从Spring Initializr开始

出识springcloud我们这里需要建立两个项目来感受下微服务

一、配置服务

1. Spring Initializr. 用idea自带的 Spring Initializr. 建立第一个项目

2.加入依赖

<?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 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>2.3.1.RELEASE</version>
      <relativePath/> <!-- lookup parent from repository -->
   </parent>
   <groupId>com.example</groupId>
   <artifactId>demo</artifactId>
   <version>0.0.1-SNAPSHOT</version>
   <name>demo</name>
   <description>Demo project for Spring Boot</description>

   <properties>
      <java.version>1.8</java.version>
      <spring-cloud.version>Hoxton.SR5</spring-cloud.version>
   </properties>

   <dependencies>
      <dependency>
         <groupId>org.springframework.cloud</groupId>
         <artifactId>spring-cloud-config-server</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>

3.修改application.properties文件改个端口不然后面启动两个项目端口冲突

server.port=8888

4.在你的git仓库中提交一个文件a-bootiful-client.properties 用以感受我们的springcloud项目与Git的结合使用

message = Hello world

文件中写上这个就行便于等下测试

5。再次修改application.properties

spring.cloud.config.server.git.uri=https://gitee.com/你的仓库地址.git
#spring.cloud.config.server.git.searchPaths=config
#
spring.cloud.config.server.git.username=你的用户名

spring.cloud.config.server.git.password=你的密码

spring.application.name=a-bootiful-client#刚才上传的文件名

6.修改DemoApplication 加上@EnableConfigServer注解

package com.example.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.config.server.EnableConfigServer;

@EnableConfigServer
@SpringBootApplication
public class DemoApplication {

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

}

7.这个时候我们可以来建立第二项目啦

8.pom.xml

<?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>2.3.1.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>demo</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Hoxton.SR5</spring-cloud.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-config</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>

9.org.springframework.cloud:spring-cloud-starter-config依赖然后在properties里配置就能保证在不需要重启jvm的情况下（当然还需要别的依赖和操作请看到最后）刷新配置

这里我写在了bootstrap.properties文件里你也可以写在application.properties或者application.yml里

spring.application.name=a-bootiful-client
# N.B. this is the default:
spring.cloud.config.uri=http://localhost:8888

启用/refresh 修改application.properties

management.endpoints.web.exposure.include=*

10.客户端可以通过使用传统的机制（如访问所述配置服务器的任何值@ConfigurationProperties或@Value("${…}")或通过Environment）

package com.example.demo;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.context.config.annotation.RefreshScope;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@SpringBootApplication
public class DemoApplication {

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

}
@RefreshScope
@RestController
class MessageRestController {

    @Value("${message:Hello default}")
    private String message;

    @RequestMapping("/message")
    String getMessage() {
        return this.message;
    }
}

11.千辛万苦终于来到测试了

① http://localhost:8080/message 你会看见Hello world

②修改a-bootiful-client.properties（记得commit）的message 改为Hello spring 访问http://localhost:8888/a-bootiful-client/default你可以查看是否已经更改

③再点击http://localhost:8080/message这个你会发现依然是Hello world 字样what？？？？不是说是无刷新获取的么？？？？？这个时候不要苦恼继续进行第四步

④以post方式请求http://localhost:8080/actuator/refresh 然后再http://localhost:8080/message看看是不是已经变成了Hello spring？？？？那就对了

（这里是用的org.springframework.boot:spring-boot-starter-actuator 使用refresh以强制客户端刷新自身并提取新值）