javaʹÓÃͨÅä·û¼ò»¯·ºÐÍʹÓÃ
ÔÚʹÓà Java™ ÓïÑԵķºÐÍʱ£¬Í¨Åä·û·Ç³£ÁîÈËÀ§»ó£¬²¢ÇÒ×î³£¼ûµÄÒ»¸ö´íÎó¾ÍÊÇÔÚʹÓÃÓнçͨÅä·ûµÄÁ½ÖÖÐÎʽµÄÆäÖÐÖ®Ò»£¨“? super T” ºÍ “? extends T”£©Ê±³öÏÖ´íÎó¡£Äú³ö´íÁËÂ𣿱ð¾ÚÉ¥£¬¼´Ê¹ÊÇר¼ÒÒ²»á·¸ÕâÖÖ´íÎ󣬱¾Ô Brian Goetz ½«Õ¹Ê¾ÈçºÎ±ÜÃâÕâ¸ö´íÎó¡£
ÔÚ Java ÓïÑÔÖУ¬Êý×éÊÇбäµÄ£¨ÒòΪһ¸ö Integer ͬʱҲÊÇÒ»¸ö Number£¬Ò»¸ö Integer Êý×éͬʱҲÊÇÒ»¸ö Number Êý×飩£¬µ«ÊÇ·ºÐͲ»ÊÇÕâÑùµÄ£¨List<Integer> ²¢²»µÈÓÚ List<Number>£©¡£ÈËÃÇ»áÕùÂÛÄÄЩѡÔñÊÇ “ÕýÈ·µÄ”£¬ÄÄЩѡÔñÊÇ “´íÎóµÄ” — µ±È»£¬Ã¿ÖÖÑ¡Ôñ¶¼¸÷ÓÐÓÅȱµã — µ«ÓÐÒ»µãºÁÎÞÒÉÎÊ£¬´æÔÚÁ½ÖÖʹÓòî±ðºÜСµÄÓïÒå¹¹ÔìÅÉÉúÀàÐ͵ÄÀàËÆ»úÖÆ£¬Õ⽫µ¼Ö´óÁ¿´íÎóºÍÎó½â¡£
ÓнçͨÅä·û£¨Ò»Ð©ÓÐȤµÄ “? extends T” ͨÓÃÀàÐÍ˵Ã÷·û£©ÊÇÓïÑÔÌṩµÄÒ»ÖÖ¹¤¾ß£¬ÓÃÀ´´¦ÀíбäÐÔȱ·¦ — ÓнçͨÅä·ûÔÊÐíÀàÉùÃ÷·½·¨²ÎÊý»ò·µ»ØÖµºÎʱ¾ßÓÐбäÐÔ£¨»òÏà·´£¬ÉùÃ÷·½·¨²ÎÊý»ò·µ»ØÖµºÎʱ¾ßÓÐÄæ±äÐÔ£¨contravariant£©£©¡£ËäÈ»Á˽âºÎʱʹÓÃÓнçͨÅä·ûÊÇ·ºÐͽÏΪ¸´Ôӵķ½Ã棬µ«ÊÇ£¬Ê¹ÓÃÓнçͨÅä·ûµÄѹÁ¦Í¨³£¶¼ÂäÔÚ¿â×÷ÕßµÄÉíÉÏ£¬¶ø·Ç¿âÓû§¡£×î³£¼ûµÄÓнçͨÅä·û´íÎó¾ÍÊÇÍü¼ÇʹÓÃËüÃÇ£¬Õâ¾ÍÏÞÖÆÁËÀàµÄʹÓ㬻òÊÇÇ¿ÖÆÓû§²»µÃ²»ÖØÓÃÏÖÓеÄÀà¡£
ÓнçͨÅä·ûµÄ×÷ÓÃ
ÈÃÎÒÃÇ´ÓÒ»¸ö¼òµ¥µÄ·ºÐÍÀ࿪ʼ£¨Ò»¸ö³ÆÎª Box µÄÖµÈÝÆ÷£©£¬Ëü³ÖÓÐÒ»¸ö¾ßÓÐÒÑÖªÀàÐ͵ÄÖµ£º
public interface Box<T> {
public T get();
public void put(T element);
}
ÓÉÓÚ·ºÐͲ»¾ß±¸Ð±äÐÔ£¬Box<Integer> ²¢²»µÈͬÓÚ Box<Number>£¬¾¡¹Ü Integer ÊôÓÚ Number¡£µ«ÊǶÔÓÚ Box ÕâÑùµÄ¼òµ¥·ºÐÍÀàÀ´Ëµ£¬Õâ²»³ÉÎÊÌ⣬²¢ÇÒ³£³£±»ºöÂÔ£¬ÒòΪ Box<T> µÄ½Ó¿ÚÍêȫָ¶¨Îª T ÀàÐ͵ıäÁ¿ — ¶ø²»ÊÇͨ¹ý T ·ºÐÍ»¯µÄÀàÐÍ¡£Ö±½Ó´¦ÀíÀàÐͱäÁ¿ÔÊÐíʵÏÖ¶à̬ÐÔ¡£Çåµ¥ 1 չʾÁËÕâÖÖ¶à̬ÐÔµÄÁ½¸öʾÀý£º»ñÈ¡ Box<Integer> µÄÄÚÈÝ£¬²¢½«Ëü×÷Ϊһ¸ö Number£¬È»ºó½«Ò»¸ö Integer ·ÅÈë Box<Number> ÖУº
Çåµ¥ 1. ͨ¹ý·ºÐÍÀàÀûÓùÌÓеĶà̬ÐÔ
Box<Integer> iBox = new BoxImpl<Integer>(3);
Number num = iBox.get();
Box<Number> nBox = new BoxImpl<Number>(3.2);
Integer i = 3;
nBox.put(i);
ͨ¹ýʹÓüòµ¥µÄ Box À࣬ʹÎÒÃÇÈ·ÐÅ¿ÉÒÔûÓÐбäÐÔ£¬ÒòΪÔÚÐèҪʵÏÖ¶à̬
Ïà¹ØÎĵµ£º
Java¶¯Ì¬´úÀíÀàλÓÚjava.lang.reflect°üÏ£¬Ò»°ãÖ÷񻃾¼°µ½ÒÔÏÂÁ½¸öÀࣺ
(1)Interface InvocationHandler£º¸Ã½Ó¿ÚÖнö¶¨ÒåÁËÒ»¸ö·½·¨
§public object invoke(Object obj,Method method, Object[] args)
ÔÚʵ¼ÊʹÓÃʱ£¬µÚÒ»¸ö²ÎÊýobjÒ»°ãÊÇÖ¸´úÀíÀ࣬methodÊDZ»´úÀíµÄ·½·¨£¬ÈçÉÏÀýÖеÄrequest()£¬argsΪ¸ ......
¶¯Ì¬´úÀíÊÇÖ¸¿Í»§Í¨¹ý´úÀíÀàÀ´µ÷ÓÃÆäËü¶ÔÏóµÄ·½·¨
¶¯Ì¬´úÀíʹÓó¡ºÏ:
•
Ô¶³Ì·½·¨µ÷ÓÃ(RMI)
•
1.´´½¨Ò»¸öʵÏÖ½Ó¿ÚInvocationHandlerµÄÀ࣬Ëü±ØÐëʵÏÖinvoke·½·¨
2.´´½¨±»´úÀíµÄÀàÒÔ¼°½Ó¿Ú
3.ͨ¹ýProxyµÄ¾²Ì¬·½·¨
newProxyInstance(ClassLoader loader, Class[] interfaces, Invocat ......
File£¨ÎļþÀࣩ
¾¡¹Üjava.io¶¨ÒåµÄ´ó¶àÊýÀàÊÇʵÐÐÁ÷ʽ²Ù×÷µÄ£¬FileÀ಻ÊÇ¡£ËüÖ±½Ó´¦ÀíÎļþºÍÎļþϵͳ¡£Ò²¾ÍÊÇ˵£¬FileÀàûÓÐÖ¸¶¨ÐÅÏ¢ÔõÑù´ÓÎļþ¶ÁÈ¡»òÏòÎļþ´æ´¢£»ËüÃèÊöÁËÎļþ±¾ÉíµÄÊôÐÔ¡£File¶ÔÏóÓÃÀ´»ñÈ¡»ò´¦ÀíÓë´ÅÅÌÎļþÏà¹ØµÄÐÅÏ¢£¬ÀýÈçȨÏÞ£¬Ê±¼ä£¬ÈÕÆÚºÍĿ¼·¾¶¡£´ËÍâ ......
ÔÚµ÷ÊÔµÄʱºò£¬Èç¹ûÒªÏÔʾbyteµÄÖµÊÇ·ñÓëÔ¤ÆÚÒ»Ö£¬Ò»°ãת»»Îª16½øÖƵÄ×Ö·û´®£¬»òÕßʹÓÃbase64ת»»ºó£¬È»ºóÏÔʾ³öÀ´¡£
/**
* ×Ö·û´®×ª»»³ÉÊ®Áù½øÖÆ×Ö·û´®
*/
public static String str2HexStr(String str) {
char[] chars = "0123456789ABCDEF".toCharArray();
StringBuilder sb = new StringBuilder("");
......
Java ÐòÁл¯¼ò½é
Java ¶ÔÏóÐòÁл¯ÊÇ JDK 1.1 ÖÐÒýÈëµÄÒ»×鿪´´ÐÔÌØÐÔÖ®Ò»£¬ÓÃÓÚ×÷ΪһÖÖ½« Java ¶ÔÏóµÄ״̬ת»»Îª×Ö½ÚÊý×飬ÒÔ±ã´æ´¢»ò´«ÊäµÄ»úÖÆ£¬ÒÔºó£¬ÈÔ¿ÉÒÔ½«×Ö½ÚÊý×éת»»»Ø Java ¶ÔÏóÔÓеÄ״̬¡£
ʵ¼ÊÉÏ£¬ÐòÁл¯µÄ˼ÏëÊÇ “¶³½á” ¶ÔÏó״̬£¬´«Êä¶ÔÏó״̬£¨Ð´µ½´ÅÅÌ¡¢Í¨¹ýÍøÂç´«ÊäµÈµÈ£©£¬È»ºó “½ ......