SpringCloud入门(四)-服务消费者(Ribbon)

Ribbon是Netflix发布的云中间层服务开源项目，其主要功能是提供客户端实现负载均衡算法。Ribbon客户端组件提供一系列完善的配置项如连接超时，重试等。简单的说，Ribbon是一个客户端负载均衡器，我们可以在配置文件中Load Balancer后面的所有机器，Ribbon会自动的帮助你基于某种规则（如简单轮询，随机连接等）去连接这些机器，我们也很容易使用Ribbon实现自定义的负载均衡算法。

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创建hello-spring-cloud-web-admin-ribbon目录

创建pom.xml

代码语言：javascript复制

<?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>com.funtl</groupId>
        <artifactId>hello-spring-cloud-dependencies</artifactId>
        <version>1.0.0-SNAPSHOT</version>
        <relativePath>../hello-spring-cloud-dependencies/pom.xml</relativePath>
    </parent>
 
    <artifactId>hello-spring-cloud-web-admin-ribbon</artifactId>
    <packaging>jar</packaging>
 
    <name>hello-spring-cloud-web-admin-ribbon</name>
    <url>http://www.funtl.com</url>
    <inceptionYear>2018-Now</inceptionYear>
 
    <dependencies>
        <!-- Spring Boot Begin -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <!-- Spring Boot End -->
 
        <!-- Spring Cloud Begin -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
        </dependency>
        <!-- Spring Cloud End -->
 
        <!-- 解决 thymeleaf 模板引擎一定要执行严格的 html5 格式校验问题 -->
        <dependency>
            <groupId>net.sourceforge.nekohtml</groupId>
            <artifactId>nekohtml</artifactId>
        </dependency>
    </dependencies>
 
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <mainClass>com.einblatt.hello.spring.cloud.web.admin.ribbon.WebAdminRibbonApplication</mainClass>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

托管pom管理依赖创建项目基础目录src/main/java src/main/resources

创建启动类WebAdminRibbonApplication

代码语言：javascript复制

package com.funtl.hello.spring.cloud.web.admin.ribbon;

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

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

配置程序端口号

代码语言：javascript复制

spring:
  application:
    name: hello-spring-cloud-web-admin-ribbon
  thymeleaf:
    cache: false
    mode: LEGACYHTML5
    encoding: UTF-8
    servlet:
      content-type: text/html
server:
  port: 8764

eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/   #Eureka服务注册中心地址

Configuration

配置注入RestTemplate的Bean，并通过@LoadBalanced注解开启负载均衡功能

代码语言：javascript复制

package com.funtl.hello.spring.cloud.web.admin.ribbon.config;
 
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;
 
@Configuration
public class RestTemplateConfiguration {
    @Bean
    @LoadBalanced
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }
}

创建测试用的Service

在这里我们直接用的程序名替代了具体的 URL 地址，在 Ribbon 中它会根据服务名来选择具体的服务实例，根据服务实例在请求的时候会用具体的 URL 替换掉服务名

代码语言：javascript复制

package com.funtl.hello.spring.cloud.web.admin.ribbon.service;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;
 
@Service
public class AdminService {
 
    @Autowired
    private RestTemplate restTemplate;
    
    public String sayHi(String message) {
        return restTemplate.getForObject("http://HELLO-SPRING-CLOUD-SERVICE-ADMIN/hi?message="   message, String.class);
    }
}

创建测试用的Controller

代码语言：javascript复制

package com.funtl.hello.spring.cloud.web.admin.ribbon.controller;
 
import com.funtl.hello.spring.cloud.web.admin.ribbon.service.AdminService;
import org.springframework.beans.factory.annotation.Autowired;
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 AdminController {
 
    @Autowired
    private AdminService adminService;
 
    @RequestMapping(value = "hi", method = RequestMethod.GET)
    public String sayHi(@RequestParam String message) {
        return adminService.sayHi(message);
    }
}

将Eureka服务启动，服务提供者启动两个（8762和8763两个端口）

访问http://localhost:8764/hi?message=HelloRibbon

多次访问，浏览器交替显示

负载均衡 负载均衡缓存 php maven

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