在spring中利用Guava实现本地Cache的具体配置 第二篇<二>

通过直接实现org.springframework.cache.Cache 接口来管理和实现缓存

public class GuavaCacheUtil implements Cache {

private static Logger log = LoggerFactory.getLogger(GuavaCacheUtil.class);
private static final Object NULL_HOLDER = new NullHolder();
private static final String DEFAULT_NAME = "system_cache";
private final String name;
private final com.google.common.cache.Cache<Object, Object> cache;
private final boolean allowNullValues;
private static GuavaCacheUtil guavaCacheUtil = new GuavaCacheUtil();

public static GuavaCacheUtil builder() {
return guavaCacheUtil;
}

private GuavaCacheUtil() {
this(DEFAULT_NAME, CacheBuilder.newBuilder().maximumSize(100).expireAfterWrite(1, TimeUnit.HOURS).build());
}

private GuavaCacheUtil(String name, com.google.common.cache.Cache<Object, Object> cache) {
this(name, cache, true);
}

private GuavaCacheUtil(String name, com.google.common.cache.Cache<Object, Object> cache, boolean allowNullValues) {
Assert.notNull(name, "Name must not be null");
Assert.notNull(cache, "Cache must not be null");
this.name = name;
this.cache = cache;
this.allowNullValues = allowNullValues;
}

@Override
public String getName() {
return this.name;
}

@Override
public Object getNativeCache() {
return this.cache;
}

@Override
public ValueWrapper get(Object key) {
key = getKey(key.toString());
Object value = this.cache.getIfPresent(key);
log.info("getKey = {}, getObject = {}", key, JsonUtil.objectToJson(value));
return toWrapper(value);
}

@Override
public <T> T get(Object key, Class<T> aClass) {
key = getKey(key.toString());
T value = fromStoreValue(this.cache.getIfPresent(key), aClass);
log.info("getKey = {}, getObject = {}", key, JsonUtil.objectToJson(value));
return value;
}

@Override
public <T> T get(Object o, Callable<T> callable) {
return null;
}

@Override
public void put(Object key, Object value) {
key = getKey(key.toString());
this.cache.put(key, toStoreValue(value));
log.info("getKey = {}, getObject = {}", key, JsonUtil.objectToJson(value));
}

@Override
public ValueWrapper putIfAbsent(Object key, Object value) {
PutIfAbsentCallable callable = new PutIfAbsentCallable(value);
try {
Object result = this.cache.get(key, callable);
return (callable.called ? null : toWrapper(result));
} catch (ExecutionException e) {
throw new IllegalStateException(e);
}
}

@Override
public void evict(Object key) {
this.cache.invalidate(key);
log.info("deleteKey = {}", key);
}

@Override
public void clear() {
this.cache.invalidateAll();
log.info("clearAll");
}

private ValueWrapper toWrapper(Object value) {
return (value != null ? new SimpleValueWrapper(fromStoreValue(value, null)) : null);
}

private static class NullHolder implements Serializable {
}

private Object toStoreValue(Object userValue) {
if (this.allowNullValues && userValue == null) {
return NULL_HOLDER;
}
return userValue;
}

private <T> T fromStoreValue(Object storeValue, Class<T> aClass) {
if (this.allowNullValues && storeValue == NULL_HOLDER) {
return null;
}
if (storeValue != null && aClass != null && !aClass.isInstance(storeValue)) {
throw new IllegalStateException("Cached value is not of required type [" + aClass.getName() + "]: " + storeValue);
}
return (T) storeValue;
}

private class PutIfAbsentCallable implements Callable<Object> {

private final Object value;

private boolean called;

public PutIfAbsentCallable(Object value) {
this.value = value;
}

@Override
public Object call() throws Exception {
this.called = true;
return toStoreValue(this.value);
}
}

private String getKey(String key) {
return name + ":" + key;
}
}

public static String testCachePut(){
Cache cache = GuavaCacheUtil.builder();
cache.put("user_id:1","20");
String user_id = cache.get("user_id:1", String.class);
System.out.println(user_id);
return user_id;
}

public static String testCacheGet(){
Cache cache = GuavaCacheUtil.builder();
cache.put("user_id:2","30");
String user_id = cache.get("user_id:1", String.class);
System.out.println(user_id);
System.out.println(cache.get("user_id:2",String.class));
return user_id;
}

public static void main(String[] args) {
testGuavaCachePut();
testGuavaCacheGet();
}