璋㈤鏈洪潰璇曡锛氫竴鍦鸿浜哄摥绗戜笉寰楃殑Java澶у巶闈㈣瘯

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HashMap搴曞眰鏁版嵁缁撴瀯HashMap鍦↗DK 1.8涓殑搴曞眰缁撴瀯鏄�**鏁扮粍+閾捐〃+绾㈤粦鏍�**锛歕n- 鍒濆瀹归噺涓�16锛岃礋杞藉洜瀛愪负0.75- 褰撻摼琛ㄩ暱搴︹墺8涓旀暟缁勯暱搴︹墺64鏃讹紝閾捐〃杞负绾㈤粦鏍慭n- 褰撶孩榛戞爲鑺傜偣鈮�6鏃讹紝绾㈤粦鏍戣浆涓洪摼琛╘n- 鎵╁鏈哄埗锛氬閲忕炕鍊嶏紝閲嶆柊hash鍒嗛厤```java// HashMap鑺傜偣缁撴瀯treeNode extends LinkedHashMap.Entrystatic class Node implements Map.Entry { final int hash; final K key; V value; Node next;}```#### 2. ArrayList vs LinkedList| 鐗规�� | ArrayList | LinkedList ||------|-----------|------------|| 搴曞眰缁撴瀯 | 鍔ㄦ�佹暟缁� | 鍙屽悜閾捐〃 || 闅忔満璁块棶 | O(1) | O(n) || 鎻掑叆鍒犻櫎 | O(n) | O(1) || 鍐呭瓨鍗犵敤 | 杈冨皯 | 杈冨锛堥渶瑕佸瓨鍌ㄥ墠鍚庢寚閽堬級 || 閫傜敤鍦烘櫙 | 鏌ヨ澶氾紝澧炲垹灏� | 澧炲垹澶氾紝鏌ヨ灏� |#### 3. ConcurrentHashMap 1.7 vs 1.8**JDK 1.7**锛歕n- 鍒嗘閿侊紙Segment锛夋満鍒禱n- 榛樿16涓猄egment锛屾瘡涓猄egment鐙珛鍔犻攣- 鏁版嵁缁撴瀯锛氭暟缁�+閾捐〃**JDK 1.8**锛歕n- CAS + synchronized- 閿佺矑搴︽洿缁嗭紝閿佷綇閾捐〃/绾㈤粦鏍戠殑棣栬妭鐐筡n- 鏁版嵁缁撴瀯锛氭暟缁�+閾捐〃+绾㈤粦鏍慭n- 骞跺彂搴︽洿楂橈紝鎬ц兘鏇村ソ#### 4. Java鍐呭瓨妯″瀷锛圝MM锛塡nJava鍐呭瓨妯″瀷涓昏鍖呭惈锛歕n- **鍫嗭紙Heap锛�**锛氬瓨鏀惧璞″疄渚嬶紝鍨冨溇鍥炴敹鐨勪富瑕佸尯鍩焅n- **鏍堬紙Stack锛�**锛氬瓨鏀惧眬閮ㄥ彉閲忋�佹柟娉曡皟鐢ㄩ摼- **鏂规硶鍖猴紙Method Area锛�**锛氬瓨鏀剧被淇℃伅銆佸父閲忋�侀潤鎬佸彉閲廫n- **绋嬪簭璁℃暟鍣�**锛氳褰曞綋鍓嶇嚎绋嬫墽琛岀殑瀛楄妭鐮佽鍙穃n- **鏈湴鏂规硶鏍�**锛歂ative鏂规硶浣跨敤**JMM鏍稿績姒傚康**锛歕n- 鍘熷瓙鎬с�佸彲瑙佹�с�佹湁搴忔�n- happens-before鍘熷垯- volatile銆乻ynchronized鍐呭瓨璇箟---### 绗簩杞瓟妗圽n#### 1. Spring Bean鐢熷懡鍛ㄦ湡```1. 瀹炰緥鍖栵紙Instantiation锛塡n2. 灞炴�ц祴鍊硷紙Populate锛塡n3. Aware鎺ュ彛鍥炶皟锛圔eanNameAware銆丅eanFactoryAware绛夛級4. BeanPostProcessor鍓嶇疆澶勭悊锛坧ostProcessBeforeInitialization锛塡n5. 鍒濆鍖栨柟娉曪紙InitializingBean.afterPropertiesSet / @PostConstruct锛塡n6. BeanPostProcessor鍚庣疆澶勭悊锛坧ostProcessAfterInitialization锛塡n7. 浣跨敤闃舵8. 閿�姣佹柟娉曪紙DisposableBean.destroy / @PreDestroy锛塡n```#### 2. Spring Boot鑷姩瑁呴厤鍘熺悊```java@SpringBootApplication= @SpringBootConfiguration + @EnableAutoConfiguration + @ComponentScan@EnableAutoConfiguration= @AutoConfigurationPackage + @Import(AutoConfigurationImportSelector.class)AutoConfigurationImportSelector:- 鍔犺浇 META-INF/spring.factories锛�2.7+涓� META-INF/spring/org.springframework.boot.autoconfigure.AutoConfiguration.imports锛塡n- 绛涢�夌鍚堟潯浠剁殑閰嶇疆绫伙紙@Conditional娉ㄨВ锛塡n- 娉ㄥ唽鍒癝pring瀹瑰櫒```#### 3. MyBatis #{} vs ${}| 鐗规�� | #{} | ${} ||------|-----|-----|| 澶勭悊鏂瑰紡 | 棰勭紪璇戯紙?鍗犱綅绗︼級 | 瀛楃涓叉浛鎹� || SQL娉ㄥ叆 | 闃叉 | 鏈夐闄� || 浣跨敤鍦烘櫙 | 鍙傛暟鍊� | 琛ㄥ悕銆佸垪鍚嶇瓑 |#### 4. RabbitMQ娑堟伅鍙潬鎬т繚璇乗n**鐢熶骇鑰呬笉涓㈠け**锛歕n- 寮�鍚疌onfirm纭妯″紡- 澶辫触閲嶈瘯鏈哄埗- 鏈湴娑堟伅琛�+瀹氭椂浠诲姟**MQ涓嶄涪澶�**锛歕n- 娑堟伅鎸佷箙鍖栵紙exchange銆乹ueue銆乵essage閮芥寔涔呭寲锛塡n- 闀滃儚闃熷垪**娑堣垂鑰呬笉涓㈠け**锛歕n- 鎵嬪姩ACK- 涓氬姟澶勭悊鎴愬姛鍚庡啀纭- 姝讳俊闃熷垪澶勭悊澶辫触娑堟伅**骞傜瓑鎬у鐞�**锛歕n- 鍞竴娑堟伅ID + 鏁版嵁搴撳幓閲嶈〃- Redis鍘熷瓙鎿嶄綔锛坰etnx锛塡n- 涓氬姟鐘舵�佹満鎺у埗#### 5. xxl-job鎵ц鍣ㄦ敞鍐屾祦绋媆n```1. 鎵ц鍣ㄥ惎鍔紝璇诲彇閰嶇疆锛堟墽琛屽櫒鍚嶇О銆佸湴鍧�绛夛級2. 璋冪敤璋冨害涓績 API锛�/registry锛夋敞鍐孿n3. 璋冨害涓績灏嗘墽琛屽櫒淇℃伅瀛樺叆鏁版嵁搴揬n4. 鎵ц鍣ㄥ畾鏈熷彂閫佸績璺筹紙/beat锛塡n5. 璋冨害涓績鏍规嵁娉ㄥ唽淇℃伅璺敱浠诲姟6. 鎵ц鍣ㄤ笅绾挎椂鑷姩/鎵嬪姩娉ㄩ攢```---### 绗笁杞瓟妗圽n#### 1. 鐧句竾绾х敤鎴峰湪绾挎灦鏋勮璁n```鐢ㄦ埛 鈫� CDN 鈫� Nginx璐熻浇鍧囪　 鈫� 缃戝叧灞� 鈫� 寰湇鍔￠泦缇n 鈫揬n Redis闆嗙兢锛堢紦瀛橈級 鈫揬n MySQL闆嗙兢锛堝垎搴撳垎琛級 鈫揬n 娑堟伅闃熷垪锛堝紓姝ヨВ鑰︼級```**鍏抽敭璁捐**锛歕n- 鏈嶅姟鏃犵姸鎬佸寲锛屾按骞虫墿灞昞n- 璇诲啓鍒嗙 + 鍒嗗簱鍒嗚〃锛堟寜鐢ㄦ埛ID鍝堝笇锛塡n- 澶氱骇缂撳瓨锛堟湰鍦扮紦瀛�+鍒嗗竷寮忕紦瀛橈級- 寮傛鍖栵紙娑堟伅闃熷垪鍓婂嘲锛塡n- 闄愭祦鐔旀柇锛圫entinel/Hystrix锛塡n#### 2. Redis鎸佷箙鍖栨柟寮廫n| 鏂瑰紡 | 鍘熺悊 | 浼樼偣 | 缂虹偣 ||------|------|------|------|| RDB | 瀹氭椂蹇収 | 鏂囦欢绱у噾锛屾仮澶嶅揩 | 鍙兘涓㈠け鏁版嵁 || AOF | 璁板綍鍐欏懡浠� | 鏁版嵁鏇村畨鍏� | 鏂囦欢澶э紝鎭㈠鎱� || 娣峰悎鎸佷箙鍖� | RDB+AOF | 鍏奸【涓よ�� | Redis 4.0+ |#### 3. 缂撳瓨涓夊ぇ闂瑙ｅ喅鏂规**缂撳瓨绌块��**锛堟煡璇笉瀛樺湪鐨勬暟鎹級锛歕n- 甯冮殕杩囨护鍣ㄦ嫤鎴猏n- 缂撳瓨绌哄�硷紙璁剧疆鐭繃鏈熸椂闂达級- 鎺ュ彛灞傚鍔犳牎楠孿n**缂撳瓨鍑荤┛**锛堢儹鐐筴ey杩囨湡锛夛細- 浜掓枼閿侊紙synchronized/Redis鍒嗗竷寮忛攣锛塡n- 閫昏緫杩囨湡锛堜笉璁剧疆鐗╃悊杩囨湡锛屽紓姝ユ洿鏂帮級**缂撳瓨闆穿**锛堝ぇ閲弅ey鍚屾椂杩囨湡锛夛細- 闅忔満杩囨湡鏃堕棿锛堝熀纭�鏃堕棿+闅忔満鍊硷級- 澶氱骇缂撳瓨- 闄愭祦闄嶇骇#### 4. 绱㈠紩澶辨晥鍦烘櫙- 瀵圭储寮曞垪杩涜璁＄畻鎴栧嚱鏁版搷浣淺n- LIKE '%xxx'锛堝墠缂�妯＄硦鏌ヨ锛塡n- OR杩炴帴锛堝叾涓竴涓瓧娈垫棤绱㈠紩锛塡n- 绫诲瀷闅愬紡杞崲锛堝瓧绗︿覆涓嶅姞寮曞彿锛塡n- 杩濆弽鏈�宸﹀墠缂�鍘熷垯锛堝鍚堢储寮曪級- != 鎴� <> 鎿嶄綔绗n- IS NULL / IS NOT NULL锛堟煇浜涙儏鍐碉級#### 5. 鍗曚緥妯″紡浜旂鍐欐硶```java// 1. 楗挎眽寮忥紙绾跨▼瀹夊叏锛岀被鍔犺浇鏃跺垵濮嬪寲锛塡npublic class Singleton { private static final Singleton instance = new Singleton(); private Singleton() {} public static Singleton getInstance() { return instance; }}// 2. 鎳掓眽寮忥紙绾跨▼涓嶅畨鍏級public class Singleton { private static Singleton instance; private Singleton() {} public static Singleton getInstance() { if (instance == null) instance = new Singleton(); return instance; }}// 3. 鍙岄噸妫�鏌ラ攣锛堟帹鑽愶級public class Singleton { private static volatile Singleton instance; private Singleton() {} public static Singleton getInstance() { if (instance == null) { synchronized (Singleton.class) { if (instance == null) { instance = new Singleton(); } } } return instance; }}// 4. 闈欐�佸唴閮ㄧ被锛堟帹鑽愶級public class Singleton { private Singleton() {} private static class Holder { private static final Singleton INSTANCE = new Singleton(); } public static Singleton getInstance() { return Holder.INSTANCE; }}// 5. 鏋氫妇寮忥紙鏈�瀹夊叏锛岄槻鍙嶅皠锛塡npublic enum Singleton { INSTANCE; public void doSomething() {}}```**volatile浣滅敤**锛歕n- 绂佹鎸囦护閲嶆帓搴忥紙闃叉鍏朵粬绾跨▼鑾峰彇鍒版湭鍒濆鍖栧畬鎴愮殑瀵硅薄锛塡n- 淇濊瘉鍙鎬э紙涓�涓嚎绋嬩慨鏀瑰悗锛屽叾浠栫嚎绋嬬珛鍗冲彲瑙侊級---## 鎬荤粨閫氳繃璋㈤鏈虹殑闈㈣瘯缁忓巻锛屾垜浠彲浠ョ湅鍒帮細1. **鍩虹瑕佹墡瀹�**锛氶泦鍚堛�佸绾跨▼銆丣VM绛夊熀纭�鐭ヨ瘑蹇呴』鐗㈠浐2. **鍘熺悊瑕佺悊瑙�**锛氫笉浠呬細鐢紝杩樿鐭ラ亾搴曞眰瀹炵幇鍘熺悊3. **鍦烘櫙瑕佺粨鍚�**锛氭妧鏈鑳界粨鍚堝疄闄呬笟鍔″満鏅垎鏋怽n4. **娣卞害瑕佹寲鎺�**锛氶潰璇曞畼鍠滄杩介棶锛岃鑳藉眰灞傛繁鍏n5. **鎬佸害瑕佽瘹鎭�**锛氫笉浼氱殑闂鍙互鎵胯锛屼笉瑕佽儭涔卞洖绛擻n甯屾湜杩欑瘒鏂囩珷鑳藉府鍔╂鍦ㄥ噯澶囬潰璇曠殑灏忎紮浼翠滑锛岀澶у閮借兘鎷垮埌蹇冧华鐨刼ffer锛乗n---*锛堟湰鏂囩函灞炶櫄鏋勶紝濡傛湁闆峰悓锛岄偅璇存槑浣犱篃閬囧埌杩囪阿椋炴満锛�*