1.公平鎖、非公平鎖

2.可重入鎖（遞歸鎖）

3.自旋鎖

AtomicReference atomicReference = new AtomicReference();//原子引用線程

下面代碼5秒鐘自旋了10萬次，還是很消耗CPU的

package HighConcurrency;import java.util.concurrent.TimeUnit; import java.util.concurrent.atomic.AtomicReference;public class SpinLockDemo {//原子引用線程AtomicReference<Thread> atomicReference = new AtomicReference<>();public void myLock(){Thread thread = Thread.currentThread();System.out.println(Thread.currentThread().getName()+"\t come in");while(!atomicReference.compareAndSet(null,thread)){System.out.println(Thread.currentThread().getName()+"線程自旋。。。");}}public void myunLock(){Thread thread = Thread.currentThread();atomicReference.compareAndSet(thread,null);System.out.println(Thread.currentThread().getName()+"\t invoked myUnLock");}public static void main(String []args){SpinLockDemo spinLockDemo = new SpinLockDemo();new Thread(()->{spinLockDemo.myLock();//暫停線程一會try {TimeUnit.SECONDS.sleep(5); } catch (InterruptedException e) { e.printStackTrace(); }spinLockDemo.myunLock();},"AA").start();try {TimeUnit.SECONDS.sleep(1); } catch (InterruptedException e) { e.printStackTrace(); }new Thread(()->{spinLockDemo.myLock();spinLockDemo.myunLock();},"BB").start();} }

4.獨占鎖(寫鎖)|共享鎖(讀鎖)

獨占鎖：指該鎖一次只能被一個線程持有，ReentrantLock和synchronized都是獨占鎖
共享鎖：可被多個線程所持有。對ReentrantReadWriteLock其讀鎖是共享鎖，其寫鎖是獨占鎖。
讀鎖的共享鎖可保證高并發讀是非常都效的

class MyCache{ //資源類private volatile Map<String,Object> map = new HashMap<>();private ReentrantReadWriteLock rwLock = new ReentrantReadWriteLock();//寫緩存框架，讀、寫、清空public void get(String key,Object value){ //讀rwLock.readLock().lock();try {System.out.println(Thread.currentThread().getName() + "\t 正在讀取：");try { TimeUnit.MILLISECONDS.sleep(300); } catch (InterruptedException e) { e.printStackTrace(); }Object object = map.get(key);System.out.println(Thread.currentThread().getName() + "\t 讀取完成" + object);}catch (Exception e){e.printStackTrace();}finally {rwLock.readLock().unlock();}}public void put(String key,Object value){ //寫rwLock.writeLock().lock();try {System.out.println(Thread.currentThread().getName()+"\t 正在寫入" + key);try { TimeUnit.MILLISECONDS.sleep(300); } catch (InterruptedException e) { e.printStackTrace(); }System.out.println(Thread.currentThread().getName()+"\t 寫入完成");}catch (Exception e){e.printStackTrace();}finally {rwLock.writeLock().unlock();}}} public class ReadWriteLockDemo {public static void main(String[] args) {MyCache myCache = new MyCache();//線程操作資源類for (int i = 0; i < 5; i++) {final int tempInt = i;new Thread(() -> {myCache.put(tempInt+"",tempInt+"");},"線程"+String.valueOf(i)).start();}for (int i = 0; i < 5; i++) {final int tempInt = i;new Thread(() -> {myCache.get(tempInt+"",tempInt+"");},"線程"+String.valueOf(i)).start();}} }

總結

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