写优先的读者写者问题（Java实现）

starry宇

于 2022-03-01 23:53:35 发布

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文章标签： java 开发语言学习 intellij idea

本文链接：https://blog.youkuaiyun.com/starry_yu/article/details/123219393

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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() {
            @Override
            public void actionPerformed(ActionEvent e) {
                new Thread(new Read(reader)).start();
                reader++;
            }
        });
        jButton2.addActionListener(new ActionListener() {
            @Override
            public 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count
                    if(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