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spring boot hello world example


Spring boot is a module of spring framework which is used to create stand-alone, production-grade Spring based Applications with minimum programmer’s efforts. It is developed on top of core spring framework. The main concept behind spring boot is to avoid lot of boilerplate code and configuration to improve development, unit test etc.

Spring boot hello world example

Directory Structure

Spring security

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.codesjava;
 
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.codesjava.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.codesjava.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<java.util.Map<java.lang.String, java.lang.Object>> 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.codesjava.App                        : Started App in 3.777 seconds (JVM running for 4.394)


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