web_server/src/main/java/thyyxxk/webserver/utils/CacheOnce.java

package thyyxxk.webserver.utils;


import java.util.HashMap;
import java.util.Map;
import java.util.Objects;
import java.util.function.Function;


/**
 * @author Administrator
 */
public class CacheOnce<T> {
    private final Map<String, Object> map = new HashMap<>();

    @SuppressWarnings("unchecked")
    T get(String name) {
        if (map.containsKey(name)) {
            return (T) map.get(name);
        }
        return null;
    }

    @SuppressWarnings("unchecked")
    T get(String name, Function<String, Object> filter) {
        Objects.requireNonNull(filter);

        if (map.containsKey(name)) {
            return (T) map.get(name);
        }
        Object object = filter.apply(name);
        if (object == null) {
            return null;
        } else {
            map.put(name, object);
            return (T) (object);
        }
    }


}