Spring Cloud 入門教程二、服務消費者（Ribbon）

時間 2019-11-07

標籤 spring cloud 入門教程服務消費者 ribbon 欄目 Spring 简体版

原文原文鏈接

1、前言

一、什麼是Ribbon

Ribbon是Netflix開源的實現了負載均衡等功能的RPC客戶端。
支持HTTP、TCP、UDP協議，且有必定的容錯、緩存等機制。java

Spring Cloud基於Ribbon封裝了Spring Cloud Ribbon，方便結合Eureka、Consul等服務治理框架使用。Ribbon的主要做用是：從服務器端拿到對應服務列表後以負載均衡的方式訪問對應服務。git

從這張圖上來講，Ribbon主要是從Eureka拿到服務列表以後，以負載均衡的策略選擇其中一臺發起調用。github

二、本篇環境信息

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

三、準備工做

Eureka服務端搭建

參考：https://ken.io/note/spring-cloud-eureka-quickstartweb

服務提供者搭建

參考：https://ken.io/note/spring-cloud-eureka-quickstartspring

項	說明
GroupId	io.ken.springcloud.testservice
ArtifactId	testservice

pom.xml、啓動類（App.java）保持不變apache

2、服務提供者準備

一、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

二、DTO準備

建立共用的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;
    }
}

建立Plus.java用做加法運算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;
    }
}

三、編寫服務入口

建立服務入口 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;
    }

}

四、訪問測試

啓動TestService

分別以端口8602,8603啓動testservice。
此時testservice等因而在Eureka Server註冊了兩個實例緩存

分別訪問 http://localhost:8602，http://localhost:8603服務器

將會看到如下信息：app

# 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"
}

3、服務消費者搭建（Ribbon）

一、建立Ribbon項目

建立一個Spring Boot工程

使用maven-archtype-quickstart模板建立項目負載均衡

項	說明
GroupId	io.ken.springcloud.ribbonclient
ArtifactId	ribbonclient

在pom.xml加入相關依賴

<?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>

二、配置Ribbon啓動類

配置啓動類

修改\src\main\java\io\ken\springcloud\eurekaserver\App.java
基於Spring Boot建立啓動類，添加上 @EnableDiscoveryClient 註解

而且向程序的ioc注入一個bean: restTemplate，並經過@LoadBalanced註解代表這個restRemplate開啓負載均衡的功能。

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();
    }
}

三、編寫Eureka服務訪問

建立TestService.java

TestService做爲訪問testservice的代理服務類，經過RestTemplate訪問遠程testservice，Ribbon會負責把servicename替換成實際要訪問的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);
    }
}

四、編寫服務入口

建立TestController

TestController做爲訪問服務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);
    }
}

五、配置Eureka Client

在\src\main下建立文件夾resources文件夾並設置爲Resources Root

在resources文件夾下建立application.yml文件並配置Eureka Client

server:
  port: 8604

spring:
  application:
    name: ribbonclient

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

六、服務訪問/消費測試

RibonClient項目啓動後，訪問 http://localhost:8604/ti
會交替顯示如下內容

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

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