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\n\u5355\u4f8b\u6a21\u5f0f\u6982\u5ff5\uff1a
\n\u987e\u540d\u601d\u4e49\uff0c\u5355\u4f8b\u6a21\u5f0f\u6307\u7684\u662f\u5728\u8f6f\u4ef6\u7cfb\u7edf\u8fd0\u884c\u8fc7\u7a0b\u4e2d\uff0c\u67d0\u4e2a\u7c7b\u53ea\u5b58\u5728\u4e00\u4e2a\u5b9e\u4f8b\uff0c\u56e0\u6b64\u4e00\u4e2a\u7c7b\u5b9e\u73b0 \u5355\u4f8b\u6a21\u5f0f\u65f6\u9700\u8981\u5177\u5907\u4ee5\u4e0b3\u4e2a\u6761\u4ef6\uff1a
\n1\u3001\t\u7c7b\u7684\u5185\u90e8\u5b9a\u4e49\u4e00\u4e2a\u8be5\u7c7b\u7684\u9759\u6001\u79c1\u6709\u6210\u5458\u53d8\u91cf;
\n2\u3001\t\u6784\u9020\u65b9\u6cd5\u4e3a\u79c1\u6709;
\n3\u3001\t\u63d0\u4f9b\u9759\u6001\u5de5\u5382\u65b9\u6cd5\uff0c\u4f9b\u5916\u90e8\u83b7\u53d6\u7c7b\u7684\u5b9e\u4f8b;
\n\u5355\u4f8b\u6a21\u5f0f\u5b9e\u73b0\u65b9\u5f0f\uff1a
\n1\u3001\u61d2\u6c49\u5f0f\u5355\u4f8b
\npublic class Singleton {
\nprivate static Singleton instanee;
\nprivate Singleton() {
\n}
\npublic synchronized static Singleton getlnstance() {
\nIf (instance == null) {
\ninstance = new Singleton();
\n}
\nreturn instance;
\n}
\n}
\n\u61d2\u6c49\u5f0f\u5355\u4f8b\u5373\u5728\u4f7f\u7528\u4f7f\u7528\u65f6\u624d\u521b\u5efa\u7c7b\u7684\u5b9e\u4f8b\uff0c\u5de5\u5382\u65b9\u6cd5\u589e\u52a0\u7c7bsynchronized\u5173\u952e\u5b57\u4ee5\u4fdd\u8bc1\u7ebf \u7a0b\u5b89\u5168\u3002\u5728\u591a\u7ebf\u7a0b\u8bbf\u95ee\u7684\u73af\u5883\u4e0b\uff0c\u540c\u6b65\u65b9\u6cd5\u5bfc\u81f4\u7cfb\u7edf\u6027\u80fd\u4e0b\u964d\u3002\u4f18\u70b9\u5728\u4e8e\uff0c\u7c7b\u52a0\u8f7d\u65f6\u4e0d\u7528\u81ea\u884c \u5b9e\u4f8b\u5316\u5bf9\u8c61\uff0c\u907f\u514d\u52a0\u8f7d\u7f13\u6162\u3002
\n2,\u997f\u6c49\u5f0f\u5355\u4f8b
\npublic class Singleton {
\nprivate static Singleton instance = new Singleton();
\nprivate Singleton() {
\n}
\npublic static Singleton getInstance() {
\nif (instance = null) {
\ninstance = new Singleton();
\nreturn instance;
\n}
\n}
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\n3\u3001\u53cc\u91cd\u68c0\u6d4b\u5355\u4f8b
\npublic class Singleton {
\nprivate static volatile Singleton instance;
\nprivate Singleton() {
\n}
\npublic static Singleton getInstance() {
\nif (instance == null) {
\nsynchronized (Singleton.class) {
\nif (instance == null) {
\ninstance = new Singleton():
\n}
\n}
\n}
\nreturn instance;
\n}
\n}
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\nJVM\u5728\u521b\u5efa\u4e00\u4e2a\u5bf9\u8c61\u65f6\u4f1a\u8fdb\u884c\u4ee5\u4e0b\u6b65\u9aa4\uff1a
\n1\u3001\t\u5206\u914d\u5bf9\u8c61\u5185\u5b58\u7a7a\u95f4;
\n2\u3001\t\u521d\u59cb\u5316\u5bf9\u8c61;
\n3\u3001\t\u8bbe\u7f6einstance\u6307\u5411\u5206\u914d\u7684\u5185\u5b58\u5730\u5740;
\n\u7f16\u8bd1\u5668\u4e3a\u4e86\u4f18\u5316\u6027\u80fd\uff0c\u53ef\u80fd\u4f1a\u5c062\u30013\u64cd\u4f5c\u8c03\u6362\u987a\u5e8f\uff0c\u5047\u8bbeA\u7ebf\u7a0b\u5728\u6267\u884cnew Singleton()\u65b9 \u6cd5\u65f6\uff0c\u7531\u4e8e2\u30013\u64cd\u4f5c\u91cd\u6392\u5e8f\uff0c\u800c\u521d\u59cb\u5316\u5bf9\u8c61\u64cd\u4f5c\u5c1a\u672a\u5b8c\u6210\u65f6\u91ca\u653e\u4e86\u9501\u3002\u7ebf\u7a0bB\u83b7\u53d6\u9501\u4e4b\u540e\u4f1a \u53d1\u73b0instance\u5df2\u7ecf\u4e0d\u4e3a\u7a7a\uff0c\u5f53\u7ebf\u7a0bB\u83b7\u53d6\u5230instance\u5bf9\u8c61\u540e\u5982\u679c\u76f4\u63a5\u4f7f\u7528\u5c31\u4f1a\u51fa\u9519\uff0c\u539f\u56e0\u5c31 \u662f\u5bf9\u8c61\u6ca1\u6709\u8fdb\u884c\u521d\u59cb\u5316\u64cd\u4f5c\u3002\u800cvolatile\u5173\u952e\u5b57\u80fd\u907f\u514d\u91cd\u6392\u5e8f\uff0c\u56e0\u6b64\u80fd\u4fdd\u8bc1\u7ebf\u7a0b\u5b89\u5168\u3002\u603b\u4f53 \u4e0a\u6765\u8bf4\uff0c\u53cc\u91cd\u68c0\u6d4b\u7531\u4e8e\u52a0\u4e86\u9501\uff0c\u591a\u7ebf\u7a0b\u5e76\u53d1\u4e0b\u8fd8\u662f\u4f1a\u6709\u6548\u7387\u95ee\u9898\u3002
\n4\u3001\t\u679a\u4e3e\u5355\u4f8b
\npublic enum Singleton {
\nINSTANCE
\n}
\n\u679a\u4e3e\u5355\u4f8b\u6a21\u5f0f\uff0c\u4e0d\u4f1a\u5b58\u5728\u7ebf\u7a0b\u5b89\u5168\u95ee\u9898\uff0c\u4e0d\u8fc7\u5728Android\u5e73\u53f0\u4e0b\uff0c\u679a\u4e3e\u7c7b\u6027\u80fd\u76f8\u5bf9\u8f83\u4f4e\u3002
\n5\u3001\u9759\u6001\u5185\u90e8\u7c7b\u5355\u4f8b
\npublic class Singleton {
\nprivate Singleton() {
\n}
\npublic static Singleton getInstanceO {
\nreturn SingletonFactory.instance;
\n}
\nstatic class SingletonFactory {
\nprivate final static Singleton instance = new Singleton();
\n)
\n}
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\n\u7ed3\u675f\u8bed
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