娣卞叆鎺㈢┒JVM涔嬬被鍔犺浇涓庡弻浜插娲炬満鍒?/h1>

Posted 2021-04-17 鐮佸啘寮€鑺?/a> 娣卞叆

相关的知识，希望对你有一定的参考价值。

鎶€鏈共璐?馃憠 蹇呭畾濂変笂

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鑳屾櫙浠嬬粛

鏂囩珷鐩綍

• 鍓嶈█

• 绫荤殑鐢熷懡鍛ㄦ湡

• 鍔犺浇

• 楠岃瘉

• 鍑嗗

• 瑙ｆ瀽

• 鍒濆鍖?/p>

• 妗堜緥涓€

• 妗堜緥浜?/p>

• 妗堜緥涓?/p>

• 妗堜緥鍥?/p>

• 绫诲姞杞藉櫒

• 绫诲姞杞藉櫒鍜屽弻浜插娲炬ā鍨?/p>

• 鐮村潖鍙屼翰濮旀淳妯″瀷

• 绗竴娆?/p>

• SPI

• Tomcat

• OSGI

• 鎬荤粨

鍓嶈█

鍓嶉潰瀛︿範浜嗚櫄鎷熸満鐨勫唴瀛樼粨鏋勩€佸璞＄殑鍒嗛厤鍜屽垱寤猴紝浣嗗璞℃墍瀵瑰簲鐨勭被鏄€庝箞鍔犺浇鍒拌櫄鎷熸満涓潵鐨勫憿锛熷姞杞借繃绋嬩腑闇€瑕佸仛浜涗粈涔堬紵浠€涔堟槸鍙屼翰濮旀淳鏈哄埗浠ュ強涓轰粈涔堣鎵撶牬鍙屼翰濮旀淳鏈哄埗锛?/p>

绫荤殑鐢熷懡鍛ㄦ湡

绫荤殑鐢熷懡鍛ㄦ湡鍖呭惈浜嗗涓婄殑7涓樁娈碉紝鍏朵腑楠岃瘉銆?span class="mq-48">鍑嗗銆?span class="mq-49">瑙ｆ瀽缁熺О涓?span class="mq-50">杩炴帴 锛岀被鐨勫姞杞戒富瑕佹槸鍓嶄簲涓樁娈碉紝姣忎釜闃舵鍩烘湰涓婁繚鎸佸涓婇『搴?/span>寮€濮?/span>锛堜粎浠呮槸寮€濮嬶紝瀹為檯涓婃墽琛屾槸浜ゅ弶娣峰悎鐨勶級锛屽彧鏈?span class="mq-52">瑙ｆ瀽闃舵涓嶄竴瀹氾紝鍦?span class="mq-53">鍒濆鍖栧悗涔熸湁鍙兘鎵嶅紑濮嬫墽琛岃В鏋愶紝杩欐槸涓轰簡鏀寔鍔ㄦ€佽瑷€銆?/p>

鍔犺浇

鍔犺浇灏辨槸灏嗗瓧鑺傜爜鐨勪簩杩涘埗娴佽浆鍖栦负鏂规硶鍖?/span>鐨勮繍琛屾椂鏁版嵁缁撴瀯锛屽苟鐢熸垚绫绘墍瀵硅薄鐨凜lass瀵硅薄锛屽瓧鑺傜爜浜岃繘鍒舵祦鍙互鏄垜浠紪璇戝悗鐨刢lass鏂囦欢锛屼篃鍙互浠庣綉缁滀腑鑾峰彇锛屾垨鑰呰繍琛屾椂鍔ㄦ€佺敓鎴愶紙鍔ㄦ€佷唬鐞嗭級绛夌瓑銆?br class="mq-57">閭ｄ粈涔堟椂鍊欎細瑙﹀彂绫诲姞杞藉憿锛熻繖涓湪铏氭嫙鏈鸿鑼冧腑娌℃湁鏄庣‘瀹氫箟锛屽彧鏄瀹氫簡浣曟椂闇€瑕佹墽琛屽垵濮嬪寲锛堢◢鍚庤缁嗗垎鏋愶級銆?/p>

楠岃瘉

杩欎釜闃舵寰堝ソ鐞嗚В锛屽氨鏄繘琛屽繀瑕佺殑鏍￠獙锛岀‘淇濆姞杞藉埌鍐呭瓨涓殑瀛楄妭鐮佹槸绗﹀悎瑕佹眰鐨勶紝涓昏鍖呭惈浠ヤ笅鍥涗釜鏍￠獙姝ラ锛堜簡瑙ｅ嵆鍙級锛?/p>

• 鏂囦欢鏍煎紡鏍￠獙锛氳繖涓樁娈佃鏍￠獙鐨勪笢瑗块潪甯稿锛屼富瑕佺殑鏈変笅闈㈣繖浜涳紙瀹為檯涓婅繙杩滀笉姝級

• 鏄惁浠ラ瓟鏁?xCAFEBABE寮€澶淬€?/p>

• 涓汇€佹鐗堟湰鍙锋槸鍚﹀湪褰撳墠Java铏氭嫙鏈烘帴鍙楄寖鍥翠箣鍐呫€?/p>

• 甯搁噺姹犵殑甯搁噺涓槸鍚︽湁涓嶈鏀寔鐨勫父閲忕被鍨嬶紙妫€鏌ュ父閲弔ag鏍囧織锛夈€?/p>

• 鎸囧悜甯搁噺鐨勫悇绉嶇储寮曞€间腑鏄惁鏈夋寚鍚戜笉瀛樺湪鐨勫父閲忔垨涓嶇鍚堢被鍨嬬殑甯搁噺銆?/p>

• CONSTANT_Utf8_info鍨嬬殑甯搁噺涓槸鍚︽湁涓嶇鍚圲TF-8缂栫爜鐨勬暟鎹€?/p>

• Class鏂囦欢涓悇涓儴鍒嗗強鏂囦欢鏈韩鏄惁鏈夎鍒犻櫎鐨勬垨闄勫姞鐨勫叾浠栦俊鎭€?/p>

• 銆傘€傘€傘€傘€傘€?/p>

• 鍏冩暟鎹牎楠岋細瀵瑰瓧鑺傜爜鎻忚堪淇℃伅杩涜璇箟鍒嗘瀽銆?/p>

• 杩欎釜绫绘槸鍚︽湁鐖剁被锛堥櫎浜唈ava.lang.Object涔嬪锛屾墍鏈夌殑绫婚兘搴斿綋鏈夌埗绫伙級銆?/p>

• 杩欎釜绫荤殑鐖剁被鏄惁缁ф壙浜嗕笉鍏佽琚户鎵跨殑绫伙紙琚玣inal淇グ鐨勭被锛夈€?/p>

• 濡傛灉杩欎釜绫讳笉鏄娊璞＄被锛屾槸鍚﹀疄鐜颁簡鍏剁埗绫绘垨鎺ュ彛涔嬩腑瑕佹眰瀹炵幇鐨勬墍鏈夋柟娉曘€?/p>

• 绫讳腑鐨勫瓧娈点€佹柟娉曟槸鍚︿笌鐖剁被浜х敓鐭涚浘锛堜緥濡傝鐩栦簡鐖剁被鐨刦inal瀛楁锛屾垨鑰呭嚭鐜颁笉绗﹀悎瑙勫垯鐨勬柟娉曢噸杞斤紝渚嬪鏂规硶鍙傛暟閮戒竴鑷达紝浣嗚繑鍥炲€肩被鍨嬪嵈涓嶅悓绛夛級銆?/p>

• 銆傘€傘€傘€傘€傘€?/p>

• 瀛楄妭鐮佹牎楠岋細纭繚绋嬪簭娌℃湁璇硶鍜岄€昏緫閿欒锛岃繖鏄暣涓獙璇侀樁娈垫渶澶嶆潅鐨勪竴涓楠ゃ€?/p>

• 淇濊瘉浠绘剰鏃跺埢鎿嶄綔鏁版爤鐨勬暟鎹被鍨嬩笌鎸囦护浠ｇ爜搴忓垪閮借兘閰嶅悎宸ヤ綔锛屼緥濡備笉浼氬嚭鐜扮被浼间簬鈥滃湪鎿嶄綔鏍堟斁缃簡涓€涓?int 绫诲瀷鐨勬暟鎹紝浣跨敤鏃跺嵈鎸?long 绫诲瀷鏉ュ姞杞藉叆鏈湴鍙橀噺琛ㄤ腑鈥濊繖鏍风殑鎯呭喌銆?/p>

• 淇濊瘉浠讳綍璺宠浆鎸囦护閮戒笉浼氳烦杞埌鏂规硶浣撲互澶栫殑瀛楄妭鐮佹寚浠や笂銆?/p>

• 淇濊瘉鏂规硶浣撲腑鐨勭被鍨嬭浆鎹㈡€绘槸鏈夋晥鐨勶紝渚嬪鍙互鎶?涓瓙绫诲璞¤祴鍊肩粰鐖剁被鏁版嵁绫诲瀷锛岃繖鏄畨鍏ㄧ殑锛屼絾鏄妸鐖剁被瀵硅薄璧嬪€肩粰瀛愮被鏁版嵁绫诲瀷锛岀敋鑷虫妸瀵硅薄璧嬪€肩粰涓庡畠姣棤缁ф壙鍏崇郴銆佸畬鍏ㄤ笉鐩稿共鐨勪竴涓暟鎹被鍨嬶紝鍒欐槸鍗遍櫓鍜屼笉鍚堟硶鐨勩€?/p>

• 銆傘€傘€傘€傘€傘€?/p>

• 绗﹀彿寮曠敤楠岃瘉锛氳繖涓樁娈靛彂鐢熷湪绗﹀彿寮曠敤杞负鐩存帴寮曠敤鐨勬椂鍊欙紝鍗冲疄闄呬笂鏄湪瑙ｆ瀽闃舵涓繘琛岀殑銆?/p>

• 绗﹀彿寮曠敤涓€氳繃瀛楃涓叉弿杩扮殑鍏ㄩ檺瀹氬悕鏄惁鑳芥壘鍒板搴旂殑绫汇€?/p>

• 鍦ㄦ寚瀹氱被涓槸鍚﹀瓨鍦ㄧ鍚堟柟娉曠殑瀛楁鎻忚堪绗﹀強绠€鍗曞悕绉版墍鎻忚堪鐨勬柟娉曞拰瀛楁銆?/p>

• 绗﹀彿寮曠敤涓殑绫汇€佸瓧娈点€佹柟娉曠殑鍙闂€? private銆?protected. public銆?)銆?/p>

• 鏄惁鍙褰撳墠绫昏闂€?/p>

• 銆傘€傘€傘€傘€傘€?/p>

鍑嗗

璇ラ樁娈垫槸涓?span class="mq-93">绫诲彉閲?/span>锛坰tatic锛夊垎閰嶅唴瀛樺苟璁剧疆闆跺€硷紝鍗崇被鍙缁忚繃鍑嗗闃舵鍏朵腑鐨勯潤鎬佸彉閲忓氨鏄彲浣跨敤鐨勪簡锛屼絾姝ゆ椂绫诲彉閲忕殑鍊艰繕涓嶆槸鎴戜滑鎯宠鐨勫€硷紝闇€瑕佺粡杩囧垵濮嬪寲闃舵鎵嶄細灏嗘垜浠笇鏈涚殑鍊艰祴鍊肩粰瀵瑰簲鐨勯潤鎬佸彉閲忋€?/p>

瑙ｆ瀽

• java.lang.NoSuchFieldError锛氭壘涓嶅埌瀛楁

• java.lang.IllegalAccessError锛氫笉鍏锋湁璁块棶鏉冮檺

• java.lang.NoSuchMethodError锛氭壘涓嶅埌鏂规硶

鍒濆鍖?/h2>

杩欐槸绫诲姞杞借繃绋嬩腑鐨勬渶鍚庝竴涓楠わ紝涓昏鏄敹闆嗙被鐨?span class="mq-101">闈欐€佸彉閲忕殑璧嬪€煎姩浣?/span>鍜?span class="mq-102">static鍧椾腑鐨勮鍙?/span>鍚堟垚<cinit>鏂规硶锛岄€氳繃璇ユ柟娉曟牴鎹垜浠殑鎰忔効涓?span class="mq-103">闈欐€佸彉閲忚祴鍊?/span>浠ュ強鎵цstatic鍧?/span>锛岃鏂规硶浼氳鍔犻攣锛岀‘淇濆绾跨▼鎯呭喌涓嬪彧鏈変竴涓嚎绋嬭兘鍒濆鍖栨垚鍔燂紝鍒╃敤璇ョ壒鎬у彲浠ュ疄鐜?span class="mq-105">鍗曚緥妯″紡銆傝櫄鎷熸満瑙勫畾浜?span class="mq-106">鏈変笖鍙湁閬囧埌浠ヤ笅鎯呭喌鏃跺繀椤诲厛纭繚瀵瑰簲绫荤殑鍒濆鍖栧畬鎴愶紙鍔犺浇銆佸噯澶囧繀鐒跺湪姝や箣鍓嶏級锛?/p>

• 閬囧埌new銆乬etstatic銆乸utstatic鎴杋nvokestatic杩欏洓鏉″瓧鑺傜爜鎸囦护鏃躲€傝兘澶熺敓鎴愯繖鍥涙潯鎸囦护鐨勫吀鍨婮ava浠ｇ爜鍦烘櫙鏈夛細

• 浣跨敤new鍏抽敭瀛楀疄渚嬪寲瀵硅薄鐨勬椂鍊欍€?/p>

• 璇诲彇鎴栬缃竴涓被鍨嬬殑闈欐€佸瓧娈碉紙琚玣inal淇グ銆佸凡鍦ㄧ紪璇戞湡鎶婄粨鏋滄斁鍏ュ父閲忔睜鐨勯潤鎬佸瓧娈甸櫎澶栵級鐨勬椂鍊欍€?/p>

• 璋冪敤涓€涓被鍨嬬殑闈欐€佹柟娉曠殑鏃跺€欍€?/p>

• 鍙嶅皠璋冪敤绫绘椂銆?/p>

• 褰撳垵濮嬪寲绫荤殑鏃跺€欙紝濡傛灉鍙戠幇鍏剁埗绫昏繕娌℃湁杩涜杩囧垵濮嬪寲锛屽垯闇€瑕佸厛瑙﹀彂鍏剁埗绫荤殑鍒濆鍖栥€?/p>

• 褰撹櫄鎷熸満鍚姩鏃讹紝鐢ㄦ埛闇€瑕佹寚瀹氫竴涓鎵ц鐨勪富绫伙紙鍖呭惈main()鏂规硶鐨勯偅涓被锛夛紝铏氭嫙鏈轰細鍏堝垵濮嬪寲杩欎釜涓荤被銆?/p>

• 褰撲娇鐢↗DK 7鏂板姞鍏ョ殑鍔ㄦ€佽瑷€鏀寔鏃讹紝濡傛灉涓€涓猨ava.lang.invoke.MethodHandle瀹炰緥鏈€鍚庣殑瑙ｆ瀽缁撴灉涓篟EF_getStatic銆丷EF_putStatic銆丷EF_invokeStatic銆丷EF_newInvokeSpecial鍥涚绫诲瀷鐨勬柟娉曞彞鏌勶紝骞朵笖杩欎釜鏂规硶鍙ユ焺瀵瑰簲鐨勭被娌℃湁杩涜杩囧垵濮嬪寲锛屽垯闇€瑕佸厛瑙﹀彂鍏跺垵濮嬪寲銆?/p>

• 褰撲竴涓帴鍙ｄ腑瀹氫箟浜咼DK 8鏂板姞鍏ョ殑榛樿鏂规硶锛堣default鍏抽敭瀛椾慨楗扮殑鎺ュ彛鏂规硶锛夋椂锛屽鏋滄湁杩欎釜鎺ュ彛鐨勫疄鐜扮被鍙戠敓浜嗗垵濮嬪寲锛岄偅璇ユ帴鍙ｈ鍦ㄥ叾涔嬪墠琚垵濮嬪寲銆?/p>

涓嬮潰鍒嗘瀽鍑犱釜妗堜緥浠ｇ爜锛岃鑰呬滑鍙互鍏堟€濊€冨悗鍐嶈繍琛屼唬鐮佺湅鐪嬪拰鑷繁鎯崇殑鏄惁涓€鏍枫€?/p>

妗堜緥涓€

鍏堝畾涔夊涓嬩袱涓被锛?/p>

public class SuperClazz {
	static 	{
		System.out.println("SuperClass init锛?);
	}
	public static int value=123;
	public static final String HELLOWORLD="hello world";
	public static final int WHAT = value;
}

public class SubClaszz extends SuperClazz {
	static{
		System.out.println("SubClass init锛?);
	}

}

 
   
   
 

  
    
    
  
1
  
    
    
  


 
   
   
 

鐒跺悗杩涜涓嬮潰鐨勮皟鐢細

public class Initialization {
	public static void main(String[]args){
		Initialization initialization = new Initialization();
		initialization.M1();
	}
	
	public void M1(){
		System.out.println(SubClaszz.value);
	}
}

 
   
   
 

  
    
    
  
1
  
    
    
  


 
   
   
 

绗竴涓渚嬫槸閫氳繃瀛愮被鍘诲紩鐢ㄧ埗绫讳腑鐨?span class="mq-223">闈欐€佸彉閲?/span>锛屼袱涓被閮戒細鍔犺浇鍜屽垵濮嬪寲涔堬紵鎵撳嵃缁撴灉鐪嬬湅锛?/p>

SuperClass init锛?br>123

 
   
   
 

  
    
    
  


 
   
   
 

鍙互鐪嬪埌鍙湁鐖剁被鍒濆鍖栦簡锛岄偅涔堢埗绫诲繀鐒舵槸鍔犺浇浜嗙殑锛岄棶棰樺氨鍦ㄤ簬瀛愮被鏈夋病鏈夎鍔犺浇鍛紵鍙互鍔犱笂鍙傛暟锛?XX:+TraceClassLoading鍐嶆墽琛岋紙璇ュ弬鏁扮殑浣滅敤灏辨槸鎵撳嵃琚姞杞戒簡鐨勭被锛夛紝鍙互鐪嬪埌瀛愮被鏄鍔犺浇浜嗙殑銆傛墍浠?span class="mq-230">閫氳繃瀛愮被寮曠敤鐖剁被闈欐€佸彉閲忥紝鐖跺瓙绫婚兘浼氳鍔犺浇锛屼絾鍙湁鐖剁被浼氳繘琛屽垵濮嬪寲銆?br class="mq-231">涓轰粈涔堝憿锛熷弽缂栬瘧鍚庡彲浠ョ湅鍒扮敓鎴愪簡濡備笅鎸囦护锛?/p>

0: getstatic     #5                  // Field java/lang/System.out:Ljava/io/PrintStream;
3: getstatic     #6                  // Field ex7/init/SubClaszz.value:I
6: invokevirtual #7                  // Method java/io/PrintStream.println:(I)V
9: return

 
   
   
 

  
    
    
  


 
   
   
 

鍏抽敭灏辨槸getstatic鎸囦护灏变細瑙﹀彂绫荤殑鍒濆鍖栵紝浣嗘槸涓轰粈涔堝瓙绫讳笉浼氬垵濮嬪寲鍛紵鍥犱负杩欎釜鍙橀噺鏄潵鑷簬鐖剁被鐨勶紝涓轰簡鎻愰珮鏁堢巼锛屾墍浠ヨ櫄鎷熸満杩涜浜嗕紭鍖栵紝杩欑鎯呭喌鍙渶瑕佸垵濮嬪寲鐖剁被灏辫浜嗐€?/p>

妗堜緥浜?/h3>

璋冪敤涓嬮潰鐨勬柟娉曪細

	public void M2(){
		SubClaszz[]sca = new SubClaszz[10];
	}

 
   
   
 

  
    
    
  
1
 
   
   
 

鎵ц鍚庡彲浠ュ彂鐜帮紝浣跨敤鏁扮粍锛屼笉浼氳Е鍙戝垵濮嬪寲锛屼絾鐖跺瓙绫婚兘浼氳鍔犺浇銆?/p>

妗堜緥涓?/h3>

	public void M3(){
		System.out.println(SuperClazz.HELLOWORLD);
	

寮曠敤甯搁噺涓嶄細瑙﹀彂绫荤殑鍔犺浇鍜屽垵濮嬪寲锛屽洜涓哄父閲忓湪缂栬瘧鍚庡氨宸茬粡瀛樺湪褰撳墠class鐨勫父閲忔睜銆?/p>

妗堜緥鍥?/h3>

	public void M4(){
		System.out.println(SubClaszz.WHAT);
	}

 
   
   
 

  
    
    
  


 
   
   
 

閫氳繃甯搁噺鍘诲紩鐢ㄥ叾瀹冪殑闈欐€佸彉閲忎細鍙戠敓浠€涔堝憿锛熻繖涓拰妗堜緥涓€缁撴灉鏄竴鏍风殑銆?/p>

绫诲姞杞藉櫒

绫诲姞杞藉櫒鍜屽弻浜插娲炬ā鍨?/h2>

鍦ㄦ垜浠钩鏃跺紑鍙戜腑锛岀‘瀹氫竴涓被闇€瑕侀€氳繃瀹屽叏闄愬畾鍚?/span>锛岃€屼笉鑳界畝鍗曠殑閫氳繃鍚嶅瓧锛屽洜涓哄湪涓嶅悓鐨勮矾寰勪笅鎴戜滑鏄彲浠ュ畾涔夊悓鍚嶇殑绫荤殑銆傞偅涔堝湪铏氭嫙鏈轰腑鍙堟槸鎬庝箞鍖哄垎绫荤殑鍛紵鍦ㄨ櫄鎷熸満涓渶瑕?span class="mq-319">绫诲姞杞藉櫒+瀹屽叏闄愬畾鍚?/span>涓€璧锋潵鎸囧畾涓€涓被鐨勫敮涓€鎬э紝鍗崇浉鍚岄檺瀹氬悕鐨勭被鑻ョ敱涓や釜涓嶅悓鐨勭被鍔犺浇鍣ㄥ姞杞斤紝閭ｈ櫄鎷熸満灏变笉浼氭妸瀹冧滑褰撳仛涓€涓被銆備粠杩欓噷鎴戜滑鍙互鐪嬪嚭绫诲姞杞藉櫒涓€瀹氭槸鏈夊涓殑锛岄偅涔堜笉鍚岀殑绫诲姞杞藉櫒鏄€庝箞缁勭粐鐨勶紵瀹冧滑鍙堝垎鍒渶瑕佸姞杞藉摢浜涚被鍛紵

浠庤櫄鎷熻搴︾湅锛屽彧鏈変袱绉嶇被鍨嬬殑绫诲姞杞藉櫒锛?span class="mq-325">鍚姩绫诲姞杞藉櫒锛圔ootstrapClassLoader锛?span class="mq-326">鍜?/span>闈炲惎鍔ㄧ被鍔犺浇鍣?/span>銆傚墠鑰呮槸C++瀹炵幇锛屽睘浜庤櫄鎷熸満鐨勪竴閮ㄥ垎锛屽悗鑰呭垯鏄敱Java瀹炵幇鐨勶紝鐙珛浜庤櫄鎷熸満鐨勫閮紝骞朵笖鍏ㄩ儴缁ф壙鑷娊璞＄被java.lang.ClassLoader銆?br class="mq-327">浣嗕粠Java鏈韩鏉ョ湅锛屼竴鐩翠繚鎸佺潃涓夊眰绫诲姞杞藉櫒銆?span class="mq-329">鍙屼翰濮旀淳鐨勭粨鏋勶紝褰撶劧闄や簡Java鏈韩鎻愪緵鐨勪笁灞傜被鍔犺浇鍣紝鎴戜滑杩樺彲浠ヨ嚜瀹氫箟瀹炵幇绫诲姞杞藉櫒銆傚涓婂浘锛屼笂闈笁涓氨鏄師鐢熺殑绫诲姞杞藉櫒锛屾瘡涓€涓兘鏄笅涓€涓被鍔犺浇鍣ㄧ殑鐖跺姞杞藉櫒锛屾敞鎰忚繖閲岄兘鏄噰鐢?span class="mq-331">缁勫悎鑰岄潪缁ф壙銆傚綋寮€濮嬪姞杞界被鏃讹紝棣栧厛浜ょ粰鐖跺姞杞藉櫒鍔犺浇锛岀埗鍔犺浇鍣ㄥ姞杞戒簡瀛愬姞杞藉櫒灏变笉鐢ㄥ啀鍔犺浇浜嗭紝鑰岃嫢鏄埗鍔犺浇鍣ㄥ姞杞戒笉浜嗭紝灏变細浜ょ粰瀛愬姞杞藉櫒鍔犺浇锛岃繖灏辨槸鍙屼翰濮旀淳鏈哄埗銆傝繖灏卞ソ姣斿伐浣滀腑閬囧埌浜嗘棤娉曞鐞嗙殑浜嬶紝浣犱細鍘昏绀虹洿鎺ラ瀵硷紝鐩存帴棰嗗澶勭悊涓嶄簡锛屽啀鎵句笂灞傞瀵硷紝鐒跺悗涓婂眰棰嗗瑙夊緱杩欐槸涓皬浜嬶紝涓嶇敤浠栦翰鑷姩鎵嬶紝灏辫浣犵殑鐩存帴棰嗗鍘诲仛锛屾帴鐫€浠栧張浜ょ粰浣犲幓鍋氱瓑绛夈€備笅闈㈡潵鐪嬬湅姣忎釜绫诲姞杞藉櫒鐨勫叿浣撲綔鐢細

• BootstrapClassLoader锛氬惎鍔ㄧ被鍔犺浇鍣紝椤惧悕鎬濅箟锛岃繖涓被鍔犺浇鍣ㄤ富瑕佽礋璐ｅ姞杞絁DK lib鍖咃紝浠ュ強-Xbootclasspath鍙傛暟鎸囧畾鐨勭洰褰曪紝骞朵笖铏氭嫙鏈哄鏂囦欢鍚嶈繘琛屼簡闄愬畾锛屼篃灏辨槸璇村嵆浣挎垜浠嚜宸卞啓涓猨ar鏀惧叆鍒颁笂杩扮洰褰曪紝涔熶笉浼氳鍔犺浇銆傜敱浜庤绫诲姞杞藉櫒鏄疌++浣跨敤锛屾墍浠ユ垜浠殑Java绋嬪簭涓棤娉曠洿鎺ュ紩鐢紝璋冪敤java.lang.ClassLoader.getClassLoader()鏂规硶鏃堕粯璁よ繑鍥炵殑鏄痭ull銆?/p>

• ExtClassLoader锛氭墿灞曠被鍔犺浇鍣紝涓昏璐熻矗鍔犺浇JDK lib/ext鍖咃紝浠ュ強琚郴缁熷彉閲廽ava.ext.dirs鎸囧悜鐨勬墍鏈夌被搴擄紝杩欎釜绫诲簱鍙互瀛樻斁鎴戜滑鑷繁鍐欑殑閫氱敤jar銆?/p>

• AppClassLoader锛氬簲鐢ㄧ▼搴忕被鍔犺浇鍣紝璐熻矗鍔犺浇鐢ㄦ埛classpath涓婄殑鎵€鏈夌被銆傚畠鏄痡ava.lang.ClassLoader.getSystemClassLoader()鐨勮繑鍥炲€硷紝涔熸槸鎴戜滑绋嬪簭鐨勯粯璁ょ被鍔犺浇鍣紙濡傛灉鎴戜滑娌℃湁鑷畾涔夌被鍔犺浇鍣ㄧ殑璇濓級銆?/p>

閫氳繃杩欎笁涓被鍔犺浇浠ュ強鍙屼翰濮旀淳鏈哄埗锛屼竴涓樉鑰屾槗瑙佺殑濂藉灏辨槸锛屼笉鍚岀殑绫婚殢瀹冪殑绫诲姞杞藉櫒澶╃劧鍏锋湁浜嗗姞杞戒紭鍏堢骇锛屽儚Object銆丼tring绛夌瓑杩欎簺鏍稿績绫诲簱鑷劧灏变細鍦ㄦ垜浠殑搴旂敤绋嬪簭绫讳箣鍓嶈鍔犺浇锛屼娇寰楃▼搴忔洿瀹夊叏锛屼笉浼氬嚭鐜伴敊璇紝Spring鐨勭埗瀛愬鍣ㄤ篃鏄繖鏍风殑涓€涓璁°€傞€氳繃涓嬮潰杩欐浠ｇ爜鍙互鐪嬪埌姣忎釜绫绘墍瀵瑰簲鐨勭被鍔犺浇鍣細

public class ClassLoader {
    public static void main(String[] args) {
        System.out.println(String.class.getClassLoader()); //鍚姩绫诲姞杞藉櫒
        System.out.println(sun.net.spi.nameservice.dns.DNSNameService.class.getClassLoader());//鎷撳睍绫诲姞杞藉櫒
        System.out.println(ClassLoader.class.getClassLoader());//搴旂敤绋嬪簭绫诲姞杞藉櫒
    }
}

 
   
   
 

  
    
    
  


 
   
   
 

杈撳嚭锛?/p>

null
sun.misc.Launcher$ExtClassLoader@4b67cf4d
sun.misc.Launcher$AppClassLoader@14dad5dc

 
   
   
 

  
    
    
  


 
   
   
 

鐮村潖鍙屼翰濮旀淳妯″瀷

鍒氬垰鎴戜妇浜嗗伐浣滀腑鐨勪竴涓緥瀛愭潵璇存槑鍙屼翰濮旀淳鏈哄埗锛屼絾鐜板疄涓垜浠笉闇€瑕佷簨浜嬮兘鍘昏绀洪瀵硷紝鍚屾牱绫诲姞杞藉櫒涔熶笉鏄畬鍏ㄩ伒寰弻浜插娲炬満鍒讹紝鍦ㄥ繀瑕佺殑鏃跺€欐槸鍙互鎵撶牬杩欎釜瑙勫垯鐨勩€備笅闈㈠垪涓惧洓涓牬鍧忕殑鎯呭喌锛屽湪姝や箣鍓嶆垜浠渶瑕佸厛浜嗚В涓嬪弻浜?濮旀淳鐨勪唬鐮佸疄鐜板師鐞嗭紝鍦╦ava.lang.ClassLoader绫讳腑鏈変竴涓?span class="mq-415">loadClass浠ュ強findClass鏂规硶锛?/p>

    protected Class<?> loadClass(String name, boolean resolve)
        throws ClassNotFoundException
    {
        synchronized (getClassLoadingLock(name)) {
            // First, check if the class has already been loaded
            Class<?> c = findLoadedClass(name);
            if (c == null) {
                long t0 = System.nanoTime();
                try {
                    if (parent != null) {
                        c = parent.loadClass(name, false);
                    } else {
                        c = findBootstrapClassOrNull(name);
                    }
                } catch (ClassNotFoundException e) {
                    // ClassNotFoundException thrown if class not found
                    // from the non-null parent class loader
                }

                if (c == null) {
                    // If still not found, then invoke findClass in order
                    // to find the class.
                    long t1 = System.nanoTime();
                    c = findClass(name);

                    // this is the defining class loader; record the stats
                    sun.misc.PerfCounter.getParentDelegationTime().addTime(t1 - t0);
                    sun.misc.PerfCounter.getFindClassTime().addElapsedTimeFrom(t1);
                    sun.misc.PerfCounter.getFindClasses().increment();
                }
            }
            if (resolve) {
                resolveClass(c);
            }
            return c;
        }
    }

    protected Class<?> findClass(String name) throws ClassNotFoundException {
        throw new ClassNotFoundException(name);
    }

 
   
   
 

  
    
    
  


 
   
   
 

浠庝笂闈㈠彲浠ョ湅鍒伴鍏堟槸璋冪敤parent鍘诲姞杞界被锛屾病鏈夊姞杞藉埌鎵嶈皟鐢ㄨ嚜韬殑findClass鏂规硶鍘诲姞杞姐€備篃灏辨槸璇寸敤鎴峰湪瀹炵幇鑷畾涔夌被鍔犺浇鍣ㄧ殑鏃跺€欓渶瑕佽鐩栫殑鏄?span class="mq-581">fiindClass鑰屼笉鏄?span class="mq-582">loadClass锛岃繖鏍锋墠鑳芥弧瓒?span class="mq-583">鍙屼翰濮旀淳妯″瀷銆?br class="mq-584">涓嬮潰鍏蜂綋鏉ョ湅鐪嬬牬鍧忓弻浜插娲剧殑鍑犱釜鍦烘櫙銆?/p>

绗竴娆?/h3>

绗竴娆＄牬鍧忔槸鍦ㄥ弻浜插娲炬ā鍨嬪嚭鐜颁箣鍓嶏紝 鍥犱负璇ユā鍨嬫槸鍦↗DK1.2涔嬪悗鎵嶅紩鍏ョ殑锛岄偅涔堝湪姝や箣鍓嶏紝鎶借薄绫籮ava.lang.ClassLoader灏卞凡缁忓瓨鍦ㄤ簡锛岀敤鎴疯嚜瀹氫箟鐨勭被鍔犺浇鍣ㄩ兘浼氬幓瑕嗙洊璇ョ被涓殑loadClass鏂规硶锛屾墍浠ュ弻浜插娲炬ā鍨嬪嚭鐜板悗锛屽氨鏃犳硶閬垮厤鐢ㄦ埛瑕嗙洊璇ユ柟娉曪紝鍥犳鏂板浜?span class="mq-588">findClass寮曞鐢ㄦ埛鍘昏鐩栬鏂规硶瀹炵幇鑷繁鐨勭被鍔犺浇閫昏緫銆?/p>

SPI

绗簩娆＄牬鍧忔槸鐢变簬杩欎釜妯″瀷鏈韩缂洪櫡瀵艰嚧鐨勶紝鍥犱负璇ユā鍨嬩繚璇佷簡绫荤殑鍔犺浇浼樺厛绾э紝浣嗘槸鏈変簺鎺ュ彛鏄疛ava瀹氫箟鍦ㄦ牳蹇冪被搴撲腑锛屼絾鍏蜂綋鐨勬湇鍔″疄鐜版槸鐢辩敤鎴锋彁渚涚殑锛岃繖鏃跺€欏氨涓嶅緱涓嶇牬鍧忚妯″瀷鎵嶈兘瀹炵幇锛屽吀鍨嬬殑灏辨槸Java涓殑SPI鏈哄埗锛堝SPI涓嶄簡瑙ｇ殑璇昏€呭彲浠ョ炕闃呮垜涔嬪墠鐨勬枃绔犳垨鏄叾瀹冭祫鏂欙紝杩欓噷涓嶈繘琛岄槓杩帮級銆侸
DBC鐨勯┍鍔ㄥ姞杞藉氨鏄疭PI瀹炵幇鐨勶紝鎵€浠ョ洿鎺ョ湅鍒?span class="mq-592">java.sql.DriverManager绫伙紝璇ョ被涓湁涓€涓潤鎬佸垵濮嬪寲鍧楋細

    static {
        loadInitialDrivers();
        println("JDBC DriverManager initialized");
    }

    private static void loadInitialDrivers() {
        String drivers;
        try {
            drivers = AccessController.doPrivileged(new PrivilegedAction<String>() {
                public String run() {
                    return System.getProperty("jdbc.drivers");
                }
            });
        } catch (Exception ex) {
            drivers = null;
        }

        AccessController.doPrivileged(new PrivilegedAction<Void>() {
            public Void run() {

                ServiceLoader<Driver> loadedDrivers = ServiceLoader.load(Driver.class);
                Iterator<Driver> driversIterator = loadedDrivers.iterator();
                
                try{
                    while(driversIterator.hasNext()) {
                        driversIterator.next();
                    }
                } catch(Throwable t) {
                // Do nothing
                }
                return null;
            }
        });

        println("DriverManager.initialize: jdbc.drivers = " + drivers);

        if (drivers == null || drivers.equals("")) {
            return;
        }
        String[] driversList = drivers.split(":");
        println("number of Drivers:" + driversList.length);
        for (String aDriver : driversList) {
            try {
                println("DriverManager.Initialize: loading " + aDriver);
                Class.forName(aDriver, true,
                        ClassLoader.getSystemClassLoader());
            } catch (Exception ex) {
                println("DriverManager.Initialize: load failed: " + ex);
            }
        }
    }

 
   
   
 

  
    
    
  


  
    
    
  


  
    
    
  
51
 
   
   
 

涓昏鐪?span class="mq-800">ServiceLoader.load鏂规硶锛岃繖涓氨鏄€氳繃SPI鍘诲姞杞芥垜浠紩鍏?span class="mq-801">java.sql.Driver瀹炵幇绫伙紙姣斿寮曞叆mysql鐨勯┍鍔ㄥ寘灏辨槸com.mysql.cj.jdbc.Driver锛夛細

    public static <S> ServiceLoader<S> load(Class<S> service) {
        ClassLoader cl = Thread.currentThread().getContextClassLoader();
        return ServiceLoader.load(service, cl);
    }

 
   
   
 

  
    
    
  


 
   
   
 

杩欎釜鏂规硶涓昏鏄粠褰撳墠绾跨▼涓幏鍙栫被鍔犺浇鍣紝鐒跺悗閫氳繃杩欎釜绫诲姞杞藉櫒鍘诲姞杞?span class="mq-840">椹卞姩瀹炵幇绫?/span>锛堣繖涓彨绾跨▼涓婁笅鏂囩被鍔犺浇鍣?/span>锛屾垜浠篃鍙互浣跨敤杩欎釜鎶€宸у幓鎵撶牬鍙屼翰濮旀淳锛夛紝閭ｈ繖閲屼細鑾峰彇鍒板摢涓€涓被鍔犺浇鍣ㄥ憿锛熷叿浣撶殑璁剧疆鏄湪sun.misc.Launcher绫荤殑鏋勯€犲櫒涓細

    public Launcher() {
        Launcher.ExtClassLoader var1;
        try {
            var1 = Launcher.ExtClassLoader.getExtClassLoader();
        } catch (IOException var10) {
            throw new InternalError("Could not create extension class loader", var10);
        }

        try {
            this.loader = Launcher.AppClassLoader.getAppClassLoader(var1);
        } catch (IOException var9) {
            throw new InternalError("Could not create application class loader", var9);
        }

        Thread.currentThread().setContextClassLoader(this.loader);
        String var2 = System.getProperty("java.security.manager");
        if (var2 != null) {
            SecurityManager var3 = null;
            if (!"".equals(var2) && !"default".equals(var2)) {
                try {
                    var3 = (SecurityManager)this.loader.loadClass(var2).newInstance();
                } catch (IllegalAccessException var5) {
                } catch (InstantiationException var6) {
                } catch (ClassNotFoundException var7) {
                } catch (ClassCastException var8) {
                }
            } else {
                var3 = new SecurityManager();
            }

            if (var3 == null) {
                throw new InternalError("Could not create SecurityManager: " + var2);
            }

            System.setSecurityManager(var3);
        }

   
 
   
   
 

  
    
    
  


 
   
   
 

鍙互鐪嬪埌璁剧疆鐨勫氨鏄?span class="mq-1018">AppClassLoader銆備綘鍙兘浼氭湁鐐圭枒鎯戯紝杩欎釜绫诲姞杞藉櫒鍔犺浇绫荤殑鏃跺€欎笉涔熸槸鍏堣皟鐢ㄧ埗绫诲姞杞藉櫒鍔犺浇涔堬紝鎬庝箞灏辨墦鐮村弻浜插娲句簡鍛紵鍏跺疄鎵撶牬鍙屼翰濮旀淳鎸囩殑灏辨槸绫荤殑灞傛缁撴瀯锛屽欢浼告剰鎬濆氨鏄被鐨勫姞杞戒紭鍏堢骇锛岃繖閲屾湰搴旇鏄湪鍔犺浇鏍稿績绫诲簱鐨勬椂鍊欏嵈鎻愬墠灏嗘垜浠簲鐢ㄧ▼搴忎腑鐨勭被搴撶粰鍔犺浇鍒拌櫄鎷熸満涓潵浜嗐€?/p>

Tomcat

涓婂浘鏄疶omcat绫诲姞杞界殑绫诲浘锛屽墠闈笁涓笉鐢ㄨ锛?span class="mq-1022">CommonClassLoader銆?span class="mq-1023">CatalinaClassLoader銆?span class="mq-1024">SharedClassLoader銆?span class="mq-1025">WebAppClassLoader銆?span class="mq-1026">JspClassLoader鍒欐槸Tomcat鑷繁瀹炵幇鐨勭被鍔犺浇鍣紝鍒嗗埆鍔犺浇common鍖?/span>銆?span class="mq-1028">server鍖?/span>銆?span class="mq-1029">shared鍖?/span>銆?span class="mq-1030">WebApp/WEB-INF/lib鍖?/span>浠ュ強JSP鏂囦欢锛屽墠闈笁涓湪tomcat 6涔嬪悗宸茬粡鍚堝苟鍒版牴鐩綍涓嬬殑lib鐩綍涓嬨€傝€?span class="mq-1032">WebAppClassLoader鍒欐槸姣忎竴涓簲鐢ㄧ▼搴忓搴斾竴涓紝JspClassLoader鏄瘡涓€涓狫SP鏂囦欢閮戒細瀵瑰簲涓€涓紝骞朵笖杩欎袱涓被鍔犺浇鍣ㄩ兘娌℃湁鐖剁被鍔犺浇鍣紝杩欎篃灏辫繚鑳屼簡鍙屼翰濮旀淳妯″瀷銆?br class="mq-1034">涓轰粈涔堟瘡涓簲鐢ㄧ▼搴忛渶瑕佸崟鐙殑WebAppClassLoader瀹炰緥锛熷洜涓烘瘡涓簲鐢ㄧ▼搴忛渶瑕佸郊姝ら殧绂伙紝鍋囧鍦ㄤ袱涓簲鐢ㄤ腑瀹氫箟浜嗕竴鏍风殑绫伙紙瀹屽叏闄愬畾鍚嶏級锛屽鏋滈伒寰弻浜插娲鹃偅灏卞彧浼氬瓨鍦ㄤ竴浠戒簡锛屽彟澶栦笉鍚岀殑搴旂敤杩樻湁鍙兘渚濊禆鍚屼竴涓被搴撶殑涓嶅悓鐗堟湰锛岃繖涔熼渶瑕侀殧绂伙紝鎵€浠ユ瘡涓€涓簲鐢ㄧ▼搴忛兘浼氬搴斾竴涓?span class="mq-1037">WebAppClassLoader锛屽畠浠叡浜殑绫诲簱鍙互璁?span class="mq-1038">SharedClassLoader鍔犺浇锛屽彟澶栬繖浜涚被鍔犺浇鍔犺浇鐨勭被瀵筎omcat鏈韩鏉ヨ涔熸槸闅旂鐨勶紙CatalinaClassLoader鍔犺浇鐨勶級銆?br class="mq-1039">涓轰粈涔堟瘡涓狫SP鏂囦欢闇€瑕佸搴斿崟鐙殑涓€涓?span class="mq-1040">JspClassLoader瀹炰緥锛熻繖鏄敱浜嶫SP鏄敮鎸佽繍琛屾椂淇敼鐨勶紝淇敼鍚庝細涓㈠純鎺変箣鍓嶇紪璇戠敓鎴愮殑class锛屽苟閲嶆柊鐢熸垚涓€涓?span class="mq-1041">JspClassLoader瀹炰緥鍘诲姞杞芥柊鐨刢lass銆?br class="mq-1042">浠ヤ笂灏辨槸Tomcat涓轰粈涔堣鎵撶牬鍙屼翰濮旀淳妯″瀷鐨勫師鍥犮€?/p>

OSGI

OSGI鏄敤浜庡疄鐜版ā鍧楃儹閮ㄧ讲锛屽儚Eclipse鐨勬彃浠剁郴缁熷氨鏄埄鐢∣SGI瀹炵幇鐨勶紝杩欎釜鎶€鏈潪甯稿鏉傚悓鏃朵娇鐢ㄧ殑涔熻秺鏉ヨ秺灏戜簡锛屾劅鍏磋叮鐨勮鑰呭彲鑷鏌ラ槄璧勬枡瀛︿範锛岃繖閲屼笉鍐嶈繘琛岄槓杩般€?/p>

 

  

 

鎬荤粨

绫诲姞杞界殑杩囩▼璁╂垜浠簡瑙ｅ埌涓€涓被鏄浣曡鍔犺浇鍒板唴瀛樹腑锛岄渶瑕佺粡杩囧摢浜涢樁娈碉紱鑰岀被鍔犺浇鍣ㄥ拰鍙屼翰濮旀淳妯″瀷鍒欐槸鍛婅瘔鎴戜滑搴旇鎬庝箞鍘诲姞杞界被銆佺被鐨勫姞杞戒紭鍏堢骇鏄€庢牱鐨勶紝鍏朵腑鐨勮璁℃€濇兂鎴戜滑涔熷彲浠ュ涔犲€熼壌锛涙渶鍚庨渶瑕佹繁鍒荤悊瑙ｇ殑鏄负浠€涔堥渶瑕佹墦鐮村弻浜插娲撅紝鍦ㄩ亣鍒扮浉搴旂殑鍦烘櫙鏃跺簲璇ユ€庝箞鍋氥€?/p>

end

骞茶揣鍒嗕韩

鍥炲銆?01銆戣幏鍙?nbsp; 銆婂叏鏍堟灦鏋勫笀銆嬭绋?nbsp;

鍥炲銆?02銆戣幏鍙?銆婇珮绾у疄鎴樻灦鏋勫笀璇剧▼銆嬭绋?nbsp;

鍥炲銆?03銆戣幏鍙?銆婇珮绾ф灦鏋勫笀鍏ㄥ鏁欑▼銆嬭绋?nbsp;

鍥炲銆?05銆戣幏鍙?nbsp;銆婂ぇ鏁版嵁涔婬ive瑙嗛銆嬭绋?nbsp;

鍥炲銆?08銆戣幏鍙?nbsp;銆妚3 RabbitMQ娑堟伅涓棿浠舵妧鏈簿璁层€嬭绋?nbsp;

鍥炲銆?09銆戣幏鍙?nbsp; 銆婂ぇ鏁版嵁涔媄ookeeper瑙嗛銆嬭绋?nbsp;

鏇村瀛︿範璧勬枡璇疯仈绯绘垜鍝︼紒锛侊紒

 
   
   
 

  
    
    
  
鏈夌儹闂ㄦ帹鑽?/span>馃憞
 
   
   
 
 
   
   
 

  
    
    
  
 
   
 
    
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鎶€鏈€丣VM銆丣ava骞跺彂銆丼SM銆佸井鏈嶅姟銆佹暟鎹簱銆佹暟鎹粨鏋勭瓑绛夈€?/span>
鍠滄鐨勭殑璇濓紝鐐逛釜鈥?/strong>鍦ㄧ湅鈥?/strong>榧撳姳涓€涓嬪惂
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以上是关于娣卞叆鎺㈢┒JVM涔嬬被鍔犺浇涓庡弻浜插娲炬満鍒?/h1>

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