1.設計了一個介面用於包裝其它 pojo,以計算是否過期
public interface CatchWrapper<T>{
public long getCatchedTime();
public T getValue();
public boolean valid();
}
某一個實作:
public class DeviceCatchWrapper implements CatchWrapper<Device> {
private final long catchedTime;
private final Device device;
private static final long CATCH_TIME = 20*1000;
public DeviceCatchWrapper(Device device) {
this.device = device;
catchedTime = System.currentTimeMillis();
}
@Override
public long getCatchedTime() {
return catchedTime;
}
@Override
public Device getValue() {
return device;
}
@Override
public boolean valid() {
return System.currentTimeMillis() - catchedTime < CATCH_TIME;
}
}
另有一個管理類,主要是刪除過期的快取
public class DeviceCatchWrapperManager<T> {
private static final ScheduledExecutorService service = Executors.newSingleThreadScheduledExecutor();
private final ConcurrentMap<String, CatchWrapper<T>> catchStore;
private final long initialDelay;
private final long delay;
private TimeUnit unit;
private volatile boolean stop = false;
public DeviceCatchWrapperManager(ConcurrentMap<String,CatchWrapper<T>> catchStore, long initialDelay,
long delay, TimeUnit unit) {
this.catchStore = catchStore;
this.initialDelay = initialDelay;
this.delay = delay;
this.unit = unit;
}
/**
* 周期性检查过期的缓存,然后删除
*/
public void startLoop() {
service.scheduleWithFixedDelay(new Runnable() {
@Override
public void run() {
for (Entry<String, CatchWrapper<T>> entry : catchStore.entrySet()) {
if (stop)
break;
String key = entry.getKey();
CatchWrapper<T> cw = entry.getValue();
if (!cw.valid()){
System.out.println("Device catch manager --------------->remove:"+key);
catchStore.remove(key, cw);
}
}
}
}, initialDelay, delay, unit);
}
/**
* 停在对缓存进行过期检查
*/
public void stop() {
stop = true;
service.shutdownNow();
}
}
但是真正建構子 傳參數錯誤
private final ConcurrentMap<String, DeviceCatchWrapper> catchMap = new ConcurrentHashMap<>();
下面的报错,参数不对
private final DeviceCatchWrapperManager<Device> catchManager = new DeviceCatchWrapperManager<Device>(catchMap, 2, 2, TimeUnit.HOURS);
改怎麼解決這個錯誤 或是什麼改進呢?
ConcurrentMapDeviceCatchWrapper> catchMap = new ConcurrentHashMap(); 這句話有問題CatchWrapperdr. >( );試試
改成ConcurrentMap