Cache warm-up is a mechanism in which data is loaded into a cache system (such as Redis) in advance when a Spring Boot project is started.
So the question is, when after the Spring Boot project is started? Where can I load data into the cache system?
Implementation plan overview
After Spring Boot is started, cache warm-up can be achieved by the following means:
1. Use the startup listening event to achieve cache warm-up.
2. Use the @PostConstruct annotation to implement cache warm-up.
3. Use CommandLineRunner or ApplicationRunner to implement cache warm-up.
4. Implement the InitializingBean interface and override the afterPropertiesSet method to achieve cache warm-up.
Specific implementation plan
① Start the listening event
You can use ApplicationListener to listen for application context initialization completion events such as ContextRefreshedEvent or ApplicationReadyEvent. After these events are triggered, the operation of data loading into the cache is executed. The specific implementation is as follows:
@Component
public class CacheWarmer implements ApplicationListener<ContextRefreshedEvent> {
@Override
public void onApplicationEvent(ContextRefreshedEvent event) {
// Execute cache preheating service... ("key", dataList);
}
}
Or listen for the ApplicationReadyEvent event, as shown in the following code:
@Component
public class CacheWarmer implements ApplicationListener<ApplicationReadyEvent> {
@Override
public void onApplicationEvent(ApplicationReadyEvent event) {
// Execute cache preheating service... ("key", dataList);
}
}
② @PostConstruct annotation
Add the @Component annotation on the class that needs to be cached warmed up, and add the @PostConstruct annotation and cached warmed up business logic to its method. The specific implementation code is as follows:
@Component
public class CachePreloader {
@Autowired
private YourCacheManager cacheManager;
@PostConstruct
public void preloadCache() {
// Execute cache preheating service... ("key", dataList);
}
}
③ CommandLineRunner or ApplicationRunner
CommandLineRunner and ApplicationRunner are both interfaces to be executed after Spring Boot application is started. They both allow us to execute some custom initialization logic after the application is started, such as cache warm-up. The CommandLineRunner implementation example is as follows:
@Component
public class MyCommandLineRunner implements CommandLineRunner {
@Override
public void run(String... args) throws Exception {
// Execute cache preheating service... ("key", dataList);
}
}
The ApplicationRunner implementation example is as follows:
@Component
public class MyApplicationRunner implements ApplicationRunner {
@Override
public void run(ApplicationArguments args) throws Exception {
// Execute cache preheating service... ("key", dataList);
}
}
The difference between CommandLineRunner and ApplicationRunner is as follows:
1. Different method signatures:
The CommandLineRunner interface has a run(String… args) method that takes command line parameters as an array of variable length strings.
The ApplicationRunner interface provides a run(ApplicationArguments args) method, which receives an ApplicationArguments object as a parameter, which provides access to all incoming command line parameters (including option and non-optional parameters).
2. Different parameters analysis methods:
The CommandLineRunner interface is simpler and more direct, suitable for handling simple command line parameters.
The ApplicationRunner interface provides a more powerful parameter resolution capability, which can obtain detailed parameter information through ApplicationArguments, such as obtaining option parameters and their values, non-option parameter lists, and querying whether specific parameters exist.
3. Different usage scenarios:
CommandLineRunner can be used when only a simple set of command line parameters is needed.
For complex scenarios that require fine control and parsing command line parameters, it is recommended to use ApplicationRunner.
④ Implement the InitializingBean interface
Implement the InitializingBean interface and override the afterPropertiesSet method. You can perform cache warm-up after Spring Bean initialization is completed. The specific implementation code is as follows:
@Component
public class CachePreloader implements InitializingBean {
@Autowired
private YourCacheManager cacheManager;
@Override
public void afterPropertiesSet() throws Exception {
// Execute cache preheating service... ("key", dataList);
}
}
summary
Cache warm-up is a mechanism in which data is loaded into a cache system (such as Redis) in advance when a Spring Boot project is started. It can be done by listening to the ContextRefreshedEvent or ApplicationReadyEvent startup event, or using the @PostConstruct annotation, or implementing the CommandLineRunner interface, the ApplicationRunner interface, and the InitializingBean interface.
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