SpringCloud简单入门

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最新推荐文章于 2025-06-18 09:30:04 发布

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分类专栏： spring cloud 文章标签： spring cloud

本文链接：https://blog.youkuaiyun.com/genaro26/article/details/87366490

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本文详细介绍了使用SpringCloud搭建微服务架构的过程，包括服务注册中心、服务提供者和服务消费者的创建，以及通过Ribbon和RestTemplate实现的服务间负载均衡调用。

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在学习SpringCloud遇到过许多坑，这里记录一下。

首先，新建一个maven pom工程，命名为spring-cloud-demo-parent，该工程作为父工程

pom.xml的内容为：

<?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>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.1.2.RELEASE</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
  	<groupId>com.huangbl</groupId>
  	<artifactId>spring-cloud-demo-parent</artifactId>
  	<version>1.0.0-SNAPSHOT</version>
  	<packaging>pom</packaging>
  	<name>spring-cloud-demo-parent</name>
  	
  	<properties>
  		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    	<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
		<java.version>1.8</java.version>
		<spring-cloud.version>Finchley.RELEASE</spring-cloud.version>
	</properties>
  	
  	<dependencies>
  		<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </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>

一、创建服务注册中心

在spring-cloud-demo-parent中新建一个模块cloud-demo-registry-center，其pom.xml的内容为

<?xml version="1.0"?>
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  	<modelVersion>4.0.0</modelVersion>
  	<parent>
    	<groupId>com.huangbl</groupId>
    	<artifactId>spring-cloud-demo-parent</artifactId>
    	<version>1.0.0-SNAPSHOT</version>
  	</parent>
  	<artifactId>cloud-demo-registry-center</artifactId>
  	<packaging>war</packaging>
  	<name>cloud-demo-registry-center Maven Webapp</name>
  	<url>http://maven.apache.org</url>
  	<dependencies>
  		<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>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        </dependency>
  	</dependencies>
  	<build>
    	<finalName>cloud-demo-registry-center</finalName>
    	<plugins>
            <!--<plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>-->
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <mainClass>com.huangbl.cloud.registry.center.Application</mainClass>
                </configuration>
                <executions>
                    <execution>
                        <goals>
                            <goal>repackage</goal><!--可以把依赖的包都打包到生成的Jar包中-->
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
  	</build>
</project>

新建包名com.huangbl.cloud.registry.center，并在该包下建立Application和ServletInitializer.java两个类，其内容分别为：

Application.java

package com.huangbl.cloud.registry.center;

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

/**
 * @className Application
 * @description TODO
 * @author huangbl
 * @date 2019/02/14 17:01
 * @return
 */
@EnableEurekaServer
@SpringBootApplication
public class Application {

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

其中，@EnableEurekaServer注解标识这是一个服务注册中心

ServletInitializer.java

package com.huangbl.cloud.registry.center;

import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.web.servlet.support.SpringBootServletInitializer;

public class ServletInitializer extends SpringBootServletInitializer {

    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
        return application.sources(Application.class);
    }

}

在src/main/resources下新建application.properties

server.port=8081
server.servlet.context-path=/cloud-demo-registry-center

spring.application.name=eureka-cloud-demo-registry-center

eureka.instance.hostname=127.0.0.1
eureka.client.register-with-eureka=false
eureka.client.fetch-registry=false
eureka.client.service-url.defaultZone=http://${eureka.instance.hostname}:${server.port}/eureka/

其中

eureka.client.register-with-eureka=false
eureka.client.fetch-registry=false

表示这是一个eureka server，否则程序会尝试注册成eureka client。

此时，运行Application.java，地址栏输入“http://127.0.0.1:8081/cloud-demo-registry-center/”可进入eureka server界面

二、创建服务提供者

在spring-cloud-demo-parent内建立一个maven模块cloud-demo-provider，其pom.xml内容为

<?xml version="1.0"?>
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  	<modelVersion>4.0.0</modelVersion>
  	<parent>
    	<groupId>com.huangbl</groupId>
    	<artifactId>spring-cloud-demo-parent</artifactId>
    	<version>1.0.0-SNAPSHOT</version>
  	</parent>
  	<artifactId>cloud-demo-provider</artifactId>
  	<packaging>war</packaging>
  	<name>cloud-demo-provider Maven Webapp</name>
  	<url>http://maven.apache.org</url>
  	<dependencies>
    	<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>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
  	</dependencies>
  	<build>
    	<finalName>cloud-demo-provider</finalName>
    	<plugins>
            <!--<plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>-->
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <mainClass>com.huangbl.cloud.provider.Application</mainClass>
                </configuration>
                <executions>
                    <execution>
                        <goals>
                            <goal>repackage</goal><!--可以把依赖的包都打包到生成的Jar包中-->
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
  	</build>
</project>

新建包com.huangbl.cloud.provider，在该包下建立Application.java和ServletInitializer.java两个文件，文件内容和cloud-demo-registry-center中的大致相同，唯一不同的是Application.java中将@EnableEurekaServer换成@EnableEurekaClient

在src/main/resources下新建application.properties，文件内容为

server.port=8082
server.servlet.context-path=/cloud-demo-provider

spring.application.name=eureka-cloud-demo-provider

eureka.client.service-url.defaultZone=http://127.0.0.1:8081/cloud-demo-registry-center/eureka

其中spring.application.name是向服务注册中心注册时的Application名称，后面服务消费者访问服务提供者相关接口时也需要用到，而eureka.client.service-url.defaultZone是连接服务注册中心的地址，这里有个坑需要注意一下，如果服务注册中心（cloud-demo-registry-center）设置了server.servlet.context-path，假设此时该值为cloud-demo-registry-center，则cloud-demo-provider中eureka.client.service-url.defaultZone的值需要在eureka前加上cloud-demo-registry-center，即“http://127.0.0.1:8081/cloud-demo-registry-center/eureka”，否则为“http://127.0.0.1:8081/eureka”。

在com.huangbl.cloud.provider下新建controller包，并创建UserController.java

package com.huangbl.cloud.provider.controller;

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

@RestController
@RequestMapping("/user")
public class UserController {

	
	@RequestMapping("/find")
	public String find(String nickName) {
		String result = "Hello " + nickName + ",this is cloud-demo-provider";
		return result;
	}
	
}

三、创建服务消费者

同样的道理，在spring-cloud-demo-parent中建立子模块cloud-demo-consumer，其pom.xml内容为

<?xml version="1.0"?>
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  	<modelVersion>4.0.0</modelVersion>
  	<parent>
    	<groupId>com.huangbl</groupId>
    	<artifactId>spring-cloud-demo-parent</artifactId>
    	<version>1.0.0-SNAPSHOT</version>
  	</parent>
  	<artifactId>cloud-demo-consumer</artifactId>
  	<packaging>war</packaging>
  	<name>cloud-demo-consumer Maven Webapp</name>
  	<url>http://maven.apache.org</url>
  	<dependencies>
    	<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>
            <scope>provided</scope>
        </dependency>
        <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>
  	</dependencies>
  	<build>
    	<finalName>cloud-demo-consumer</finalName>
    	<plugins>
            <!--<plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>-->
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <mainClass>com.huangbl.cloud.consumer.Application</mainClass>
                </configuration>
                <executions>
                    <execution>
                        <goals>
                            <goal>repackage</goal><!--可以把依赖的包都打包到生成的Jar包中-->
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
  	</build>
</project>

新建com.huangbl.cloud.consumer包，在该包下建立Application.java和ServletInitializer.java文件

Application.java

package com.huangbl.cloud.consumer;

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.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

/**
 * @className Application
 * @description TODO
 * @author huangbl
 * @date 2018/11/26 17:01
 * @return
 */
@EnableEurekaClient
@EnableDiscoveryClient
@SpringBootApplication
public class Application {

	@Bean
    @LoadBalanced
    RestTemplate restTemplate() {
        return new RestTemplate();
    }
	
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

由于本文中服务与服务之间的调用采用ribbon+restTemplate（ribbon是一个负载均衡客户端，如果服务提供者有多个，则会自动选择其中一个）的方式，所以需要服务启动的时候注入RestTemplate。

ServletInitializer.java内容与前面的一样

在src/main/resources下新建application.properties

server.port=8083
server.servlet.context-path=/cloud-demo-consumer

spring.application.name=eureka-cloud-demo-consumer
eureka.client.service-url.defaultZone=http://127.0.0.1:8081/cloud-demo-registry-center/eureka

在com.huangbl.cloud.consumer下新建controller包，创建TestController.java

package com.huangbl.cloud.consumer.controller;

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
@RequestMapping("/test")
public class TestController {

	@Autowired
	private RestTemplate restTemplate;
	
	@RequestMapping("/index")
	public String index() {
		String result = restTemplate.getForObject("http://EUREKA-CLOUD-DEMO-PROVIDER/cloud-demo-provider/user/find?nickName=sheep", String.class);
		return result;
	}
	
}

上面的代码就完成了调用服务生产者的接口，其中的“EUREKA-CLOUD-DEMO-PROVIDER”就是服务提供者中配置的spring.application.name（这里有个坑，访问的名称需要以http://127.0.0.1:8081/cloud-demo-registry-center/界面上显示的为准，界面显示的为全大写，而我设置的是小写），“http://EUREKA-CLOUD-DEMO-PROVIDER”会在请求时替换成实际的服务提供者的ip和端口，不能直接写成ip+端口的方式，这样无法请求而且也达不到负载均衡的效果。