SpringBoot Cache 入门

首先搭载开发环境，不会的可以参考笔者之前的文章SpringBoot入门

添加依赖

<dependency>

    <groupId>org.springframework.boot</groupId>

    <artifactId>spring-boot-starter-cache</artifactId>

   </dependency>

开始配置Cache

a. 在启动类增加一个注解@EnableCaching

@SpringBootApplication

   @MapperScan("com.tanoak.mapper")

   @EnableCaching

   public class BootCacheApplication {

   

    public static void main(String[] args) {

    SpringApplication.run(BootCacheApplication.class, args);

    }

   }

b.  pojo

@Data

    public class Teacher {//使用Lombok注解

     private Integer id;

     private String lastName;

     private String email;

    

     /**

     *性别 1男  0女

     */

     private Integer sex;

     private Integer sId;

    }

c. Mapper



 @Mapper

    public interface TeacherMapper {

    

     @Select("SELECT * FROM teacher WHERE id =#{id}")

     Teacher getTeaById(Integer id);

    

     @Update("UPDATE teacher SET lastName =#{lastName},email=#{email},sex=#{sex},s_id=#{sId} WHERE id=#{id}")

     Integer update(Teacher teacher) ;

    

     @Delete("DELETE FROM teacher WHERE id =#{id}")

     Integer deleteById(Integer id) ;

    

     @Insert("INSERT INTO teacher(lastName,email,sex,t_id) VALUES(#{lastName},#{email},#{sex},#{sId})")

     Integer insert(Teacher teacher) ;

    }

d. Service

public interface TeacherService {

   

    /**

    *  根据ID查询实体

    * @param id

    * @return

    */

   

    Teacher getEmpById(Integer id) ;

    Integer update(Teacher teacher) ;

    Integer remove(Integer id) ;

   }

   

   //实现类

   

   @Service

   public class TeacherServiceImpl implements TeacherService {

   

    private static final Logger logger = LoggerFactory.getLogger(TeacherServiceImpl.class);

   

    @Resource

    private TeacherMapper teacherMapper ;

   

    @Override

    @Cacheable(cacheNames = {"emp"},condition = "#id>0")

    public Teacher getEmpById(Integer id) {

    logger.info("进行查询实体 ID为"+id);

    return teacherMapper.getTeaById(id) ;

    }

   

    @Override

    public Integer update(Teacher teacher) {

    logger.info("修改的实体为"+teacher.toString());

    return teacherMapper.update(teacher) ;

    }

   

    @Override

    public Integer remove(Integer id) {

    logger.info("删除的实体 ID为"+id);

    return teacherMapper.deleteById(id) ;

    }

   }

e. Controller

@RestController

 public class TeacherController {

 

  @Resource

  private TeacherService teacherService ;

 

  @GetMapping("/tea/{id}")

  @Cacheable(cacheNames = "tea")

  public Teacher getTea(@PathVariable("id")Integer id){

  return  teacherService.getEmpById(id) ;

  }

 }

然后就开启缓存，本篇文章结束！开个玩笑，在正常的开发中，我们的CRUD需要进行缓存的环节一般是在查询，更新，删除，在一些特殊的业务场景下也会对插入进行缓存，这里不做考虑。然后我们根据需求想要解决这个问题，那么Cache对应的注解就出现了

#根据方法的请求参数对其结果进行缓存

    @Cacheable

    -----------

    #保证方法被调用，又希望结果被缓存。

    @CachePut

    ------------

    清空缓存

    @CacheEvict

了解这三个注解我们来看下如何使用吧

@Cacheable

这个注解有多个属性

key  缓存的 key 支持SpEl表达式

keyGenerator  自定义Key生成策略  二选一（key or keyGenerator）



condition   符合指定条件缓存



unless 条件为true不缓存

@Override

 @Cacheable(cacheNames = "tea",key = "#id",condition = "#id>1")

 public Teacher getTeaById(Integer id) {

 logger.info("进行查询实体 ID为"+id);

 return teacherMapper.getTeaById(id) ;

}



@GetMapping("/tea/{id}")

 public Teacher getTea(@PathVariable("id")Integer id){

 return  teacherService.getEmpById(id) ;

 }

自定义KeyGenerator

public class MyKeyGenerator {



 @Bean("mykeyGenerator")

 public KeyGenerator keyGenerator(){

 return new KeyGenerator(){

 @Override

 public Object generate(Object target, Method method, Object ...params){

 return method.getName() +"{"+Arrays.asList(params) +"}";

 }

 };

 }

}

 @Cacheable(cacheNames = "tea",keyGenerator="mykeyGenerator")

 public Teacher getTeaById(Integer id) {

 logger.info("进行查询实体 ID为"+id);

 return teacherMapper.getTeaById(id) ;

 }



@GetMapping("/tea2/{id}")

 public Teacher getTea2(@PathVariable("id")Integer id){

 return  teacherService.getTeaById(id) ;

 }```

目前解决了查询的缓存，接下来处理更新的缓存

## @CachePut

这个注解是在方法执行完成后调用的与@Cacheable的调用顺序刚好相反

@GetMapping("/tea")

@CachePut(cacheNames = "tea")

public Teacher upTea(Teacher teacher){

teacherService.update(teacher) ;

return teacher ;

}```

可以看到，再次点击查询的时候没有发送sql语句，说明已经缓存成功

@CacheEvict

清空缓存，来认识一下

@Override

 @CacheEvict(cacheNames = "tea",key = "#id")

 public Integer remove(Integer id) {

 logger.info("删除的实体 ID为"+id);

//  return teacherMapper.deleteById(id) ;

 return 1 ;

 }

 //然后再Controller中调用

 @GetMapping("/tea3/{id}")

 public String delTea(@PathVariable("id")Integer id){

 teacherService.remove(id) ;

 System.out.println("测试删除缓存 id为"+id);

 return "OK" ;

 }```

Cache的基本用法到这里就结束了，下片文章我们深入探讨它的运行机制。如理解有误，请指正

巴特西

SpringBoot Cache 入门

@Cacheable

@CacheEvict

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