鍙互涓鴻綾誨垱寤哄敮涓涓涓瀯閫犲櫒錛屽茍灝嗘瀯閫犲櫒鐨勫彲瑙佽緗負(fù)縐佹湁銆傚煎緱娉ㄦ剰鐨勬槸錛屽鏋滄垜浠垱寤轟簡(jiǎn)鍏朵粬鐨勯潪縐佹湁鐨勬瀯閫犲櫒錛屾垨鑰呮牴鏈病鏈変負(fù)璇ョ被鎻?br />
渚涙瀯閫犲櫒錛岄偅涔堝叾浠栦漢鍛樿繕鏄兘瀹炰緥鍖栨垜浠殑綾匯?nbsp;濡傛灉涓嶅笇鏈涙彁鍓嶅垱寤哄崟渚嬪璞★紝鎴戜滑鍙互絳夊埌絎竴嬈′嬌鐢ㄨ鍗曚緥瀵硅薄鐨勬椂鍊欏湪鍒涘緩瀹冿紝鍗?br />
婊炲悗鍒濆鍖栥傛粸鍚庡垵濮嬪寲鍗曚緥瀵硅薄鏈変袱涓悊鐢憋細(xì)
1.涔熻鍦ㄩ潤鎬佸垵濮嬪寲鏃墮棿錛屼綘娌℃湁鍏充簬濡備綍鍒濆鍖栧崟渚嬪璞＄殑瓚沖淇℃伅銆?br />
2.閫夋嫨婊炲悗鍒濆鍖栧崟渚嬬殑鐩殑涔熻涓轟簡(jiǎn)絳夊緟璧勬簮錛岃濡傛暟鎹簱榪炴帴錛屽挨鍏舵槸鍦ㄦ煇浜涚壒瀹氫細(xì)璇濅腑涓嶉渶瑕佽繖涓崟渚嬬殑搴旂敤紼嬪簭涓?br />
濡傛灉鍦ㄥ綰跨▼鐜涓鍗曚緥閲囩敤婊炲悗鍒濆鍖栵紝閭ｄ箞鎴戜滑蹇呴』灝忓績闃叉澶氫釜綰跨▼鍚屾椂鍒濆鍖栬
閫氬父鍗曚緥妯″紡鍦↗ava璇█涓紝鏈変袱縐嶆瀯寤烘柟寮忥細(xì)
- 鎳掓眽鏂瑰紡:鎸囧叏灞鐨勫崟渚嬪疄渚嬪湪絎竴嬈¤浣跨敤鏃舵瀯寤恒傚歡榪熷垵濮嬪寲銆?
- 楗挎眽鏂瑰紡:鎸囧叏灞鐨勫崟渚嬪疄渚嬪湪綾昏杞芥椂鏋勫緩銆?鎬ュ垏鍒濆鍖栥?
1錛岄タ姹夊紡鍗曚緥綾?br />
public class Singleton1 {
private Singleton1() {
} // 鍦ㄨ嚜宸卞唴閮ㄥ畾涔夎嚜宸變竴涓疄渚? // 娉ㄦ剰榪欐槸private 鍙緵鍐呴儴璋冪敤 private static Singleton1 instance = new Singleton1(); /** * 榪欓噷鎻愪緵浜?jiǎn)涓涓緵澶栭儴璁塊棶鏈琧lass鐨勯潤鎬佹柟娉曪紝鍙互鐩存帴璁塊棶銆銆 * @return */ public static Singleton1 getInstance() { return instance; }
}
2錛屾噿姹夊紡鍗曚緥綾?/p>
public class Singleton2 { private static Singleton2 instance = null; /** * 榪欎釜鏂規(guī)硶姣斾笂闈㈡湁鎵鏀硅繘錛屼笉鐢ㄦ瘡嬈￠兘榪涜鐢熸垚瀵硅薄錛屽彧鏄涓嬈°銆銆 * 浣跨敤鏃剁敓鎴愬疄渚嬶紝鎻愰珮浜?jiǎn)鏁堢巼锛?br />
* @return */ public static Singleton2 getInstance() { if (instance == null) instance = new Singleton2(); return instance; }}涓嬮潰涓昏澶氱嚎紼嬮棶棰橈紝鍦ㄦ噿姹夊崟渚嬩腑錛屽崟綰跨▼鏄病鏈夐棶棰樼殑錛屼絾澶氱嚎紼嬫椂灝變細(xì)鏈夊彲鑳藉嚭鐜頒袱涓垨鑰呬互涓婄殑Singletion2瀹炰緥鐨勬儏鍐點(diǎn)?br />
渚嬪錛氱嚎紼?鍦ㄥ垽鏂璱nstance==null涓虹湡錛屾壂琛宯ew鎿嶄綔鏃訛紝鍦ㄦ墽琛宯ew鎿嶄綔涔嬪墠錛屽垽鏂負(fù)鐪熶箣鍚庯紝綰跨▼2姝ｅソ鎵ц鍒ゆ柇鎿嶄綔錛岃繖鏃秈nstance榪樹負(fù)null.鍥犳錛岀嚎紼?涔熶細(xì)鎵цnew鎿嶄綔銆備互姝ょ被鎺紝鍦ㄩ珮騫跺彂涓嬮潰錛屽氨鍙兘瀛樺湪涓や釜鎴栬呬互涓婄殑Singletion2鐨勫疄渚嬨傛樉鐒?dòng)灱寴q欐槸涓嶆紜殑銆?br />
鍥犳鏀瑰彉浠ｇ爜濡備笅錛?br />
public class Singleton3 { private static Singleton3 instance = null; /** * 榪欎釜鏂規(guī)硶姣斾笂闈㈡湁鎵鏀硅繘錛屼笉鐢ㄦ瘡嬈￠兘榪涜鐢熸垚瀵硅薄錛屽彧鏄涓嬈°銆銆 * 浣跨敤鏃剁敓鎴愬疄渚嬶紝鎻愰珮浜?jiǎn)鏁堢巼锛?br />
* 涓轟簡(jiǎn)澶氱嚎紼嬩笉鍑洪敊錛屽姞鍏ヤ簡(jiǎn)鍚屾鏍囧織 * @return */ public static synchronized Singleton3 getInstance() { if (instance == null) instance = new Singleton3(); return instance; }}浣嗚繖鏍峰張浜х敓浜?jiǎn)涓涓棶棰橈紝姣忔鑾峰彇瀹炰緥鏃舵柟娉曢兘鏄悓姝ョ殑錛屾樉鐒舵ц兘寰堝彈褰卞搷鐨勶紝鎵浠ョ戶緇洿鏀逛唬鐮佸涓嬶細(xì)
鍏堣涓涓嬶細(xì)volatile錛堢綉涓婃妱鐨勶級(jí)
volatile, 鐢ㄦ洿浣庣殑浠ｄ環(huán)鏇夸唬鍚屾
涓轟粈涔?/span>浣跨敤volatile姣斿悓姝ヤ唬浠鋒洿浣?
鍚屾鐨勪唬浠? 涓昏鐢卞叾瑕嗙洊鑼冨洿鍐沖畾, 濡傛灉鍙互闄嶄綆鍚屾鐨勮鐩栬寖鍥? 鍒欏彲浠ュぇ騫呮彁鍗囩▼搴忔ц兘.
鑰寁olatile鐨勮鐩栬寖鍥翠粎浠呭彉閲忕駭鍒殑. 鍥犳瀹冪殑鍚屾浠ｄ環(huán)寰堜綆.
volatile鍘熺悊鏄粈涔?
volatile鐨勮涔? 鍏跺疄鏄憡璇夊鐞嗗櫒, 涓嶈灝嗘垜鏀懼叆宸ヤ綔鍐呭瓨, 璇風(fēng)洿鎺ュ湪涓誨瓨鎿嶄綔鎴?(宸ヤ綔鍐呭瓨璇﹁java鍐呭瓨妯″瀷)
鍥犳, 褰撳鏍告垨澶氱嚎紼嬪湪璁塊棶璇ュ彉閲忔椂, 閮藉皢鐩存帴鎿嶄綔涓誨瓨, 榪欎粠鏈川涓? 鍋氬埌浜?jiǎn)鍙橀噺鍏变?
volatile鐨勬湁浠涔堜紭鍔?
1, 鏇村ぇ鐨勭▼搴忓悶鍚愰噺
2, 鏇村皯鐨勪唬鐮佸疄鐜板綰跨▼
3, 紼嬪簭鐨勪幾緙╂ц緝濂?br />
4, 姣旇緝濂界悊瑙? 鏃犻渶澶珮鐨勫涔?fàn)鎴愭?br />
volatile鏈変粈涔堝姡鍔?
1, 瀹規(guī)槗鍑洪棶棰?br />
2, 姣旇緝闅捐璁?br />
volatile浣跨敤jdk瑕佹眰1.5鐗堟湰鍙?.5浠ヤ笂銆?br />
鏀硅繘鍚庣殑浠ｇ爜濡備笅錛堝張鍙弻閲嶅姞閿侊級(jí)錛?br />
public class Singleton4 { private static volatile Singleton4 instance; /** * 鍙岄噸鍔犻攣瀹炵幇澶氱嚎紼嬭繍鐢ㄥ拰鎬ц兘浼樺寲 * @return */ public static Singleton4 getInstance() { if (instance == null) { synchronized(Singleton4.class) { //1 if (instance == null) //2 instance = new Singleton4(); //3 } } return instance; }}
鍙傝冭嚜絎仈緗戝拰head first璁捐妯″紡銆?br />
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