Spring boot hello world

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Spring boot hello world example

Directory Structure

pom.xml file

Modify auto created POM file. We need to add parent in pom to make it a spring boot application. After that add spring-boot-starter-web dependency and java version. 

<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>codesjava</groupId>
  <artifactId>SpringBoot01</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>jar</packaging>
 
  <name>SpringBoot01</name>
  <url>http://maven.apache.org</url>
 
  <properties>
    <java.version>1.8</java.version>  
  </properties>
 
  <parent>  
    <groupId>org.springframework.boot</groupId>  
    <artifactId>spring-boot-starter-parent</artifactId>  
    <version>1.4.2.RELEASE</version>  
 </parent>  
 
  <dependencies>
    <dependency>  
        <groupId>org.springframework.boot</groupId>  
        <artifactId>spring-boot-starter-web</artifactId>  
    </dependency>  
 
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
  </dependencies>
</project>

Now, right click on project -> click on Maven -> click on update project -> Popup window will open -> click Ok to update the project.
It is a initializer class which runs a SpringApplication.

package com.w3schools;
 
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
 
@SpringBootApplication  
public class App {
    public static void main( String[] args ) {
    	SpringApplication.run(App.class, args);  
    }
}

On console

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v1.4.2.RELEASE)
 
2018-04-30 23:56:45.653  INFO 12576 --- [           main] com.w3schools.App                        : Starting App on INDEL-L-28V8JC2 with PID 12576 (started by jsingh in D:\Spring Security\SpringBoot01)
2018-04-30 23:56:45.670  INFO 12576 --- [           main] com.w3schools.App                        : No active profile set, falling back to default profiles: default
2018-04-30 23:56:45.776  INFO 12576 --- [           main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@70e8f8e: startup date [Mon Apr 30 23:56:45 IST 2018]; root of context hierarchy
2018-04-30 23:56:47.757  INFO 12576 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 8080 (http)
2018-04-30 23:56:47.778  INFO 12576 --- [           main] o.apache.catalina.core.StandardService   : Starting service Tomcat
2018-04-30 23:56:47.779  INFO 12576 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet Engine: Apache Tomcat/8.5.6
2018-04-30 23:56:48.000  INFO 12576 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2018-04-30 23:56:48.000  INFO 12576 --- [ost-startStop-1] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 2231 ms
2018-04-30 23:56:48.218  INFO 12576 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean  : Mapping servlet: 'dispatcherServlet' to [/]
2018-04-30 23:56:48.234  INFO 12576 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'characterEncodingFilter' to: [/*]
2018-04-30 23:56:48.234  INFO 12576 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2018-04-30 23:56:48.234  INFO 12576 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'httpPutFormContentFilter' to: [/*]
2018-04-30 23:56:48.234  INFO 12576 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'requestContextFilter' to: [/*]
2018-04-30 23:56:48.503  INFO 12576 --- [           main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@70e8f8e: startup date [Mon Apr 30 23:56:45 IST 2018]; root of context hierarchy
2018-04-30 23:56:48.581  INFO 12576 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error]}" onto public org.springframework.http.ResponseEntity&lt;java.util.Map&lt;java.lang.String, java.lang.Object&gt;&gt; org.springframework.boot.autoconfigure.web.BasicErrorController.error(javax.servlet.http.HttpServletRequest)
2018-04-30 23:56:48.581  INFO 12576 --- [           main] 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)
2018-04-30 23:56:48.596  INFO 12576 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-04-30 23:56:48.612  INFO 12576 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-04-30 23:56:48.643  INFO 12576 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-04-30 23:56:48.754  INFO 12576 --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
2018-04-30 23:56:48.832  INFO 12576 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8080 (http)
2018-04-30 23:56:48.848  INFO 12576 --- [           main] com.w3schools.App                        : Started App in 3.777 seconds (JVM running for 4.394)