spring boot学习(十三)SpringBoot缓存(EhCache 2.x 篇)

      <!--开启 cache 缓存-->
      <dependency>
          <groupId>org.springframework.boot</groupId>
          <artifactId>spring-boot-starter-cache</artifactId>
      </dependency>
      <!-- ehcache 缓存 -->
      <dependency>
          <groupId>net.sf.ehcache</groupId>
          <artifactId>ehcache</artifactId>
      </dependency>

<?xml version="1.0" encoding="UTF-8"?>
<ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:noNamespaceSchemaLocation="http://ehcache.org/ehcache.xsd"
         updateCheck="false">
    <defaultCache
            eternal="false"
            maxElementsInMemory="1000"
            overflowToDisk="false"
            diskPersistent="false"
            timeToIdleSeconds="0"
            timeToLiveSeconds="600"
            memoryStoreEvictionPolicy="LRU" />

    <!-- 这里的 users 缓存空间是为了下面的 demo 做准备 -->
    <cache
            name="users"
            eternal="false"
            maxElementsInMemory="100"
            overflowToDisk="false"
            diskPersistent="false"
            timeToIdleSeconds="0"
            timeToLiveSeconds="300"
            memoryStoreEvictionPolicy="LRU" />
</ehcache>

public class User {

    private long id;
    private String uuid;
    private String name;
    private Integer age;

    //省略 get、set 及 toString 方法
}

@Mapper
public interface UserDao{

    void delete(String uuid);

    User update(User user);

    User findByUuid(String uuid);

    int save(@Param("user") User user);
}

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="qg.fangrui.boot.dao.UserDao">
    <!--目的：为Dao接口方法提供SQL语句-->

    <!--映射实体对象-->
    <resultMap id="UserResultMap" type="qg.fangrui.boot.model.User">
        <id property="id" column="id" />
        <result property="uuid" column="uuid" />
        <result property="name" column="name" />
        <result property="age" column="age" />
    </resultMap>


    <insert id="save">
        INSERT INTO users(name, age, uuid)
        VALUES (#{user.name}, #{user.age}, #{user.uuid})
    </insert>

    <select id="findByUuid" resultType="User">
        SELECT * FROM users WHERE uuid = #{uuid}
    </select>

    <delete id="delete">
        DELETE FROM users WHERE uuid = #{uuid}
    </delete>

</mapper>

@Service
public class UserService {

    //这里的单引号不能少，否则会报错，被识别是一个对象
    private static final String CACHE_KEY = "‘user‘";
    private static final String DEMO_CACHE_NAME = "users";

    @Autowired
    private UserDao userDao;

    //删除用户数据
    @CacheEvict(value = DEMO_CACHE_NAME,key = "‘user_‘+#uuid")//这是清除缓存
    public void delete(String uuid){
        userDao.delete(uuid);
    }

    //更新用户数据
    @CachePut(value = DEMO_CACHE_NAME,key = "‘user_‘+#user.getUuid()")
    public User update(User user) throws CacheException{
        User user1 = userDao.findByUuid(user.getUuid());
        if (null == user1){
            throw new  CacheException("Not Find");
        }
        user1.setAge(user.getAge());
        user1.setName(user.getName());
        return user1;
    }

    //查找用户数据
    @Cacheable(value=DEMO_CACHE_NAME,key="‘user_‘+#uuid")
    public User findByUuid(String uuid){
        //若找不到缓存将打印出提示语句
        System.err.println("没有走缓存！"+uuid);
        return userDao.findByUuid(uuid);
    }

    //保存用户数据
    @CacheEvict(value=DEMO_CACHE_NAME,key=CACHE_KEY)
    public int save(User user){
        return userDao.save(user);
    }
}

@RestController
public class EhcacheController {

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

    @Autowired
    private UserService userService;

    @RequestMapping("/encache")
    public String EhcacheTest(){
        logger.debug("进行Encache缓存测试");
        System.out.println("====生成第一个用户====");
        User user1 = new User();
        //生成第一个用户的唯一标识符 UUID
        String u1_uuid = UUID.randomUUID().toString();
        //去掉 UUID 的 - 符号
        String uuid1 = u1_uuid.substring(0,8)+u1_uuid.substring(9,13)+u1_uuid.substring(14,18)+u1_uuid.substring(19,23)+u1_uuid.substring(24);
        user1.setName("张三");
        user1.setAge(18);
        user1.setUuid(uuid1);
        if (userService.save(user1) == 0){
            throw new JdbcException("用户对象插入数据库失败");
        }

        //第一次查询
        System.out.println(userService.findByUuid(user1.getUuid()));
        //通过缓存查询
        System.out.println(userService.findByUuid(user1.getUuid()));

        System.out.println("====修改数据====");
        User user2 = new User();
        user2.setName("李四-update");
        user2.setAge(22);
        user2.setId(user1.getId());
        user2.setUuid(user1.getUuid());
        try {
            System.out.println(userService.update(user2));
        } catch (CacheException e){
            e.printStackTrace();
        }

        System.out.println(userService.findByUuid(user2.getUuid()));
        return "success";
    }
}