1.参考文档

https://spring.io/guides/gs/spring-boot/

https://docs.spring.io/spring-boot/docs/current-SNAPSHOT/reference/htmlsingle/

spring boot是非常简单的，已经集成了非常多的东西，只需要写少许代码就能实现一个web服务。本例，两个java文件，一个pom文件，既可。

2.在idea新建一个maven项目。

3.修改pom.xml文件如下：

<?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>org.springframework</groupId>
    <artifactId>gs-spring-boot</artifactId>
    <version>0.1.0</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.3.RELEASE</version>
    </parent>

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

    <properties>
        <java.version>1.8</java.version>
    </properties>


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

</project>

4.在src/main/java下新建package hello

5.在hello下新建文件HelloController.java，内容如下

package hello;

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

@RestController
public class HelloController {

    @RequestMapping("/")
    public String index() {
        return "Greetings from Spring Boot!";
    }

}

6.在hello下新建文件Application.java，内容如下

package hello;

import java.util.Arrays;

import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.Bean;

@SpringBootApplication
public class Application {

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

    //下面的函数不是必需，可以注释掉
//    @Bean
//    public CommandLineRunner commandLineRunner(ApplicationContext ctx) {
//        return args -> {
//
//            System.out.println("Let's inspect the beans provided by Spring Boot:");
//
//            String[] beanNames = ctx.getBeanDefinitionNames();
//            Arrays.sort(beanNames);
//            for (String beanName : beanNames) {
//                System.out.println(beanName);
//            }
//
//        };
//    }

}

7.在pom.xml文件所在的目录执行mvn pakcage，编译打包

8.在pom.xml文件所在目录执行 java -jar target/gs-spring-boot-0.1.0.jar

9.在浏览器输入localhost:8080，可以看到字符串Greetings from Spring Boot!