【技能库】@Cacheable @CachePut Spring 缓存示例（142）

注意：配置一定要正确，Cache对象相关注解一定要在spring管理的其他对象中调用，不能是引用内部方法调用，因为缓存切面靠的就是代理proxy机制完成的。

配置

   <!-- 启动缓存注解功能 -->    <cache:annotation-driven/>    <!--generic cache manager -->    <bean id="cacheManager" class="org.springframework.cache.support.SimpleCacheManager">        <property name="caches">            <set>                <bean class="com.finance.cache.DuoTalkTimesCache" p:name="duoTalkTimesCache"/>            </set>        </property>    </bean>

Controller

    @RequestMapping(value = "/get", method = RequestMethod.GET)    @ResponseBody    public int getTalkTimes() {        int x = duoTalkTimesDao.annotationCacheGet("duoduo");        return x;    }    @ResponseBody    @RequestMapping(value = "/put", method = RequestMethod.GET)    public String putTaslTimes() {        Integer 消息= duoTalkTimesDao.annotationCachePut("duoduo");        return String.valueOf(消息);    }

Repository

@Servicepublic class DuoTalkTimesDao {    @Resource    private DuoTalkTimesCache duoTalkTimesCache;    /**     * 将结果缓存，一定会执行db操作     * @param key     * @return     */    @CachePut(value = "duoTalkTimesCache")    public Integer annotationCachePut(String key) {        System.out.println("更新数据库");// 模拟走数据库        return new Random().nextInt(10);    }    /**     * 根据key 去取缓存结果，如果有不走db操作，否则执行db操作，并将结果缓存。     * @param key     * @return     */    @Cacheable(value = "duoTalkTimesCache")    public Integer annotationCacheGet(String key) {        System.out.println("查询数据库");//模拟查询数据库        return new Random().nextInt(10);    }}

Cache

@Servicepublic class DuoTalkTimesCache implements Cache {    private static final Logger log = LoggerFactory.getLogger(DuoTalkTimesCache.class);    private static String talktimes = "0";    private String name;    public void setName(String name) {        this.name = name;    }    @Override    public String getName() {        return name;    }    @Override    public Object getNativeCache() {        return null;    }    @Override    public ValueWrapper get(Object key) {        Integer integer = get(key, Integer.class);        log.info("get first by key {}", key);        return integer == null ? null : new SimpleValueWrapper(integer);    }    @Override    public <T> T get(Object key, Class<T> type) {        log.info("get by key {}", key);        if (key == null || !(key instanceof String)) {            return null;        }        String value = talktimes;//from cache        if (StringUtils.isBlank(value)) {            return null;        }        return type.cast(Integer.parseInt(value));    }    @Override    public void put(Object key, Object value) {        log.info("put by key {} {}", key, value);        if (key == null || !(key instanceof String)) {            log.info("put by key {} {}", key, value);            return;        }        if (value == null || !(value instanceof Integer)) {            log.info("put by key {} {}", key, value);            return;        }        try {            //写入缓存            talktimes = String.valueOf(Integer.parseInt(talktimes) + (Integer) value);            log.info("put by key {} result = {}", key, talktimes);        } catch (Exception e) {            log.error("入缓存失败", e);        }    }    @Override    public void evict(Object key) {        log.info("get by key {}", key);        if (key == null || !(key instanceof String)) {            return;        }        try {            //删除缓存        } catch (Exception e) {            log.error("evict exception", e);        }    }    @Override    public void clear() {        //清空    }}

SpEl:表达式两种用法
SpEL expressions can be used with XML or annotation-based configuration metadata for defining BeanDefinitions. In both cases the syntax to define the expression is of the form #{ }.

//XML<bean id="numberGuess" class="org.spring.samples.NumberGuess">    <property name="randomNumber" value="#{ T(java.lang.Math).random() * 100.0 }"/>    <!-- other properties --></bean><bean id="taxCalculator" class="org.spring.samples.TaxCalculator">    <property name="defaultLocale" value="#{ systemProperties['user.region'] }"/>    <!-- other properties --></bean>//注解public static class FieldValueTestBean    @Value("#{ systemProperties['user.region'] }")    private String defaultLocale;    public void setDefaultLocale(String defaultLocale) {        this.defaultLocale = defaultLocale;    }    public String getDefaultLocale() {        return this.defaultLocale;    }} @Cacheable(value="accountCache")// 使用了一个缓存名叫 accountCache  public Account getAccountByName(String userName) {    // 方法内部实现不考虑缓存逻辑，直接实现业务   return getFromDB(userName);  }  @CachePut(value="accountCache",key="#account.getName()")// 更新 accountCache 缓存 public Account updateAccount(Account account) {    return updateDB(account);  }  private Account updateDB(Account account) {    System.out.println("real updating db..."+account.getName());    return account;  }