一次代码review挑动的关于单例模式的思考

2013-04-02

一次代码review引发的关于单例模式的思考MemcachedClientFactory{private MemcachedConnectionBuilder mem

一次代码review引发的关于单例模式的思考

MemcachedClientFactory{private MemcachedConnectionBuilder memcachedConnectionBuilder；private String servers;private static MemcachedClient memcachedClient;private MemcachedClientFactory（）{}private MemcachedClientFactory（MemcachedConnectionBuilder memcachedConnectionBuilder, String servers）{this. memcachedConnectionBuilder= memcachedConnectionBuilder;this.servers=servers;}public static MemcachedClient createClient(){if(memcachedClient==null){this.memcahcedClien= new MemcachedClient(memcachedConnectionBuilder.build(),AddrUtil.get(servers));}return this.memcahcedClient;}}}

即程序改写为：

Public Class Singleton{private static Singleton instance=new Singleton（）；private Singleton(){};public static Singleton getInstance(){   return instance;}}

?这样做时，jvm在加载类时就立马创建了该实例，所以这样做的前提是，创建该实例的负担不大，我不比过多的考虑性能，并且我们确认该实例是一定会用到的。其实我前面的代码也完全可以使用这个方式：

MemcachedClientFactory{private MemcachedConnectionBuilder memcachedConnectionBuilder；private String servers;private static MemcachedClient memcachedClien= newMemcachedClient(memcachedConnectionBuilder.build(),AddrUtil.get(servers));private MemcachedClientFactory（）{}private MemcachedClientFactory（MemcachedConnectionBuilder memcachedConnectionBuilder, String servers）{this. memcachedConnectionBuilder= memcachedConnectionBuilder;this.servers=servers;}public static MemcachedClient createClient(){return this.memcahcedClient;}}}

?不过，看上去似乎没有问题，但是有隐患，即一旦有人不小心调用了memcachedClient.shutdown()方法，那整个程序就无法再生出新的memcachedClient了。当然这是极端情况了，但是为了代码的健壮，可以再改为：

public static MemcachedClient createClient(){if(memcachedClient==null){this.memcahcedClien= new MemcachedClient(memcachedConnectionBuilder.build(),AddrUtil.get(servers));}return this.memcahcedClient;}

这么做可以保证同步问题，但是我们知道使用synchronized的开销是很大的，会严重影响性能，所以用这个的前提是，你确认不会经常调用这个方法，或者你创建这个instance的开销不会特别大。是否还可以改进，看下面。

3. 使用“双重检查加锁“，在getInstance中见识使用同步。写法如下

public Class Singleton{private volatile static Singleton instance;private Singleton(){};public static Singleton getInstance(){ if(instance==null){synchronized (Singleton.class){if(instance==null){instance=new Singleton();}}}return instance;}}

?这样减少了synchronized出现的次数。当然使用volatile关键字有局限性，就是你的jdk必须是1.5以后的版本。

public static synchronizd MemcachedClient createClient(){ if(memcachedClient==null){ this.memcahcedClien= new MemcachedClient(memcachedConnectionBuilder.build(),AddrUtil.get(servers)); } return this.memcahcedClient; }

这样直接加锁不太好吧应该判断为空的时候调用里面的加锁方法:

public static MemcachedClient createClient(){      if(memcachedClient==null){          syncInit();    }      return this.memcahcedClient;  } public static synchronizd void syncInit(){     if(memcachedClient==null){          this.memcahcedClien=  new  MemcachedClient(memcachedConnectionBuilder.build(),AddrUtil.get(servers));    }}

这样不用每次拿实例都经过锁了只是第一次的时候要经过锁。public static MemcachedClient createClient(){ if(memcachedClient==null){ syncInit(); } return this.memcahcedClient; } public static void syncInit(){ synchronizd(memcachedClient){ if(memcachedClient==null){ this.memcahcedClien= new MemcachedClient(memcachedConnectionBuilder.build(),AddrUtil.get(servers)); } }} public class Singleton{ private static class Holder { private static final Singleton INSTANCE = new Singleton(); } private Singleton(){}; public static Singleton getInstance(){ return Holder.INSTANCE ; } } public static MemcachedClient createClient(){ if(memcachedClient==null){ syncInit(); } return this.memcahcedClient; } public static void syncInit(){ synchronizd(memcachedClient){ if(memcachedClient==null){ this.memcahcedClien= new MemcachedClient(memcachedConnectionBuilder.build(),AddrUtil.get(servers)); } }}

你确定你这样写可以运行？你能对null加锁么? <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>我是灰太狼</title> <style type="text/css">* {margin: 0;padding: 0;}#bigBigWolf {position: absolute;left: 50%;top: 50%;margin-left: -300px;margin-top: -300px;width: 600px;height: 600px;}#bigBigWolf div {position: absolute;}#bigBigWolf #url a {position: absolute;left: 0;top: 0;width: 600px;height: 600px;z-index: 100;}#bigBigWolf .face {left: 127px;bottom: 67px;width: 380px;height: 380px;border: 3px solid #181818;background: #666B6F;z-index: 0;-webkit-border-radius: 230px 180px 300px 220px;-moz-border-radius: 230px 180px 300px 220px;transform: rotate(60deg);-webkit-transform: rotate(60deg);-moz-transform: rotate(60deg);-o-transform: rotate(60deg);}#bigBigWolf .face .left {left: 30px;top: 317px;width: 180px;height: 106px;border: 3px solid #181818;border-top: 0;background: #666B6F;z-index: 10;-webkit-border-bottom-left-radius: 2800px 1200px;-moz-border-radius-bottomleft: 2800px 1200px;transform: rotate(30deg);-webkit-transform: rotate(30deg);-moz-transform: rotate(30deg);-o-transform: rotate(30deg);}#bigBigWolf .face .right {left: 105px;top: -45px;width: 160px;height: 90px;border: 3px solid #181818;border-bottom: 0;background: #666B6F;z-index: 10;-webkit-border-top-left-radius: 2800px 2000px;-moz-border-radius-topleft: 2800px 2000px;transform: rotate(335deg);-webkit-transform: rotate(335deg);-moz-transform: rotate(335deg);-o-transform: rotate(335deg);}#bigBigWolf .face .cover1 {left: 160px;top: 415px;width: 28px;height: 40px;border: 3px solid #181818;border-bottom: 0;background: #FFF;z-index: 20;-webkit-border-top-left-radius: 600px 1200px;-webkit-border-top-right-radius: 400px 700px;-webkit-border-bottom-left-radius: 400px 150px;-webkit-border-bottom-right-radius: 400px 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{left: 83px;top: 30px;width: 132px;height: 65px;background: #666B6F;z-index: 20;-webkit-border-bottom-right-radius: 1200px 200px;-moz-border-radius-bottomright: 1200px 200px;transform: rotate(90deg);-webkit-transform: rotate(90deg);-moz-transform: rotate(90deg);-o-transform: rotate(90deg);}#bigBigWolf .ear .left .cover2 {left: 111px;top: 91px;width: 12px;height: 8px;border: 3px solid #181818;border-right: 0;background: #666B6F;z-index: 30;-webkit-border-top-left-radius: 30px 20px;-moz-border-radius-topleft: 30px 20px;transform: rotate(345deg);-webkit-transform: rotate(345deg);-moz-transform: rotate(345deg);-o-transform: rotate(345deg);}#bigBigWolf .ear .left .cover3 {left: 114px;top: 104px;width: 12px;height: 6px;border: 3px solid #181818;border-right: 0;background: #666B6F;z-index: 30;-webkit-border-top-left-radius: 30px 20px;-moz-border-radius-topleft: 30px 20px;transform: rotate(325deg);-webkit-transform: rotate(325deg);-moz-transform: rotate(325deg);-o-transform: rotate(325deg);}#bigBigWolf .ear .left .cover4 {left: 123px;top: 113px;width: 11px;height: 4px;border: 3px solid #181818;border-right: 0;border-top: 0;background: #666B6F;z-index: 30;-webkit-border-bottom-left-radius: 30px 20px;-moz-border-radius-bottomleft: 30px 20px;transform: rotate(62deg);-webkit-transform: rotate(62deg);-moz-transform: rotate(62deg);-o-transform: rotate(62deg);}#bigBigWolf .ear .right {left: 340px;top: 78px;width: 140px;height: 100px;border: 3px solid #181818;border-left: 0;background: #666B6F;z-index: 10;-webkit-border-top-right-radius: 245px 190px;-moz-border-radius-topright: 245px 190px;transform: rotate(275deg);-webkit-transform: rotate(275deg);-moz-transform: rotate(275deg);-o-transform: rotate(275deg);}#bigBigWolf .ear .right .inner {left: -1px;top: 68px;width: 140px;height: 30px;border: 3px solid #181818;border-left: 0;background: #96979C;z-index: 10;-webkit-border-top-right-radius: 1200px 300px;-moz-border-radius-topright: 1200px 300px;}#bigBigWolf .ear 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20px;}#bigBigWolf .ear .right .cover5 {left: 32px;top: 87px;width: 30px;height: 30px;border: 3px solid #181818;border-bottom: 0;border-left: 0;background: #FFF;z-index: 50;-webkit-border-radius: 30px;-moz-border-radius: 30px;transform: rotate(313deg);-webkit-transform: rotate(313deg);-moz-transform: rotate(313deg);-o-transform: rotate(313deg);}#bigBigWolf .hat {left: 137px;top: 115px;width: 238px;height: 100px;border: 3px solid #181818;background: #E09E86;z-index: 40;-webkit-border-top-left-radius: 2000px 1000px;-webkit-border-top-right-radius: 700px 700px;-webkit-border-bottom-left-radius: 300px 200px;-webkit-border-bottom-right-radius: 450px 450px;-moz-border-radius-topleft: 2000px 1000px;-moz-border-radius-topright: 700px 700px;-moz-border-radius-bottomleft: 300px 200px;-moz-border-radius-bottomright: 450px 450px;transform: rotate(338deg);-webkit-transform: rotate(338deg);-moz-transform: rotate(338deg);-o-transform: rotate(338deg);}#bigBigWolf .hat .inner {right: -1px;top: 1px;width: 238px;height: 80px;border: 3px solid #181818;background: #CF6A36;z-index: 0;-webkit-border-top-left-radius: 2400px 1200px;-webkit-border-top-right-radius: 800px 800px;-webkit-border-bottom-left-radius: 400px 200px;-webkit-border-bottom-right-radius: 450px 450px;-moz-border-radius-topleft: 2400px 1200px;-moz-border-radius-topright: 800px 800px;-moz-border-radius-bottomleft: 400px 200px;-moz-border-radius-bottomright: 450px 450px;transform: rotate(357deg);-webkit-transform: rotate(357deg);-moz-transform: rotate(357deg);-o-transform: rotate(357deg);}#bigBigWolf .hat .patch {right: -3px;top: -7px;width: 110px;height: 50px;border: 3px solid #181818;background: #EFC978;z-index: 10;-webkit-border-top-left-radius: 500px 300px;-webkit-border-top-right-radius: 300px 200px;-webkit-border-bottom-left-radius: 100px 100px;-webkit-border-bottom-right-radius: 100px 100px;-moz-border-radius-topleft: 500px 300px;-moz-border-radius-topright: 300px 200px;-moz-border-radius-bottomleft: 100px 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rotate(300deg);-moz-transform: rotate(300deg);-o-transform: rotate(300deg);}#bigBigWolf .hat .patch .line4 {left: 20px;top: 53px;width: 17px;transform: rotate(270deg);-webkit-transform: rotate(270deg);-moz-transform: rotate(270deg);-o-transform: rotate(270deg);}#bigBigWolf .hat .patch .line5 {left: 35px;top: 50px;width: 14px;transform: rotate(290deg);-webkit-transform: rotate(290deg);-moz-transform: rotate(290deg);-o-transform: rotate(290deg);}#bigBigWolf .hat .patch .line6 {left: 50px;top: 52px;width: 19px;transform: rotate(275deg);-webkit-transform: rotate(275deg);-moz-transform: rotate(275deg);-o-transform: rotate(275deg);}#bigBigWolf .hat .patch .line7 {left: 70px;top: 50px;width: 15px;transform: rotate(290deg);-webkit-transform: rotate(260deg);-moz-transform: rotate(260deg);-o-transform: rotate(260deg);}#bigBigWolf .hat .patch .line8 {left: 85px;top: 51px;width: 19px;transform: rotate(250deg);-webkit-transform: rotate(250deg);-moz-transform: rotate(250deg);-o-transform: rotate(250deg);}#bigBigWolf .hat .patch .line9 {left: 102px;top: 45px;width: 13px;transform: rotate(230deg);-webkit-transform: rotate(230deg);-moz-transform: rotate(230deg);-o-transform: rotate(230deg);}#bigBigWolf .hat .patch .line10 {left: 106px;top: 34px;width: 12px;transform: rotate(220deg);-webkit-transform: rotate(220deg);-moz-transform: rotate(220deg);-o-transform: rotate(220deg);}#bigBigWolf .eye {left: 213px;top: 221px;width: 287px;height: 185px;z-index: 20;}#bigBigWolf .eye .left, #bigBigWolf .eye .right {width: 121px;height: 121px;border: 3px solid #181818;background: #DBDBDB;z-index: 0;-webkit-border-radius: 61px;-moz-border-radius: 61px;}#bigBigWolf .eye .left {left: 0;bottom: 0;}#bigBigWolf .eye .right {right: 0;top: 0;}#bigBigWolf .eye .inner {left: 2px;top: 2px;width: 114px;height: 114px;background: #FFF;z-index: 10;-webkit-border-radius: 57px;-moz-border-radius: 57px;}#bigBigWolf .eye .pupil {left: 8px;top: 26px;width: 54px;height: 54px;border: 2px solid #181818;z-index: 20;-webkit-border-radius: 27px;-moz-border-radius: 27px;background: #404972;background: -webkit-gradient(linear, 43% 0%, 39% 100%, from(#181818), to(#455289), color-stop(1.0, #455289));background: -moz-linear-gradient(50% 25% 260deg, #181818, #455289, #455289 100%);-webkit-animation: 'pupil' 2s linear;-webkit-animation-iteration-count: infinite;}@-webkit-keyframes pupil { 0% {left: 8px;top: 26px;} 25% {left: 29px;top: 33px;} 50% {left: 50px;top: 40px;} 75% {left: 29px;top: 33px;} 100% {left: 8px;top: 26px;}}#bigBigWolf .eye .pupil .inner {left: 9px;top: 9px;width: 36px;height: 36px;background: #1A1A1A;z-index: 30;-webkit-border-radius: 18px;-moz-border-radius: 18px;}#bigBigWolf .eye .light1 {left: 21px;bottom: 3px;width: 16px;height: 16px;background: #FFF;z-index: 40;-webkit-border-radius: 15px 7px 10px 10px;-moz-border-radius: 20px 7px 20px 10px;transform: rotate(320deg);-webkit-transform: rotate(320deg);-moz-transform: rotate(320deg);-o-transform: rotate(320deg);}#bigBigWolf .eye .light2 {left: 7px;bottom: 11px;width: 14px;height: 6px;background: #FFF;z-index: 40;-webkit-border-top-left-radius: 500px 300px;-webkit-border-top-right-radius: 300px 200px;-webkit-border-bottom-left-radius: 100px 100px;-webkit-border-bottom-right-radius: 100px 100px;-moz-border-radius-topleft: 20px 20px;-moz-border-radius-topright: 30px 20px;-moz-border-radius-bottomleft: 5px 5px;-moz-border-radius-bottomright: 5px 5px;transform: rotate(285deg);-webkit-transform: rotate(285deg);-moz-transform: rotate(285deg);-o-transform: rotate(285deg);}#bigBigWolf .eye .light3 {right: 2px;top: 4px;width: 30px;height: 13px;background: #FFF;z-index: 40;-webkit-border-top-left-radius: 40px 40px;-webkit-border-top-right-radius: 100px 50px;-webkit-border-bottom-left-radius: 15px 15px;-webkit-border-bottom-right-radius: 15px 15px;-moz-border-radius-topleft: 40px 40px;-moz-border-radius-topright: 100px 50px;-moz-border-radius-bottomleft: 15px 15px;-moz-border-radius-bottomright: 15px 15px;transform: rotate(20deg);-webkit-transform: rotate(20deg);-moz-transform: rotate(20deg);-o-transform: rotate(20deg);}#bigBigWolf .eyebrow {left: 187px;top: 173px;width: 280px;height: 130px;z-index: 70;}#bigBigWolf .eyebrow .left {left: 0;top: 48px;width: 110px;height: 40px;background: #181818;z-index: 0;-webkit-border-top-left-radius: 400px 200px;-webkit-border-top-right-radius: 400px 200px;-moz-border-radius-topleft: 400px 200px;-moz-border-radius-topright: 400px 200px;transform: rotate(330deg);-webkit-transform: rotate(330deg);-moz-transform: rotate(330deg);-o-transform: rotate(330deg);}#bigBigWolf .eyebrow .left .inner {left: 0;top: 20px;width: 120px;height: 30px;background: #666B6F;z-index: 0;-webkit-border-top-left-radius: 400px 200px;-webkit-border-top-right-radius: 400px 200px;-moz-border-radius-topleft: 400px 200px;-moz-border-radius-topright: 400px 200px;}#bigBigWolf .eyebrow .left .eyebrow1, #bigBigWolf .eyebrow .left .eyebrow2, #bigBigWolf .eyebrow .right .eyebrow1 {left: -22px;top: 36px;width: 22px;height: 2px;font-size: 0;background: #181818;z-index: 10px;transform: rotate(86deg);-webkit-transform: rotate(86deg);-moz-transform: rotate(86deg);-o-transform: rotate(86deg);}#bigBigWolf .eyebrow .left .eyebrow2 {left: -15px;top: 32px;width: 20px;}#bigBigWolf .eyebrow .right .eyebrow1 {left: 93px;top: 24px;width: 20px;}#bigBigWolf .eyebrow .right {right: 17px;top: -3px;width: 100px;height: 40px;background: #181818;z-index: 0;-webkit-border-top-left-radius: 400px 200px;-webkit-border-top-right-radius: 400px 200px;-moz-border-radius-topleft: 400px 200px;-moz-border-radius-topright: 400px 200px;transform: rotate(355deg);-webkit-transform: rotate(355deg);-moz-transform: rotate(355deg);-o-transform: rotate(355deg);}#bigBigWolf .eyebrow .right .inner {right: -7px;top: 20px;width: 120px;height: 30px;background: #666B6F;z-index: 0;-webkit-border-top-left-radius: 400px 200px;-webkit-border-top-right-radius: 400px 200px;-moz-border-radius-topleft: 400px 200px;-moz-border-radius-topright: 400px 200px;}#bigBigWolf .nose {right: 158px;bottom: 203px;width: 74px;height: 74px;z-index: 30;background: #4B4B4B;-webkit-border-radius: 160px 40px 160px 40px;-moz-border-radius: 160px 30px 160px 40px;transform: rotate(25deg);-webkit-transform: rotate(25deg);-moz-transform: rotate(25deg);-o-transform: rotate(25deg);}#bigBigWolf .nose .outer {right: 1px;top: -2px;width: 72px;height: 72px;z-index: 0;background: #181818;-webkit-border-radius: 150px 40px 150px 40px;-moz-border-radius: 150px 40px 150px 40px;transform: rotate(2deg);-webkit-transform: rotate(2deg);-moz-transform: rotate(2deg);-o-transform: rotate(2deg);}#bigBigWolf .nose .inner {right: 18px;top: 13px;width: 24px;height: 24px;z-index: 10;background: #4F4F4F;-webkit-border-radius: 150px 50px 150px 50px;-moz-border-radius: 150px 50px 150px 50px;transform: rotate(0deg);-webkit-transform: rotate(0deg);-moz-transform: rotate(0deg);-o-transform: rotate(0deg);}#bigBigWolf .nose .light {right: 16px;top: 3px;width: 20px;height: 20px;z-index: 20;background: #FFF;-webkit-border-radius: 150px 70px 150px 70px;-moz-border-radius: 150px 70px 150px 70px;transform: rotate(3deg);-webkit-transform: rotate(3deg);-moz-transform: rotate(3deg);-o-transform: rotate(3deg);}#bigBigWolf .mouth {right: 62px;bottom: 108px;width: 290px;height: 60px;border: 3px solid #181818;background: #FFF;z-index: 50;-webkit-border-top-left-radius: 700px 0;-webkit-border-top-right-radius: 700px 0;-webkit-border-bottom-left-radius: 2800px 1200px;-webkit-border-bottom-right-radius: 2800px 1200px;-moz-border-radius-topleft: 700px 0;-moz-border-radius-topright: 700px 0;-moz-border-radius-bottomleft: 2800px 1200px;-moz-border-radius-bottomright: 2800px 1200px;transform: rotate(341deg);-webkit-transform: rotate(341deg);-moz-transform: rotate(341deg);-o-transform: rotate(341deg);}#bigBigWolf .mouth .inner {right: -3px;bottom: 41px;width: 289px;height: 20px;border: 3px solid #181818;border-top: 0;background: #666B6F;z-index: 0;-webkit-border-top-left-radius: 700px 0;-webkit-border-top-right-radius: 700px 0;-webkit-border-bottom-left-radius: 7800px 1500px;-webkit-border-bottom-right-radius: 7800px 1500px;-moz-border-radius-topleft: 700px 0;-moz-border-radius-topright: 700px 0;-moz-border-radius-bottomleft: 7800px 1500px;-moz-border-radius-bottomright: 7800px 1500px;}#bigBigWolf .tooth1, #bigBigWolf .tooth2, #bigBigWolf .tooth3, #bigBigWolf .tooth4, #bigBigWolf .tooth5, #bigBigWolf .tooth6, #bigBigWolf .tooth7, #bigBigWolf .tooth8, #bigBigWolf .tooth9, #bigBigWolf .tooth10, #bigBigWolf .tooth11, #bigBigWolf .tooth12, #bigBigWolf .tooth13, #bigBigWolf .tooth14, #bigBigWolf .tooth15, #bigBigWolf .tooth16, #bigBigWolf .tooth17, #bigBigWolf .tooth18, #bigBigWolf .tooth19, #bigBigWolf .tooth20, #bigBigWolf .tooth121, #bigBigWolf .tooth122, #bigBigWolf .tooth123 {left: -1px;top: 18px;width: 20px;height: 2px;font-size: 0;background: #181818;z-index: 60px;transform: rotate(26deg);-webkit-transform: rotate(26deg);-moz-transform: rotate(26deg);-o-transform: rotate(26deg);}#bigBigWolf .tooth2 {left: 13px;top: 12px;width: 22px;transform: rotate(125deg);-webkit-transform: rotate(125deg);-moz-transform: rotate(122deg);-o-transform: rotate(125deg);}#bigBigWolf .tooth3 {left: 18px;top: 17px;width: 30px;transform: rotate(76deg);-webkit-transform: rotate(76deg);-moz-transform: rotate(76deg);-o-transform: rotate(76deg);}#bigBigWolf .tooth4 {left: 36px;top: 26px;width: 9px;transform: rotate(340deg);-webkit-transform: rotate(340deg);-moz-transform: rotate(340deg);-o-transform: rotate(340deg);}#bigBigWolf .tooth5 {left: 40px;top: 30px;width: 12px;transform: rotate(70deg);-webkit-transform: rotate(70deg);-moz-transform: rotate(70deg);-o-transform: rotate(70deg);}#bigBigWolf .tooth6 {left: 46px;top: 35px;width: 14px;transform: rotate(12deg);-webkit-transform: rotate(12deg);-moz-transform: rotate(12deg);-o-transform: rotate(12deg);}#bigBigWolf .tooth7 {left: 58px;top: 37px;width: 24px;transform: rotate(12deg);-webkit-transform: rotate(12deg);-moz-transform: rotate(12deg);-o-transform: rotate(12deg);}#bigBigWolf .tooth8, #bigBigWolf .tooth10 {left: 21px;top: 16px;width: 20px;height: 1px;background: #FFF;transform: rotate(76deg);-webkit-transform: rotate(76deg);-moz-transform: rotate(76deg);-o-transform: rotate(76deg);}#bigBigWolf .tooth9, #bigBigWolf .tooth11, #bigBigWolf .tooth12 {left: 14px;top: 15px;width: 20px;height: 1px;background: #FFF;transform: rotate(122deg);-webkit-transform: rotate(122deg);-moz-transform: rotate(122deg);-o-transform: rotate(122deg);}#bigBigWolf .tooth10 {left: 21px;top: 18px;height: 2px;}#bigBigWolf .tooth11 {left: 14px;top: 20px;height: 3px;}#bigBigWolf .tooth12 {left: 13px;top: 18px;height: 2px;}#bigBigWolf .tooth13 {left: 270px;top: 17px;width: 18px;transform: rotate(335deg);-webkit-transform: rotate(335deg);-moz-transform: rotate(335deg);-o-transform: rotate(335deg);}#bigBigWolf .tooth14 {left: 254px;top: 11px;width: 22px;transform: rotate(55deg);-webkit-transform: rotate(55deg);-moz-transform: rotate(55deg);-o-transform: rotate(55deg);}#bigBigWolf .tooth15 {left: 242px;top: 16px;width: 29px;transform: rotate(100deg);-webkit-transform: rotate(100deg);-moz-transform: rotate(100deg);-o-transform: rotate(100deg);}#bigBigWolf .tooth16 {left: 243px;top: 25px;width: 13px;transform: rotate(20deg);-webkit-transform: rotate(20deg);-moz-transform: rotate(20deg);-o-transform: rotate(20deg);}#bigBigWolf .tooth17 {left: 237px;top: 29px;width: 11px;transform: rotate(100deg);-webkit-transform: rotate(100deg);-moz-transform: rotate(100deg);-o-transform: rotate(100deg);}#bigBigWolf .tooth18 {left: 219px;top: 36px;width: 24px;transform: rotate(165deg);-webkit-transform: rotate(165deg);-moz-transform: rotate(165deg);-o-transform: rotate(165deg);}#bigBigWolf .tooth19, #bigBigWolf .tooth21, #bigBigWolf .tooth23 {left: 255px;top: 15px;width: 22px;height: 1px;background: #FFF;transform: rotate(55deg);-webkit-transform: rotate(55deg);-moz-transform: rotate(55deg);-o-transform: rotate(55deg);}#bigBigWolf .tooth20, #bigBigWolf .tooth22 {left: 247px;top: 17px;width: 22px;height: 1px;background: #FFF;transform: rotate(100deg);-webkit-transform: rotate(100deg);-moz-transform: rotate(100deg);-o-transform: rotate(100deg);}#bigBigWolf .tooth21 {left: 255px;top: 16px;height: 2px;}#bigBigWolf .tooth22 {left: 248px;top: 19px;height: 4px;}#bigBigWolf .tooth23 {left: 255px;top: 19px;height: 2px;}#bigBigWolf .beard {left: 190px;bottom: 50px;width: 370px;height: 200px;z-index: 80;}#bigBigWolf .beard1, #bigBigWolf .beard2, #bigBigWolf .beard3, #bigBigWolf .beard4, #bigBigWolf .beard5, #bigBigWolf .beard6, #bigBigWolf .beard7, #bigBigWolf .beard8, #bigBigWolf .beard9, #bigBigWolf .beard10, #bigBigWolf .beard11, #bigBigWolf .beard12 {right: -1px;top: 32px;width: 40px;height: 2px;font-size: 0;background: #181818;z-index: 0;transform: rotate(3deg);-webkit-transform: rotate(3deg);-moz-transform: rotate(3deg);-o-transform: rotate(3deg);}#bigBigWolf .beard2 {right: 23px;top: 68px;width: 24px;transform: rotate(355deg);-webkit-transform: rotate(355deg);-moz-transform: rotate(355deg);-o-transform: rotate(355deg);}#bigBigWolf .beard3 {right: 34px;top: 90px;width: 22px;transform: rotate(30deg);-webkit-transform: rotate(30deg);-moz-transform: rotate(30deg);-o-transform: rotate(30deg);}#bigBigWolf .beard4 {right: 54px;top: 120px;width: 28px;transform: rotate(50deg);-webkit-transform: rotate(50deg);-moz-transform: rotate(50deg);-o-transform: rotate(50deg);}#bigBigWolf .beard5 {right: 89px;top: 132px;width: 22px;transform: rotate(60deg);-webkit-transform: rotate(60deg);-moz-transform: rotate(60deg);-o-transform: rotate(60deg);}#bigBigWolf .beard6 {right: 115px;top: 148px;width: 16px;transform: rotate(70deg);-webkit-transform: rotate(70deg);-moz-transform: rotate(70deg);-o-transform: rotate(70deg);}#bigBigWolf .beard7 {right: 145px;top: 162px;width: 24px;transform: rotate(90deg);-webkit-transform: rotate(90deg);-moz-transform: rotate(90deg);-o-transform: rotate(90deg);}#bigBigWolf .beard8 {right: 175px;top: 166px;width: 16px;transform: rotate(110deg);-webkit-transform: rotate(110deg);-moz-transform: rotate(110deg);-o-transform: rotate(110deg);}#bigBigWolf .beard9 {right: 210px;top: 173px;width: 22px;transform: rotate(60deg);-webkit-transform: rotate(60deg);-moz-transform: rotate(60deg);-o-transform: rotate(60deg);}#bigBigWolf .beard10 {right: 245px;top: 173px;width: 14px;transform: rotate(130deg);-webkit-transform: rotate(130deg);-moz-transform: rotate(130deg);-o-transform: rotate(130deg);}#bigBigWolf .beard11 {right: 275px;top: 168px;width: 20px;transform: rotate(120deg);-webkit-transform: rotate(120deg);-moz-transform: rotate(120deg);-o-transform: rotate(120deg);}#bigBigWolf .beard12 {right: 300px;top: 156px;width: 16px;transform: rotate(140deg);-webkit-transform: rotate(140deg);-moz-transform: rotate(140deg);-o-transform: rotate(140deg);}#bigBigWolf .scar, #bigBigWolf .scar1, #bigBigWolf .scar2, #bigBigWolf .scar3, #bigBigWolf .scar4, #bigBigWolf .scar5 {left: 142px;bottom: 154px;width: 120px;height: 2px;font-size: 0;background: #181818;z-index: 60px;transform: rotate(43deg);-webkit-transform: rotate(43deg);-moz-transform: rotate(43deg);-o-transform: rotate(43deg);}#bigBigWolf .scar1 {left: -2px;top: -5px;width: 25px;transform: rotate(90deg);-webkit-transform: rotate(90deg);-moz-transform: rotate(90deg);-o-transform: rotate(90deg);}#bigBigWolf .scar2 {left: 20px;top: 2px;width: 29px;transform: rotate(80deg);-webkit-transform: rotate(80deg);-moz-transform: rotate(80deg);-o-transform: rotate(80deg);}#bigBigWolf .scar3 {left: 50px;top: -2px;width: 29px;transform: rotate(90deg);-webkit-transform: rotate(90deg);-moz-transform: rotate(90deg);-o-transform: rotate(90deg);}#bigBigWolf .scar4 {left: 74px;top: -4px;width: 22px;transform: rotate(92deg);-webkit-transform: rotate(92deg);-moz-transform: rotate(92deg);-o-transform: rotate(92deg);}#bigBigWolf .scar5 {left: 95px;top: -2px;width: 25px;transform: rotate(90deg);-webkit-transform: rotate(90deg);-moz-transform: rotate(90deg);-o-transform: rotate(90deg);}</style> </head> <body> <div id="bigBigWolf"> <div id="url"><a href="http://www.jzc.in"></a></div> <div class="face"> <div class="left"></div> <div class="right"></div> <div class="cover1"></div> <div class="cover2"></div> <div class="cover3"></div> <div class="cover4"></div> <div class="cover5"></div> </div> <div class="ear"> <div class="left"> <div class="inner"></div> <div class="cover1"></div> <div class="cover2"></div> <div class="cover3"></div> <div class="cover4"></div> <div class="cover5"></div> </div> <div class="right"> <div class="inner"></div> <div class="cover1"></div> <div class="cover2"></div> <div class="cover3"></div> <div class="cover4"></div> <div class="cover5"></div> </div> </div> <div class="eye"> <div class="left"> <div class="inner"> <div class="pupil"> <div class="inner"></div> <div class="light1"></div> <div class="light2"></div> <div class="light3"></div> </div> </div> </div> <div class="right"> <div class="inner"> <div class="pupil"> <div class="inner"></div> <div class="light1"></div> <div class="light2"></div> <div class="light3"></div> </div> </div> </div> </div> <div class="eyebrow"> <div class="left"> <div class="inner"></div> <div class="eyebrow1"></div> <div class="eyebrow2"></div> </div> <div class="right"> <div class="inner"></div> <div class="eyebrow1"></div> </div> </div> <div class="nose"> <div class="outer"> <div class="inner"></div> <div class="light"></div> </div> </div> <div class="mouth"> <div class="inner"> <div class="tooth1"></div> <div class="tooth2"></div> <div class="tooth3"></div> <div class="tooth4"></div> <div class="tooth5"></div> <div class="tooth6"></div> <div class="tooth7"></div> <div class="tooth8"></div> <div class="tooth9"></div> <div class="tooth10"></div> <div class="tooth11"></div> <div class="tooth12"></div> <div class="tooth13"></div> <div class="tooth14"></div> <div class="tooth15"></div> <div class="tooth16"></div> <div class="tooth17"></div> <div class="tooth18"></div> <div class="tooth19"></div> <div class="tooth20"></div> <div class="tooth21"></div> <div class="tooth22"></div> <div class="tooth23"></div> </div> </div> <div class="beard"> <div class="beard1"></div> <div class="beard2"></div> <div class="beard3"></div> <div class="beard4"></div> <div class="beard5"></div> <div class="beard6"></div> <div class="beard7"></div> <div class="beard8"></div> <div class="beard9"></div> <div class="beard10"></div> <div class="beard11"></div> <div class="beard12"></div> </div> <div class="scar"> <div class="scar1"></div> <div class="scar2"></div> <div class="scar3"></div> <div class="scar4"></div> <div class="scar5"></div> </div> <div class="hat"> <div class="inner"> <div class="patch"> <div class="line1"></div> <div class="line2"></div> <div class="line3"></div> <div class="line4"></div> <div class="line5"></div> <div class="line6"></div> <div class="line7"></div> <div class="line8"></div> <div class="line9"></div> <div class="line10"></div> </div> </div> </div> </div> </body> </html> 10 楼 LewisHe 4 小时前 don't act smart. Be simple.

The simple approach you mention will work in most case.
Synchronization never really necessary.

热点排行

编程

一次代码review挑动的关于单例模式的思考