Spring Cloud 入门教程2、服务消费者（Ribbon）

KenTalk

发布于 2018-09-11 11:36:25

8720

发布于 2018-09-11 11:36:25

文章被收录于专栏：Ken的杂谈Ken的杂谈

一、前言

1、什么是Ribbon

Ribbon是Netflix开源的实现了负载均衡等功能的RPC客户端。

支持HTTP、TCP、UDP协议，且有一定的容错、缓存等机制。

Spring Cloud基于Ribbon封装了Spring Cloud Ribbon，方便结合Eureka、Consul等服务治理框架使用。Ribbon的主要作用是：从服务器端拿到对应服务列表后以负载均衡的方式访问对应服务。

从这张图上来说，Ribbon主要是从Eureka拿到服务列表之后，以负载均衡的策略选择其中一台发起调用。

2、本篇环境信息

框架	版本
Spring Boot	2.0.0.RELEASE
Spring Cloud	Finchley.BUILD-SNAPSHOT
JDK	1.8.x

3、准备工作

Eureka服务端搭建

参考：https://cloud.tencent.com/developer/article/1333816

服务提供者搭建

参考：https://cloud.tencent.com/developer/article/1333816

项	说明
GroupId	io.ken.springcloud.testservice
ArtifactId	testservice

pom.xml、启动类（App.java）保持不变

二、服务提供者准备

1、配置Eureka地址

application.yml 配置

server:
  port: 8602

spring:
  application:
    name: testservice

eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8800/eureka/

app:
  ip: localhost

2、DTO准备

创建共用的ResponseDTO：Result.java

package io.ken.springcloud.testservice.model;

public class Result {

    private int code;

    private String message;

    private Object content;

    private String serviceName;

    private String host;

    public int getCode() {
        return code;
    }

    public void setCode(int code) {
        this.code = code;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    public Object getContent() {
        return content;
    }

    public void setContent(Object content) {
        this.content = content;
    }

    public String getServiceName() {
        return serviceName;
    }

    public void setServiceName(String serviceName) {
        this.serviceName = serviceName;
    }

    public String getHost() {
        return host;
    }

    public void setHost(String host) {
        this.host = host;
    }
}

创建Plus.java用作加法运算RequestDTO

package io.ken.springcloud.testservice.model;

public class Plus {

    private int numA;

    private int numB;

    public int getNumA() {
        return numA;
    }

    public void setNumA(int numA) {
        this.numA = numA;
    }

    public int getNumB() {
        return numB;
    }

    public void setNumB(int numB) {
        this.numB = numB;
    }
}

3、编写服务入口

创建服务入口 TestController.java

package io.ken.springcloud.testservice.controller;

import io.ken.springcloud.testservice.model.Plus;
import io.ken.springcloud.testservice.model.Result;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class TestController {

    @Value("${spring.application.name}")
    private String serviceName;

    @Value("${app.ip}")
    private String address;

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

    @RequestMapping("/")
    public Object index() {
        Result result = new Result();
        result.setServiceName(serviceName);
        result.setHost(String.format("%s:%s", address, port));
        result.setMessage("hello");
        return result;
    }

    @RequestMapping("/plus")
    public Object plus(Plus plus) {
        Result result = new Result();
        result.setServiceName(serviceName);
        result.setHost(String.format("%s:%s", address, port));
        result.setMessage("success");
        result.setContent(plus.getNumA() + plus.getNumB());
        return result;
    }

}

4、访问测试

启动TestService

分别以端口8602,8603启动testservice。

此时testservice等于是在Eureka Server注册了两个实例

分别访问 http://localhost:8602，http://localhost:8603

将会看到以下信息：

# http://localhost:8602
{
  "code": 0,
  "message": "success",
  "content": 0,
  "serviceName": "testservice",
  "host": "localhost:8062"
}

# http://localhost:8603
{
  "code": 0,
  "message": "success",
  "content": 0,
  "serviceName": "testservice",
  "host": "localhost:8063"
}

三、服务消费者搭建（Ribbon）

1、创建Ribbon项目

创建一个Spring Boot工程

使用maven-archtype-quickstart模板创建项目

项	说明
GroupId	io.ken.springcloud.ribbonclient
ArtifactId	ribbonclient

在pom.xml加入相关依赖

<?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>

    <groupId>io.ken.springcloud.ribbonclient</groupId>
    <artifactId>ribbonclient</artifactId>
    <version>1.0-SNAPSHOT</version>

    <name>ribbonclient</name>
    <url>http://ken.io</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.0.RELEASE</version>
    </parent>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Finchley.BUILD-SNAPSHOT</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <dependencies>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
        </dependency>

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

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
            <scope>test</scope>
        </dependency>

    </dependencies>

    <repositories>
        <repository>
            <id>spring-snapshots</id>
            <name>Spring Snapshots</name>
            <url>https://repo.spring.io/libs-snapshot</url>
            <snapshots>
                <enabled>true</enabled>
            </snapshots>
        </repository>
    </repositories>

    <build>
        <finalName>ribbonclient</finalName>
    </build>

</project>

2、配置Ribbon启动类

配置启动类

修改\src\main\java\io\ken\springcloud\eurekaserver\App.java

基于Spring Boot创建启动类，添加上 @EnableDiscoveryClient 注解

并且向程序的ioc注入一个bean: restTemplate，并通过@LoadBalanced注解表明这个restRemplate开启负载均衡的功能。

package io.ken.springcloud.ribbonclient;

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.web.client.RestTemplate;

@EnableDiscoveryClient
@SpringBootApplication
public class App {

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

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

3、编写Eureka服务访问

创建TestService.java

TestService作为访问testservice的代理服务类，通过RestTemplate访问远程testservice，Ribbon会负责把servicename替换成实际要访问的host

package io.ken.springcloud.ribbonclient.service;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;

@Service
public class TestService {

    @Autowired
    private RestTemplate restTemplate;

    public Object index() {
        return restTemplate.getForObject("http://testservice", String.class);
    }

    public Object plus(int numA, int numB) {
        String url = String.format("http://testservice/plus?numA=%s&numB=%s", numA, numB);
        return restTemplate.getForObject(url, String.class);
    }
}

4、编写服务入口

创建TestController

TestController作为访问服务testservice的入口

package io.ken.springcloud.ribbonclient.controller;

import io.ken.springcloud.ribbonclient.service.TestService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class TestController {

    @Autowired
    private TestService testService;

    @RequestMapping("/")
    public Object index() {
        return "ribbon client";
    }

    @RequestMapping("/ti")
    public Object ti() {
        return testService.index();
    }

    @RequestMapping("/plus")
    public Object plus(@RequestParam("numa") int numA, @RequestParam("numb") int numB) {
        return testService.plus(numA, numB);
    }
}

5、配置Eureka Client

在\src\main下创建文件夹resources文件夹并设置为Resources Root

在resources文件夹下创建application.yml文件并配置Eureka Client

server:
  port: 8604

spring:
  application:
    name: ribbonclient

eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8800/eureka/

6、服务访问/消费测试

RibonClient项目启动后，访问 http://localhost:8604/ti

会交替显示以下内容

{
  "code": 0,
  "message": "hello",
  "content": null,
  "serviceName": "testservice",
  "host": "localhost:8602"
}

{
  "code": 0,
  "message": "hello",
  "content": null,
  "serviceName": "testservice",
  "host": "localhost:8603"
}