几个缓存注解的作用：
@Cacheable：将方法的返回结果根据key指定的键保存在缓存中，以后要获取相同的数据直接从缓存中共获取
-
cacheNames/value：指定Cache组件名称
-
key：指定缓存时使用的key，默认使用方法参数值，可以使用#a0、#p0、#参数名等，支持SpEL表达式，root可省略
-
keyGenerator：指定key的生成器的组件id，如自定义的KeyGenerator
-
cacheManager：指定缓存管理器
-
cacheResolver：指定缓存解析器
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condition：指定在哪种条件下缓存，如condition = “#id>=1”在参数>=1时缓存
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unless：指定该条件为真时不缓存
-
sync：指定是否使用异步模式
@CachePut：不管缓存中是否有需要的数据，都会执行该注解标注的方法，并将结果更新到缓存，属性见上
@CacheEvit：执行方法后，清除key指定的缓存
-
allEntries：默认为false，值为true，删除所有缓存
-
beforeInvocation：默认为false，值为true，在方法调用之前清除缓存
@CacheConfig：定义一些通用或公共的规则，如cacheNames、keyGenerator等
可使用的SpEL表达式：
使用缓存的步骤：
（1）创建一个Spring Boot应用，勾选Cache、Web、MySQL、Mybatis模块,在主程序类上添加注解，开启基于注解的缓存
@MapperScan(basePackages = "com.youngpain.cache.mapper")
@SpringBootApplication
@EnableCaching
（2）创建JavaBean，和数据库中的表对应，并配置数据源
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
#开启驼峰命名法
mybatis:
configuration:
map-underscore-to-camel-case: true
logging:
level:
com.youngpain.cache.mapper: debug
（3）创建mapper接口进行增删改查操作
/**
* 部门表的增删改查操作
*/
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）创建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）创建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）测试结果：
@Cacheable：第一次查询数据，控制台发出sql语句，之后再查询直接从缓存中获取
@CachePut：调用方法修改某个数据后，再次查询该数据是从缓存中获取的更新后的数据
@CacheEvict：调用该方法后，再次查询某个数据需要重新发出sql语句查询
ps：之前只是用markdown记笔记，今天第一次用markdown写文章，写起来好舒服啊QAQ
总结
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