ribbon源码全流程分析

ribbon源码分析：https://www.processon.com/view/link/615166bc079129511c8f2b88

一、环境搭建

创建demo-user-service工程

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<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>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.8.RELEASE</version>
    </parent>

    <groupId>com.zzhua</groupId>
    <artifactId>demo-user-service</artifactId>
    <version>1.0-SNAPSHOT</version>


    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
            <version>2.0.1.RELEASE</version>
        </dependency>
        <!--
		<dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
            <version>2.0.1.RELEASE</version>
        </dependency>
		-->
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

application.yml

server:
  port: 8080
order:
  ribbon:
    listOfServers: http://127.0.0.1:8081/,http://127.0.0.1:8082/

启动类

package com.zzhua;

import com.netflix.client.config.IClientConfig;
import com.netflix.loadbalancer.*;
import com.zzhua.rule.FirstRule;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;

import java.util.List;

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

UserController

package com.zzhua.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.cloud.client.loadbalancer.LoadBalancerClient;
import org.springframework.context.annotation.Bean;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

@RestController
public class UserController {
    
    

    @Autowired
    private LoadBalancerClient loadBalancerClient;

    @Autowired
    private RestTemplate restTemplate;

    @RequestMapping("user")
    public Object user() {
    
    
        ServiceInstance si = loadBalancerClient.choose("order");
        String result = new RestTemplate().getForObject(String.format("http://%s:%s/order", si.getHost(), si.getPort()), String.class);
        return result;
    }

    @RequestMapping("user2")
    public Object user2() {
    
    
        String result = restTemplate.getForObject("http://order/order", String.class);
        return result;
    }

    @Bean
    @LoadBalanced
    public RestTemplate restTemplate() {
    
    
        return new RestTemplate();
    }
}

创建demo-order-service

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<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>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.8.RELEASE</version>
    </parent>

    <groupId>com.zzhua</groupId>
    <artifactId>demo-order-service</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

application.yml为空内容

启动类

package com.zzhua;

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

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

OrderController

package com.zzhua.controller;

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

@RestController
public class OrderController {
    
    

    @Value("${server.port}")
    private int port;

    @RequestMapping("order")
    public Object order() {
    
    
        return "order: " + port;
    }
}

测试

访问：localhost:8080/user & localhost:8080/user2 都可以看到负载均衡的效果