1、會計學1第第 多線程多線程多個線程在多處理器上運行多個線程在單處理器上運行Thread 3 Thread 2 Thread 1 Thread 3 Thread 2 Thread 1 第1頁/共34頁 / 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頁/共34頁TestThrea

3、dRun第3頁/共34頁 / 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頁/共34頁TestRunnableRun第5頁/共34頁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頁/共34頁第7頁/共34頁第8頁/共34頁第9頁/共34頁 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頁/共34頁線程有五種狀態：新建、就緒、運行、阻塞或結束。 新建 就緒 Thread created 結束 運行 start() run() 等待目標線程結束 join() run() returns yield(), or time out interrupt() 用完等待時間 等待通知 sleep() wait() 目標線 程結束 notify() or notifyAll() 時間到 阻塞 Interrupted() 第11頁/共34頁第12頁/共34頁第13頁/共34頁第14頁/共34頁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頁/共34頁ClockWithAudioRun第16頁/共34頁ClockWithAudioOnSeparateThreadRun第17頁/共34頁線程池是管理開發執行很多任務的理想方法。JDK

11、1.5 使用 Executor 接口在線程池中執行任務， ExecutorService 接口用來管理和控制任務。 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頁/共34頁為了創建 Executor 對象, 使用 Executors 的靜態方法. 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頁/共34頁 如果一個共享資源被多個線程同時訪問，可能會遭到破壞。Stepbalance t

15、hreadi threadj10 newBalance = bank.getBalance() + 1;20 newBalance = bank.getBalance() + 1;31 bank.setBalance(newBalance);41 bank.setBalance(newBalance);第20頁/共34頁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頁/共34頁 獲準對account對象加鎖 解除對account對象的鎖定 threadi 執行deposit方法 獲準對account對象加鎖 執行deposit方法 解除對account對象的鎖定 threadj - 等待對account對象加鎖 第22頁/共34頁第23頁/共34頁第24頁/共34頁 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頁/共34頁AccountWithSyncUsingLockRun第26頁/共34頁第27頁/共34頁 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頁/共34頁ThreadCooperationRun第29頁/共34頁 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