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该题系吉林大学19级软件学院操作系统课设题之一
先输入初始时的写者读者情况，优先级顺序做了随机处理
代码如下
GUI：
import javax.swing.*;
import javax.swing.border.Border;
import javax.swing.text.BadLocationException;
import javax.swing.text.SimpleAttributeSet;
import javax.swing.text.StyleConstants;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.LinkedList;
import java.util.concurrent.Semaphore;public class ReadAndWrite extends JFrame {public static Semaphore rw = new Semaphore(1);public static Semaphore mutex = new Semaphore(1);public static Semaphore w = new Semaphore(1);public static Semaphore fresh = new Semaphore(1);public static int count = 0;public static LinkedList<String> Re = new LinkedList<String>();//读空间public static LinkedList<String> Wr = new LinkedList<String>();//写空间public static LinkedList<String> ing = new LinkedList<String>();//正在的状态private int reader = 0;//写者数量和编号记录private int writer = 0;//读者数量和编号记录//三个大的文本区域static JTextPane jTextPane1 = new JTextPane();//读static JTextPane jTextPane2 = new JTextPane();//文件static JTextPane jTextPane3 = new JTextPane();//写ReadAndWrite(int a, int b){super("写优先的读者写者问题");reader = a+1;writer = b+1;for(int i = 1;i<=a;i++)new Thread(new Read(i)).start();for(int i = 1;i<=b;i++)new Thread(new Write(i)).start();setBounds(400,300,600,500);JPanel jPanel1 = new JPanel(new BorderLayout());//读JPanel jPanel2 = new JPanel(new BorderLayout());//临界区JPanel jPanel3 = new JPanel(new BorderLayout());//写jPanel1.setBackground(Color.CYAN);jPanel2.setBackground(Color.PINK);jPanel3.setBackground(Color.CYAN);this.add(jPanel1,BorderLayout.WEST);this.add(jPanel2,BorderLayout.CENTER);this.add(jPanel3,BorderLayout.EAST);JLabel label1 = new JLabel(" 读者 ");JLabel label2 = new JLabel(" 临界区");JLabel label3 = new JLabel(" 写者 ");label1.setFont(new Font("宋体",Font.BOLD,20));label2.setFont(new Font("宋体",Font.BOLD,20));label3.setFont(new Font("宋体",Font.BOLD,20));jPanel1.add(label1,BorderLayout.NORTH);jPanel2.add(label2,BorderLayout.NORTH);jPanel3.add(label3,BorderLayout.NORTH);jTextPane2.setLayout(new FlowLayout(FlowLayout.CENTER));//没起作用jTextPane1.setEditable(false);//禁止编辑jTextPane2.setEditable(false);jTextPane3.setEditable(false);//三个大的文本区域jTextPane1.setFont(new Font("宋体",Font.BOLD,16));jTextPane2.setFont(new Font("宋体",Font.BOLD,16));jTextPane3.setFont(new Font("宋体",Font.BOLD,16));jPanel1.add(new JScrollPane(jTextPane1),BorderLayout.CENTER);jPanel2.add(new JScrollPane(jTextPane2),BorderLayout.CENTER);jPanel3.add(new JScrollPane(jTextPane3),BorderLayout.CENTER);JButton jButton1 = new JButton("加入读者");JButton jButton2 = new JButton("加入写者");jButton1.addActionListener(new ActionListener() {@Overridepublic void actionPerformed(ActionEvent e) {new Thread(new Read(reader)).start();reader++;}});jButton2.addActionListener(new ActionListener() {@Overridepublic void actionPerformed(ActionEvent e) {new Thread(new Write(writer)).start();writer++;}});jPanel1.add(jButton1,BorderLayout.SOUTH);jPanel3.add(jButton2,BorderLayout.SOUTH);setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);setVisible(true);}public static void insert1(String str)//读模块的gui部分{SimpleAttributeSet set = new SimpleAttributeSet();StyleConstants.setUnderline(set, true);try{jTextPane1.getDocument().insertString(jTextPane1.getDocument().getLength(), str + "\n", set);}catch (BadLocationException e){e.printStackTrace();}}public static void insert2(String str)//被访问文件模块的gui部分{SimpleAttributeSet set = new SimpleAttributeSet();StyleConstants.setUnderline(set, true);try{jTextPane2.getDocument().insertString(jTextPane2.getDocument().getLength(), str + "\n", set);}catch (BadLocationException e){e.printStackTrace();}}public static void insert3(String str)//写模块的gui部分{SimpleAttributeSet set = new SimpleAttributeSet();StyleConstants.setUnderline(set, true);try{jTextPane3.getDocument().insertString(jTextPane3.getDocument().getLength(), str + "\n", set);}catch (BadLocationException e){e.printStackTrace();}}public static void refresh(){jTextPane1.setText(null);jTextPane2.setText(null);jTextPane3.setText(null);for(String a : Re){insert1("读者"+a);}for(String b : ing){insert2(b);}for(String c : Wr){insert3("写者"+c);}}public static void main(String[] args){int a = Integer.parseInt(JOptionPane.showInputDialog("请输入初始读者数量"));int b = Integer.parseInt(JOptionPane.showInputDialog("请输入初始写者数量"));new ReadAndWrite(a,b);
// new Thread(new Read(1)).start();
// new Thread(new Read(2)).start();
// new Thread(new Read(3)).start();
// new Thread(new Write(1)).start();
// new Thread(new Write(2)).start();}
}写者
import java.util.concurrent.Semaphore;import java.util.Random;public class Read extends Thread{private int num;Read(int num){this.num = num;}public void run() {try {synchronized(this){Random random = new Random();wait(random.nextInt(500));ReadAndWrite.insert1("读者"+num+"打算读文件");ReadAndWrite.Re.add(num+"打算读文件");ReadAndWrite.w.acquire(); //实现写有先ReadAndWrite.mutex.acquire(); //防止读者之间同步访问count，读者互斥访问countif(ReadAndWrite.count==0)ReadAndWrite.rw.acquire(); //实现读写互斥ReadAndWrite.count++; //我只要有东西正在读你，你就不许给我写东西，实现多读者同步的关键ReadAndWrite.mutex.release();ReadAndWrite.w.release();//以下为读文件的阶段ReadAndWrite.insert2("读者"+num+"正在读文件");ReadAndWrite.ing.add("读者"+num+"正在读文件");wait(random.nextInt(5000)+1500);ReadAndWrite.insert2("读者"+num+"结束读文件");ReadAndWrite.insert1("读者"+num+"完成读文件");ReadAndWrite.ing.remove("读者"+num+"正在读文件");ReadAndWrite.Re.remove(num+"打算读文件");//以上为读文件的阶段wait(3000);ReadAndWrite.fresh.acquire(); //实现刷新页面时，线程的互斥ReadAndWrite.refresh(); //刷新页面，通过队列的信息刷新页面ReadAndWrite.fresh.release();ReadAndWrite.mutex.acquire();ReadAndWrite.count--; //文件读完了，读完一个出来一个，count--了if(ReadAndWrite.count==0)ReadAndWrite.rw.release();ReadAndWrite.mutex.release();}} catch (InterruptedException e) {System.out.println("读者"+num+"出现错误！");e.printStackTrace();}}}
读者
import java.util.Random;public class Write extends Thread
{private int num;Write(int num){this.num = num;}public void run(){try{synchronized(this){Random random = new Random();wait(random.nextInt(500));ReadAndWrite.insert3("写者"+num+"打算写文件");ReadAndWrite.Wr.add(num+"打算写文件");ReadAndWrite.w.acquire();ReadAndWrite.rw.acquire();ReadAndWrite.insert2("写者"+num+"正在写文件");ReadAndWrite.ing.add("写者"+num+"正在写文件");wait(random.nextInt(10000)+3000);ReadAndWrite.insert2("写者"+num+"结束写文件");ReadAndWrite.insert3("写者"+num+"完成写文件");ReadAndWrite.ing.remove("写者"+num+"正在写文件");ReadAndWrite.Wr.remove(num+"打算写文件");wait(3000);ReadAndWrite.fresh.acquire();ReadAndWrite.refresh();//刷新页面，通过队列的信息刷新页面ReadAndWrite.fresh.release();ReadAndWrite.rw.release();ReadAndWrite.w.release();}} catch (InterruptedException e){System.out.println("写者"+num+"出现错误！");e.printStackTrace();}}
}环境：IDEA
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