第 多线程PPT学习教案

1、会计学1第第 多线程多线程多个线程在多处理器上运行多个线程在单处理器上运行Thread 3 Thread 2 Thread 1 Thread 3 Thread 2 Thread 1 第1页/共34页 / Custom thread class public class CustomThread extends Thread . public CustomThread(.) . / Override the run method in Thread public void run() / Tell system how to run custom thread . . / Client clas

2、s public class Client . public void someMethod() . / Create a thread CustomThread thread1 = new CustomThread(.); / Start a thread thread1.start(); . / Create another thread CustomThread thread2 = new CustomThread(.); / Start a thread thread2.start(); . java.lang.Thread CustomThread 第2页/共34页TestThrea

3、dRun第3页/共34页 / Custom thread class public class CustomThread implements Runnable . public CustomThread(.) . / Implement the run method in Runnable public void run() / Tell system how to run custom thread . . / Client class public class Client . public void someMethod() . / Create an instance of Cust

4、omThread CustomThread customThread = new CustomThread(.); / Create a thread Thread thread = new Thread(customThread); / Start a thread thread.start(); . . java.lang.Runnable CustomThread 第4页/共34页TestRunnableRun第5页/共34页java.lang.Thread +Thread(tagert: Runnable) +run(): void +start(): void +interrupt(

5、): void +isAlive(): boolean +setPriority(p: int): void +join(): void +sleep(millis: long): void +yield(): void +isInterrupted(): Boolean +currentThread(): Thread java.lang.Runnable 第6页/共34页第7页/共34页第8页/共34页第9页/共34页 t2.join() -char token +getToken +setToken +paintComponet +mouseClicked Thread t1 -char

6、 token +getToken +setToken +paintComponet +mouseClicked Wait for t2 to finish +getToken +setToken +paintComponet +mouseClickeThread t2 -char token +getToken +setToken +paintComponet +mouseClicked t2 finished -char token +getToken (A) Using the join() method -char token anObj.wait() -char token +getT

7、oken +setToken +paintComponet +mouseClicked Thread t1 -char token +getToken +setToken +paintComponet +mouseClicked Wait for notification Thread t2 -char token +getToken +setToken +paintComponet +mouseClicked (B) Using the wait(), notify(), or notifyAll() -char token anObj.notify() -char token +getTo

8、ken +setToken +paintComponet +mouseClicked 第10页/共34页线程有五种状态：新建、就绪、运行、阻塞或结束。 新建 就绪 Thread created 结束 运行 start() run() 等待目标线程结束 join() run() returns yield(), or time out interrupt() 用完等待时间 等待通知 sleep() wait() 目标线 程结束 notify() or notifyAll() 时间到 阻塞 Interrupted() 第11页/共34页第12页/共34页第13页/共34页第14页/共34页Cloc

9、kClockControlClockAppRun ClockApp +AppletClock() +main(args: String): void JApplet -char token +getToken +setToken +paintComponet +mouseClicked ClockControl -clock: Clock jbtResume: JButton -jbtSuspend: JButton +ClockControl() +actionPerformed(e: ActionEvent): void JPanel -char token +getToken +setT

10、oken +paintComponet +mouseClicked Clock +Clock() +run(): void +suspend(): void +resume(): void StillClock -char token +getToken +setToken +paintComponet +mouseClicked Runnable 1 1 ActionListener 1 1 第15页/共34页ClockWithAudioRun第16页/共34页ClockWithAudioOnSeparateThreadRun第17页/共34页线程池是管理开发执行很多任务的理想方法。JDK

11、1.5 使用 Executor 接口在线程池中执行任务， ExecutorService 接口用来管理和控制任务。 ExecutorService 是 Executor的子接口. Shuts down the executor, but allows the tasks in the executor to complete. Once shutdown, it cannot accept new tasks. Shuts down the executor immediately even though there are unfinished threads in the pool. Re

12、turns a list of unfinished tasks. Returns true if the executor has been shutdown. Returns true if all tasks in the pool are terminated. interface java.util.concurrent.Executor +execute(Runnable object): void Executes the runnable task. interface java.util.concurrent.ExecutorService +shutdown(): void

13、 +shutdownNow(): List +isShutdown(): boolean +isTerminated(): boolean 第18页/共34页为了创建 Executor 对象, 使用 Executors 的静态方法. Creates a thread pool with a fixed number of threads executing concurrently. A thread may be reused to execute another task after its current task is finished. Creates a thread pool t

14、hat creates new threads as needed, but will reuse previously constructed threads when they are available. java.util.concurrent.Executors +newFixedThreadPool(numberOfThreads: int): ExecutorService +newCachedThreadPool(): ExecutorService ExecutorDemoRun第19页/共34页 如果一个共享资源被多个线程同时访问，可能会遭到破坏。Stepbalance t

15、hreadi threadj10 newBalance = bank.getBalance() + 1;20 newBalance = bank.getBalance() + 1;31 bank.setBalance(newBalance);41 bank.setBalance(newBalance);第20页/共34页AccountWithoutSyncRun Account -balance: int +getBalance(): int +deposit(amount: int): void 100 AccountWithoutSync -bank: Account -thread: T

16、hread +main(args: String): void java.lang.Object -char token +getToken +setToken +paintComponet +mouseClicked java.lang.Object -char token +getToken +setToken +paintComponet +mouseClicked AddAPennyThread +run(): void java.lang.Thread -char token +getToken +setToken +paintComponet +mouseClicked 1 1 1

17、 第21页/共34页 获准对account对象加锁 解除对account对象的锁定 threadi 执行deposit方法 获准对account对象加锁 执行deposit方法 解除对account对象的锁定 threadj - 等待对account对象加锁 第22页/共34页第23页/共34页第24页/共34页 Same as ReentrantLock(false). Creates a lock with the given fairness policy. When the fairness is true, the longest-waiting thread will get th

18、e lock. Otherwise, there is no particular access order. interface java.util.concurrent.locks.Lock +lock(): void +unlock(): void +newCondition(): Condition Acquires the lock. Releases the lock. Returns a new Condition instance that is bound to this Lock instance. java.util.concurrent.locks.ReentrantL

19、ock +ReentrantLock() +ReentrantLock(fair: boolean) 第25页/共34页AccountWithSyncUsingLockRun第26页/共34页第27页/共34页 synchronized (anObject) try / Wait for the condition to become true while (!condition) anObject.wait(); / Do something when condition is true catch (InterruptedException ex) ex.printStackTrace()

20、; Thread 1 synchronized (anObject) / When condition becomes true anObject.notify(); or anObject.notifyAll(); . Thread 2 resume 第28页/共34页ThreadCooperationRun第29页/共34页 synchronized (object1) / do something here synchronized (object2) / do something here Thread 1 synchronized (object2) / do something here synchronized (object1) / do something here Thread 2 Step 1 2 3 4 5 6 Wait for Thread 2 to release