概述

在微服务架构中，业务都会被拆分成一个独立的服务，服务与服务的通讯是基于 http restful 的。Spring cloud 有两种服务调用方式，一种是 ribbon + restTemplate，另一种是 feign。

Ribbon+RestTemplate

Ribbon 是一个负载均衡客户端，可以很好的控制 http 和 tcp 的一些行为。

创建服务消费者

完整pom文件

<?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 https://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>2.2.2.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.xzt</groupId>
    <artifactId>cloud-ribbon-service</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>cloud-ribbon-service</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Hoxton.SR1</spring-cloud.version>
    </properties>

    <dependencies>
        <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>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
    </dependencies>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

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

</project>

application.yml

spring:
  application:
    name: cloud-ribbon-service

server:
  port: 8764

eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/

Configuration

配置注入 RestTemplate 的 Bean，并通过 @LoadBalanced 注解表明开启负载均衡功能 s

package com.xzt.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 {
    @LoadBalanced
    @Bean
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }
}

Service

package com.xzt.ribbon.test.service;

import com.xzt.ribbon.test.beans.User;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;

@Service
public class AdminService {

    private Logger logger = LoggerFactory.getLogger(AdminService.class);
    @Autowired
    private RestTemplate restTemplate;

    public String sayHi(String message) {
        return restTemplate.getForObject("http://CLOUD-ADMIN-SERVICE/hi?message=" + message, String.class);
    }

    public String postHi(String userName, String password) {
        User user = new User();
        user.setUserName(userName);
        user.setPassword(password);
        User res = restTemplate.postForObject("http://CLOUD-ADMIN-SERVICE/req_post", user, User.class);
        return String.format("%s ,welcome! I am from port %s", userName, res.getPort());
    }
}

Controller

package com.xzt.ribbon.test.controller;

import com.xzt.ribbon.test.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.RestController;

@RestController
public class AdminController {
    @Autowired
    private AdminService adminService;

    @RequestMapping(value = "hi", method = RequestMethod.GET)
    public String sayHi(String message) {
        return adminService.sayHi(message);
    }

    @RequestMapping(value = "req_post", method = RequestMethod.GET)
    public String postHi(String userName, String password) {
        return adminService.postHi(userName, password);
    }
}

在`cloud-admin-service` 增加以下接口

@RequestMapping(value = "req_post", method = RequestMethod.POST)
public User postHi(@RequestBody User user){
    logger.info("userName:{}----password:{}",user.getUserName(),user.getPassword());
    user.setPort(port);
    return user;
}

测试

GET

访问http://localhost:8764/hi?message=12345,将出现以下内容

1	Hi，your message is : 12345 i am from port : 8762

POST

访问http://localhost:8764/req_post?userName=mo&password=123456,将出现以下内容

1	mo ,welcome! I am from port 8762

如果配置多个cloud-admin-service服务，多次访问此接口，端口号应当随之变化

Spring Cloud Netflix 创建服务消费者——Ribbon（四）

概述