spring-cloud-ribbon负载均衡(二)

通过eureka+ribbon来实现负载均衡，ribbon是一个为客户端提供负载均衡功能的服务，它内部提供了一个叫做ILoadBalance的接口代表负载均衡器的操作。RestTemplate 构建RestTemplate对应的bean，在method上使用注解LoadBalanced表示restTemplate使用LoadBalancerClient执行请求。ribbonServerList会被DiscoveryEnabledNIWSServerList重写，扩展成从Eureka注册中心中获取服务端列表。同时它也会用NIWSDiscoveryPing来取代IPing，它将职责委托给Eureka来确定服务端是否已经启动。

1、注册发现服务

(1)application

package com.neo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;

@SpringBootApplication
@EnableEurekaServer
public class SpringCloudEurekaApplication {

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

(2)properties

spring.application.name=spring-cloud-eureka

server.port=8000
eureka.client.register-with-eureka=false
eureka.client.fetch-registry=false

eureka.client.serviceUrl.defaultZone=http://localhost:8000/eureka/

(3)pom.xml

注：eureka依赖了ribbon，所以不需引入ribbon的jar包

<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>4.0.0modelVersion>

    <groupId>com.wei.qingroupId>
    <artifactId>spring-cloud-eurekaartifactId>
    <version>0.0.1-SNAPSHOTversion>
    <packaging>jarpackaging>

    <name>spring-cloud-eurekaname>
    <description>Demo project for Spring cloud eurekadescription>

    <parent>
        <groupId>org.springframework.bootgroupId>
        <artifactId>spring-boot-starter-parentartifactId>
        <version>1.5.3.RELEASEversion>
        <relativePath/> 
    parent>

    <properties>
        <project.build.sourceEncoding>UTF-8project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8project.reporting.outputEncoding>
        <java.version>1.7java.version>
        <spring-cloud.version>Dalston.RELEASEspring-cloud.version>
    properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-eureka-serverartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-testartifactId>
            <scope>testscope>
        dependency>
    dependencies>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloudgroupId>
                <artifactId>spring-cloud-dependenciesartifactId>
                <version>${spring-cloud.version}version>
                <type>pomtype>
                <scope>importscope>
            dependency>
        dependencies>
    dependencyManagement>

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


project>

2、ribbon-service

(1)corsConfig

package com.wei.qin;

import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.CorsRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

/**
 * 配置跨域访问，开发环境使用，生产环境可取消
 * 
 * @author Davis
 * @date 2017年6月8日 下午5:28:59
 */
@Configuration  
public class CorsConfig extends WebMvcConfigurerAdapter {  

    @Override  
    public void addCorsMappings(CorsRegistry registry) {  
        registry.addMapping("/**")  
                .allowedOrigins("*")   
                .allowCredentials(true)  
                .allowedMethods("GET", "POST", "DELETE", "PUT")  
                .maxAge(3600);  
    }  

}  

(2)application

package com.wei.qin;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.http.client.SimpleClientHttpRequestFactory; 
import org.springframework.web.client.RestTemplate;

/**
 * 
 * 
 * @auther dwx
 *
 * 2017年8月21日
 */
@SpringBootApplication
@EnableDiscoveryClient 
public class ClientApplication {

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

    /**
     * LoadBalanced 注解表明restTemplate使用LoadBalancerClient执行请求
     *
     * @return
     */
    @Bean
    @LoadBalanced
    public RestTemplate restTemplate() {
        RestTemplate template = new RestTemplate();
        SimpleClientHttpRequestFactory factory = (SimpleClientHttpRequestFactory) template.getRequestFactory();
        factory.setConnectTimeout(3000);
        factory.setReadTimeout(3000);
        return template;
    }  
}

(3)ClientController

package com.wei.qin;

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

@RestController
public class ClientController {

    @Autowired
    RestTemplate client;


    @RequestMapping("/test")
    public String helloWorld() {
        return client.getForObject("http://spring-cloud-producer/hello?name=111", String.class);
    }
}

注：spring-cloud-producer为其他服务的serviceid

(4)properties
默认情况下，ribbon负载均衡使用的是轮询策略，也可以自定义负载均衡策略。比如自定义随机策略：
1、在properties中加入下面代码：
ribbon-service.ribbon.NFLoadBalancerRuleClassName=com.netflix.loadbalancer.RandomRule
注： ribbon-service是spring.application.name

spring.application.name=ribbon-service
server.port=9000
eureka.client.serviceUrl.defaultZone=http://localhost:8000/eureka/

(5)pom.xml

<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>4.0.0modelVersion>

  <groupId>com.wei.qingroupId>
  <artifactId>springcloudribbon2artifactId>
  <version>0.0.1-SNAPSHOTversion>
  <packaging>jarpackaging>

  <name>springcloudribbon2name>
  <url>http://maven.apache.orgurl> 

   <parent>
        <groupId>org.springframework.bootgroupId>
        <artifactId>spring-boot-starter-parentartifactId>
        <version>1.5.3.RELEASEversion>
        <relativePath/> 
    parent>

    <properties>
        <project.build.sourceEncoding>UTF-8project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8project.reporting.outputEncoding>
        <java.version>1.7java.version>
        <spring-cloud.version>Dalston.RELEASEspring-cloud.version>
    properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-eurekaartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-testartifactId>
            <scope>testscope>
        dependency>
    dependencies>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloudgroupId>
                <artifactId>spring-cloud-dependenciesartifactId>
                <version>${spring-cloud.version}version>
                <type>pomtype>
                <scope>importscope>
            dependency>
        dependencies>
    dependencyManagement>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.bootgroupId>
                <artifactId>spring-boot-maven-pluginartifactId>
            plugin>
        plugins>
    build>
project>

3、其他服务spring-cloud-producer
(1)properties

spring.application.name=spring-cloud-producer
server.port=8006
eureka.client.serviceUrl.defaultZone=http://localhost:8000/eureka/

(2)controller

package com.neo.controller;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HelloController {

    @RequestMapping("/hello")
    public String index(@RequestParam String name) {
        return "hello "+name+"，this is first messge";
    }
}

(3)application

package com.neo;

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

@SpringBootApplication
@EnableDiscoveryClient
public class ProducerApplication {

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