????9?????????????????????

????????

?????????????????????

???????????ò??ü???????

catch (SocketException e)
{
    LOG.error("server error"?? e);
    throw new ConnectionException(e.getMessage()?? e);
}

????????????????????????

???????????????У???????????

LOG.warn("Failed to login by "+username+");

???????

????1??????????????????????re-throw??????????????????????????throw????????????????????????????????????????????????????????re-throw?????exception??д???????trace( ??cause)???????????????

????2????????????????????????????WARN??????ù??????????????????????????????????????????????????????????????????????

???????

?????????????????????????μ????Щ????????????????????????????????

????1??????????????????????

????2????????????????????????????????????????????????????????????λ????

????10????????????

????????

??????JAVA?У????????Collection?е?Map??Cache??????????????????????ó????????

cache = new LRULinkedHashMap< K?? V>(maxCapacity);

???????

?????????????????ж????LinkedHashMap??????????????????????????16??????16×LOAD_FACTOR????resize(2 * table.length)??????2???????? Entry[] newTable = new Entry[newCapacity]; transfer(newTable)????????????Copy?? ?????????????????????CACHE???????16?????????????????????????????鸴??????????????????????ú??????????resize?? ??????????????????????ú????????Cache???????????ù???????????????ο????±????????￡? ?????????cache????? ????????????4???????????

?????? memory for reference fields (4 bytes each);

?????? memory for primitive fields

Java type  Bytes required
boolean  1
byte  
char  2
short  
int  4
float  
long  8
double  

???????

??????????map?? ????stringBuffer???????????resize???????????????????????????????????????????￡?????????????? resize???????????????

??????Java????У??????????????Щ???????????????????л???????????????????????????????????????????????????????