{"id":84,"date":"2023-02-13T21:59:29","date_gmt":"2023-02-13T13:59:29","guid":{"rendered":"https:\/\/www.appblog.cn\/?p=84"},"modified":"2023-02-13T22:00:28","modified_gmt":"2023-02-13T14:00:28","slug":"java-multi-threag-programming-singleton","status":"publish","type":"post","link":"https:\/\/www.appblog.cn\/index.php\/2023\/02\/13\/java-multi-threag-programming-singleton\/","title":{"rendered":"Java\u591a\u7ebf\u7a0b\u7f16\u7a0b\u4e03\uff08\u5355\u4f8b\u6a21\u5f0f\uff09"},"content":{"rendered":"

\u997f\u6c49\u6a21\u5f0f(\u7acb\u5373\u52a0\u8f7d)<\/h2>\n

\u201c\u997f\u6c49\u6a21\u5f0f\u201d\u4e5f\u5c31\u662f\u7acb\u5373\u52a0\u8f7d\uff0c\u5728\u4f7f\u7528\u7c7b\u65f6\u5bf9\u5e94\u7684\u5bf9\u8c61\u5df2\u7ecf\u521b\u5efa<\/p>\n

public class MySingleton  {\n    private static MySingleton mySingleton = new MySingleton();\n\n    private MySingleton() {\n    }\n\n    public static MySingleton getInstance() {\n        return mySingleton;\n    }\n\n    public static void main(String[] args) {\n        for (int i = 0; i < 3; i++) {\n            new Thread(new Runnable() {\n                public void run() {\n                    System.out.println(Thread.currentThread().getName() + "  " + MySingleton.getInstance().hashCode());\n                }\n            }).start();\n        }\n    }\n}<\/code><\/pre>\n
\u8fd0\u884c\u7ed3\u679c\u4e3a\uff1a<\/p>\n
Thread-0  321580105\nThread-1  321580105\nThread-2  321580105<\/code><\/pre>\n
\u7531\u7ed3\u679c\u53ef\u77e5\uff0c\u4e09\u4e2a\u7ebf\u7a0b\u4e2d\u7684hashCode\u4e00\u6837\uff0c\u5219\u8bc1\u660e\u6240\u6253\u5370\u7684\u662f\u540c\u4e00\u4e2a\u5bf9\u8c61\uff0c\u5373\u7acb\u5373\u52a0\u8f7d\u997f\u6c49\u5f0f\u7684\u5355\u4f8b\u6a21\u5f0f\u3002<\/p>\n
\u61d2\u6c49\u6a21\u5f0f(\u5ef6\u8fdf\u52a0\u8f7d)<\/h2>\n
\u5ef6\u8fdf\u52a0\u8f7d\u548c\u7acb\u5373\u52a0\u8f7d\u76f8\u5bf9\uff0c\u4e5f\u5c31\u662f\u5728\u4f7f\u7528\u65f6\u624d\u521b\u5efa\uff0c\u901a\u5e38\u7684\u5b9e\u73b0\u662f\u5728get()\u65b9\u6cd5\u4e2d\u8fdb\u884cnew\u5b9e\u4f8b\u5316\u3002<\/p>\n
\u61d2\u6c49\u5355\u4f8b\u7b80\u5355\u4f7f\u7528<\/h3>\n
\u4fee\u6539\u4e0a\u9762\u7684\u5355\u4f8b\u4ee3\u7801\u4e3a\uff1a<\/p>\n
public class MySingleton  {\n\n    private static MySingleton mySingleton;\n\n    private MySingleton() {\n    }\n\n    public static MySingleton getInstance() {\n        if (mySingleton == null) {\n            mySingleton = new MySingleton();\n        }\n        return mySingleton;\n    }\n}<\/code><\/pre>\n
\u5176\u4ed6\u4e0d\u53d8\uff0c\u8fd0\u884c\u7ed3\u679c\u4e3a\uff1a<\/p>\n
Thread-0  500866883\nThread-1  500866883\nThread-2  500866883<\/code><\/pre>\n
\u7531\u7ed3\u679c\u53ef\u77e5\uff0c\u4e09\u4e2a\u7ebf\u7a0b\u4e2d\u7684hashCode\u4e00\u6837\uff0c\u5219\u8bc1\u660e\u6240\u6253\u5370\u7684\u662f\u540c\u4e00\u4e2a\u5bf9\u8c61\uff0c\u5373\u7acb\u5373\u5ef6\u8fdf\u61d2\u6c49\u5f0f\u7684\u5355\u4f8b\u6a21\u5f0f\u3002<\/p>\n
\u61d2\u6c49\u5355\u4f8b\u7684\u7f3a\u70b9<\/h3>\n
\u867d\u7136\u4e0a\u8ff0\u4ee3\u7801\u5b9e\u73b0\u4e86\u5355\u4f8b\u6a21\u5f0f\uff0c\u4f46\u662f\u5728\u591a\u7ebf\u7a0b\u7684\u73af\u5883\u4e0b\uff0c\u201c\u61d2\u6c49\u5f0f\u201d\u7684\u5355\u4f8b\u5c31\u6709\u4e00\u5b9a\u51e0\u7387\u51fa\u73b0\u9519\u8bef\uff0c\u4e0d\u80fd\u4fdd\u6301\u5355\u4f8b\u7684\u72b6\u6001\u3002\u4e3e\u4e2a\u6817\u5b50\uff1a<\/p>\n
public class MySingleton {\n\n    private static MySingleton mySingleton;\n\n    private MySingleton() {\n    }\n\n    public static MySingleton getInstance() {\n        try {\n            if (mySingleton == null) {\n                Thread.sleep(3000);\n                mySingleton = new MySingleton();\n                System.out.println("\u521b\u5efa\u5355\u4f8b\u5bf9\u8c61 " + mySingleton);\n            }\n        } catch (InterruptedException e) {\n            e.printStackTrace();\n        }\n        return mySingleton;\n    }\n\n    public static void main(String[] args) {\n        for (int i = 0; i < 3; i++) {\n            new Thread(new Runnable() {\n                public void run() {\n                    System.out.println(Thread.currentThread().getName()+"  "+MySingleton.getInstance().hashCode());\n                }\n            }).start();\n        }\n    }\n}<\/code><\/pre>\n
\u8fd0\u884c\u7ed3\u679c\u5982\u4e0b\uff1a<\/p>\n
\u521b\u5efa\u5355\u4f8b\u5bf9\u8c61 cn.appblog.thread.MySingleton@182acfc9\nThread-0  405658889\n\u521b\u5efa\u5355\u4f8b\u5bf9\u8c61 cn.appblog.thread.MySingleton@182acfc9\nThread-1  405658889\n\u521b\u5efa\u5355\u4f8b\u5bf9\u8c61 cn.appblog.thread.MySingleton@9c3310a5\nThread-2  158381581<\/code><\/pre>\n
\u7531\u7ed3\u679c\u53ef\u77e5\uff0c\u4e0d\u518d\u662f\u5355\u4f8b\u3002\u7531\u4e8e\u591a\u4e2a\u7ebf\u7a0b\u64cd\u4f5c\u4e00\u4e2a\u53d8\u91cf\uff0c\u5bfc\u81f4\u5176\u4e0d\u786e\u5b9a\u6027\uff0c\u6240\u4ee5\u6211\u4eec\u9700\u8981\u5bf9\u5176\u8fdb\u884c\u540c\u6b65\u5904\u7406\uff0c\u53ef\u4ee5\u5728getInstance()<\/code>\u65b9\u6cd5\u524d\u52a0\u4e0asynchronized<\/code>\u5173\u952e\u5b57\uff0c\u5982\uff1a<\/p>\n
\u8fd0\u884c\u7ed3\u679c\u4e3a\uff1a<\/p>\n
public synchronized static MySingleton getInstance() {\n    try {\n        if (mySingleton == null) {\n            Thread.sleep(3000);\n            mySingleton = new MySingleton();\n            System.out.println("\u521b\u5efa\u5355\u4f8b\u5bf9\u8c61 " + mySingleton);\n        }\n    } catch (InterruptedException e) {\n        e.printStackTrace();\n    }\n    return mySingleton;\n}<\/code><\/pre>\n
\u8fd0\u884c\u7ed3\u679c\u4e3a\uff1a<\/p>\n
\u521b\u5efa\u5355\u4f8b\u5bf9\u8c61 cn.appblog.thread.MySingleton@619d7c8\nThread-0  102356936\nThread-1  102356936\nThread-2  102356936<\/code><\/pre>\n
\u7531\u4e8e\u5728\u540c\u4e00\u65f6\u95f4\u53ea\u80fd\u6709\u4e00\u4e2a\u7ebf\u7a0b\u8bbf\u95ee\uff0c\u53ea\u6709\u5f53\u83b7\u53d6\u9501\u7684\u7ebf\u7a0b\u5c06\u5176\u91ca\u653e\u5176\u4ed6\u7ebf\u7a0b\u624d\u80fd\u8bbf\u95eegetInstance()\u540c\u6b65\u65b9\u6cd5\uff0c\u4e5f\u5c31\u6210\u529f\u907f\u514d\u4e86\u975e\u7ebf\u7a0b\u5b89\u5168\u95ee\u9898\u3002<\/p>\n
\u6211\u4eec\u8fd8\u53ef\u4ee5\u5229\u7528\u540c\u6b65\u4ee3\u7801\u5757\u6765\u89e3\u51b3\u8fd9\u4e2a\u95ee\u9898\uff0c\u5982\uff1a<\/p>\n
public static MySingleton getInstance() {\n    try {\n        synchronized (MySingleton.class) {\n            if (mySingleton == null) {\n                Thread.sleep(3000);\n                mySingleton = new MySingleton();\n                System.out.println("\u521b\u5efa\u5355\u4f8b\u5bf9\u8c61 " + mySingleton);\n            }\n        }\n    } catch (InterruptedException e) {\n        e.printStackTrace();\n    }\n    return mySingleton;\n}<\/code><\/pre>\n
\u6216\u8005\u4f7f\u7528ReentrantLock<\/code><\/p>\n
public class MySingleton {\n\n    private static MySingleton mySingleton;\n\n    private static ReentrantLock lock = new ReentrantLock();\n\n    private MySingleton() {\n    }\n\n    public static MySingleton getInstance() {\n        try {\n            lock.lock();\n            if (mySingleton == null) {\n                Thread.sleep(3000);\n                mySingleton = new MySingleton();\n                System.out.println("\u521b\u5efa\u5355\u4f8b\u5bf9\u8c61 " + mySingleton);\n            }\n        } catch (InterruptedException e) {\n            e.printStackTrace();\n        } finally {\n            lock.unlock();\n        }\n        return mySingleton;\n    }\n}<\/code><\/pre>\n
\u6216\u8005<\/p>\n
public class MySingleton {\n\n    private static MySingleton mySingleton;\n\n    private static ReentrantReadWriteLock lock = new ReentrantReadWriteLock();\n\n    private MySingleton() {\n    }\n\n    public static MySingleton getInstance() {\n        try {\n            lock.writeLock().lock();\n            if (mySingleton == null) {\n                Thread.sleep(3000);\n                mySingleton = new MySingleton();\n                System.out.println("\u521b\u5efa\u5355\u4f8b\u5bf9\u8c61 " + mySingleton);\n            }\n        } catch (InterruptedException e) {\n            e.printStackTrace();\n        } finally {\n            lock.writeLock().unlock();\n        }\n        return mySingleton;\n    }\n}<\/code><\/pre>\n
\u4e0a\u8ff0\u65b9\u6cd5\u90fd\u53ef\u4ee5\u89e3\u51b3\u8fd9\u4e2a\u975e\u7ebf\u7a0b\u5b89\u5168\u95ee\u9898\uff0c\u4f46\u662f\u5176\u6267\u884c\u6548\u7387\u4f4e\u4e0b\u3002\u540c\u6b65\u4ee3\u7801\u5757\u53ef\u4ee5\u540c\u6b65\u548c\u5f02\u6b65\u6df7\u5408\u5206\u522b\u6267\u884c\u6765\u63d0\u9ad8\u7ebf\u7a0b\u7684\u6267\u884c\u6548\u7387\uff0c\u6211\u4eec\u53ea\u5173\u6ce8\u5173\u4e8e\u4fee\u6539\u5171\u4eab\u53d8\u91cf\u7684\u90a3\u4e9b\u903b\u8f91\u4ee3\u7801\u5373\u53ef\uff0c\u5982\u679c\u6309\u7167\u8fd9\u79cd\u601d\u60f3\u6765\u4fee\u6539\u5982\u4e0b\uff1a<\/p>\n
public class MySingleton {\n\n    private static MySingleton mySingleton;\n\n    private MySingleton() {\n    }\n\n    public static MySingleton getInstance() {\n        try {\n            if (mySingleton == null) {\n                synchronized (MySingleton.class) {\n                    Thread.sleep(3000);\n                    mySingleton = new MySingleton();\n                    System.out.println("\u521b\u5efa\u5355\u4f8b\u5bf9\u8c61 " + mySingleton);\n                }\n            }\n        } catch (InterruptedException e) {\n            e.printStackTrace();\n        }\n        return mySingleton;\n    }\n}<\/code><\/pre>\n
\u8fd0\u884c\u7ed3\u679c\u5982\u4e0b\uff1a<\/p>\n
\u521b\u5efa\u5355\u4f8b\u5bf9\u8c61 cn.appblog.thread.MySingleton@108c737f\nThread-0  277650063\n\u521b\u5efa\u5355\u4f8b\u5bf9\u8c61 cn.appblog.thread.MySingleton@db6222b\nThread-1  230058813\n\u521b\u5efa\u5355\u4f8b\u5bf9\u8c61 cn.appblog.thread.MySingleton@1dda492b\nThread-2  500844802<\/code><\/pre>\n
\u7531\u6b64\u6765\u770b\uff0c\u867d\u7136\u7a0b\u5e8f\u7684\u8fd0\u884c\u6548\u7387\u63d0\u9ad8\u4e86\uff0c\u4f46\u662f\u6700\u6838\u5fc3\u7684\u591a\u7ebf\u7a0b\u5b89\u5168\u95ee\u9898\u5e76\u672a\u5f97\u5230\u89e3\u51b3\uff0c\u56e0\u6b64\u6211\u4eec\u91c7\u7528DCL\u53cc\u68c0\u67e5\u9501\u673a\u5236\uff08\u5728\u540c\u6b65\u4ee3\u7801\u5757\u91cc\u518d\u8fdb\u884c\u4e00\u6b21\u5224\u7a7a\uff0c\u8fd9\u6837\u5728\u4e0b\u4e2a\u7ebf\u7a0b\u83b7\u53d6\u9501\u6765\u6267\u884c\u65f6\u5c31\u4f1a\u5224\u65ad\u5f53\u524d\u662f\u5426\u5df2\u7ecf\u521b\u5efa\uff0c\u53ef\u4ee5\u907f\u514d\u518d\u6b21\u91cd\u65b0\u521b\u5efa\u5b9e\u4f8b\uff09\u5982\uff1a<\/p>\n
public class MySingleton {\n\n    private static MySingleton mySingleton;\n\n    private MySingleton() {\n    }\n\n    public static MySingleton getInstance() {\n        try {\n            if (mySingleton == null) {\n                Thread.sleep(3000);\n                synchronized (MySingleton.class) {\n                    if (mySingleton == null) {\n                        mySingleton = new MySingleton();\n                        System.out.println("\u521b\u5efa\u5355\u4f8b\u5bf9\u8c61 " + mySingleton);\n                    }\n                }\n            }\n        } catch (InterruptedException e) {\n            e.printStackTrace();\n        }\n        return mySingleton;\n    }\n}<\/code><\/pre>\n
\u8fd0\u884c\u7ed3\u679c\uff1a<\/p>\n
\u521b\u5efa\u5355\u4f8b\u5bf9\u8c61 cn.appblog.thread.MySingleton@8f62e66\nThread-0  150351562\nThread-1  150351562\nThread-2  150351562<\/code><\/pre>\n
\u7531\u7ed3\u679c\u53ef\u77e5\uff0c\u6210\u529f\u89e3\u51b3\u975e\u7ebf\u7a0b\u5b89\u5168\u95ee\u9898\u548c\u6548\u7387\u4f4e\u4e0b\u7684\u95ee\u9898\u3002<\/p>\n
\u9759\u6001\u5185\u7f6e\u7c7b\u6a21\u5f0f<\/h2>\n
\u91c7\u7528\u9759\u6001\u5185\u90e8\u7c7b\u7684\u9759\u6001\u5bf9\u8c61\u6765\u5b9e\u73b0\u5355\u4f8b<\/p>\n
public class MySingleton {\n\n    private static class MySingletonHelper {\n        private static MySingleton mySingleton = new MySingleton();\n    }\n    private MySingleton() {\n    }\n\n    public static MySingleton getInstance() {\n        return MySingletonHelper.mySingleton;\n    }\n}<\/code><\/pre>\n
\u540c\u6837\u7684main\u65b9\u6cd5\u8fd0\u884c\u7ed3\u679c\u4e3a\uff1a<\/p>\n
Thread-0  1603718986\nThread-1  1603718986\nThread-2  1603718986<\/code><\/pre>\n
\u5e8f\u5217\u5316\u548c\u53cd\u5e8f\u5217\u5316\u7684\u5355\u4f8b\u5b9e\u73b0<\/h2>\n
\u5982\u679c\u9047\u5230\u4e86\u5e8f\u5217\u5316\u5bf9\u8c61\uff0c\u4f7f\u7528\u9ed8\u8ba4\u7684\u65b9\u5f0f\u8fd0\u884c\u5f97\u5230\u7684\u7ed3\u679c\u8fd8\u662f\u591a\u4f8b\u7684\u3002<\/p>\n
public class MySingleton implements Serializable {\n    private static class MySingletonHelper {\n        private static MySingleton mySingleton = new MySingleton();\n    }\n    private MySingleton() {\n    }\n    public static MySingleton getInstance() {\n        return MySingletonHelper.mySingleton;\n    }\n\n    public static void main(String[] args) {\n        try {\n            MySingleton instance = MySingleton.getInstance();\n            FileOutputStream fileOutputStream = new FileOutputStream(new File("mySingleton.txt"));\n            ObjectOutputStream objectOutputStream = new ObjectOutputStream(fileOutputStream);\n            objectOutputStream.writeObject(instance);\n            objectOutputStream.close();\n            fileOutputStream.close();\n            System.out.println(instance.hashCode());\n        } catch (IOException e) {\n            e.printStackTrace();\n        }\n        try {\n            FileInputStream fileInputStream = new FileInputStream(new File("mySingleton.txt"));\n            ObjectInputStream objectInputStream = new ObjectInputStream(fileInputStream);\n            MySingleton mySingleton = (MySingleton) objectInputStream.readObject();\n            objectInputStream.close();\n            fileInputStream.close();\n            System.out.println(mySingleton.hashCode());\n        } catch (IOException e) {\n            e.printStackTrace();\n        } catch (ClassNotFoundException e) {\n            e.printStackTrace();\n        }\n    }\n}<\/code><\/pre>\n
\u8fd0\u884c\u7ed3\u679c\u4e3a\uff1a<\/p>\n
1670675563\n189568618<\/code><\/pre>\n
\u51fa\u73b0\u591a\u4f8b\u60c5\u51b5\uff08\u5177\u4f53\u539f\u56e0\u5c06\u4f1a\u5728\u540e\u7eed\u6587\u7ae0\u4e2d\u8fdb\u884c\u5256\u6790\uff0c\u8fd9\u91cc\u5c31\u76f4\u63a5\u7ed9\u51fa\u89e3\u51b3\u65b9\u6848\uff09<\/p>\n
\u7531\u4e8e\u5e8f\u5217\u5316\/\u53cd\u5e8f\u5217\u5316\u4f1a\u7834\u574f\u5355\u4f8b\u6a21\u5f0f\uff0c\u6240\u4ee5\u9700\u8981\u5728\u5355\u4f8b\u6a21\u5f0f\u4e2d\u52a0\u4e0a\u5982\u4e0b\u65b9\u6cd5\uff0c\u8fd4\u56de\u6211\u4eec\u7684\u5355\u4f8b\u53d8\u91cf\uff1a<\/p>\n
public class MySingleton implements Serializable {\n    private MySingleton() {\n    }\n    private static class MySingletonHelper {\n        private static MySingleton mySingleton = new MySingleton();\n    }\n    public static MySingleton getInstance() {\n        return MySingletonHelper.mySingleton;\n    }\n\n    protected Object readResolve() {\n        System.out.println("\u8c03\u7528 readResolve \u65b9\u6cd5\uff01");\n        return MySingletonHelp.mySingleton;\n    }\n}<\/code><\/pre>\n
\u5c31\u89e3\u51b3\u6211\u4eec\u5355\u4f8b\u88ab\u7834\u574f\u7684\u95ee\u9898\u3002<\/p>\n
\u4f7f\u7528static\u4ee3\u7801\u5757\u5b9e\u73b0\u5355\u4f8b<\/h2>\n
public class MySingleton {\n    private static MySingleton mySingleton = null;\n    static {\n        mySingleton = new MySingleton();\n    }\n    private MySingleton() {\n    }\n    public static MySingleton getInstance() {\n        return mySingleton;\n    }\n\n    public static void main(String[] args) {\n        for (int i = 0; i < 3; i++) {\n            new Thread(new Runnable() {\n                public void run() {\n                    System.out.println(Thread.currentThread().getName()+"  "+MySingleton.getInstance().hashCode());\n                }\n            }).start();\n        }\n    }\n\n}<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"
\u997f\u6c49\u6a21\u5f0f(\u7acb\u5373\u52a0\u8f7d) \u201c\u997f\u6c49\u6a21\u5f0f\u201d\u4e5f\u5c31\u662f\u7acb\u5373\u52a0\u8f7d\uff0c\u5728\u4f7f\u7528\u7c7b\u65f6\u5bf9\u5e94\u7684\u5bf9\u8c61\u5df2\u7ecf\u521b\u5efa public class My […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[43],"tags":[53],"class_list":["post-84","post","type-post","status-publish","format-standard","hentry","category-java-basic","tag-singleton"],"_links":{"self":[{"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/posts\/84","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/comments?post=84"}],"version-history":[{"count":0,"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/posts\/84\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/media?parent=84"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/categories?post=84"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/tags?post=84"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}