1、实验目的与要求
(1) 掌握线程同步的概念及实现技术；
(2) 线程综合编程练习
2、实验内容和步骤
实验1：测试程序并进行代码注释。
测试程序1：
l 在Elipse环境下调试教材651页程序14-7，结合程序运行结果理解程序；
l 掌握利用锁对象和条件对象实现的多线程同步技术。
1 package synch; 2 3 import java.util.*; 4 import java.util.concurrent.locks.*; 5 6 /** 7 * A bank with a number of bank accounts that uses locks for serializing access. 8 * @version 1.30 2004-08-01 9 * @author Cay Horstmann 10 */ 11 public class Bank 12 { 13 private final double[] accounts;//银行的基本数据 14 private Lock bankLock;//锁对象 15 private Condition sufficientFunds; 16 17 /** 18 * Constructs the bank. 19 * @param n the number of accounts 20 * @param initialBalance the initial balance for each account 21 */ 22 public Bank(int n, double initialBalance) 23 { 24 accounts = new double[n]; 25 Arrays.fill(accounts, initialBalance); 26 bankLock = new ReentrantLock(); 27 sufficientFunds = bankLock.newCondition(); 28 } 29 30 /** 31 * Transfers money from one account to another. 32 * @param from the account to transfer from 33 * @param to the account to transfer to 34 * @param amount the amount to transfer 35 */ 36 public void transfer(int from, int to, double amount) throws InterruptedException 37 { 38 bankLock.lock(); 39 try 40 { //锁对象的引用条件对象 41 while (accounts[from] < amount) 42 sufficientFunds.await(); 43 System.out.print(Thread.currentThread());//打印出线程号 44 accounts[from] -= amount; 45 System.out.printf(" %10.2f from %d to %d", amount, from, to); 46 accounts[to] += amount; 47 System.out.printf(" Total Balance: %10.2f%n", getTotalBalance()); 48 sufficientFunds.signalAll(); 49 } 50 finally 51 { 52 bankLock.unlock(); 53 } 54 } 55 56 /** 57 * Gets the sum of all account balances. 58 * @return the total balance 59 */ 60 public double getTotalBalance() 61 { 62 bankLock.lock();//加锁 63 try 64 { 65 double sum = 0; 66 67 for (double a : accounts) 68 sum += a; 69 70 return sum; 71 } 72 finally 73 { 74 bankLock.unlock();//解锁 75 } 76 } 77 78 /** 79 * Gets the number of accounts in the bank. 80 * @return the number of accounts 81 */ 82 public int size() 83 { 84 return accounts.length; 85 } 86 }