These annotations are called at specific moments in the bean lifecycle.<\/p>\n\n\n\n
They allow you to define methods executed after a bean is created and before the beans are destroyed.<\/p>\n\n\n\n
Both annotations come from Jakarta EE and can be used in Spring projects.<\/p>\n\n\n\n
They are useful for managing resources that are only used in the bean\u2019s life cycle scope.<\/p>\n\n\n\n
We have a Before sending messages, you need to create a connection to an external API and authenticate.<\/p>\n\n\n\n So our Now, let’s create the This bean will be request-scoped, so it becomes easier to see the bean lifecycle.<\/p>\n\n\n\n The scope will be So we used the We used the And we can use the resource we created in Bean in all the other methods.<\/p>\n\n\n\n To exercise this code, we can create this controller:<\/p>\n\n\n Calling the endpoint In this blog post, you learned how to leverage the @PostConstruct and @PreDestroy annotations to add custom behavior during the lifecycle of your Spring beans.<\/p>\n\n\n\n If you found this topic interesting, follow me for more insights into Spring annotations and other valuable tips!<\/p>\n\n\n\n Willian Moya (@WillianFMoya) \/ X (twitter.com)<\/a><\/p>\n\n\n\nCustomNotificationService<\/code> bean that uses an ExternalMessageSender<\/code><\/p>\n\n\n\nExternalMessageSender<\/code> should look like this:<\/p>\n\n\n\npublic class ExternalMessageSender {\n\n public void authenticate(String apiKey, String secret) {\n log.info("Called on bean creation");\n }\n\n public void sendMessage(String recipient, String content) {\n log.info("Message sent to " + recipient + ": " + content + " when processing the request");\n }\n\n public void closeConnection() {\n log.info("Called on bean destruction");\n }\n}\n\n<\/pre><\/div>\n\n\nCustomNotificationService<\/code> bean, where the fun happens.<\/p>\n\n\n\nrequested<\/code> so the bean will be available only in the It will be created when a request is made, and destroyed after the request is done.<\/p>\n\n\n\n@Service\n@Scope(value = "request", proxyMode = ScopedProxyMode.TARGET_CLASS)\npublic class CustomNotificationService {\n\n private ExternalMessageSender messageSender;\n\n @PostConstruct\n public void initialize() {\n messageSender = new ExternalMessageSender("<https:\/\/api.example.com\/messages>");\n messageSender.authenticate("api_key", "secret");\n }\n\n public void sendNotification(String userId, String message) {\n messageSender.sendMessage(userId, message);\n }\n\n @PreDestroy\n public void cleanup() {\n messageSender.closeConnection();\n }\n}\n\n\n<\/pre><\/div>\n\n\ninitialize()<\/code> method as @PostConstruct<\/code> after the bean was created.<\/p>\n\n\n\ncleanup()<\/code> method will be used before the bean was destroyed.<\/p>\n\n\n\n\n\/\/ NotificationController class\n@RestController\npublic class NotificationController {\n \/\/ ... (Autowired notificationService) ...\n\n @PostMapping("\/send-notification")\n public String sendNotification(@RequestBody NotificationRequest request) {\n String userId = request.userId();\n String message = request.message();\n notificationService.sendNotification(userId, message);\n return "Notification sent successfully!";\n }\n}\n\n\/\/ NotificationRequest record\npublic record NotificationRequest(\n String userId,\n String message\n) {}\n\n\n<\/pre><\/div>\n\n\n\/send-notification<\/code>, you’ll see the following output in logs, demonstrating the methods being executed at each stage of the bean’s lifecycle:<\/p>\n\n\n\n2024-06-27T21:30:48.287-03:00 INFO 14944 --- [nio-8080-exec-3] c.s.m.postandpre.ExternalMessageSender : Called on bean creation\n2024-06-27T21:30:48.287-03:00 INFO 14944 --- [nio-8080-exec-3] c.s.m.postandpre.ExternalMessageSender : Message sent to 123: Hello world @PostConstruct and @PreDestroy. when processing the request\n2024-06-27T21:30:48.289-03:00 INFO 14944 --- [nio-8080-exec-3] c.s.m.postandpre.ExternalMessageSender : Called on bean destruction\n\n\n<\/pre><\/div>\n\n\n
Conclusion<\/h3>\n\n\n\n