201871010111-刘佳华《面向对象程序设计（java）》第十七周学习总结(代码片段)

 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;
14    /**与同步控制有关的类对象*/
15    private Lock bankLock;           //lock对象
16    private Condition sufficientFunds;//condition对象   
17 
18    /**
19     * Constructs the bank.
20     * @param n the number of accounts
21     * @param initialBalance the initial balance for each account
22     */
23    public Bank(int n, double initialBalance)
24    
25       accounts = new double[n];
26       Arrays.fill(accounts, initialBalance); //数组account的填充
27       bankLock = new ReentrantLock();
28       sufficientFunds = bankLock.newCondition();
29    
30 
31    /**
32     * Transfers money from one account to another.
33     * @param from the account to transfer from
34     * @param to the account to transfer to
35     * @param amount the amount to transfer
36     */
37    public void transfer(int from, int to, double amount) throws InterruptedException //模拟行内转账操作
38    
39       bankLock.lock(); //加锁操作
40       try
41       
42          while (accounts[from] < amount)
43             sufficientFunds.await();         //阻塞事件队列
44          System.out.print(Thread.currentThread());
45          accounts[from] -= amount;
46          System.out.printf(" %10.2f from %d to %d", amount, from, to);
47          accounts[to] += amount;
48          System.out.printf(" Total Balance: %10.2f%n", getTotalBalance());
49          sufficientFunds.signalAll();//唤醒所有线程
50       
51       finally
52       
53          bankLock.unlock(); //解除锁操作
54       
55    
56 
57    /**
58     * Gets the sum of all account balances.
59     * @return the total balance
60     */
61    public double getTotalBalance()
62    
63       bankLock.lock();
64       try
65       
66          double sum = 0;
67 
68          for (double a : accounts)
69             sum += a;
70 
71          return sum;
72       
73       finally
74       
75          bankLock.unlock();
76       
77    
78 
79    /**
80     * Gets the number of accounts in the bank.
81     * @return the number of accounts
82     */
83    public int size()
84    
85       return accounts.length;
86    
87 

package synch;

/**
 * This program shows how multiple threads can safely access a data structure.
 * @version 1.31 2015-06-21
 * @author Cay Horstmann
 */
public class SynchBankTest

   public static final int NACCOUNTS = 100;
   public static final double INITIAL_BALANCE = 1000;
   public static final double MAX_AMOUNT = 1000;
   public static final int DELAY = 10;
   
   public static void main(String[] args)
   
      Bank bank = new Bank(NACCOUNTS, INITIAL_BALANCE);
      for (int i = 0; i < NACCOUNTS; i++)
      
         int fromAccount = i;
         Runnable r = () -> 
            try
            
               while (true)
               
                  int toAccount = (int) (bank.size() * Math.random());
                  double amount = MAX_AMOUNT * Math.random();
                  bank.transfer(fromAccount, toAccount, amount);
                  Thread.sleep((int) (DELAY * Math.random()));//随机生成时间，使正在执行的线程休眠
               
            
            catch (InterruptedException e)
            
                        
         ;
         Thread t = new Thread(r);
         t.start();
      
   

package synch2;

import java.util.*;

/**
 * A bank with a number of bank accounts that uses synchronization primitives.
 * @version 1.30 2004-08-01
 * @author Cay Horstmann
 */
public class Bank

   private final double[] accounts;

   /**
    * Constructs the bank.
    * @param n the number of accounts
    * @param initialBalance the initial balance for each account
    */
   public Bank(int n, double initialBalance)
   
      accounts = new double[n];
      Arrays.fill(accounts, initialBalance);
   

   /**
    * Transfers money from one account to another.
    * @param from the account to transfer from
    * @param to the account to transfer to
    * @param amount the amount to transfer
    */
   public synchronized void transfer(int from, int to, double amount) throws InterruptedException//sysynchronized关键字修饰方法实现加锁操作
   
      while (accounts[from] < amount)
         wait();  //wait()方法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
      System.out.print(Thread.currentThread());//Thread.currentThread()返回当前执行线程的Thread对象
      accounts[from] -= amount;
      System.out.printf(" %10.2f from %d to %d", amount, from, to);
      accounts[to] += amount;
      System.out.printf(" Total Balance: %10.2f%n", getTotalBalance());
      notifyAll(); //解除那些在该对象上调用wait方法的线程的阻塞状态
   

   /**
    * Gets the sum of all account balances.
    * @return the total balance
    */
   public synchronized double getTotalBalance()
   
      double sum = 0;

      for (double a : accounts)
         sum += a;

      return sum;
   

   /**
    * Gets the number of accounts in the bank.
    * @return the number of accounts
    */
   public int size()
   
      return accounts.length;
   

package synch2;

/**
 * This program shows how multiple threads can safely access a data structure,
 * using synchronized methods.
 * @version 1.31 2015-06-21
 * @author Cay Horstmann
 */
public class SynchBankTest2

   public static final int NACCOUNTS = 100;
   public static final double INITIAL_BALANCE = 1000;
   public static final double MAX_AMOUNT = 1000;
   public static final int DELAY = 10;

   public static void main(String[] args)
   
      Bank bank = new Bank(NACCOUNTS, INITIAL_BALANCE);
      for (int i = 0; i < NACCOUNTS; i++)
      
         int fromAccount = i;
         /**lamber表达式*/
         /*Runnable r = () -> 
            try
            
               while (true)
               
                  int toAccount = (int) (bank.size() * Math.random());
                  double amount = MAX_AMOUNT * Math.random();
                  bank.transfer(fromAccount, toAccount, amount);
                  Thread.sleep((int) (DELAY * Math.random()));
               
            
            catch (InterruptedException e)
            
            
         ;*/
        /**直接声明
         *  Runnable r=new Runnable() 
            
            @Override
            public void run() 
                try
                
                   while (true)
                   
                      int toAccount = (int) (bank.size() * Math.random());
                      double amount = MAX_AMOUNT * Math.random();
                      bank.transfer(fromAccount, toAccount, amount);
                      Thread.sleep((int) (DELAY * Math.random()));
                   
                
                catch (InterruptedException e)
                
                
             ;
                
            
        ;*/
         
         /**
                                  *  匿名内部类
                      */
         Thread t = new Thread(new Runnable()
             
             @Override
             public void run() 
                 try
                 
                    while (true)
                    
                       int toAccount = (int) (bank.size() * Math.random());
                       double amount = MAX_AMOUNT * Math.random();
                       bank.transfer(fromAccount, toAccount, amount);
                       Thread.sleep((int) (DELAY * Math.random()));
                    
                 
                 catch (InterruptedException e)
                 
                 
              ;
                 
             
         );
         t.start();
      
   

package op;

class Cbank

     private static int s=2000;
     public  synchronized 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();