杨玲201771010133《面向对象程序设计（java）》第十七周学习总结
《面向对象程序设计（java）》第十七周学习总结
第一部分：实验部分
实验名称：实验十七 线程同步控制
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。
1package synch; 2 3import java.util.*;
4import 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*/
11publicclass Bank
12{
13privatefinaldouble[] accounts;//银行运转的基本数据
14private Lock bankLock;//锁对象
15private 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*/
22public Bank(int n, double initialBalance)
23 {
24 accounts = newdouble[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*/
36publicvoid transfer(int from, int to, double amount) throws InterruptedException
37 {
38 bankLock.lock();
39try
40 {//锁对象的引用条件对象
41while (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.signal();
49 }
50finally
51 {
52 bankLock.unlock();
53 }
54 }
55
56/**
57 * Gets the sum of all account balances.
58 * @return the total balance
59*/
60publicdouble getTotalBalance()
61 {
62 bankLock.lock();//加锁
63try
64 {
65double sum = 0;
66
67for (double a : accounts)
68 sum += a;
69
70return sum;
71 }
72finally
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*/
82publicint size()
83 {
84return accounts.length;
85 }
86 }
1package synch; 2 3/**
4 * This program shows how multiple threads can safely access a data structure.
5 * @version 1.31 2015-06-21
6 * @author Cay Horstmann
7*/
8publicclass SynchBankTest
9{
10publicstaticfinalint NACCOUNTS = 100;
11publicstaticfinaldouble INITIAL_BALANCE = 1000;
12publicstaticfinaldouble MAX_AMOUNT = 1000;
13publicstaticfinalint DELAY = 10;
14
15publicstaticvoid main(String[] args)
16 {
17 Bank bank = new Bank(NACCOUNTS, INITIAL_BALANCE);
18for (int i = 0; i < NACCOUNTS; i++)
19 {
20int fromAccount = i;
21 Runnable r = () -> {
22try
23 {
24while (true)
25 {
26int toAccount = (int) (bank.size() * Math.random());
27double amount = MAX_AMOUNT * Math.random();
28 bank.transfer(fromAccount, toAccount, amount);
29 Thread.sleep((int) (DELAY * Math.random()));
30 }
31 }
32catch (InterruptedException e)
33 {
34 }
35 };
36 Thread t = new Thread(r);
37 t.start();
38 }
39 }
40 }
运行结果如下：
测试程序2：
l 在Elipse环境下调试教材655页程序14-8，结合程序运行结果理解程序；
l 掌握synchronized在多线程同步中的应用。
1package synch2; 2 3import java.util.*;
4
5/**
6 * A bank with a number of bank accounts that uses synchronization primitives.
7 * @version 1.30 2004-08-01
8 * @author Cay Horstmann
9*/
10publicclass Bank
11{
12privatefinaldouble[] accounts;
13
14/**
15 * Constructs the bank.
16 * @param n the number of accounts
17 * @param initialBalance the initial balance for each account
18*/
19public Bank(int n, double initialBalance)
20 {
21 accounts = newdouble[n];
22 Arrays.fill(accounts, initialBalance);
23 }
24
25/**
26 * Transfers money from one account to another.
27 * @param from the account to transfer from
28 * @param to the account to transfer to
29 * @param amount the amount to transfer
30*/
31publicsynchronizedvoid transfer(int from, int to, double amount) throws InterruptedException
32 {
33while (accounts[from] < amount)
34 wait();//导致线程进入等待状态直到它被通知。该方法只能在一个同步方法中调用。
35 System.out.print(Thread.currentThread());//打印出线程号
36 accounts[from] -= amount;
37 System.out.printf(" %10.2f from %d to %d", amount, from, to);//第一个打印结果保留两位小数（最大范围是十位），
38 accounts[to] += amount;
39 System.out.printf(" Total Balance: %10.2f%n", getTotalBalance());
40 notifyAll();//解除那些在该对象上调用wait方法的线程阻塞状态。该方法只能在同步方法或同步块内部调用。
41 }
42
43/**
44 * Gets the sum of all account balances.
45 * @return the total balance
46*/
47publicsynchronizeddouble getTotalBalance()
48 {
49double sum = 0;
50
51for (double a : accounts)
52 sum += a;
53
54return sum;
55 }
56
57/**
58 * Gets the number of accounts in the bank.
59 * @return the number of accounts
60*/
61publicint size()
62 {
63return accounts.length;
64 }
65 }
1package synch2; 2 3/**
4 * This program shows how multiple threads can safely access a data structure,
5 * using synchronized methods.
6 * @version 1.31 2015-06-21
7 * @author Cay Horstmann
8*/
9publicclass SynchBankTest2
10{
11publicstaticfinalint NACCOUNTS = 100;
12publicstaticfinaldouble INITIAL_BALANCE = 1000;
13publicstaticfinaldouble MAX_AMOUNT = 1000;
14publicstaticfinalint DELAY = 10;
15
16publicstaticvoid main(String[] args)
17 {
18 Bank bank = new Bank(NACCOUNTS, INITIAL_BALANCE);
19for (int i = 0; i < NACCOUNTS; i++)
20 {
21int fromAccount = i;
22 Runnable r = () -> {
23try
24 {
25while (true)
26 {
27int toAccount = (int) (bank.size() * Math.random());
28double amount = MAX_AMOUNT * Math.random();
29 bank.transfer(fromAccount, toAccount, amount);
30 Thread.sleep((int) (DELAY * Math.random()));
31 }
32 }
33catch (InterruptedException e)
34 {
35 }
36 };
37 Thread t = new Thread(r);
38 t.start();
39 }
40 }
41 }
运行结果如下：
y
测试程序3：
l 在Elipse环境下运行以下程序，结合程序运行结果分析程序存在问题；
l 尝试解决程序中存在问题。
class Cbank
{
private static int s=2000;
public static void sub(int m)
{
int temp=s;
temp=temp-m;
try {
Thread.sleep((int)(1000*Math.random()));
}
catch (InterruptedException e) { }
s=temp;
System.out.println("s="+s);
}
}
class Customer extends Thread
{
public void run()
{
for( int i=1; i<=4; i++)
Cbank.sub(100);
}
}
public class Thread3
{
public static void main(String args[])
{
Customer customer1 = new Customer();
Customer customer2 = new Customer();
customer1.start();
customer2.start();
}
}
1class Cbank 2{ 3privatestaticint s=2000; 4synchronizedpublicstaticvoid sub(int m) 5 { 6int temp=s; 7 temp=temp-m; 8try { 9 Thread.sleep((int)(1000*Math.random()));10 }11catch (InterruptedException e) { }12 s=temp;13 System.out.println("s="+s);14 }15 }1617
18class Customer extends Thread
19{
20
21publicvoid run()
22 {
23for( int i=1; i<=4; i++)
24 Cbank.sub(100);
25 }
26 }
27publicclass Thread3
28{
29publicstaticvoid main(String args[])
30 {
31 Customer customer1 = new Customer();
32 Customer customer2 = new Customer();
33 customer1.start();
34 customer2.start();
35 }
36 }
运行结果如下：
实验2 编程练习
利用多线程及同步方法，编写一个程序模拟火车票售票系统，共3个窗口，卖10张票，程序输出结果类似（程序输出不唯一，可以是其他类似结果）。
Thread-0窗口售：第1张票
Thread-0窗口售：第2张票
Thread-1窗口售：第3张票
Thread-2窗口售：第4张票
Thread-2窗口售：第5张票
Thread-1窗口售：第6张票
Thread-0窗口售：第7张票
Thread-2窗口售：第8张票
Thread-1窗口售：第9张票
Thread-0窗口售：第10张票
1publicclass Demo { 2publicstaticvoid main(String[] args) { 3 Mythread mythread = new Mythread(); 4 Thread t1 = new Thread(mythread); 5 Thread t2 = new Thread(mythread); 6 Thread t3 = new Thread(mythread); 7 t1.start(); 8 t2.start(); 9 t3.start();10 }11 }1213class Mythread implements Runnable {
14int t = 1;
15boolean flag = true;
16
17 @Override
18publicvoid run() {
19// TODO Auto-generated method stub
20while (flag) {
21try {
22 Thread.sleep(500);
23 } catch (Exception e) {
24// TODO: handle exception
25 e.printStackTrace();
26 }
27
28synchronized (this) {
29if (t <= 10) {
30 System.out.println(Thread.currentThread().getName() + "窗口售：第" + t + "张票");
31 t++;
32 }
33if (t > 10) {
34 flag = false;
35 }
36 }
37
38 }
39 }
40 }
运行结果如下：
4. 实验总结：
通过本学期的实验课程学习，真的学到了很多，尤其是在老师和助教学长的耐心指导下，从最开始JDK的安装到后来自己能写出可以运行的程序，很开心。
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