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浇鍣ㄦ湁寰堝绉嶃€傚綋鎴戜滑瑕佸姞杞戒竴涓被鏃讹紝搴旇鍔犺浇鍝釜绫诲姞杞藉櫒鍛紵杩欏氨闇€瑕佹彁鍒板弻浜插娲炬ā鍨嬨€傛牴鎹畼缃戜粙缁嶏細ClassLoader绫讳娇鐢ㄥ鎵樻ā鍨嬫潵鎼滅储绫诲拰璧勬簮銆侰lassLoader鐨勬瘡涓疄渚嬮兘鏈変竴涓叧鑱旂殑鐖剁被鍔犺浇鍣ㄣ€傚綋璇锋眰鏌ユ壘绫绘垨璧勬簮鏃讹紝ClassLoader瀹炰緥灏嗗湪灏濊瘯鏌ユ壘绫绘垨璧勬簮鏈韩涔嬪墠灏嗙被鎴栬祫婧愮殑鎼滅储濮旀墭缁欏叾鐖剁被鍔犺浇鍣ㄣ€傝櫄鎷熸満鐨勫唴缃被鍔犺浇鍣ㄧО涓衡€滃紩瀵肩被鍔犺浇鍣ㄢ€濓紝瀹冩湰韬病鏈夌埗绫伙紝浣嗗彲浠ヤ綔涓篊lassLoader瀹炰緥鐨勭埗绫汇€傝繃鍘荤殑澶ц嚧鎰忔€濇槸锛欳lassLoader绫讳娇鐢ㄥ鎵樻ā鍨嬫潵鏌ユ壘绫诲拰璧勬簮銆傛瘡涓狢lassLoader瀹炰緥閮芥湁涓€涓叧鑱旂殑鐖剁被鍔犺浇鍣ㄣ€傚綋闇€瑕佹煡鎵剧被鎴栬祫婧愭椂锛孋lassLoader瀹炰緥浼氬湪灏濊瘯鏌ユ壘绫绘垨璧勬簮鏈韩涔嬪墠灏嗙被鎴栬祫婧愮殑鎼滅储濮旀墭缁欏叾鐖剁被鍔犺浇鍣ㄣ€傝櫄鎷熸満涓唴缃殑绉颁负鈥滃紩瀵肩被鍔犺浇鍣ㄢ€濈殑绫诲姞杞藉櫒鏈韩娌℃湁鐖剁被鍔犺浇鍣紝浣嗗彲浠ヤ綔涓篊lassLoader瀹炰緥鐨勭埗绫诲姞杞藉櫒銆備粠涓婇潰鐨勪粙缁嶅彲浠ョ湅鍑猴細ClassLoader绫讳娇鐢ㄥ鎵樻ā鍨嬫潵鏌ユ壘绫诲拰璧勬簮銆傚弻浜插娲炬ā鍨嬭姹傞櫎椤跺眰鍚姩绫诲姞杞藉櫒涔嬪鐨勬墍鏈夌被鍔犺浇鍣ㄩ兘搴旇鏈夎嚜宸辩殑鐖剁被鍔犺浇鍣ㄣ€傚湪灏濊瘯鏌ユ壘绫绘垨璧勬簮鏈韩涔嬪墠锛孋lassLoader瀹炰緥灏嗗绫绘垨璧勬簮鐨勬悳绱㈠鎵樼粰鍏剁埗绫诲姞杞藉櫒銆備笅鍥炬墍绀虹殑鍚勪釜绫诲姞杞藉櫒涔嬮棿鐨勫眰娆″叧绯伙紝绉颁负绫诲姞杞藉櫒鐨勨€滃弻浜插娲炬ā鍨嬧€濄€傛敞鎰忊殸锔忥細鍙屼翰濮旀墭妯″瀷涓嶆槸寮哄埗绾︽潫锛岃€屾槸JDK瀹樻柟鎺ㄨ崘鐨勪竴绉嶆柟寮忋€傚鏋滄垜浠洜涓轰竴浜涚壒娈婄殑闇€瑕侊紝鎯宠鎵撶牬鍙屼翰濮旀淳妯″紡锛屼篃鏄彲浠ョ殑銆傚叿浣撴柟娉曞悗闈細浠嬬粛銆傚叾瀹炶繖涓闀跨殑缈昏瘧寰堝鏄撹鍒汉璇В銆傛垜浠竴鑸悊瑙ｇ埗姣嶅弻鏂归兘鏄埗姣嶃€傝繖閲岀殑鐖舵瘝鏇村鐨勮〃杈句簡鈥滅埗姣嶄竴浠ｂ€濈殑浜恒€傚苟涓嶆槸璇寸湡鐨勬湁MotherClassLoader鍜孎atherClassLoader銆備釜浜鸿寰楃炕璇戞垚鍗曚翰濮旀墭妯″瀷姣旇緝濂姐€備笉杩囨棦鐒跺凡缁忕炕璇戞垚鍙屼翰濮旀淳妯″紡鍦ㄥ浗鍐呮祦浼犱簡锛岀収鐫€杩欎釜妯″紡璧颁篃鏄彲浠ョ殑銆傚彧鏄笉瑕佽璇В銆傚彟澶栵紝绫诲姞杞藉櫒涔嬮棿鐨勭埗瀛愬叧绯讳竴鑸笉鏄€氳繃缁ф壙鍏崇郴鏉ュ疄鐜扮殑锛岃€屾槸閫氬父浣跨敤缁勫悎鍏崇郴鏉ュ鐢ㄧ埗鍔犺浇鍣ㄧ殑浠ｇ爜銆俻ublicabstractclassClassLoader{...//缁勫悎privatefinalClassLoaderparent;protectedClassLoader(ClassLoaderparent){this(checkCreateClassLoader(),parent);}...}澶嶅埗浠ｇ爜鍦ㄩ潰鍚戝璞＄紪绋嬩腑锛屾湁涓€涓潪甯哥粡鍏哥殑璁捐鍘熷垯锛欳ompositionisbetterthaninheritance锛屽鐢ㄧ粍鍚堬紝灏戠敤缁ф壙銆傚弻浜插鎵樻ā鍨嬬殑鎵ц杩囩▼鍙屼翰濮旀墭妯″瀷鐨勫疄鐜颁唬鐮侀潪甯哥畝鍗曪紝閫昏緫涔熼潪甯告竻鏅帮紝鍏ㄩ儴閮介泦涓湪java.lang.ClassLoader鐨刲oadClass()涓€傜浉鍏充唬鐮佸涓嬨€俻rotectedClassloadClass(Stringname,booleanresolve)throwsClassNotFoundException{synchronized(getClassLoadingLock(name)){//棣栧厛妫€鏌ョ被鏄惁宸茬粡鍔犺浇Classc=findLoadedClass(name);if(c==null){//濡傛灉c涓簄ull锛岃鏄庣被杩樻病鏈夊姞杞絣ongt0=System.nanoTime();try{if(parent!=null){//褰撶埗绫荤殑鍔犺浇鍣ㄤ笉涓虹┖鏃讹紝閫氳繃鐖剁被loadClass鍔犺浇绫籧=parent.loadClass(name,false);}else{//褰撶埗绫诲姞杞藉櫒涓虹┖鏃讹紝璋冪敤鍚姩绫诲姞杞藉櫒鍔犺浇绫籧=findBootstrapClassOrNull(name);}}catch(ClassNotFoundExceptione){//闈炵┖鐖剁被鐨勭被鍔犺浇鍣ㄦ壘涓嶅埌瀵瑰簲鐨勭被锛屾姏鍑哄紓甯竲if(c==null){//褰撶埗绫诲姞杞藉櫒鏃犳硶鍔犺浇鏃?璋冪敤findClass鏂规硶鍔犺浇杩欎釜绫?/鐢ㄦ埛鍙互閫氳繃閲嶅啓杩欎釜鏂规硶鏉ヨ嚜瀹氫箟绫诲姞杞藉櫒longt1=System.nanoTime();c=findClass(鍚嶅瓧);//鐢ㄤ簬缁熻绫诲姞杞藉櫒鐩稿叧淇℃伅sun.misc.PerfCounter.getParentDelegationTime().addTime(t1-t0);sun.misc.PerfCounter.getFindClassTime().addElapsedTimeFrom(t1);sun.misc.PerfCounter.getFindClasses().increment();}}if(resolve){//ResolveClass(c);}returnc;}}姣忓綋涓€涓被鍔犺浇鍣ㄦ敹鍒板姞杞借姹傛椂锛屽畠浼氶鍏堝皢璇锋眰杞彂缁欑埗绫诲姞杞藉櫒銆傚鏋滅埗绫诲姞杞藉櫒娌℃湁鎵惧埌璇锋眰鐨勭被锛岀被鍔犺浇鍣ㄥ皢灏濊瘯鍔犺浇瀹冦€傜粨鍚堜笂闈㈢殑婧愮爜锛岀畝鍗曟€荤粨涓€涓嬪弻浜插娲炬ā鍨嬬殑鎵ц杩囩▼锛氬姞杞戒竴涓被鏃讹紝绯荤粺浼氬厛鍒ゆ柇褰撳墠绫绘槸鍚﹀凡缁忓姞杞姐€傚凡缁忓姞杞借繃鐨勭被浼氱洿鎺ヨ繑鍥烇紝鍚﹀垯浼氬皾璇曞姞杞斤紙姣忎釜鐖剁被鍔犺浇鍣ㄩ兘浼氱粡鍘嗚繖涓繃绋嬶級銆傜被鍔犺浇鍣ㄥ湪杩涜绫诲姞杞芥椂锛屼笉浼氬厛灏濊瘯鑷繁鍔犺浇绫伙紝鑰屾槸灏嗚繖涓姹傚鎵樼粰鐖剁被鍔犺浇鍣ㄦ潵瀹屾垚锛堣皟鐢ㄧ埗鍔犺浇鍣╨oadClass()鏂规硶鍔犺浇绫伙級銆傚湪杩欑鎯呭喌涓嬶紝鎵€鏈夌殑璇锋眰鏈€缁堥兘浼氳浼犻€掑埌椤跺眰鐨勫惎鍔ㄧ被鍔犺浇鍣˙ootstrapClassLoader銆傚彧鏈夊綋鐖跺姞杞藉櫒鎶ュ憡鏃犳硶瀹屾垚鍔犺浇璇锋眰鏃讹紙瀹冨湪鍏舵悳绱㈣寖鍥村唴娌℃湁鎵惧埌闇€瑕佺殑绫伙級锛屽瓙鍔犺浇鍣ㄦ墠浼氬皾璇曡嚜琛屽姞杞斤紙璋冪敤鑷繁鐨刦indClass()鏂规硶鍔犺浇绫伙級.馃寛灞曞紑涓€涓嬶細JVM鍒ゆ柇涓や釜Java绫绘槸鍚︾浉鍚岀殑鍏蜂綋瑙勫垯锛欽VM涓嶄粎瑕佺湅绫荤殑鍏ㄥ悕鏄惁鐩稿悓锛岃繕瑕佺湅鍔犺浇杩欎釜绫荤殑绫诲姞杞藉櫒鏄惁鐩稿悓銆傚彧鏈夊綋涓や釜绫荤浉鍚屾椂锛屼袱涓被鎵嶈璁や负鏄浉鍚岀殑銆傚嵆浣夸袱涓被婧愯嚜鍚屼竴涓狢lass鏂囦欢锛岀敱鍚屼竴涓櫄鎷熸満鍔犺浇锛屽彧瑕佸姞杞藉畠浠殑绫诲姞杞藉櫒涓嶅悓锛岃繖涓や釜绫诲氨涓€瀹氭槸涓嶅悓鐨勩€傚弻浜插娲炬ā鍨嬬殑濂藉鍙屼翰濮旀淳妯″瀷淇濊瘉浜咼ava绋嬪簭鐨勭ǔ瀹氳繍琛岋紝鍙互閬垮厤绫荤殑閲嶅鍔犺浇锛圝VM鍖哄垎涓嶅悓绫荤殑鏂瑰紡涓嶄粎浠呮槸鏍规嵁绫诲悕锛岃€屾槸鍔犺浇鍚屼竴涓被鏂囦欢閫氳繃涓嶅悓鐨勭被鍔犺浇鍣紙涓嶅悓鐨勭被锛夛紝涔熶繚璇佷簡Java鐨勬牳蹇傾PI涓嶈绡℃敼銆傚鏋滀笉浣跨敤鍙屼翰濮旀淳妯″瀷锛岃€屾槸姣忎釜绫诲姞杞藉櫒鑷繁鍔犺浇锛屽氨浼氬嚭鐜颁竴浜涢棶棰樸€備緥濡傦紝濡傛灉鎴戜滑鍐欎簡涓€涓悕涓簀ava.lang.Object鐨勭被锛岄偅涔堝綋绋嬪簭杩愯鏃讹紝绯荤粺灏变細鏈変袱涓笉鍚岀殑Object绫汇€傚弻浜插鎵樻ā鍨嬪彲浠ヤ繚璇佸姞杞界殑鏄疛RE涓殑Object绫伙紝鑰屼笉鏄綘鍐欑殑Object绫汇€傝繖鏄洜涓哄綋AppClassLoader鍔犺浇浣犵殑Object绫绘椂锛屽畠浼氬鎵樼粰ExtClassLoader鍔犺浇锛岃€孍xtClassLoader浼氬鎵樼粰BootstrapClassLoader銆侭ootstrapClassLoader鍙戠幇鑷繁宸茬粡鍔犺浇浜哋bject绫伙紝浼氱洿鎺ヨ繑鍥烇紝鑰屼笉鏄姞杞戒綘鍐欑殑Object绫汇€?鎵撶牬鍙屼翰濮旀墭妯″瀷鐨勬柟娉曚负浜嗛伩寮€鍙屼翰濮旀墭鏈哄埗锛屾垜浠彲浠ヨ嚜宸卞畾涔変竴涓被鍔犺浇鍣紝鐒跺悗閲嶅啓loadClass()銆傪煇涗慨澶嶏紙鍙傝锛歩ssue871锛夛細濡傛灉鑷畾涔塴oader锛岄渶瑕佺户鎵緾lassLoader銆傚鏋滄垜浠笉鎯崇牬鍧忓弻浜插鎵樻ā鍨嬶紝鍙渶閲嶅啓ClassLoader绫讳腑鐨刦indClass()鏂规硶鍗冲彲銆備笉鑳借鐖剁被鍔犺浇鍣ㄥ姞杞界殑绫伙紝鏈€缁堜細閫氳繃杩欎釜鏂规硶鍔犺浇銆備絾鏄紝濡傛灉瑕佹墦鐮村弻浜插娲炬ā鍨嬶紝鍒欓渶瑕侀噸鍐檒oadClass()鏂规硶銆備负浠€涔堥噸鍐檒oadClass()鏂规硶浼氱牬鍧忓弻浜插娲炬ā鍨嬶紵鍙屼翰濮旀墭妯″瀷鐨勬墽琛岃繃绋嬪凡缁忚В閲婅繃锛氬綋绫诲姞杞藉櫒鍔犺浇涓€涓被鏃讹紝瀹冧笉浼氬厛灏濊瘯鑷繁鍔犺浇绫伙紝鑰屾槸灏嗚繖涓姹傚鎵樼粰鐖剁被鍔犺浇鍣ㄦ潵瀹屾垚锛堣皟鐢ㄧ埗鍔犺浇鍣╨oadClass()鏂规硶鍔犺浇绫伙級銆備负浜嗚兘澶熷厛鍔犺浇Web搴旂敤鐩綍涓嬬殑绫伙紝鍐嶅姞杞藉叾浠栫洰褰曚笅鐨勭被锛屾垜浠瘮杈冪啛鎮夌殑Tomcat鏈嶅姟鍣ㄥ畾鍒朵簡绫诲姞杞藉櫒WebAppClassLoader鏉ユ墦鐮村弻浜插娲炬満鍒躲€傝繖涔熸槸Tomcat涓媁eb搴旂敤涔嬮棿绫婚殧绂荤殑鍏蜂綋鍘熷垯銆俆omcat鐨勭被鍔犺浇鍣ㄧ殑灞傛缁撴瀯濡備笅锛氭湁鍏磋叮鐨勫皬浼欎即鍙互鑷鐮旂┒Tomcat鐨勭被鍔犺浇鍣ㄧ殑灞傛缁撴瀯锛屾湁鍔╀簬鎴戜滑鐞嗚ВTomcat闅旂Web搴旂敤鐨勫師鐞嗐€傛帹鑽愭潗璐ㄦ槸銆婃繁鍏ユ媶瑙?Tomcat & Jetty銆嬨€傛帹鑽愰槄璇汇€婃繁鍏ユ媶瑙?Java 铏氭嫙鏈恒€嬫繁鍏ヨВ鏋怞ava绫诲姞杞藉櫒鍘熺悊锛歜log.csdn.net/xyang81/art...Java绫诲姞杞藉櫒锛圕lassLoader锛夛細gityuan.com/2016/01/24/...绫诲姞杞藉櫒inJava:www.baeldung.com/java-classl...ClassClassLoader-Oracle瀹樻柟鏂囨。锛歞ocs.oracle.com/javase/8/do...甯稿勾闅炬噦鐨凧avaClassLoader涓嶆噦灏辫€佷簡鍏讹細zhuanlan.zhihu.com/p/51374915鍚庤涓撴敞Java鍘熷垱骞茶揣鍒嗕韩锛屽垵绾у紑婧怞avaGuide锛堛€奐ava瀛︿範+闈㈣瘯鎸囧崡銆嬫兜鐩栦簡澶ч儴鍒咼ava绋嬪簭鍛橀渶瑕佹帉鎻＄殑鏍稿績鐭ヨ瘑銆備负Java闈㈣瘯鍋氬噯澶囷紝JavaGuide鏄閫夛紒锛夛紝鐩墠鏈?20k+Stars銆?/p>
