Category: spring Boot

Spring Boot – Sending Email ”; Previous Next By using Spring Boot RESTful web service, you can send an email with Gmail Transport Layer Security. In this chapter, let us understand in detail how to use this feature. First, we need to add the Spring Boot Starter Mail dependency in your build configuration file. Maven users can add the following dependency into the pom.xml file. <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-mail</artifactId> </dependency> Gradle users can add the following dependency in your build.gradle file. compile(”org.springframework.boot:spring-boot-starter-mail”) The code of main Spring Boot application class file is given below − package com.tutorialspoint.emailapp; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; @SpringBootApplication public class EmailappApplication { public static void main(String[] args) { SpringApplication.run(EmailappApplication.class, args); } } You can write a simple Rest API to send to email in Rest Controller class file as shown. package com.tutorialspoint.emailapp; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; @RestController public class EmailController { @RequestMapping(value = “/sendemail”) public String sendEmail() { return “Email sent successfully”; } } You can write a method to send the email with Attachment. Define the mail.smtp properties and used PasswordAuthentication. private void sendmail() throws AddressException, MessagingException, IOException { Properties props = new Properties(); props.put(“mail.smtp.auth”, “true”); props.put(“mail.smtp.starttls.enable”, “true”); props.put(“mail.smtp.host”, “smtp.gmail.com”); props.put(“mail.smtp.port”, “587”); Session session = Session.getInstance(props, new javax.mail.Authenticator() { protected PasswordAuthentication getPasswordAuthentication() { return new PasswordAuthentication(“[email protected]”, “<your password>”); } }); Message msg = new MimeMessage(session); msg.setFrom(new InternetAddress(“[email protected]”, false)); msg.setRecipients(Message.RecipientType.TO, InternetAddress.parse(“[email protected]”)); msg.setSubject(“Tutorials point email”); msg.setContent(“Tutorials point email”, “text/html”); msg.setSentDate(new Date()); MimeBodyPart messageBodyPart = new MimeBodyPart(); messageBodyPart.setContent(“Tutorials point email”, “text/html”); Multipart multipart = new MimeMultipart(); multipart.addBodyPart(messageBodyPart); MimeBodyPart attachPart = new MimeBodyPart(); attachPart.attachFile(“/var/tmp/image19.png”); multipart.addBodyPart(attachPart); msg.setContent(multipart); Transport.send(msg); } Now, call the above sendmail() method from the Rest API as shown − @RequestMapping(value = “/sendemail”) public String sendEmail() throws AddressException, MessagingException, IOException { sendmail(); return “Email sent successfully”; } Note − Please switch ON allow less secure apps in your Gmail account settings before sending an email. The complete build configuration file is given below. Maven – 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 http://maven.apache.org/xsd/maven-4.0.0.xsd”> <modelVersion>4.0.0</modelVersion> <groupId>com.tutorialspoint</groupId> <artifactId>emailapp</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>emailapp</name> <description>Demo project for Spring Boot</description> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.5.9.RELEASE</version> <relativePath/> <!– lookup parent from repository –> </parent> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding> <java.version>1.8</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-mail</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project> Gradle – build.gradle buildscript { ext { springBootVersion = ”1.5.9.RELEASE” } repositories { mavenCentral() } dependencies { classpath(“org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}”) } } apply plugin: ”java” apply plugin: ”eclipse” apply plugin: ”org.springframework.boot” group = ”com.tutorialspoint” version = ”0.0.1-SNAPSHOT” sourceCompatibility = 1.8 repositories { mavenCentral() } dependencies { compile(”org.springframework.boot:spring-boot-starter-web”) compile(”org.springframework.boot:spring-boot-starter-mail”) testCompile(”org.springframework.boot:spring-boot-starter-test”) } Now, you can create an executable JAR file, and run the Spring Boot application by using the Maven or Gradle commands shown below − For Maven, you can use the command as shown − mvn clean install After “BUILD SUCCESS”, you can find the JAR file under the target directory. For Gradle, you can use the command as shown − gradle clean build After “BUILD SUCCESSFUL”, you can find the JAR file under the build/libs directory. Now, run the JAR file by using the command given below − java –jar <JARFILE> You can see that the application has started on the Tomcat port 8080. Now hit the following URL from your web browser and you will receive an email. http://localhost:8080/sendemail Print Page Previous Next Advertisements ”;

Spring Boot – Actuator ”; Previous Next Spring Boot Actuator provides secured endpoints for monitoring and managing your Spring Boot application. By default, all actuator endpoints are secured. In this chapter, you will learn in detail about how to enable Spring Boot actuator to your application. Enabling Spring Boot Actuator To enable Spring Boot actuator endpoints to your Spring Boot application, we need to add the Spring Boot Starter actuator dependency in our build configuration file. Maven users can add the below dependency in your pom.xml file. <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-actuator</artifactId> </dependency> Gradle users can add the below dependency in your build.gradle file. compile group: ”org.springframework.boot”, name: ”spring-boot-starter-actuator” In the application.properties file, we need to disable the security for actuator endpoints. management.security.enabled = false YAML file users can add the following property in your application.yml file. management: security: enabled: false If you want to use the separate port number for accessing the Spring boot actutator endpoints add the management port number in application.properties file. management.port = 9000 YAML file users can add the following property in your application.yml file. management: port: 9000 Now, you can create an executable JAR file, and run the Spring Boot application by using the following Maven or Gradle commands. For Maven, you can use the following command − mvn clean install After “BUILD SUCCESS”, you can find the JAR file under the target directory. For Gradle, you can use the following command − gradle clean build After “BUILD SUCCESSFUL”, you can find the JAR file under the build/libs directory. Now, you can run the JAR file by using the following command − java –jar <JARFILE> Now, the application has started on the Tomcat port 8080. Note that if you specified the management port number, then same application is running on two different port numbers. Some important Spring Boot Actuator endpoints are given below. You can enter them in your web browser and monitor your application behavior. ENDPOINTS USAGE /metrics To view the application metrics such as memory used, memory free, threads, classes, system uptime etc. /env To view the list of Environment variables used in the application. /beans To view the Spring beans and its types, scopes and dependency. /health To view the application health /info To view the information about the Spring Boot application. /trace To view the list of Traces of your Rest endpoints. Print Page Previous Next Advertisements ”;

Spring Boot – OAuth2 with JWT ”; Previous Next In this chapter, you will learn in detail about Spring Boot Security mechanisms and OAuth2 with JWT. Authorization Server Authorization Server is a supreme architectural component for Web API Security. The Authorization Server acts a centralization authorization point that allows your apps and HTTP endpoints to identify the features of your application. Resource Server Resource Server is an application that provides the access token to the clients to access the Resource Server HTTP Endpoints. It is collection of libraries which contains the HTTP Endpoints, static resources, and Dynamic web pages. OAuth2 OAuth2 is an authorization framework that enables the application Web Security to access the resources from the client. To build an OAuth2 application, we need to focus on the Grant Type (Authorization code), Client ID and Client secret.   JWT Token JWT Token is a JSON Web Token, used to represent the claims secured between two parties. You can learn more about the JWT token at www.jwt.io/. Now, we are going to build an OAuth2 application that enables the use of Authorization Server, Resource Server with the help of a JWT Token. You can use the following steps to implement the Spring Boot Security with JWT token by accessing the database. First, we need to add the following dependencies in our build configuration file. Maven users can add the following dependencies in your pom.xml file. <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-jdbc</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-security</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.security.oauth</groupId> <artifactId>spring-security-oauth2</artifactId> </dependency> <dependency> <groupId>org.springframework.security</groupId> <artifactId>spring-security-jwt</artifactId> </dependency> <dependency> <groupId>com.h2database</groupId> <artifactId>h2</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> <dependency> <groupId>org.springframework.security</groupId> <artifactId>spring-security-test</artifactId> <scope>test</scope> </dependency> Gradle users can add the following dependencies in the build.gradle file. compile(”org.springframework.boot:spring-boot-starter-security”) compile(”org.springframework.boot:spring-boot-starter-web”) testCompile(”org.springframework.boot:spring-boot-starter-test”) testCompile(”org.springframework.security:spring-security-test”) compile(“org.springframework.security.oauth:spring-security-oauth2″) compile(”org.springframework.security:spring-security-jwt”) compile(“org.springframework.boot:spring-boot-starter-jdbc”) compile(“com.h2database:h2:1.4.191”) where, Spring Boot Starter Security − Implements the Spring Security Spring Security OAuth2 − Implements the OAUTH2 structure to enable the Authorization Server and Resource Server. Spring Security JWT − Generates the JWT Token for Web security Spring Boot Starter JDBC − Accesses the database to ensure the user is available or not. Spring Boot Starter Web − Writes HTTP endpoints. H2 Database − Stores the user information for authentication and authorization. The complete build configuration file is given below. <?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>com.tutorialspoint</groupId> <artifactId>websecurityapp</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>websecurityapp</name> <description>Demo project for Spring Boot</description> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.5.9.RELEASE</version> <relativePath /> <!– lookup parent from repository –> </parent> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding> <java.version>1.8</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-jdbc</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-security</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.security.oauth</groupId> <artifactId>spring-security-oauth2</artifactId> </dependency> <dependency> <groupId>org.springframework.security</groupId> <artifactId>spring-security-jwt</artifactId> </dependency> <dependency> <groupId>com.h2database</groupId> <artifactId>h2</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> <dependency> <groupId>org.springframework.security</groupId> <artifactId>spring-security-test</artifactId> <scope>test</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project> Gradle – build.gradle buildscript { ext { springBootVersion = ”1.5.9.RELEASE” } repositories { mavenCentral() } dependencies { classpath(“org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}”) } } apply plugin: ”java” apply plugin: ”eclipse” apply plugin: ”org.springframework.boot” group = ”com.tutorialspoint” version = ”0.0.1-SNAPSHOT” sourceCompatibility = 1.8 repositories { mavenCentral() } dependencies { compile(”org.springframework.boot:spring-boot-starter-security”) compile(”org.springframework.boot:spring-boot-starter-web”) testCompile(”org.springframework.boot:spring-boot-starter-test”) testCompile(”org.springframework.security:spring-security-test”) compile(“org.springframework.security.oauth:spring-security-oauth2″) compile(”org.springframework.security:spring-security-jwt”) compile(“org.springframework.boot:spring-boot-starter-jdbc”) compile(“com.h2database:h2:1.4.191”) } Now, in the main Spring Boot application, add the @EnableAuthorizationServer and @EnableResourceServer annotation to act as an Auth server and Resource Server in the same application. Also, you can use the following code to write a simple HTTP endpoint to access the API with Spring Security by using JWT Token. package com.tutorialspoint.websecurityapp; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.security.oauth2.config.annotation.web.configuration.EnableAuthorizationServer; import org.springframework.security.oauth2.config.annotation.web.configuration.EnableResourceServer; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; @SpringBootApplication @EnableAuthorizationServer @EnableResourceServer @RestController public class WebsecurityappApplication { public static void main(String[] args) { SpringApplication.run(WebsecurityappApplication.class, args); } @RequestMapping(value = “/products”) public String getProductName() { return “Honey”; } } Use the following code to define the POJO class to store the User information for authentication. package com.tutorialspoint.websecurityapp; import java.util.ArrayList; import java.util.Collection; import org.springframework.security.core.GrantedAuthority; public class UserEntity { private String username; private String password; private Collection<GrantedAuthority> grantedAuthoritiesList = new ArrayList<>(); public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } public Collection<GrantedAuthority> getGrantedAuthoritiesList() { return grantedAuthoritiesList; } public void setGrantedAuthoritiesList(Collection<GrantedAuthority> grantedAuthoritiesList) { this.grantedAuthoritiesList = grantedAuthoritiesList; } public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } } Now, use the following code and define the CustomUser class that extends the org.springframework.security.core.userdetails.User class for Spring Boot authentication. package com.tutorialspoint.websecurityapp; import org.springframework.security.core.userdetails.User; public class CustomUser extends User { private static final long serialVersionUID = 1L; public CustomUser(UserEntity user) { super(user.getUsername(), user.getPassword(), user.getGrantedAuthoritiesList()); } } You can create the @Repository class to read the User information from the database and send it to the Custom user service and also add the granted authority “ROLE_SYSTEMADMIN”. package com.tutorialspoint.websecurityapp; import java.sql.ResultSet; import java.util.ArrayList; import java.util.Collection; import java.util.List; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.jdbc.core.JdbcTemplate; import org.springframework.security.core.GrantedAuthority; import org.springframework.security.core.authority.SimpleGrantedAuthority; import org.springframework.stereotype.Repository; @Repository public class OAuthDao { @Autowired private JdbcTemplate jdbcTemplate; public UserEntity getUserDetails(String username) { Collection<GrantedAuthority> grantedAuthoritiesList = new ArrayList<>(); String userSQLQuery = “SELECT * FROM USERS WHERE USERNAME=?”; List<UserEntity> list = jdbcTemplate.query(userSQLQuery, new String[] { username }, (ResultSet rs, int rowNum) -> { UserEntity user = new UserEntity(); user.setUsername(username); user.setPassword(rs.getString(“PASSWORD”)); return user; }); if (list.size() > 0) { GrantedAuthority grantedAuthority = new SimpleGrantedAuthority(“ROLE_SYSTEMADMIN”); grantedAuthoritiesList.add(grantedAuthority); list.get(0).setGrantedAuthoritiesList(grantedAuthoritiesList); return list.get(0); } return null; } } You can create a Custom User detail service class that extends the org.springframework.security.core.userdetails.UserDetailsService to call the DAO repository class as shown. package com.tutorialspoint.websecurityapp; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.security.core.userdetails.UserDetailsService; import org.springframework.security.core.userdetails.UsernameNotFoundException; import org.springframework.stereotype.Service; @Service public class CustomDetailsService implements UserDetailsService { @Autowired OAuthDao oauthDao; @Override public CustomUser loadUserByUsername(final String username) throws UsernameNotFoundException { UserEntity userEntity = null; try { userEntity = oauthDao.getUserDetails(username); CustomUser customUser = new CustomUser(userEntity); return customUser; } catch (Exception e) { e.printStackTrace(); throw new UsernameNotFoundException(“User ” + username + ” was not found in the database”); } } } Next, create a @configuration class to enable the Web Security, defining the Password encoder (BCryptPasswordEncoder), and defining the AuthenticationManager bean. The Security configuration class should extend WebSecurityConfigurerAdapter class. package com.tutorialspoint.websecurityapp; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.security.authentication.AuthenticationManager; import org.springframework.security.config.annotation.authentication.builders.AuthenticationManagerBuilder; import org.springframework.security.config.annotation.method.configuration.EnableGlobalMethodSecurity; import org.springframework.security.config.annotation.web.builders.HttpSecurity; import org.springframework.security.config.annotation.web.builders.WebSecurity; import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;

Spring Boot – Google OAuth2 Sign-In ”; Previous Next In this chapter, we are going to see how to add the Google OAuth2 Sign-In by using Spring Boot application with Gradle build. First, add the Spring Boot OAuth2 security dependency in your build configuration file and your build configuration file is given below. buildscript { ext { springBootVersion = ”1.5.8.RELEASE” } repositories { mavenCentral() } dependencies { classpath(“org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}”) } } apply plugin: ”java” apply plugin: ”eclipse” apply plugin: ”org.springframework.boot” group = ”com.tutorialspoint.projects” version = ”0.0.1-SNAPSHOT” sourceCompatibility = 1.8 repositories { mavenCentral() } dependencies { compile(”org.springframework.boot:spring-boot-starter”) testCompile(”org.springframework.boot:spring-boot-starter-test”) compile(”org.springframework.security.oauth:spring-security-oauth2”) compile(”org.springframework.boot:spring-boot-starter-web”) testCompile(”org.springframework.boot:spring-boot-starter-test”) } Now, add the HTTP Endpoint to read the User Principal from the Google after authenticating via Spring Boot in main Spring Boot application class file as given below − package com.tutorialspoint.projects.googleservice; import java.security.Principal; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; @SpringBootApplication @RestController public class GoogleserviceApplication { public static void main(String[] args) { SpringApplication.run(GoogleserviceApplication.class, args); } @RequestMapping(value = “/user”) public Principal user(Principal principal) { return principal; } } Now, write a Configuration file to enable the OAuth2SSO for web security and remove the authentication for index.html file as shown − package com.tutorialspoint.projects.googleservice; import org.springframework.boot.autoconfigure.security.oauth2.client.EnableOAuth2Sso; import org.springframework.context.annotation.Configuration; import org.springframework.security.config.annotation.web.builders.HttpSecurity; import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter; @Configuration @EnableOAuth2Sso public class WebSecurityConfiguration extends WebSecurityConfigurerAdapter { @Override protected void configure(HttpSecurity http) throws Exception { http .csrf() .disable() .antMatcher(“/**”) .authorizeRequests() .antMatchers(“/”, “/index.html”) .permitAll() .anyRequest() .authenticated(); } } Next, add the index.html file under static resources and add the link to redirect into user HTTP Endpoint to read the Google user Principal as shown below − <!DOCTYPE html> <html> <head> <meta charset = “ISO-8859-1”> <title>Insert title here</title> </head> <body> <a href = “user”>Click here to Google Login</a> </body> </html> Note − In Google Cloud console – Enable the Gmail Services, Analytics Services and Google+ service API(s). Then, go the Credentials section and create a credentials and choose OAuth Client ID. Next, provide a Product Name in OAuth2 consent screen. Next, choose the Application Type as “Web application”, provide the Authorized JavaScript origins and Authorized redirect URIs. Now, your OAuth2 Client Id and Client Secret is created. Next, add the Client Id and Client Secret in your application properties file. security.oauth2.client.clientId = <CLIENT_ID> security.oauth2.client.clientSecret = <CLIENT_SECRET> security.oauth2.client.accessTokenUri = https://www.googleapis.com/oauth2/v3/token security.oauth2.client.userAuthorizationUri = https://accounts.google.com/o/oauth2/auth security.oauth2.client.tokenName = oauth_token security.oauth2.client.authenticationScheme = query security.oauth2.client.clientAuthenticationScheme = form security.oauth2.client.scope = profile email security.oauth2.resource.userInfoUri = https://www.googleapis.com/userinfo/v2/me security.oauth2.resource.preferTokenInfo = false Now, you can create an executable JAR file, and run the Spring Boot application by using the following Gradle command. For Gradle, you can use the command as shown − gradle clean build After “BUILD SUCCESSFUL”, you can find the JAR file under the build/libs directory. Run the JAR file by using the command java –jar <JARFILE> and application is started on the Tomcat port 8080. Now hit the URL http://localhost:8080/ and click the Google Login link. It will redirect to the Google login screen and provide a Gmail login details. If login success, we will receive the Principal object of the Gmail user. Print Page Previous Next Advertisements ”;

Spring Boot Tutorial PDF Version Quick Guide Resources Job Search Discussion Spring Boot is an open source Java-based framework used to create a Micro Service. It is developed by Pivotal Team. It is easy to create a stand-alone and production ready spring applications using Spring Boot. Spring Boot contains a comprehensive infrastructure support for developing a micro service and enables you to develop enterprise-ready applications that you can “just run”. Audience This tutorial is designed for Java developers to understand and develop production-ready spring applications with minimum configurations. It explores major features of Spring Boot such as Starters, Auto-configuration, Beans, Actuator and more. By the end of this tutorial, you will gain an intermediate level of expertise in Spring Boot. Prerequisites This tutorial is written for readers who have a prior experience of Java, Spring, Maven, and Gradle. You can easily understand the concepts of Spring Boot if you have knowledge on these concepts. It would be an additional advantage if you have an idea about writing a RESTful Web Service. If you are a beginner, we suggest you to go through tutorials related to these concepts before you start with Spring Boot. Print Page Previous Next Advertisements ”;

Spring Boot – Code Structure ”; Previous Next Spring Boot does not have any code layout to work with. However, there are some best practices that will help us. This chapter talks about them in detail. Default package A class that does not have any package declaration is considered as a default package. Note that generally a default package declaration is not recommended. Spring Boot will cause issues such as malfunctioning of Auto Configuration or Component Scan, when you use default package. Note − Java”s recommended naming convention for package declaration is reversed domain name. For example − com.tutorialspoint.myproject Typical Layout The typical layout of Spring Boot application is shown in the image given below − The Application.java file should declare the main method along with @SpringBootApplication. Observe the code given below for a better understanding − package com.tutorialspoint.myproject; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; @SpringBootApplication public class Application { public static void main(String[] args) {SpringApplication.run(Application.class, args);} } Print Page Previous Next Advertisements ”;

Discuss Spring Boot ”; Previous Next Spring Boot is an open source Java-based framework used to create a Micro Service. It is developed by Pivotal Team. It is easy to create a stand-alone and production ready spring applications using Spring Boot. Spring Boot contains a comprehensive infrastructure support for developing a microservice and enables you to develop enterprise-ready applications that you can “just run”. Print Page Previous Next Advertisements ”;

Spring Boot – Useful Resources ”; Previous Next The following resources contain additional information on Spring Boot. Please use them to get more in-depth knowledge on this. Useful Links on Spring Boot Spring Framework − Wikipedia Reference for Spring Boot. Official Website − Official Website of Spring Boot. Useful Books on Spring Boot To enlist your site on this page, please drop an email to [email protected] Print Page Previous Next Advertisements ”;

Spring Boot – Securing Web Applications ”; Previous Next If a Spring Boot Security dependency is added on the classpath, Spring Boot application automatically requires the Basic Authentication for all HTTP Endpoints. The Endpoint “/” and “/home” does not require any authentication. All other Endpoints require authentication. For adding a Spring Boot Security to your Spring Boot application, we need to add the Spring Boot Starter Security dependency in our build configuration file. Maven users can add the following dependency in the pom.xml file. <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-security</artifactId> </dependency> Gradle users can add the following dependency in the build.gradle file. compile(“org.springframework.boot:spring-boot-starter-security”) Securing a Web application First, create an unsecure web application by using Thymeleaf templates. Then, create a home.html file under src/main/resources/templates directory. <!DOCTYPE html> <html xmlns = “http://www.w3.org/1999/xhtml” xmlns:th = “http://www.thymeleaf.org” xmlns:sec = “http://www.thymeleaf.org/thymeleaf-extras-springsecurity3”> <head> <title>Spring Security Example</title> </head> <body> <h1>Welcome!</h1> <p>Click <a th:href = “@{/hello}”>here</a> to see a greeting.</p> </body> </html> The simple view /hello defined in the HTML file by using Thymeleaf templates. Now, create a hello.html under src/main/resources/templates directory. <!DOCTYPE html> <html xmlns = “http://www.w3.org/1999/xhtml” xmlns:th = “http://www.thymeleaf.org” xmlns:sec = “http://www.thymeleaf.org/thymeleaf-extras-springsecurity3”> <head> <title>Hello World!</title> </head> <body> <h1>Hello world!</h1> </body> </html> Now, we need to setup the Spring MVC – View controller for home and hello views. For this, create a MVC configuration file that extends WebMvcConfigurerAdapter. package com.tutorialspoint.websecuritydemo; import org.springframework.context.annotation.Configuration; import org.springframework.web.servlet.config.annotation.ViewControllerRegistry; import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter; @Configuration public class MvcConfig extends WebMvcConfigurerAdapter { @Override public void addViewControllers(ViewControllerRegistry registry) { registry.addViewController(“/home”).setViewName(“home”); registry.addViewController(“/”).setViewName(“home”); registry.addViewController(“/hello”).setViewName(“hello”); registry.addViewController(“/login”).setViewName(“login”); } } Now, add the Spring Boot Starter security dependency to your build configuration file. Maven users can add the following dependency in your pom.xml file. <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-security</artifactId> </dependency> Gradle users can add the following dependency in the build.gradle file. compile(“org.springframework.boot:spring-boot-starter-security”) Now, create a Web Security Configuration file, that is used to secure your application to access the HTTP Endpoints by using basic authentication. package com.tutorialspoint.websecuritydemo; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.context.annotation.Configuration; import org.springframework.security.config.annotation.authentication.builders.AuthenticationManagerBuilder; import org.springframework.security.config.annotation.web.builders.HttpSecurity; import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter; import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity; @Configuration @EnableWebSecurity public class WebSecurityConfig extends WebSecurityConfigurerAdapter { @Override protected void configure(HttpSecurity http) throws Exception { http .authorizeRequests() .antMatchers(“/”, “/home”).permitAll() .anyRequest().authenticated() .and() .formLogin() .loginPage(“/login”) .permitAll() .and() .logout() .permitAll(); } @Autowired public void configureGlobal(AuthenticationManagerBuilder auth) throws Exception { auth .inMemoryAuthentication() .withUser(“user”).password(“password”).roles(“USER”); } } Now, create a login.html file under the src/main/resources directory to allow the user to access the HTTP Endpoint via login screen. <!DOCTYPE html> <html xmlns = “http://www.w3.org/1999/xhtml” xmlns:th = “http://www.thymeleaf.org” xmlns:sec = “http://www.thymeleaf.org/thymeleaf-extras-springsecurity3”> <head> <title>Spring Security Example </title> </head> <body> <div th:if = “${param.error}”> Invalid username and password. </div> <div th:if = “${param.logout}”> You have been logged out. </div> <form th:action = “@{/login}” method = “post”> <div> <label> User Name : <input type = “text” name = “username”/> </label> </div> <div> <label> Password: <input type = “password” name = “password”/> </label> </div> <div> <input type = “submit” value = “Sign In”/> </div> </form> </body> </html> Finally, update the hello.html file – to allow the user to Sign-out from the application and display the current username as shown below − <!DOCTYPE html> <html xmlns = “http://www.w3.org/1999/xhtml” xmlns:th = “http://www.thymeleaf.org” xmlns:sec = “http://www.thymeleaf.org/thymeleaf-extras-springsecurity3”> <head> <title>Hello World!</title> </head> <body> <h1 th:inline = “text”>Hello [[${#httpServletRequest.remoteUser}]]!</h1> <form th:action = “@{/logout}” method = “post”> <input type = “submit” value = “Sign Out”/> </form> </body> </html> The code for main Spring Boot application is given below − package com.tutorialspoint.websecuritydemo; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; @SpringBootApplication public class WebsecurityDemoApplication { public static void main(String[] args) { SpringApplication.run(WebsecurityDemoApplication.class, args); } } The complete code for build configuration file is given below. Maven – 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 http://maven.apache.org/xsd/maven-4.0.0.xsd”> <modelVersion>4.0.0</modelVersion> <groupId>com.tutorialspoint</groupId> <artifactId>websecurity-demo</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>websecurity-demo</name> <description>Demo project for Spring Boot</description> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.5.9.RELEASE</version> <relativePath/> <!– lookup parent from repository –> </parent> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding> <java.version>1.8</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-security</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-thymeleaf</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> <dependency> <groupId>org.springframework.security</groupId> <artifactId>spring-security-test</artifactId> <scope>test</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project> Gradle – build.gradle buildscript { ext { springBootVersion = ”1.5.9.RELEASE” } repositories { mavenCentral() } dependencies { classpath(“org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}”) } } apply plugin: ”java” apply plugin: ”eclipse” apply plugin: ”org.springframework.boot” group = ”com.tutorialspoint” version = ”0.0.1-SNAPSHOT” sourceCompatibility = 1.8 repositories { mavenCentral() } dependencies { compile(”org.springframework.boot:spring-boot-starter-security”) compile(”org.springframework.boot:spring-boot-starter-thymeleaf”) compile(”org.springframework.boot:spring-boot-starter-web”) testCompile(”org.springframework.boot:spring-boot-starter-test”) testCompile(”org.springframework.security:spring-security-test”) } Now, create an executable JAR file, and run the Spring Boot application by using the following Maven or Gradle commands. Maven users can use the command as given below − mvn clean install After “BUILD SUCCESS”, you can find the JAR file under target directory. Gradle users can use the command as shown − gradle clean build After “BUILD SUCCESSFUL”, you can find the JAR file under the build/libs directory. Now, run the JAR file by using the command shown below − java –jar <JARFILE> Hit the URL http://localhost:8080/ in your web browser. You can see the output as shown. Print Page Previous Next Advertisements ”;

Spring Boot – Apache Kafka ”; Previous Next Apache Kafka is an open source project used to publish and subscribe the messages based on the fault-tolerant messaging system. It is fast, scalable and distributed by design. If you are a beginner to Kafka, or want to gain a better understanding on it, please refer to this link − www.tutorialspoint.com/apache_kafka/ In this chapter, we are going to see how to implement the Apache Kafka in Spring Boot application. First, we need to add the Spring Kafka dependency in our build configuration file. Maven users can add the following dependency in the pom.xml file. <dependency> <groupId>org.springframework.kafka</groupId> <artifactId>spring-kafka</artifactId> <version>2.1.0.RELEASE</version> </dependency> Gradle users can add the following dependency in the build.gradle file. compile group: ”org.springframework.kafka”, name: ”spring-kafka”, version: ”2.1.0.RELEASE” Producing Messages To produce messages into Apache Kafka, we need to define the Configuration class for Producer configuration as shown − package com.tutorialspoint.kafkademo; import java.util.HashMap; import java.util.Map; import org.apache.kafka.clients.producer.ProducerConfig; import org.apache.kafka.common.serialization.StringSerializer; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.kafka.core.DefaultKafkaProducerFactory; import org.springframework.kafka.core.KafkaTemplate; import org.springframework.kafka.core.ProducerFactory; @Configuration public class KafkaProducerConfig { @Bean public ProducerFactory<String, String> producerFactory() { Map<String, Object> configProps = new HashMap<>(); configProps.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, “localhost:9092”); configProps.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class); configProps.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class); return new DefaultKafkaProducerFactory<>(configProps); } @Bean public KafkaTemplate<String, String> kafkaTemplate() { return new KafkaTemplate<>(producerFactory()); } } To publish a message, auto wire the Kafka Template object and produce the message as shown. @Autowired private KafkaTemplate<String, String> kafkaTemplate; public void sendMessage(String msg) { kafkaTemplate.send(topicName, msg); } Consuming a Message To consume messages, we need to write a Consumer configuration class file as shown below. package com.tutorialspoint.kafkademo; import java.util.HashMap; import java.util.Map; import org.apache.kafka.clients.consumer.ConsumerConfig; import org.apache.kafka.common.serialization.StringDeserializer; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.kafka.annotation.EnableKafka; import org.springframework.kafka.config.ConcurrentKafkaListenerContainerFactory; import org.springframework.kafka.core.ConsumerFactory; import org.springframework.kafka.core.DefaultKafkaConsumerFactory; @EnableKafka @Configuration public class KafkaConsumerConfig { @Bean public ConsumerFactory<String, String> consumerFactory() { Map<String, Object> props = new HashMap<>(); props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, “localhost:2181”); props.put(ConsumerConfig.GROUP_ID_CONFIG, “group-id”); props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class); props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class); return new DefaultKafkaConsumerFactory<>(props); } @Bean public ConcurrentKafkaListenerContainerFactory<String, String> kafkaListenerContainerFactory() { ConcurrentKafkaListenerContainerFactory<String, String> factory = new ConcurrentKafkaListenerContainerFactory<>(); factory.setConsumerFactory(consumerFactory()); return factory; } } Next, write a Listener to listen to the messages. @KafkaListener(topics = “tutorialspoint”, groupId = “group-id”) public void listen(String message) { System.out.println(“Received Messasge in group – group-id: ” + message); } Let us call the sendMessage() method from ApplicationRunner class run method from the main Spring Boot application class file and consume the message from the same class file. Your main Spring Boot application class file code is given below − package com.tutorialspoint.kafkademo; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.boot.ApplicationArguments; import org.springframework.boot.ApplicationRunner; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.kafka.annotation.KafkaListener; import org.springframework.kafka.core.KafkaTemplate; @SpringBootApplication public class KafkaDemoApplication implements ApplicationRunner { @Autowired private KafkaTemplate<String, String> kafkaTemplate; public void sendMessage(String msg) { kafkaTemplate.send(“tutorialspoint”, msg); } public static void main(String[] args) { SpringApplication.run(KafkaDemoApplication.class, args); } @KafkaListener(topics = “tutorialspoint”, groupId = “group-id”) public void listen(String message) { System.out.println(“Received Messasge in group – group-id: ” + message); } @Override public void run(ApplicationArguments args) throws Exception { sendMessage(“Hi Welcome to Spring For Apache Kafka”); } } The code for complete build configuration file is given below. Maven – 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 http://maven.apache.org/xsd/maven-4.0.0.xsd”> <modelVersion>4.0.0</modelVersion> <groupId>com.tutorialspoint</groupId> <artifactId>kafka-demo</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>kafka-demo</name> <description>Demo project for Spring Boot</description> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.5.9.RELEASE</version> <relativePath /> <!– lookup parent from repository –> </parent> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding> <java.version>1.8</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter</artifactId> </dependency> <dependency> <groupId>org.springframework.kafka</groupId> <artifactId>spring-kafka</artifactId> <version>2.1.0.RELEASE</version> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project> Gradle – build.gradle buildscript { ext { springBootVersion = ”1.5.9.RELEASE” } repositories { mavenCentral() } dependencies { classpath(“org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}”) } } apply plugin: ”java” apply plugin: ”eclipse” apply plugin: ”org.springframework.boot” group = ”com.tutorialspoint” version = ”0.0.1-SNAPSHOT” sourceCompatibility = 1.8 repositories { mavenCentral() } dependencies { compile(”org.springframework.boot:spring-boot-starter”) compile group: ”org.springframework.kafka”, name: ”spring-kafka”, version: ”2.1.0.RELEASE” testCompile(”org.springframework.boot:spring-boot-starter-test”) } Now, create an executable JAR file, and run the Spring Boot application by using the below Maven or Gradle commands as shown − For Maven, use the command as shown − mvn clean install After “BUILD SUCCESS”, you can find the JAR file under the target directory. For Gradle, use the command as shown − gradle clean build After “BUILD SUCCESSFUL”, you can find the JAR file under the build/libs directory. Run the JAR file by using the command given here − java –jar <JARFILE> You can see the output in console window. Print Page Previous Next Advertisements ”;