java总结篇系列Java多线程一

Java中很重要的一个知识点，在此还是有必要总结一下的。JavaJava中多线程各重要知识点。掌握了上图中的各知识点，Java中的新建状态（New）：当线程对象对创建后，即进入了新建状态，如：ThreadtnewCPU调度执行，t.start()此线程立即就会执行；运行状态（Running）：当CPU开始调度处于就绪状态的线程时，此时线程才得以真正 绪状态是进入到运行状态的唯一，也就是说，阻塞状态（Blocked）：CPU的使用CPU调用--synchronized同步锁失败(因为锁被其它线程所占用)，它会进--sleep()join()I/O请求时，线程会进入到阻塞状二JavaJava1classMyThreadextends1classMyThreadextendsThread2345678911privateinti=publicvoidrun()for(i=0;i<100;i++){System.out.println(Thread.currentThread().getName()+""+i);}}1publicclassThreadTest234567publicstaticvoidmain(String[]args)for(inti=0;i<100;i++){System.out.println(Thread.currentThread().getName()+""+i);if(i==30){ThreadmyThread1=newThreadmyThread2=new8myThread29start()start()14}}}Threadrun()MyThread，其中时一个新的线程得以创建，并进入到线程新建状态。通过调用线程对象的start()方CPUThread对象才是真正的线程对象。11classMyRunnableimplementsRunnable2345678910privateinti=publicvoidrun()for(i=0;i<100;i++){System.out.println(Thread.currentThread().getName()+""+i);}}1publicclassThreadTest234567publicstaticvoidmain(String[]args)for(inti=0;i<100;i++){System.out.println(Thread.currentThread().getName()+""+i);if(i==30){RunnablemyRunnablenewMyRunnable Threadthread1newThread(myRunnable);myRunnable为Threadtarget创建新的线程9Threadthread2=newthread1.startstart()方法使得线程进入就绪状态}}}}ThreadRunnable1publicclassThreadTest{ publicstaticvoidmain(String[]args)4(inti=0;i<100;i++)5System.out.println(Thread.currentThread().getName()+""+6if(i==30)7RunnablemyRunnable=new8Threadthread=new9}11publicinterfaceRunnable2345void13}}15classMyRunnableimplementsRunnable25privateinti=publicvoidrun()System.out.println("inMyRunnablerun");for(i=0;i<100;i++){System.out.println(Thread.currentThread().getName()+""+}}27classMyThreadextendsThread42privateinti=publicMyThread(Runnable}publicvoidrun(){System.out.println("inMyThreadrun");for(i=0;i<100;i++){System.out.println(Thread.currentThread().getName()+""+}}1Threadthread=newRunnable1Threadthread=newRunnablerun()Runnable接口中定义的方法。publicvoidrun()if(targetpublicvoidrun()if(target!=null){}}MyThreadrun()方法。CallableFutureCallable接口的实现类，并实现clall()FutureTaskCallableFutureTaskThreadtarget来创建线程。1publicclassThreadTest{ publicstaticvoidmain(String[]args){Callable<Integer>myCallablenew MyCallableFutureTask<Integer>ftnewFutureTask<Integer>(myCallable);FutureTaskMyCallable7 for(inti=0;i<100;i++)System.out.println(Thread.currentThread().getName()+""+if(i==30)Threadthreadnew tryintsum=ft.get(); System.out.println("sum="+}catch(InterruptedExceptione)}catch(ExecutionExceptione)28}}31classMyCallableimplementsCallable<Integer>45privateinti=publicIntegercall(){intsum=0;for(;i<100;i++){System.out.println(Thread.currentThread().getName()+""+i);sum+=i;}return}1publicclassFutureTask<V>implementsRunnableFuture<V>{ 451publicinterface1publicclassFutureTask<V>implementsRunnableFuture<V>{ 451publicinterfaceRunnableFuture<V>extendsRunnable,Future<V>{ void45targetFuturecall()方法的返回值。执行下此程序，我们发现sum=4950都是最后输出的。而“主线程for循环执行完毕..”CPU的线程调度机制，我们知道，“for循环执行完毕..”的输出时机是没有任何问题的，那么为什么sum=4950会最后输出毕，ft.get()方一直阻塞，直到call()方法执行完毕才能取到返回值。三.Java多线程的就绪、运行和状运行状态转换为状态：当此线程线程执行体执行完毕或发生了异常CPUA线程yield()CPUA线程的情况。1publicclass1publicclassThreadTest2345678918publicstaticvoidmain(String[]args)MyRunnablemyRunnable=newThreadthread=newfor(inti=0;i<100;i++){System.out.println(Thread.currentThread().getName()+""+i);if(i==30){}if(i==}}}20classMyRunnableimplementsRunnableprivatebooleanpublicvoidrun()for(inti=0;i<100&&!stop;i++){System.out.println(Thread.currentThread().getName()+""+i);}}publicvoidstopThread()this.stop=}}本文承接上一篇文章《Java总结篇系列：Java多线程（一）》。四.Java多线程的阻塞状态与线程控制JavaJava1publicclassThreadTest234567891publicclassThreadTest23456789publicstaticvoidmain(String[]args)MyRunnablemyRunnable=newThreadthread=newfor(inti=0;i<100;i++)System.out.println(Thread.currentThread().getName()+""+i);if(i==30){trymainthread}catch(InterruptedExceptione) }20}}22classMyRunnableimplementsRunnablepublicvoidrun()30for(inti=0;i<100;i++)System.out.println(Thread.currentThread().getName()+""+}}sleep——让当前的正在执行的线程暂停指定的时间，并进入阻塞状态。在其睡眠的时间sleep()sleep()方法常用来暂停线1publicclassThreadTest2341publicclassThreadTest2345678920publicstaticvoidmain(String[]args)MyRunnablemyRunnable=newThreadthread=newfor(inti=0;i<100;i++)System.out.println(Thread.currentThread().getName()+""+i);if(i==30){trythread}catch(InterruptedExceptione)}}}}22classMyRunnableimplementsRunnable publicvoidrun() for(inti=0;i<100;i++) System.out.println(Thread.currentThread().getName()+""+30}}CPU线程（Daemon线程”。如JVM中的回收线程。用...伟大啊!!)。1publicclassThreadTest23publicstaticvoid1publicclassThreadTest23publicstaticvoidmain(String[]args)4ThreadmyThread=new5for(inti=0;i<100;i++)6System.out.println("mainthreadi"+7if(i==20)89}}}}classMyThreadextendsThreadpublicvoidrun()for(inti=0;i<100;i++)System.out.println("i="+try}catch(InterruptedException{//TODOAuto-generated}} 29判断线程是否 注：main线程默认是前台线程，前台线程创建中创建的子线程默认是前台线程，线程中创建的线程默认是线程。调用setDeamon(true)方法将前台线程设置为线程时，需要在start()方法调用之前。前天线后，JVM通知线程，但从接收默认的优先级都与创建它的线程的优先级相同。main线程默认具有普通优先级。设置线程优先级：setPriority(intpriorityLevel)priorityLevel1-10之间，常用11publicclassThreadTest{publicstaticvoidmain(String[]args)ThreadmyThread=newfor(inti=0;i<100;i++)System.out.println("mainthreadi="+if(i==20) 1416classMyThreadextendsThread{ publicvoidrun() for(inti=0;i<100;i++) System.out.println("i="+ 231publicclassThreadTest2publicstatic1publicclassThreadTest2publicstaticvoidmain(String[]args)ThreadmyThread1=newThreadmyThread2=newfor(inti=0;i<100;i++)System.out.println("mainthreadi="+if(i==20) 1820classMyThread1extendsThread{27publicvoidrun()for(inti=0;i<100;i++){System.out.println("myThread1--}}i="+29classMyThread2extendsThread36publicvoidrun()for(inti=0;i<100;i++){System.out.println("myThread2--}}i="+11publicclassThreadTest2345678912publicstaticvoidmain(String[]args)Accountaccount=newAccount("123456",DrawMoneyRunnabledrawMoneyRunnable=newThreadmyThread1=newThreadmyThread2=newThread(drawMoneyRunnable);}14classDrawMoneyRunnableimplementsRunnable33privateAccountprivatedoublepublicDrawMoneyRunnable(Accountaccount,doubledrawAmount)this.account=account;this.drawAmount=drawAmount;}publicvoidrun()if(account.getBalance()>=drawAmount){//1System.out.printlndrawAmount);doublebalance=account.getBalance()-drawAmount;System.out.println}}35classAccount privateStringJava多线程中的线程安全问题。一.Java线程安全例子65privatedoublepublicAccount()}publicAccount(StringaccountNo,doublebalance){this.accountNo=accountNo;this.balance=}publicStringgetAccountNo(){returnaccountNo;}publicvoidsetAccountNo(StringaccountNo){this.accountNo=accountNo;}publicdoublegetBalance(){returnbalance;}publicvoidsetBalance(doublebalance){this.balance=balance;}也就是说，对于一张只有1000余额的， Java多线程环境下的执行的不确定性。CPU可能随机的在多个处于thread1执行到//1处代trueCPUthread2，执行//1处代码，发现依然为真，然thread2thread1，接着执行完毕。此时，就会出现上述结果。。对共享资源进行的方法定义中加上synchronized关键字修饰，使得此方法称为同步方1publicsynchronizedvoidrun()1publicsynchronizedvoidrun(){ //4511synchronized(obj){ 45account对象作为锁对象。（this也是可以的，那是因runnableThreadthis1classX{Lock1classX{3345678916privatefinalLocklock=newpublicvoid//...}在博文《Java总结篇系列：java.lang.Object》中有提及到这三个方法，虽然这三个方法主ObjectObjectnotify()或notifyAll()方法来唤醒此线程。1package21package23publicclassThreadTest{56789publicstaticvoidmain(String[]args)Accountaccount=newAccount("123456",ThreaddrawMoneyThreadnewDrawMoneyThread("ThreaddepositeMoneyThreadnewDepositeMoneyThread(account,}15classDrawMoneyThreadextendsThread{privateAccountprivatedoubleamount; publicDrawMoneyThread(StringthreadName,Accountaccount,doubleamount){ this.account= this.amount= publicvoidrun() for(inti=0;i<100;i++) account.draw(amount, 3335classDepositeMoneyThreadextendsThread{ privateAccount privatedoubleamount; publicDepositeMoneyThread(StringthreadName,Accountaccount,doubleamount){ this.account= this.amount= publicvoidrun() for(inti=0;i<100;i++) account.deposite(amount, 5153classAccount{ privateStringprivatedoubleprivatebooleanflag=publicAccount()}publicAccount(StringaccountNo,doublebalance)this.accountNo=this.balance=}publicStringgetAccountNo()return}publicvoidsetAccountNo(StringaccountNo)this.accountNo=}publicdoublegetBalance()return}publicvoidsetBalance(doublebalance)this.balance=}***@parampublicsynchronizedvoiddeposite(doubleinti