性能缓慢是开发人员经常面临的一个反复出现且复杂的问题。解决此类问题的最常见方法之一是通过缓存。实际上,这种机制允许在任何类型的应用程序的性能方面实现显着改进。问题是处理缓存并不是一件容易的事。幸运的是,Spring Boot 透明地提供了缓存,这要归功于 Spring Boot 缓存抽象,这是一种允许一致使用各种缓存方法而对代码影响最小的机制。让我们看看开始处理它应该知道的一切。
首先,我们将介绍缓存的概念。然后,我们将研究最常见的 Spring Boot 缓存相关注解,了解最重要的注解是什么,在哪里以及如何使用它们。接下来,是时候看看在撰写本文时 Spring Boot 支持的最流行的缓存引擎有哪些。最后,我们将通过一个示例了解 Spring Boot 缓存的实际应用。
缓存是一种旨在提高任何类型应用程序性能的机制。它依赖于缓存,缓存可以看作是一种临时的快速访问软件或硬件组件,用于存储数据以减少处理与相同数据相关的未来请求所需的时间。处理缓存是很复杂的,但掌握这个概念对于任何开发人员来说几乎都是不可避免的。如果您有兴趣深入研究缓存、了解它是什么、它是如何工作的以及它最重要的类型是什么,您应该首先点击这个链接。
为了使用 Spring Boot 实现 Redis 缓存,我们需要创建一个小型应用程序,该应用程序将具有 CRUD 操作。然后我们将在检索、更新和删除操作中应用 Redis 缓存功能。
我们将使用 REST 创建一个 CRUD 应用程序。在这里,假设我们的实体类是 Invoice.java。为了创建一个完整的 REST 应用程序,我们将根据行业最佳实践拥有控制器、服务和存储库层。一旦我们完成了 Invoice REST Application 的开发,我们将进一步在某些方法上应用注解来获得 Redis Cache 的好处。这是在我们的应用程序中实现 Redis 缓存的分步方法。
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/rediscachetest
spring.datasource.username=root
spring.datasource.password=****
spring.jpa.database-platform=org.hibernate.dialect.MySQL8Dialect
spring.jpa.show-sql=true
spring.jpa.hibernate.ddl-auto=update
spring.cache.type=redis
spring.cache.redis.cache-null-values=true
#spring.cache.redis.time-to-live=40000
启动类注解 @EnableCaching at starter class
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cache.annotation.EnableCaching;
@SpringBootApplication
@EnableCaching
public class RedisAsaCacheWithSpringBootApplication {
public static void main(String[] args) {
SpringApplication.run(RedisAsaCacheWithSpringBootApplication.class, args);
}
}
@Data
@NoArgsConstructor
@AllArgsConstructor
@Entity
public class Invoice implements Serializable{
private static final long serialVersionUID = -4439114469417994311L;
@Id
@GeneratedValue
private Integer invId;
private String invName;
private Double invAmount;
}
创建一个接口 InvoiceRepository.java
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;
import com.dev.springboot.redis.model.Invoice;
@Repository
public interface InvoiceRepository extends JpaRepository<Invoice, Integer> {
}
自定义异常类
import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.ResponseStatus;
@ResponseStatus(HttpStatus.NOT_FOUND)
public class InvoiceNotFoundException extends RuntimeException {
private static final long serialVersionUID = 7428051251365675318L;
public InvoiceNotFoundException(String message) {
super(message);
}
}
一个具体的实现类,中间包含一些增删改查的方法
import com.dev.springboot.redis.model.Invoice;
import java.util.List;
public interface InvoiceService {
public Invoice saveInvoice(Invoice inv);
public Invoice updateInvoice(Invoice inv, Integer invId);
public void deleteInvoice(Integer invId);
public Invoice getOneInvoice(Integer invId);
public List<Invoice> getAllInvoices();
}
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.CacheEvict;
import org.springframework.cache.annotation.CachePut;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;
import com.dev.springboot.redis.exception.InvoiceNotFoundException;
import com.dev.springboot.redis.model.Invoice;
import com.dev.springboot.redis.repo.InvoiceRepository;
@Service
public class InvoiceServiceImpl implements InvoiceService {
@Autowired
private InvoiceRepository invoiceRepo;
@Override
public Invoice saveInvoice(Invoice inv) {
return invoiceRepo.save(inv);
}
@Override
@CachePut(value="Invoice", key="#invId")
public Invoice updateInvoice(Invoice inv, Integer invId) {
Invoice invoice = invoiceRepo.findById(invId)
.orElseThrow(() -> new InvoiceNotFoundException("Invoice Not Found"));
invoice.setInvAmount(inv.getInvAmount());
invoice.setInvName(inv.getInvName());
return invoiceRepo.save(invoice);
}
@Override
@CacheEvict(value="Invoice", key="#invId")
// @CacheEvict(value="Invoice", allEntries=true) //in case there are multiple records to delete
public void deleteInvoice(Integer invId) {
Invoice invoice = invoiceRepo.findById(invId)
.orElseThrow(() -> new InvoiceNotFoundException("Invoice Not Found"));
invoiceRepo.delete(invoice);
}
@Override
@Cacheable(value="Invoice", key="#invId")
public Invoice getOneInvoice(Integer invId) {
Invoice invoice = invoiceRepo.findById(invId)
.orElseThrow(() -> new InvoiceNotFoundException("Invoice Not Found"));
return invoice;
}
@Override
@Cacheable(value="Invoice")
public List<Invoice> getAllInvoices() {
return invoiceRepo.findAll();
}
}
添加Controller接口,进行请求测试
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import com.dev.springboot.redis.model.Invoice;
import com.dev.springboot.redis.service.InvoiceService;
@RestController
@RequestMapping("/invoice")
public class InvoiceController {
@Autowired
InvoiceService invoiceService;
@PostMapping("/saveInv")
public Invoice saveInvoice(@RequestBody Invoice inv) {
return invoiceService.saveInvoice(inv);
}
@GetMapping("/allInv")
public ResponseEntity<List<Invoice>> getAllInvoices(){
return ResponseEntity.ok(invoiceService.getAllInvoices());
}
@GetMapping("/getOne/{id}")
public Invoice getOneInvoice(@PathVariable Integer id) {
return invoiceService.getOneInvoice(id);
}
@PutMapping("/modify/{id}")
public Invoice updateInvoice(@RequestBody Invoice inv, @PathVariable Integer id) {
return invoiceService.updateInvoice(inv, id);
}
@DeleteMapping("/delete/{id}")
public String deleteInvoice(@PathVariable Integer id) {
invoiceService.deleteInvoice(id);
return "Employee with id: "+id+ " Deleted !";
}
}