public synchronized void syzDemo(){ System.out.println(System.currentTimeMillis()); System.out.println('進(jìn)入synchronized鎖:syzDemo'); try {Thread.sleep(1000); } catch (InterruptedException e) {e.printStackTrace(); }}二、使用在靜態(tài)方法上

public synchronized static void syzDemo1(){ System.out.println(System.currentTimeMillis()); System.out.println('進(jìn)入synchronized鎖:syzDemo1'); try {Thread.sleep(1000); } catch (InterruptedException e) {e.printStackTrace(); }}三、使用在代碼塊上

public synchronized void syzDemo2(){ synchronized (this){System.out.println(System.currentTimeMillis());System.out.println('進(jìn)入synchronized鎖:syzDemo2');try { Thread.sleep(1000);} catch (InterruptedException e) { e.printStackTrace();} }}public synchronized void syzDemo3(){ synchronized (ExcelUtil.class){ System.out.println(System.currentTimeMillis()); System.out.println('進(jìn)入synchronized鎖:syzDemo3'); try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } }}四、三種方式的區(qū)別

public static void main(String[] args) {SyzDemo syzDemo = new SyzDemo();SyzDemo syzDemo1 = new SyzDemo();Thread thread = new Thread(()->{ syzDemo.syzDemo();});thread.start();Thread thread1 = new Thread(()->{ syzDemo1.syzDemo();});thread1.start(); }4.1 不會(huì)互斥

public static void main(String[] args) {SyzDemo syzDemo = new SyzDemo();SyzDemo syzDemo1 = new SyzDemo();Thread thread = new Thread(()->{ syzDemo.syzDemo();});thread.start();Thread thread1 = new Thread(()->{ syzDemo.syzDemo();});thread1.start(); }4.2 互斥

public static void main(String[] args) {SyzDemo syzDemo = new SyzDemo();SyzDemo syzDemo1 = new SyzDemo();Thread thread = new Thread(()->{ syzDemo.syzDemo1();});thread.start();Thread thread1 = new Thread(()->{ syzDemo1.syzDemo1();});thread1.start(); }

解析：

在圖1中thread1和thread分別調(diào)用syzDemo和syzDemo1對(duì)象中的syzDemo方法，因?yàn)閮蓚€(gè)線程調(diào)用是不同的對(duì)象的兩個(gè)方法，所以不會(huì)互斥

在圖2中thread1和thread都在調(diào)用syzDemo對(duì)象中的syzDemo方法，因?yàn)閟yzDemo方法加了synchronized

在圖3中thread1和thread分別調(diào)用syzDemo和syzDemo1對(duì)象中的syzDemo1方法，但是因?yàn)閟yzDemo1方法屬于靜態(tài)方法，在類加載時(shí)就會(huì)加載到方法區(qū)，所以本質(zhì)上兩個(gè)線程都在調(diào)用同一個(gè)方法，于是產(chǎn)生了互斥

syzDemo2中與syzDemo相同：鎖定的是當(dāng)前實(shí)例的這一段代碼，只有多個(gè)線程中調(diào)用的是同一個(gè)實(shí)例且執(zhí)行到這一段代碼時(shí)才會(huì)互斥，syzDemo3于syzDemo1相同：鎖定的是當(dāng)前類的這一段代碼，只要多個(gè)線程共同執(zhí)行這一段代碼就會(huì)產(chǎn)生互斥

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