范例解说Java里的线程概念与线程同步技术

public class Book {
    private String name;
    private boolean sold = false;

    public Book(String name) {
        this.name = name;
    }
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public boolean isSold() {
        return sold;
    }

    public void setSold(boolean sold) {
        this.sold = sold;
    }
}

import java.util.List;

public class SellBookRunnable implements Runnable {
    private String saleMan;
    private List<Book> bookList;

    public SellBookRunnable(String saleMan, List<Book> bookList) {
        this.saleMan = saleMan;
        this.bookList = bookList;
    }

    public void run() {
        for (int i = 0; i < bookList.size(); i++) {
            Book book = bookList.get(i);
            sellBook(book);
        }
    }

    /**
     * 售货员卖书。我们这样描述售货员的卖书过程。
     * 
     * @param book Book
     */
    private void sellBook(Book book) {
        //从开始售书-到售书完成，使用synchronized (book)保证book不被其他售货员售出
        synchronized (book) {
            if (book.isSold()) {
                return;
            } else {
                try {
                    //为了让各线程有执行机会，设置平均售书时间为0.5秒
                    Thread.sleep(500);
                } catch (Exception e) {
                }
                
                //设置已售标志
                book.setSold(true);
                //打印该书已售信息
                System.out.println("[" + saleMan + "]" + book.getName() + " sold out:"
                        + book.isSold() + ". by "
                        + Thread.currentThread().getName());

            }
        }
    }
}

import java.util.List;

public class SellBookThread extends Thread {
    private String saleMan;
    private List<Book> bookList;

    public SellBookThread(String saleMan, List<Book> bookList) {
        this.saleMan = saleMan;
        this.bookList = bookList;
    }

    public void run() {
        for (int i = 0; i < bookList.size(); i++) {
            Book book = bookList.get(i);
            sellBook(book);
        }
    }

    /**
     * 售货员卖书。我们这样描述售货员的卖书过程。
     * 
     * @param book Book
     */
    private void sellBook(Book book) {
        //从开始售书-到售书完成，使用synchronized (book)保证book不被其他售货员售出
        synchronized (book) {
            if (book.isSold()) {
                return;
            } else {
                try {
                    //为了让各线程有执行机会，设置平均售书时间为0.5秒
                    Thread.sleep(500);
                } catch (Exception e) {
                }
                
                //设置已售标志
                book.setSold(true);
                //打印该书已售信息
                System.out.println("[" + saleMan + "]" + book.getName() + " sold out:"
                        + book.isSold() + ". by "
                        + Thread.currentThread().getName());

            }
        }
    }
}

import java.util.ArrayList;
import java.util.List;

//该类调用SellBookXxx类
public class CallSellBook {

    /**
     * 用线程模拟这个售书的过程
     */
    public static void main(String[] args) {
        //方法1：
        callSellBookThread();

        //or
        
        //方法2：
        //callSellBookRunnable();
    }
    
    //调用SellBookRunnable（Runnable接口实现类）模拟售书过程
    public static void callSellBookThread() {
        List <Book>bookList = getBookListForSale();
        
        //将预售书籍清单交给售货员SaleMan1
        Thread t1 = new SellBookThread("SaleMan1", bookList);
        //将预售书籍清单交给售货员SaleMan2
        Thread t2 = new SellBookThread("SaleMan2", bookList);

        //售货员SaleMan1开始售书
        t1.start();
        //售货员SaleMan2开始售书
        t2.start();
    }
    
    
    //调用SellBookRunnable（Runnable接口实现类）模拟售书过程
    public static void callSellBookRunnable() {
        List <Book>bookList = getBookListForSale();
        
        //将预售书籍清单交给售货员SaleMan1
        Thread t1 = new Thread(new SellBookRunnable("SaleMan1", bookList));
        //将预售书籍清单交给售货员SaleMan2
        Thread t2 = new Thread(new SellBookRunnable("SaleMan2", bookList));

        //售货员SaleMan1开始售书
        t1.start();
        //售货员SaleMan2开始售书
        t2.start();
    }

    //准备预售书籍
    public static List<Book> getBookListForSale() {
        List <Book>bookList = new ArrayList();
        for (int i = 0; i < 20; i++) {
            Book book = new Book("Book" + i);
            bookList.add(book);
        }
        
        return bookList;
    }
}