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(2008-9-27 bbh)
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¾­³£¿´µ½ºÜ¶àÈËÌÖÂÛjavaÖйØÓÚStringµÄÎÊÌâ,ÎÒÒ²¾ÍÓеãÐËȤÁË,¼øÓÚÍøÉϺܶàÈËдµÄ¶¼²î±ðºÜ´ó,
ͬÑùµÄÎÊÌâ¶¼ÊDz»Í¬µÄ˵·¨,ÎÒºÜÃÔºý,»¨ÁËÒ»ÍíÉ϶ÁÁËJava Virtual Machine SpecificationºÍ
The Java Language SpecificationµÄһЩÕ½Ú,×öÁ˺ܶàÊÔÑé,×ܽáÁËһϹØÓÚStringµÄÄÚÈÝ,»¹
ÓкܶàÄÚÈÝÎÒÒ²²»È·¶¨,ÔÚÏÂÃæÒ²¶¼Ìá³öÀ´ÁË,Ï£Íû¸ßÊÖÄÜÖ¸Õý.
Constant Pool³£Á¿³ØµÄ¸ÅÄî:
ÔÚ½²µ½StringµÄÒ»Ð©ÌØÊâÇé¿öʱ,×Ü»áÌáµ½String Pool»òÕßConstant Pool,µ«ÊÇÎÒÏëºÜ¶àÈ˶¼²»Ì«
Ã÷°×Constant Poolµ½µ×ÊǸöÔõôÑùµÄ¶«Î÷,ÔËÐеÄʱºò´æ´¢ÔÚÄÄÀï,ËùÒÔÔÚÕâÀïÏÈ˵һÏÂConstant PoolµÄÄÚÈÝ.
String PoolÊǶÔÓ¦ÓÚÔÚConstant PoolÖд洢String³£Á¿µÄÇøÓò.ϰ¹ß³ÆÎªString Pool,Ò²ÓÐÈ˳ÆÎª
String Constant Pool.ºÃÏñûÓÐÕýʽµÄÃüÃû??
ÔÚjava±àÒëºÃµÄclassÎļþÖÐ,ÓиöÇøÓò³ÆÎªConstant Pool,ËûÊÇÒ»¸öÓÉÊý×é×é³ÉµÄ±í,ÀàÐÍ
Ϊcp_info constant_pool[],ÓÃÀ´´æ´¢³ÌÐòÖÐʹÓõĸ÷ÖÖ³£Á¿,°üÀ¨Class/String/IntegerµÈ¸÷
ÖÖ»ù±¾JavaÊý¾ÝÀàÐÍ,ÏêÇé²Î¼ûThe Java Virtual Machine Specification 4.4Õ½Ú.
¶ÔÓÚConstant Pool,±íµÄ»ù±¾Í¨ÓýṹΪ:
cp_info {
        u1 tag;
        u1 info[];
}
tagÊÇÒ»¸öÊý×Ö,ÓÃÀ´±íʾ´æ´¢µÄ³£Á¿µÄÀàÐÍ,ÀýÈç8±íʾStringÀàÐÍ,5±íʾLongÀàÐÍ,info[]¸ù¾Ý
ÀàÐÍÂëtagµÄ²»Í¬»á·¢ÉúÏàÓ¦±ä»¯.
¶ÔÓÚStringÀàÐÍ,±íµÄ½á¹¹Îª:
CONSTANT_String_info {
        u1 tag;
        u2 string_index;
}
tag¹Ì¶¨Îª8,string_indexÊÇ×Ö·û´®ÄÚÈÝÐÅÏ¢,ÀàÐÍΪ:
CONSTANT_Utf8_info {
        u1 tag;
        u2 length;
        u1 bytes[length];
}
tag¹Ì¶¨Îª1,lengthΪ×Ö·û´®µÄ³¤¶È,bytes[length]Ϊ×Ö·û´®µÄÄÚÈÝ.
(ÒÔÏ´úÂëÔÚjdk6ÖбàÒë)
ΪÁËÏêϸÀí½âConstant PoolµÄ½á¹¹,ÎÒÃDzο´Ò»Ð©´úÂë:
    String s1 = "sss111";
    String s2 = "sss222";
    System.out.println(s1 + " " + s2);
ÓÉÓÚ"sss111"ºÍ"sss222"¶¼Ê


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JAVA²Ù×÷cookie

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Cookie[] cookies = request.getCookies();
 if(cookies!=null){
    for(Cookie cookie : cookies){
   if(cookie.getName().equals("mid")){
    String mid = cookie.getValue();
   }
  }
 }
´æ:
String mid ......

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JavaµÄ¶ÑÊÇÒ»¸öÔËÐÐʱÊý¾ÝÇø,ÀàµÄ(¶ÔÏó´ÓÖзÖÅä¿Õ¼ä¡£ÕâЩ¶ÔÏóͨ¹ýnew¡¢newarray¡¢anewarrayºÍmultianewarrayµÈ Ö¸ÁÁ¢£¬ËüÃDz»ÐèÒª³ÌÐò´úÂëÀ´ÏÔʽµÄÊÍ·Å¡£¶ÑÊÇÓÉÀ¬»ø»ØÊÕÀ´¸ºÔðµÄ£¬¶ÑµÄÓÅÊÆÊÇ¿ÉÒÔ¶¯Ì¬µØ·ÖÅäÄÚ´æ´óС£¬Éú´æÆÚÒ²²»±ØÊÂÏȸæËß±àÒëÆ÷£¬ÒòΪËüÊÇÔÚÔËÐÐʱ ¶¯Ì¬·ÖÅäÄÚ´æµÄ£¬JavaµÄÀ¬»øÊÕ¼¯Æ÷»á×Ô¶¯ÊÕ×ßÕâЩ²»ÔÙ ......

JAVA DATE×ܽá

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Calendar time=Calendar.getInstance();
time.clear();
time.set(Calendar.YEAR,year); //year Ϊ int
time.set(Calendar.MONTH,i-1);//×¢Òâ,Calendar¶ÔÏóĬÈÏÒ»ÔÂΪ0          
int day=time.getActualMaximum(Calendar.DAY_OF_MON ......
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