Thursday, December 22, 2022

spring boot java create kafka topic

 To create a Kafka topic in Spring Boot, you can use the AdminClient class provided by the Kafka client library. Here's an example of how you can do it:

import org.apache.kafka.clients.admin.AdminClient; import org.apache.kafka.clients.admin.NewTopic; @SpringBootApplication public class Application { public static void main(String[] args) {, args); } @Bean public NewTopic createTopic() { return new NewTopic("my-topic", 1, (short) 1); } @Bean public AdminClient adminClient(KafkaProperties properties) { Map<String, Object> configs = new HashMap<>(properties.buildAdminProperties()); return AdminClient.create(configs); } }

The createTopic() method creates a NewTopic object representing the topic you want to create. The adminClient() method creates an AdminClient object, which you can use to create the topic.

To actually create the topic, you can use the createTopics() method of the AdminClient object. Here's an example of how you can do it:

@Autowired private AdminClient adminClient; @Autowired private NewTopic topic; public void createTopic() { try { adminClient.createTopics(Collections.singleton(topic)).all().get(); } catch (InterruptedException | ExecutionException e) { // handle exception } }

This will create the topic with the specified number of partitions and replicas.

Note: The createTopics() method is a blocking operation and may take some time to complete, depending on the size of the cluster and the number of topics being created. It is recommended to run this operation asynchronously or in a separate thread.

Tuesday, December 20, 2022

spring boot test how to mock test data

 There are several ways to mock test data in Spring Boot tests. One way is to use mock objects. Mockito is a popular library for creating mock objects in Java. You can use it to create mock objects of your service classes and inject them into your test class using the @Mock annotation. You can then use the when method of the mock object to specify the behavior of the mock object and the verify method to verify that certain methods were called on the mock object.

Here's an example of how you might use Mockito to mock a service class in a Spring Boot test:

@Mock private MyService myService; 
@Test public void testMethod() { // Set up the mock object's behavior when(myService.doSomething()).thenReturn("mocked result"); // Call the method being tested String result = myController.testMethod(); // Verify that the correct method was called on the mock object verify(myService).doAnotherThing(); // Assert that the result is correct assertEquals("expected result", result); }

Another way to mock test data is to use test data builders. These are classes that you can use to create test data objects in a more concise and readable way. For example, you might have a Person class with several fields, and you can create a PersonTestDataBuilder class that has methods for setting each field and a build method that creates a new Person object with the specified field values. This can make it easier to create test data objects with a large number of fields, and it can also make your test code more readable and maintainable.

You can also use in-memory databases or test data files to store your test data. This can be useful if you need to test interactions with a database or if you have a large amount of test data that would be cumbersome to create manually. For example, you might use an in-memory database like H2 or Apache Derby to store your test data, or you might use a CSV file or a JSON file to store your test data and load it into your tests using a library like Jackson or OpenCSV.

Monday, December 19, 2022

spring boot actuator

 Spring Boot Actuator is a sub-project of Spring Boot that provides several production-grade services to help you monitor and manage your application. You can use the file to configure Actuator endpoints, set security rules, and customize other Actuator-related settings.

Here are some examples of common Actuator configuration options that you can set in the file:

  • management.endpoints.web.exposure.include: This property specifies which Actuator endpoints should be exposed via HTTP. For example, to expose all endpoints, you can set this property to *.

  • This property controls whether the /actuator/health endpoint should include detailed information about the health of your application. By default, this endpoint only returns a simple "UP" or "DOWN" status.

  • management.endpoints.web.base-path: This property sets the base path for Actuator endpoints. For example, if you set the base path to /actuator, all Actuator endpoints will be available under the /actuator path, such as /actuator/health and /actuator/info.

  • management.endpoint.shutdown.enabled: This property enables or disables the /actuator/shutdown endpoint, which allows you to gracefully shutdown your application. By default, this endpoint is disabled for security reasons.

  • management.endpoints.web.cors.allowed-origins: This property specifies which origins are allowed to access Actuator endpoints. This is useful for enabling cross-origin requests from web applications.

There are many other configuration options available for Actuator. You can find more information in the Spring Boot Actuator documentation.