Spring Boot @Controller vs @RestController Example
Learn the difference between @Controller and @RestController in Spring Boot with simple, runnable examples and clear output. Beginner-friendly guide.
spring boot
Java and Spring Boot Development Service
I help teams build, fix, and upgrade Java and Spring apps. New features, bug fixes, consultation, and migration to Spring Boot 4.
How to Run a CommandLineRunner Bean Conditionally in Spring Boot
This article shows different ways to run a CommandLineRunner bean conditionally in a Spring Boot application. Table of contents: 1. Using @ConditionalOnProperty 2. Using Environment 3. Using Spring Profiles 4. Check the Presence of Other Beans 4.1 Using @ConditionalOnBean 4.2 Using @ConditionalOnMissingBean 5. Download Source Code 6. References P.S. Tested with Spring Boot 3.1.2 1. …
Spring Boot CommandLineRunner Example
This article tells what is CommandLineRunner and different ways of implementing it or use it in Spring Boot. Table of contents: 1. What is CommandLineRunner? 2. Implementing CommandLineRunner 3. @Bean CommandLineRunner 4. Download Source Code 5. References P.S. Tested with Spring Boot 3.1.2 1. What is CommandLineRunner? The CommandLineRunner is an interface in Spring Boot. …
Spring Boot @ServiceConnection Example
Spring Boot 3.1 introduced @ServiceConnection to enable the Spring Boot’s auto-configuration to use the service connection details to connect to a remote service (Testcontainers). Tables of contents: 1. Testing with @DynamicPropertySource 2. Spring Boot 3.1 and @ServiceConnection 3. Download Source Code 4. References 1. Testing with @DynamicPropertySource The following example uses @DynamicPropertySource to register the …
Spring Boot @DynamicPropertySource Example
In Spring Boot, we can use @DynamicPropertySource to dynamically register or override property values in the ApplicationContext for integration tests. Tables of contents: 1. Testing with ApplicationContextInitializer 2. Testing with @DynamicPropertySource 3. Testing with Spring Boot 3.1 and @ServiceConnection 4. Download Source Code 5. References P.S. The @DynamicPropertySource feature is available from Spring Framework 5.2.5 …
Spring Boot @ConditionalOnProperty Example
In Spring Boot, we can use the @ConditionalOnProperty annotation to conditionally register the beans based on the property value in the application.properties or application.yml file. This article will use the @ConditionalOnProperty annotation to simulate a toggle feature to turn features on or off at runtime without any code changes. Technologies used: Spring Boot 3.1.2 Java …
Spring Data JPA Paging and Sorting example
This article shows how to do Spring Data JPA paging and sorting using the PagingAndSortingRepository interface. Technologies used: Spring Boot 3.1.2 Spring Data JPA H2 in-memory database Java 17 Maven 3 JUnit 5 Spring Integration Tests with TestRestTemplate Unit Tests with Mocking (Mockito) Table of contents: 1. Extends PagingAndSortingRepository 2. Extends JpaRepository 3. Pageable and …
Spring Boot – package javax.persistence does not exist
We migrated the project to Spring Boot 3, and the JPA entity class hits package javax.persistence does not exist. java: package javax.persistence does not exist import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; P.S. Tested with Spring Boot 3.1.2 Solution Spring Boot 3 migrated all Java EE APIs javax.* to their equivalent Jakarta EE variant …
How to load custom properties files in Spring Boot
This article shows how to use @PropertySource annotation to load custom properties files in Spring Boot. Table of contents: 1. Load default properties file 2. Load custom properties files 3. Load multiple custom properties files 4. Download Source Code 5. References P.S. Tested with Spring Boot 3.1.2 1. Load default properties file Spring default loads …
How to access values from application.properties in Spring Boot
In Spring Boot, we can use @Value annotation to access the values defined in the application.properties from Spring-managed beans. application.properties #Logging logging.level.org.springframework.web=ERROR logging.level.com.mkyong=DEBUG email.smtp.server=smtp.gmail.com import org.springframework.beans.factory.annotation.Value; @Value("${email.smtp.server}") private String server; Table of contents: 1. application.properties 1. @Value 2. Environment 3. @ConfigurationProperties 4. Download Source Code 5. References P.S. Tested with Spring Boot 3.1.2 1. application.properties …
Testing JSON in Spring Boot
This article shows how to use MockMvc and JsonPath to test JSON in Spring Boot. Table of Contents: 1. Spring Boot Test Dependencies 2. Testing JSON Simple Structure 3. Testing a List 4. Testing a Map 5. Testing JSON in Spring Boot 5.1 Spring Boot REST Controller returns JSON 5.1 Testing JSON Data 6. Download …
package javax.validation.constraints does not exist
Below is a Spring Boot application and validation bean API example. GlobalProperties.java import javax.validation.constraints.Max; import javax.validation.constraints.Min; import javax.validation.constraints.NotEmpty; import org.springframework.boot.context.properties.ConfigurationProperties; import org.springframework.stereotype.Component; import org.springframework.validation.annotation.Validated; @Component @ConfigurationProperties @Validated public class GlobalProperties { //@Value("${thread-pool}") @Max(5) @Min(0) private int threadPool; Run the Spring Boot application and hits the following error: Terminal package javax.validation.constraints does not exist Solution – …
Spring Boot Test if web server starts on a specific port
Below is a Spring Boot Test example to test whether the web server started on port 8181. P.S. Tested with Spring Boot 3 and JUnit 5. application.properties server.port = 8181 WebServerTests.java package com.mkyong; import org.junit.jupiter.api.Test; import org.springframework.boot.test.context.SpringBootTest; import org.springframework.boot.test.web.server.LocalServerPort; import static org.junit.jupiter.api.Assertions.assertEquals; @SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT) public class WebServerTests { @LocalServerPort private int port; @Test public …
Spring Boot – Unable to find a @SpringBootConfiguration
Terminal Unable to find a @SpringBootConfiguration, you need to use @ContextConfiguration or @SpringBootTest(classes=…) with your test The Spring Boot tests @SpringBootTest or @DataJpaTest need to find the @SpringBootConfiguration application class to launch the entire application and do the tests. And if Spring Boot can’t find the SpringBootConfiguration, it throws errors and stops the tests. A …
Spring Boot Hello World Example
Get started with Spring Boot. A hello world web example with Maven, Java 25, and Spring Boot 4.
Mocking Spring Data DateTimeProvider
In this article, we will demonstrate an integration test where we have to persist the entities with mocked auditing date fields when JPA Auditing is enabled. Technologies used: Spring Boot 2.4.0 Spring 5.3.1 JUnit Jupiter 5.7.0 Tomcat embed 9.0.39 Java 8 1. Project Dependencies pom.xml <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-jpa</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>com.h2database</groupId> …
Spring Boot JobRunr examples
This article shows how to use Spring Boot to create REST endpoints to run the background jobs managed by the JobRunr. Tested with: Spring Boot 2.3.12.RELEASE JobRunr 3.1.2 Maven 3 1. Directory Structure. A standard Maven project structure. 2. Project Dependencies. We need a single jobrunr-spring-boot-starter to integrate Spring Boot web and JobRunr. pom.xml <!– …
Spring Boot SSL (HTTPS) examples
In this tutorial, we will show you how to enable SSL (HTTPS) support for a Spring Boot web application (mvc + thymeleaf). Tested with Maven 3 Java 8 Spring Boot 2.2.4.RELEASE Spring Boot default embedded Tomcat 9 Self-signed certificate (PKCS12) To enable SSL or HTTPS for Spring Boot web application, puts the certificate file .p12 …
Spring Boot redirect port 8080 to 8443
In Spring Boot 2.x, we can create a ServletWebServerFactory to redirect a port from HTTP 8080 to HTTPS 8443. Access localhost:8080, it will redirect to localhost:8443 1. ServletWebServerFactory For Spring Boot 2.x, try this: pom.xml <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-thymeleaf</artifactId> </dependency> StartApplication.java package com.mkyong; import org.apache.catalina.Context; import org.apache.catalina.connector.Connector; import org.apache.tomcat.util.descriptor.web.SecurityCollection; import org.apache.tomcat.util.descriptor.web.SecurityConstraint; import …
Docker + Spring Boot examples
In this tutorial, we will show you how to Dockerize a Spring Boot web application (mvc + thymeleaf). Tested with Docker 19.03 Ubuntu 19 Java 8 or Java 11 Spring Boot 2.2.4.RELEASE Maven At the end of the article, we will create a Spring Boot MVC web application and run inside a docker container. P.S …
Spring Boot JDBC Stored Procedure Examples
In this tutorial, we will show you how to use Spring Boot JDBC SimpleJdbcCall to call a stored procedure and stored function from a Oracle database. Technologies used : Spring Boot 2.1.2.RELEASE Spring JDBC 5.1.4.RELEASE Oracle database 19c HikariCP 3.2.0 Maven 3 Java 8 Unlike JdbcTemplate, Spring Boot didn’t create any SimpleJdbcCall automatically, we have …
Spring Boot JDBC Examples
In this tutorial, we will show you how to use Spring Boot JDBC JdbcTemplate and NamedParameterJdbcTemplate. Technologies used : Spring Boot 2.1.2.RELEASE Spring JDBC 5.1.4.RELEASE HikariCP 3.2.0 H2 in-memory database 1.4.197 Maven 3 Java 8 In Spring Boot JDBC, the database related beans like DataSource, JdbcTemplate and NamedParameterJdbcTemplate will be configured and created during the …
Spring Boot – How to send email via SMTP
In this tutorial, we will show you how to send email via SMTP in Spring Boot. Technologies used : Spring Boot 2.1.2.RELEASE Spring 5.1.4.RELEASE Java Mail 1.6.2 Maven 3 Java 8 1. Project Directory 2. Maven To send email, declares spring-boot-starter-mail, it will pull the JavaMail dependencies. 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 …
Spring Boot Log4j 2 example
In this tutorial, we will show you how to use Apache Log4j 2 in Spring Boot framework. Technologies used : Spring Boot 2.1.2.RELEASE Spring 5.1.4.RELEASE Log4j 2.11.1 Maven 3 Java 8 1. Project Directory 2. Maven The key is exclude the default logback, and include log4j with spring-boot-starter-log4j2 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" …
Spring Boot + Spring Data JPA + PostgreSQL example
This article shows how to use Spring Web MVC to create REST endpoints for CRUD database operations using the Spring Data JPA and PostgreSQL. At the end of the tutorial, we will use Docker to start a PostgreSQL container to test the Spring Boot REST endpoints using curl commands. We will use Spring Test and …
Spring Boot MySQL : Table ‘DB_NAME.hibernate_sequence’ doesn’t exist
Spring Boot + Spring Data JPA + MySQL, and hits the following error message when the application starts : Tested with : Spring Boot 2.1.2.RELEASE mysql-connector-java 8.0.13 Hibernate 5.3.7 java.sql.SQLSyntaxErrorException: Table ‘DB_NAME.hibernate_sequence’ doesn’t exist at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:120) at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97) at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:122) at com.mysql.cj.jdbc.ClientPreparedStatement.executeInternal(ClientPreparedStatement.java:974) at com.mysql.cj.jdbc.ClientPreparedStatement.executeQuery(ClientPreparedStatement.java:1024) at com.zaxxer.hikari.pool.ProxyPreparedStatement.executeQuery(ProxyPreparedStatement.java:52) at com.zaxxer.hikari.pool.HikariProxyPreparedStatement.executeQuery(HikariProxyPreparedStatement.java) at org.hibernate.id.enhanced.TableStructure.executeQuery(TableStructure.java:216) at org.hibernate.id.enhanced.TableStructure.access$300(TableStructure.java:46) application.properties spring.datasource.url=jdbc:mysql://localhost:3306/test spring.datasource.username=mkyong …
Spring Boot + Spring Data JPA + MySQL example
This article shows how to use Spring Web MVC to create REST endpoints to perform CRUD database operations using the Spring Data JPA and MySQL. At the end of the tutorial, we will use Docker to start a MySQL container to test the Spring Boot REST endpoints using curl commands. We will use Spring Test …
Spring Boot + Spring Data JPA example
This article shows how to use Spring Data JPA to perform CRUD operation into a H2 in-memory database. Technologies used: Spring Boot 3.1.2 Spring Data JPA (Hibernate 6 is the default JPA implementation) H2 in-memory database Maven Java 17 Table of contents: 1. Project Directory 2. Project Dependencies 3. Spring Data JPA – Entity 4. …
Spring Boot YAML example
In this article, we will show you how to use YAML instead of properties file in Spring Boot. Tested with : Spring Boot 2.1.2.RELEASE Maven 3 Snakeyaml:jar:1.23 In short, create a application.yml in the src/resources folder, Spring Boot will load and parse .yml file automatically and bind the values into the classes which annotated with …
Spring Boot – Run code when the application starts
In Spring Boot, we can create a CommandLineRunner bean to run code when the application is fully started. StartBookApplication.java package com.mkyong; 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; import java.util.Arrays; import java.util.Comparator; import java.util.List; import java.util.stream.Collectors; @SpringBootApplication public class StartBookApplication { public static void main(String[] args) { SpringApplication.run(StartBookApplication.class, args); } // Injects …
Spring REST Integration Test Example
In this article, we will show you how to test the Spring Boot REST application. Normally, we use the MockMvc or TestRestTemplate for the integration test. Technologies used : Spring Boot 2.1.2.RELEASE Spring 5.1.4.RELEASE Maven 3 Java 8 pom.xml <!– spring integration test –> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> <!– spring integration test for security–> …
Spring + Mockito – Unable to mock save method?
Try to mock a repository save() method, but it is always returning null? P.S Tested with Spring Boot 2 + Spring Data JPA @Test public void save_book_OK() throws Exception { Book newBook = new Book(1L, "Mockito Guide", "mkyong"); when(mockRepository.save(newBook)).thenReturn(newBook); mockMvc.perform(post("/books") .content("{json}") .header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON)) .andExpect(status().isCreated()); } Solution 1. Mockito uses the equals for argument matching, try …
Spring Boot – How to init a Bean for testing?
In Spring Boot, we can create a @TestConfiguration class to initialize some beans for testing class only. P.S Tested with Spring Boot 2 1. @TestConfiguration + @Import This @TestConfiguration class will not pick up by the component scanning, we need to import it manually. TestConfig.java package com.mkyong; import org.springframework.boot.test.context.TestConfiguration; import org.springframework.boot.web.client.RestTemplateBuilder; import org.springframework.context.annotation.Bean; import java.time.Duration; …
Spring REST + Spring Security Example
In this article, we will enhance the previous Spring REST Validation Example, by adding Spring Security to perform authentication and authorization for the requested URLs (REST API endpoints) Technologies used : Spring Boot 2.1.2.RELEASE Spring 5.1.4.RELEASE Spring Security 5.1.3.RELEASE Spring Data JPA 2.1.4.RELEASE H2 In-memory Database 1.4.197 Tomcat Embed 9.0.14 JUnit 4.12 Maven 3 Java …
Spring Security – There is no PasswordEncoder mapped for the id “null”
Send a GET request with username and password, but hits the password encoder error? Tested Spring Boot 2.1.2.RELEASE 5.1.3.RELEASE $ curl localhost:8080/books -u user:password { "timestamp":"2019-02-22T15:03:49.322+0000", "status":500, "error":"Internal Server Error", "message":"There is no PasswordEncoder mapped for the id \"null\"", "path":"/books" } errors in logs java.lang.IllegalArgumentException: There is no PasswordEncoder mapped for the id "null" Here …
Spring Boot Test unable to autowired MockMvc
Spring Boot integeration test, but unable to @Autowired MockMvc P.S Tested with Spring Boot 2.1.2.RELEASE BookControllerTest.java package com.mkyong; import org.junit.Test; import org.junit.runner.RunWith; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.boot.test.context.SpringBootTest; import org.springframework.http.MediaType; import org.springframework.security.test.context.support.WithMockUser; import org.springframework.test.context.junit4.SpringRunner; import org.springframework.test.web.servlet.MockMvc; import static org.hamcrest.Matchers.is; import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get; import static org.springframework.test.web.servlet.result.MockMvcResultHandlers.print; import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.*; @RunWith(SpringRunner.class) @SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT) public class BookControllerTest { @Autowired …
Spring REST Hello World Example
In this article, we will show you how to develop a Spring Boot REST style web service to handle CRUD operations from a H2 In-memory database. Technologies used : Spring Boot 2.1.2.RELEASE Spring 5.1.4.RELEASE Spring Data JPA 2.1.4.RELEASE H2 In-memory Database 1.4.197 Tomcat Embed 9.0.14 JUnit 4.12 Maven 3 Java 8 1. Project Directory 2. …
Mockito – when() requires an argument which has to be ‘a method call on a mock’
Run the following Spring Boot + JUnit 5 + Mockito integration test. package com.mkyong.core.services; import com.mkyong.core.repository.HelloRepository; import org.junit.jupiter.api.BeforeEach; import org.junit.jupiter.api.DisplayName; import org.junit.jupiter.api.Test; import org.mockito.InjectMocks; import org.mockito.Mock; import org.springframework.boot.test.context.SpringBootTest; import static org.junit.jupiter.api.Assertions.assertEquals; import static org.mockito.Mockito.when; @SpringBootTest public class HelloServiceMockTest { @Mock private HelloRepository helloRepository; @InjectMocks // auto inject helloRepository private HelloService helloService = new HelloServiceImpl(); @BeforeEach …
Spring Boot + JUnit 5 + Mockito
In this article, we will show you how to do Spring Boot 2 integration test with JUnit 5, and also Mockito. Spring Boot 2.1.2.RELEASE JUnit 5 Mockito 2 Maven 3 In short, exclude junit4 from spring-boot-starter-test, and include the JUnit 5 jupiter engine manually, done. Let see the following Spring boot MVC web application, and …