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教育网站颜色,idea网站开发教程,建立自我追求无我什么意思,建一个网站要多久预备知识、各种同步工具synchronized wait/notify 概括#xff1a;Java内置的最基础的线程同步机制#xff0c;基于对象监视器实现。 用途#xff1a;用于简单的线程互斥和等待通知机制#xff0c;如传统的生产者-消费者问题。CountDownLatch 概括#xff1a;一次性的事件…预备知识、各种同步工具synchronized wait/notify概括Java内置的最基础的线程同步机制基于对象监视器实现。用途用于简单的线程互斥和等待通知机制如传统的生产者-消费者问题。CountDownLatch概括一次性的事件等待器通过倒计时控制线程执行顺序。用途等待多个并行任务全部完成后再继续执行如初始化完成后启动主应用。CompletableFuture概括声明式的异步编程框架支持任务链式编排和组合。用途优雅地编排多个异步任务处理复杂的异步依赖关系如并行调用多个微服务。Semaphore概括基于许可证的资源控制器限制并发访问数量。用途控制对有限资源的并发访问如数据库连接池、限流器。ReentrantLock Condition概括功能更丰富的显式锁提供比synchronized更灵活的控制。用途需要高级同步特性的场景如可中断锁、公平锁、多个等待条件。BlockingQueueBlockingQueue 是 Java 并发包中开箱即用的 “生产者 - 消费者” 解决方案本质是对 ReentrantLock Condition 的高级封装比如 ArrayBlockingQueue 底层就是用这组工具实现的一、按序打印Leetcode 1114)给你一个类publicclassFoo{publicvoidfirst(){print(first);}publicvoidsecond(){print(second);}publicvoidthird(){print(third);}}三个不同的线程 A、B、C 将会共用一个 Foo 实例。线程 A 将会调用 first() 方法线程 B 将会调用 second() 方法线程 C 将会调用 third() 方法请设计修改程序以确保 second() 方法在 first() 方法之后被执行third() 方法在 second() 方法之后被执行。classFoo{publicFoo(){}publicvoidfirst(RunnableprintFirst)throwsInterruptedException{printFirst.run();}publicvoidsecond(RunnableprintSecond)throwsInterruptedException{printSecond.run();}publicvoidthird(RunnableprintThird)throwsInterruptedException{printThird.run();}}方法一忙等待优点简单缺点空转CPU可能会死循环classFoo{privatevolatileintx0;publicFoo(){}publicvoidfirst(RunnableprintFirst)throwsInterruptedException{printFirst.run();x;}publicvoidsecond(RunnableprintSecond)throwsInterruptedException{while(x!1){}printSecond.run();x;}publicvoidthird(RunnableprintThird)throwsInterruptedException{while(x!2){}printThird.run();}}1这里x因为不是原子性操作如果有多个线程同时调用first/second/third 会出现问题2while循环里面可以加Thread.yield() 减少自旋的 CPU 消耗classFoo{privateAtomicIntegerxnewAtomicInteger(0);publicFoo(){}publicvoidfirst(RunnableprintFirst)throwsInterruptedException{printFirst.run();x.incrementAndGet();}publicvoidsecond(RunnableprintSecond)throwsInterruptedException{while(x.get()!1){Thread.yield();}printSecond.run();x.incrementAndGet();}publicvoidthird(RunnableprintThird)throwsInterruptedException{while(x.get()!2){Thread.yield();}printThird.run();}}方法二synchronized wait/notifyclassFoo{privateintx0;privatefinalObjectlocknewObject();publicFoo(){}publicvoidfirst(RunnableprintFirst)throwsInterruptedException{synchronized(lock){printFirst.run();x;lock.notifyAll();}}publicvoidsecond(RunnableprintSecond)throwsInterruptedException{synchronized(lock){while(x!1){lock.wait();}printSecond.run();x;lock.notifyAll();}}publicvoidthird(RunnableprintThird)throwsInterruptedException{synchronized(lock){while(x!2){lock.wait();}printThird.run();lock.notifyAll();}}}方法三CountDownLatchclassFoo{privatefinalCountDownLatchlatch1newCountDownLatch(1);privatefinalCountDownLatchlatch2newCountDownLatch(1);publicFoo(){}publicvoidfirst(RunnableprintFirst)throwsInterruptedException{printFirst.run();latch1.countDown();}publicvoidsecond(RunnableprintSecond)throwsInterruptedException{latch1.await();printSecond.run();latch2.countDown();}publicvoidthird(RunnableprintThird)throwsInterruptedException{latch2.await();printThird.run();}}方法四SemaphoreclassFoo{privatefinalSemaphoresem2newSemaphore(0);privatefinalSemaphoresem3newSemaphore(0);publicFoo(){}publicvoidfirst(RunnableprintFirst)throwsInterruptedException{printFirst.run();sem2.release();}publicvoidsecond(RunnableprintSecond)throwsInterruptedException{sem2.acquire();printSecond.run();sem3.release();}publicvoidthird(RunnableprintThird)throwsInterruptedException{sem3.acquire();printThird.run();}}方法五ReentrantLockConditionclassFoo{privatefinalLocklocknewReentrantLock();privatefinalConditioncond1lock.newCondition();privatefinalConditioncond2lock.newCondition();privateintflag0;publicFoo(){}publicvoidfirst(RunnableprintFirst)throwsInterruptedException{lock.lock();try{printFirst.run();flag;cond1.signal();}finally{lock.unlock();}}publicvoidsecond(RunnableprintSecond)throwsInterruptedException{lock.lock();try{while(flag!1){cond1.await();}printSecond.run();flag;cond2.signal();}finally{lock.unlock();}}publicvoidthird(RunnableprintThird)throwsInterruptedException{lock.lock();try{while(flag!2){cond2.await();}printThird.run();}finally{lock.unlock();}}}方法六CompletableFutureclassFoo{privateCompletableFutureVoidcf1newCompletableFuture();privateCompletableFutureVoidcf2newCompletableFuture();publicvoidfirst(RunnableprintFirst){printFirst.run();cf1.complete(null);// 信号first完成了}publicvoidsecond(RunnableprintSecond){cf1.join();// 阻塞等待cf1完成printSecond.run();cf2.complete(null);// 信号second完成了}publicvoidthird(RunnableprintThird){cf2.join();// 阻塞等待cf2完成printThird.run();}}二、交替打印Leetcode 1115)给你一个类classFooBar{publicvoidfoo(){for(inti0;in;i){print(foo);}}publicvoidbar(){for(inti0;in;i){print(bar);}}}两个不同的线程将会共用一个 FooBar 实例线程 A 将会调用 foo() 方法而线程 B 将会调用 bar() 方法请设计修改程序以确保 “foobar” 被输出 n 次。方法一忙等待classFooBar{privateintn;publicFooBar(intn){this.nn;}privatevolatilebooleanstatetrue;publicvoidfoo(RunnableprintFoo)throwsInterruptedException{for(inti0;in;){if(state){printFoo.run();i;statefalse;}else{Thread.yield();}}}publicvoidbar(RunnableprintBar)throwsInterruptedException{for(inti0;in;){if(!state){printBar.run();i;statetrue;}else{Thread.yield();}}}}方法二synchronized wait/notifyclassFooBar{privateintn;publicFooBar(intn){this.nn;}privatebooleanstatetrue;privatefinalObjectlocknewObject();publicvoidfoo(RunnableprintFoo)throwsInterruptedException{for(inti0;in;i){synchronized(lock){while(!state){lock.wait();}printFoo.run();statefalse;lock.notifyAll();}}}publicvoidbar(RunnableprintBar)throwsInterruptedException{for(inti0;in;i){synchronized(lock){while(state){lock.wait();}printBar.run();statetrue;lock.notifyAll();}}}}方法三SemaphoreclassFooBar{privateintn;publicFooBar(intn){this.nn;}privatefinalSemaphoresem1newSemaphore(1);privatefinalSemaphoresem2newSemaphore(0);publicvoidfoo(RunnableprintFoo)throwsInterruptedException{for(inti0;in;i){sem1.acquire();printFoo.run();sem2.release();}}publicvoidbar(RunnableprintBar)throwsInterruptedException{for(inti0;in;i){sem2.acquire();printBar.run();sem1.release();}}}方法四ReentrantLockConditionclassFooBar{privateintn;publicFooBar(intn){this.nn;}privatefinalLocklocknewReentrantLock();privatefinalConditioncondlock.newCondition();privatebooleanflagtrue;publicvoidfoo(RunnableprintFoo)throwsInterruptedException{for(inti0;in;i){lock.lock();try{while(!flag){cond.await();}printFoo.run();flagfalse;cond.signal();}finally{lock.unlock();}}}publicvoidbar(RunnableprintBar)throwsInterruptedException{for(inti0;in;i){lock.lock();try{while(flag){cond.await();}printBar.run();flagtrue;cond.signal();}finally{lock.unlock();}}}}三、打印零与奇偶数