幾個緩存注解的作用：
@Cacheable：將方法的返回結果根據key指定的鍵保存在緩存中，以后要獲取相同的數據直接從緩存中共獲取
- cacheNames/value：指定Cache組件名稱
- key：指定緩存時使用的key，默認使用方法參數值，可以使用#a0、#p0、#參數名等，支持SpEL表達式，root可省略
- keyGenerator：指定key的生成器的組件id，如自定義的KeyGenerator
- cacheManager：指定緩存管理器
- cacheResolver：指定緩存解析器
- condition：指定在哪種條件下緩存，如condition = “#id>=1”在參數>=1時緩存
- unless：指定該條件為真時不緩存
- sync：指定是否使用異步模式
@CachePut：不管緩存中是否有需要的數據，都會執行該注解標注的方法，并將結果更新到緩存，屬性見上
@CacheEvit：執行方法后，清除key指定的緩存
- allEntries：默認為false，值為true，刪除所有緩存
- beforeInvocation：默認為false，值為true，在方法調用之前清除緩存
@CacheConfig：定義一些通用或公共的規則，如cacheNames、keyGenerator等
可使用的SpEL表達式：
使用緩存的步驟：
（1）創建一個Spring Boot應用，勾選Cache、Web、MySQL、Mybatis模塊,在主程序類上添加注解，開啟基于注解的緩存
@MapperScan(basePackages = "com.youngpain.cache.mapper") @SpringBootApplication @EnableCaching
（2）創建JavaBean，和數據庫中的表對應，并配置數據源
spring: datasource: url: jdbc:mysql://localhost:3306/mybatis_database username: root password: 1741248769 driver-class-name: com.mysql.jdbc.Driver redis: host: 39.108.114.57 #開啟駝峰命名法 mybatis: configuration: map-underscore-to-camel-case: true logging: level: com.youngpain.cache.mapper: debug
（3）創建mapper接口進行增刪改查操作
/**
* 部門表的增刪改查操作
*/
public interface DepartmentMapper {
@Insert("insert into department(id,depart_name,depart_build) values(#{id},#{depart_name},#{depart_build})")
void insertDepartment(Department department);
@Delete("delete from department where id=#{id}")
void deleteDepartment(Integer id);
@Update("update department set depart_name=#{departName},depart_build=#{departBuild} where id=#{id}")
void updateDepartment(Department department);
@Select("select * from department where id=#{id}")
Department getDepartmentById(Integer id);
}
（4）創建service
@Service
@CacheConfig(cacheNames = {"departs"})
public class DepartmentService {
@Autowired
DepartmentMapper departmentMapper;
@Cacheable(key = "#a0.id")
public void insertDepartment(Department department) {
departmentMapper.insertDepartment(department);
}
@CacheEvict(key = "#p0")
public void deleteDepartment(Integer id) {
departmentMapper.deleteDepartment(id);
}
@CachePut(key = "#a0.id")
public Department updateDepartment(Department department) {
departmentMapper.updateDepartment(department);
return department;
}
@Cacheable(key = "#id", condition = "#p0>=1")
public Department getDepartmentById(Integer id) {
return departmentMapper.getDepartmentById(id);
}
}
（5）創建controller
@Controller
public class DepartmentController {
@Autowired
DepartmentService departmentService;
@GetMapping("/index")
public String index() {
return "index";
}
@GetMapping("/deleteDepart/{id}")
public String deleteDepart(@PathVariable("id") Integer id, Model model) {
model.addAttribute("condition", "delete");
Department delete = departmentService.getDepartmentById(id);
model.addAttribute("department", delete);
departmentService.deleteDepartment(id);
return "success";
}
@PostMapping("/updateDepart")
public String updateDepart(Department department, Model model) {
model.addAttribute("condition", "update");
Department update = departmentService.updateDepartment(department);
model.addAttribute("department", update);
return "success";
}
@GetMapping("/getDepart/{id}")
public String getDepartmentById(@PathVariable("id") Integer id, Model model) {
model.addAttribute("condition", "delete");
Department get = departmentService.getDepartmentById(id);
model.addAttribute("department", get);
return "success";
}
}
（6）測試結果：
@Cacheable：第一次查詢數據，控制臺發出sql語句，之后再查詢直接從緩存中獲取
@CachePut：調用方法修改某個數據后，再次查詢該數據是從緩存中獲取的更新后的數據
@CacheEvict：調用該方法后，再次查詢某個數據需要重新發出sql語句查詢
ps：之前只是用markdown記筆記，今天第一次用markdown寫文章，寫起來好舒服啊QAQ
總結
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