

import com.springclouid.lesson7.api.UserService;
import com.springclouid.lesson7.domain.User;
import org.springframework.stereotype.Service;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

/**
 * 内存实现
 */
@Service
public class InMemoryUserService implements UserService {

    private Map<Long, User> repository = new ConcurrentHashMap<>();
    @Override
    public boolean saveUser(User user) {
        return repository.put(user.getId(), user) == null;
    }

    @Override
    public List<User> findAll() {
        return new ArrayList<>(repository.values());
    }
}
实现 Web 服务
package com.springclouid.lesson7.user.service.web.controller;

import com.springclouid.lesson7.api.UserService;
import com.springclouid.lesson7.domain.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;

/**
 * 服务提供方
 */
@RestController
public class UserServiceProviderController {
    @Autowired
    private UserService userService;

    @PostMapping("/user/save")
    public boolean user(@RequestBody User user) {
        return userService.saveUser(user);
    }
}
编写引导类
package com.springclouid.lesson7;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;


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

分析调用链路

选择服务器逻辑

LoadBalancerClient（LoadBalancerClient） -> ILoadBalancer（ZoneAwareLoadBalancer） -> IRule (ZoneAvoidanceRule)

自定义实现 IRule

扩展 AbstractLoadBalancerRule ： MyRule
package com.springclouid.lesson7.user.ribbon.client.rule;

import com.netflix.client.config.IClientConfig;
import com.netflix.loadbalancer.AbstractLoadBalancerRule;
import com.netflix.loadbalancer.ILoadBalancer;
import com.netflix.loadbalancer.Server;

import java.util.List;

public class MyRule extends AbstractLoadBalancerRule {
    @Override
    public void initWithNiwsConfig(IClientConfig iClientConfig) {

    }

    @Override
    public Server choose(Object key) {
        ILoadBalancer iLoadBalancer = getLoadBalancer();

        // 获取所有可达服务器列表
        List<Server> servers = iLoadBalancer.getReachableServers();
        if (servers.isEmpty()) {
            return null;
        }

        // 永远选择最后一台服务器
        Server targetServer = servers.get(servers.size() - 1);
        return targetServer;
    }
}
将 MyRule 暴露成 Bean

通过RibbonClientConfiguration学习源码：

	@Bean
	@ConditionalOnMissingBean
	public IRule ribbonRule(IClientConfig config) {
		if (this.propertiesFactory.isSet(IRule.class, name)) {
			return this.propertiesFactory.get(IRule.class, config, name);
		}
		ZoneAvoidanceRule rule = new ZoneAvoidanceRule();
		rule.initWithNiwsConfig(config);
		return rule;
	}
    /**
     * 将 {@link MyRule} 暴露成 {@link Bean}
     * @return {@link MyRule}
     */
    @Bean
    public IRule myRule() {
        return new MyRule();
    }

配置化实现组件

通过学习PropertiesFactory 源码：

	public PropertiesFactory() {
		classToProperty.put(ILoadBalancer.class, "NFLoadBalancerClassName");
		classToProperty.put(IPing.class, "NFLoadBalancerPingClassName");
		classToProperty.put(IRule.class, "NFLoadBalancerRuleClassName");
		classToProperty.put(ServerList.class, "NIWSServerListClassName");
		classToProperty.put(ServerListFilter.class, "NIWSServerListFilterClassName");
	}

可知NFLoadBalancerClassName 等是可以配置的

实现 IPing : MyPing
/**
 * 实现{@link IPing} 接口：检查对象 /health 是否正常
 */
public class MyPing implements IPing {
    @Override
    public boolean isAlive(Server server) {
        String host = server.getHost();
        int port = server.getPort();

        // 拼接url
        // 通过 spring 的组件来实现URL的拼装
        UriComponentsBuilder builder = UriComponentsBuilder.newInstance();
        builder.scheme("http");
        builder.host(host);
        builder.port(port);
        builder.path("actuator/health");
        URI uri = builder.build().toUri();
        RestTemplate restTemplate = new RestTemplate();

        ResponseEntity responseEntity = restTemplate.getForEntity(uri, String.class);

        // 当相应状态等于200时，返回Live，否则false
        return HttpStatus.OK.equals(responseEntity.getStatusCode());
    }
}
增加配置

application.properties:

## 扩展IPing实现
user-service-provider.ribbon.NFLoadBalancerPingClassName =\
  com.springclouid.lesson7.user.ribbon.client.ping.MyPing