初学 Spring Boot，顺便记录下学习中碰到的问题，只针对初学入门需求者。
环境：
- IDE环境：Spring Tool Suite（Version: 3.7.3.RELEASE）
- Java环境：jdk1.8.0_172（x64）
- 依赖环境：Maven（apache-maven-3.3.9）
一、开发环境配置
配置开发环境部分，可以度娘搜索，或者直接参考本博客文章《Maven 的初识、安装和配置》、《单独搭建一套 WEB 开发环境》等文章，这里不再赘述。
二、新建一个Maven项目
File -》 New -》 Other；
找到 Maven 下 Maven Project，一路 Next 按钮。。。
填上 Group Id、Artifact Id，选择 Version，修改 Package，直接 Finish。
三、查看代码目录结构
3.1 自动生成目录结构如下：
3.2 自动生成代码如下：
App.java：
package com.menglanglang.test.springboot;
/**
* Hello world!
*
*/
public class App
{
public static void main( String[] args )
{
System.out.println( "Hello World!" );
}
}AppTest.java 为 junit 自动生成的测试代码，无关紧要。
pom.xml：
<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>com.menglanglang</groupId>
<artifactId>test-springboot</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>test-springboot</name>
<url>http://maven.apache.org</url>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
</dependencies>
</project>四、补全代码目录结构
由于在项目开发中，有很多静态资源，一般都放在 resources 目录下，所以这里补充两个资源目录。
方法：项目 -》 右键 -》New -》 Source Folder，在 Folder Name 中输入 src/main/resources 和 src/test/resources，补全后代码目录结构如下：
如果此时运行代码：选中 App.java -》 右键 -》 Java Application。
结果为：Hello World!
五、修改代码
pom.xml：
<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>com.menglanglang</groupId>
<artifactId>test-springboot</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>test-springboot</name>
<url>http://blog.csdn.net/tzhuwb</url>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
<!-- 该依赖包提供了MVC、AOP等的依赖包 -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<version>1.4.2.RELEASE</version>
</dependency>
</dependencies>
<!-- Add Spring repositories -->
<!-- (you don't need this if you are using a .RELEASE version) -->
<repositories>
<repository>
<id>spring-snapshots</id>
<url>http://repo.spring.io/snapshot</url>
<snapshots>
<enabled>true</enabled>
</snapshots>
</repository>
<repository>
<id>spring-milestones</id>
<url>http://repo.spring.io/milestone</url>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<id>spring-snapshots</id>
<url>http://repo.spring.io/snapshot</url>
</pluginRepository>
<pluginRepository>
<id>spring-milestones</id>
<url>http://repo.spring.io/milestone</url>
</pluginRepository>
</pluginRepositories>
</project>App.java：
package com.menglanglang.test.springboot;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
/**
* @desc 应用入口
*
* @author 孟郎郎
* @blog http://blog.csdn.net/tzhuwb
* @version 1.0
* @date 2017年11月2日下午6:48:19
*/
@SpringBootApplication
public class App {
public static void main(String[] args) {
SpringApplication.run(App.class, args);
System.out.println("Hello World!");
}
}如果此时运行代码：选中 App.java -》 右键 -》 Java Application（或者 Spring Boot App）。
结果为：
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v1.4.2.RELEASE)
2018-05-24 21:11:59.093 INFO 13028 --- [ restartedMain] com.menglanglang.test.springboot.App : Starting App on LangLang-PC with PID 13028 (D:\STS\sts-bundle\workspace\test-springboot\target\classes started by LangLang in D:\STS\sts-bundle\workspace\test-springboot)
2018-05-24 21:11:59.095 INFO 13028 --- [ restartedMain] com.menglanglang.test.springboot.App : No active profile set, falling back to default profiles: default
2018-05-24 21:11:59.141 INFO 13028 --- [ restartedMain] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@62128c3a: startup date [Thu May 24 21:11:59 CST 2018]; root of context hierarchy
2018-05-24 21:12:00.653 INFO 13028 --- [ restartedMain] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 8080 (http)
2018-05-24 21:12:00.668 INFO 13028 --- [ restartedMain] o.apache.catalina.core.StandardService : Starting service Tomcat
2018-05-24 21:12:00.669 INFO 13028 --- [ restartedMain] org.apache.catalina.core.StandardEngine : Starting Servlet Engine: Apache Tomcat/8.5.6
2018-05-24 21:12:00.747 INFO 13028 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext
2018-05-24 21:12:00.747 INFO 13028 --- [ost-startStop-1] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 1610 ms
2018-05-24 21:12:00.884 INFO 13028 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean : Mapping servlet: 'dispatcherServlet' to [/]
2018-05-24 21:12:00.887 INFO 13028 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'characterEncodingFilter' to: [/*]
2018-05-24 21:12:00.888 INFO 13028 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2018-05-24 21:12:00.888 INFO 13028 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'httpPutFormContentFilter' to: [/*]
2018-05-24 21:12:00.888 INFO 13028 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'requestContextFilter' to: [/*]
2018-05-24 21:12:01.129 INFO 13028 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@62128c3a: startup date [Thu May 24 21:11:59 CST 2018]; root of context hierarchy
2018-05-24 21:12:01.182 INFO 13028 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error]}" onto public org.springframework.http.ResponseEntity<java.util.Map<java.lang.String, java.lang.Object>> org.springframework.boot.autoconfigure.web.BasicErrorController.error(javax.servlet.http.HttpServletRequest)
2018-05-24 21:12:01.183 INFO 13028 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error],produces=[text/html]}" onto public org.springframework.web.servlet.ModelAndView org.springframework.boot.autoconfigure.web.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse)
2018-05-24 21:12:01.207 INFO 13028 --- [ restartedMain] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-05-24 21:12:01.208 INFO 13028 --- [ restartedMain] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-05-24 21:12:01.238 INFO 13028 --- [ restartedMain] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-05-24 21:12:01.363 INFO 13028 --- [ restartedMain] o.s.b.d.a.OptionalLiveReloadServer : LiveReload server is running on port 35729
2018-05-24 21:12:01.426 INFO 13028 --- [ restartedMain] o.s.j.e.a.AnnotationMBeanExporter : Registering beans for JMX exposure on startup
2018-05-24 21:12:01.473 INFO 13028 --- [ restartedMain] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8080 (http)
2018-05-24 21:12:01.479 INFO 13028 --- [ restartedMain] com.menglanglang.test.springboot.App : Started App in 2.81 seconds (JVM running for 3.238)
Hello World!到此，恭喜你，你的第一个 Spring Boot 程序已开发完毕。