bson/src/main/org/bson/BasicBSONObject.java
public long getLong(final String key) {
        Object foo = get(key);
        return ((Number) foo).longValue();
    }
public long getLong(final String key) {
        Object foo = get(key);
        return ((Number) foo).longValue();
    }
Returns the value of a field as a {@code long}.

@param key the field to return
@return the field value