前言
在此章，我們将 SpringBoot 內建 Redis緩存，Redis是一個開源的，基于記憶體的資料結構存儲，可以用作資料庫、緩存和消息代理，在本章僅講解緩存內建。
準備工作
目前項目工具及環境
- 開發工具 IDEA 2020.3
- 依賴管理 Maven
- Spring Boot
- JDK 1.8
- Redis
現在去初始化一個Spring網站初始生成一個SpringBoot項目
建立項目
點選 Next 後設定項目名稱後，點選 Finish 完成建立項目
建立實體對象
要将資料存到redis，我們需要定義一個實體來進行互動，并需要序列化實體對象
User.java
package com.github.gleans.model;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.ToString;
import javax.persistence.*;
import java.io.Serializable;
@Data
@Entity
@ToString
@NoArgsConstructor
@AllArgsConstructor
public class User implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@SequenceGenerator(name = "SEQ_GEN", sequenceName = "SEQ_USER", allocationSize = 1)
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "SEQ_GEN")
private Long id;
private String name;
private long money;
} 使用JPA的簡潔資料操作
UserRepository.java
package com.github.gleans.dao;
import com.github.gleans.model.User;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;
/**
* 操作資料庫
*/
@Repository
public interface UserRepository extends JpaRepository<User, Long> {
} 接口api代碼
UserController.java
import com.github.gleans.dao.UserRepository;
import com.github.gleans.model.User;
import lombok.extern.slf4j.Slf4j;
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.web.bind.annotation.*;
import java.util.List;
@Slf4j
@RestController
public class UserController {
private UserRepository userRepository;
@Autowired
public void setUserRepository(UserRepository userRepository) {
this.userRepository = userRepository;
}
@Cacheable(cacheNames = "userAll")
@GetMapping("user/all")
public Object getUserAll() {
return userRepository.findAll();
}
@Cacheable(value = "users", key = "#userId", unless = "#result.money < 10000")
@GetMapping("user/con/{userId}")
public Object getUserByCondition(@PathVariable Long userId) {
return userRepository.findById(userId);
}
@CachePut(value = "users", key = "#user.id")
@PutMapping("/update")
public User updatePersonByID(@RequestBody User user) {
userRepository.save(user);
return user;
}
@CacheEvict(value = "users", allEntries=true)
@DeleteMapping("/{id}")
public void deleteUserByID(@PathVariable Long id) {
List<User> userListOld = userRepository.findAll();
log.info("删除前:{}", userListOld.toString());
userRepository.deleteById(id);
List<User> userList = userRepository.findAll();
log.info("删除後:{}", userList.toString());
}
} 配置 application.yml
#Redis Config
spring:
datasource:
url: jdbc:h2:mem:activiti;DB_CLOSE_DELAY=1000
driverClassName: org.h2.Driver
username: root
password: root
cache:
type: redis
redis:
host: localhost
port: 6379
password: ekko1234
jpa:
show-sql: true
1. 啟動 Redis
項目根目錄, 使用docker-compose up -d 啟動 redis
Microsoft Windows [版本 10.0.17763.1339]
(c) 2018 Microsoft Corporation。保留所有權利。
C:\Users\ekko\Documents\SpringBootLearn>cd springboot-redis
C:\Users\ekko\Documents\SpringBootLearn\springboot-redis>docker-compose up -d
Creating network "springboot-redis_default" with the default driver
Creating my_redis ... done
C:\Users\ekko\Documents\SpringBootLearn\springboot-redis> 開啟緩存并初始化資料
在啟動類增加注解@EnableCaching開啟緩存
并實作CommandLineRunner接口來執行啟動完成之後的任務
SpringBootRedisApplication.java
import com.github.gleans.dao.UserRepository;
import com.github.gleans.model.User;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cache.annotation.EnableCaching;
@Slf4j
//springboot啟動時執行任務CommandLineRunner
@SpringBootApplication
//開啟緩存
@EnableCaching
public class SpringBootRedisApplication implements CommandLineRunner {
private UserRepository userRepository;
public static void main(String[] args) {
SpringApplication.run(SpringBootRedisApplication.class, args);
}
@Autowired
public void setUserRepository(UserRepository userRepository) {
this.userRepository = userRepository;
}
@Override
public void run(String... args) throws Exception {
log.info("開始初始化user ->user count ->{}", userRepository.count());
User james = new User(1L, "James", 2000);
User potter = new User(2L, "Potter", 4000);
User dumbledore = new User(3L, "Dumbledore", 999999);
userRepository.save(james);
userRepository.save(potter);
userRepository.save(dumbledore);
log.info("初始化完成 資料-> {}.", userRepository.findAll());
}
} 新增緩存
當我們資料庫查詢出來的值要放到緩存裡，用@Cacheable注解
@Cacheable(value = "users", key = "#userId", unless = "#result.money < 10000")
@RequestMapping(value = "/{userId}", method = RequestMethod.GET)
public Object getUser(@PathVariable Long userId) {
logger.info("擷取user資訊根據ID-> {}.", userId);
return userRepository.findById(userId);
} 我們通路 localhost:8080/1 和 localhost:8080/3 分别兩次
發現id為3的就走了一次方法 說明緩存成功
id為1的走了兩次是因為 unless裡條件成立就不會緩存到redis
更新緩存
每次當我們的資料庫的值要更改，我們緩存的也要更改 ，我們可以使用 @CachePut 注解
@CachePut(value = "users", key = "#user.id")
@PutMapping("/update")
public User updatePersonByID(@RequestBody User user) {
userRepository.save(user);
return user;
} 删除緩存
當我們的資料從資料庫删除，我們也要從緩存進行删除,我們可以使用 @CacheEvict 注解
allEntries 是否清空所有緩存内容，預設為 false，如果指定為 true，則方法調用後将立即清空所有緩存
@CacheEvict(value = "users", allEntries=true)
@DeleteMapping("/{id}")
public void deleteUserByID(@PathVariable Long id) {
logger.info("删除使用者根據ID-> {}", id);
userRepository.deleteById(id);
}