【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

   
    <cache:annotation-driven/>

    
    <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

@Service
public 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

@Service
public 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 get(Object key, Class 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
"numberGuess" class="org.spring.samples.NumberGuess">
    "randomNumber" value="#{ T(java.lang.Math).random() * 100.0 }"/>

    


"taxCalculator" class="org.spring.samples.TaxCalculator">
    "defaultLocale" value="#{ systemProperties['user.region'] }"/>

    


//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; 
 }