Java按钮点击后卡死问题

Question

client.java

package ChatExtends;
import java.awt.Color;
import java.awt.Container;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;

public class LoginWindow extends JFrame {

    User u = new User();

    public void Load() throws Exception{

        this.setName("Login");

        this.setLayout(null);

        this.setSize(600,600);

        this.setResizable(false);

        this.setLocationRelativeTo(null);

        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        Container ct = this.getContentPane();

        JPanel jp1 = new JPanel();

        JPanel jp2 = new JPanel();

        JPanel jp3 = new JPanel();

        JPanel jp4 = new JPanel();

        jp1.setSize(600, 150);

        jp2.setBounds(0,150,500,300);

        GridLayout gy = new GridLayout(4,1,5,5);

        this.setLayout(gy);

        jp4.setLayout(new GridLayout(1,2,5,5));

        jp4.setSize(600,150);

        Font f = new Font("Blackletter",Font.ITALIC,100);

        JLabel name = new JLabel("ChatW");

        name.setFont(f);

        name.setBounds(100,300,600,300);

        name.setForeground(Color.blue);

        name.setVisible(true);

        jp1.add(name);

        JLabel l = new JLabel();

        ImageIcon ic1 = new ImageIcon("images/login.png");

        l.setIcon(ic1);

        //l.setBounds(0, 100, ic1.getIconWidth(), ic1.getIconHeight());

        l.setVisible(true);

        l.setHorizontalAlignment(SwingConstants.CENTER);

        l.setVerticalAlignment(SwingConstants.CENTER);

        JTextField text1 = new JTextField(15);

        u.name = text1.getText();

        text1.setBorder(null);

        text1.setVisible(true);

        JLabel l1 = new JLabel();

        ImageIcon ic2 = new ImageIcon("images/lock.png");

        l1.setIcon(ic2);

        //l1.setBounds(0,300,ic2.getIconWidth(),ic2.getIconHeight());

        l1.setVisible(true);

        l1.setHorizontalAlignment(SwingConstants.CENTER);

        l1.setVerticalAlignment(SwingConstants.CENTER);

        JPasswordField jf = new JPasswordField(15);

        u.pass = Encryted.FinalEncrypted(new String(jf.getPassword()));

        jf.setBorder(null);

        //jf.setBounds(50,300,200,100);

        Font b = new Font("Arial",Font.ITALIC,50);

        JButton jb1 = new JButton("Login");

        jb1.setFont(b);

        jb1.setBorder(null);

        jb1.setFocusPainted(false);

        jb1.setVisible(true);

        jb1.addActionListener(new ActionListener() {

            public void actionPerformed(ActionEvent e) {

                UserOperation t = new UserOperation();

                try {
                    
                    if(t.CheckUser(u.name, u.pass)) {

                        ImageIcon i1 = new ImageIcon("../images/correct.png");

                        JOptionPane.showMessageDialog(null, "Login Success!","",JOptionPane.INFORMATION_MESSAGE,i1);

                    } else {

                        ImageIcon i2 = new ImageIcon("../images/error.png");

                        JOptionPane.showMessageDialog(null,"Login Failed!The login or password is incorrect!","",JOptionPane.INFORMATION_MESSAGE,i2);

                    }

                } catch (Exception r) {

                    r.printStackTrace();

                }

            }

        });

        JButton jb2 = new JButton("Register");

        jb2.setFont(b);

        jb2.setBorder(null);

        jb2.setFocusPainted(false);

        jb2.setVisible(true);

        jp4.add(jb1);

        jp4.add(jb2);

        jp2.add(l);

        jp2.add(text1);

        jp3.add(l1);

        jp3.add(jf);

        jp2.setVisible(true);

        this.add(jp1);

        this.add(jp2);

        this.add(jp3);

        this.add(jp4);

        this.setVisible(true);

        ct.add(jp1,"North");

        ct.add(jp2,"Center");

        ct.add(jp3,"Center");

        ct.add(jp4,"South");

    }

    
}

class User {

    String id;

    String name;

    String pass;

}

UserOperation.java

package ChatExtends;

import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.Properties;
import java.util.Random;

public class UserOperation {

    InputStream inputs = this.getClass().getResourceAsStream("../conf/server.properties");

    Properties p = new Properties();

    
    public boolean CheckUser(String name,String pass) throws Exception{

        boolean flag = false;

        Class.forName("com.mysql.cj.jdbc.Driver");

        p.load(inputs);

        String DBHost = p.getProperty("sqlhost");

        String DBName = p.getProperty("sqldata");

        String DBUser = p.getProperty("sqluser");

        String DBPass = p.getProperty("sqlpass");

        String sqlurl = "jdbc:mysql://" + DBHost + "/" + DBName;

        Connection connect = DriverManager.getConnection(sqlurl,DBUser,DBPass);
        
        String SQLSelectName = "select ? from UserInformation";

        String SQLSelectPass = "select Pass from UserInformation where Name = ?";

        String SQLCheckAvailable = "select Available from UserInformation where name = ?";

        PreparedStatement pre1 = connect.prepareStatement(SQLSelectName);

        pre1.setString(1,name);

        PreparedStatement pre2 = connect.prepareStatement(SQLSelectPass);

        pre2.setString(1,name);

        PreparedStatement pre3 = connect.prepareStatement(SQLCheckAvailable);

        pre3.setString(1,name);

        ResultSet rs1 = pre1.executeQuery();

        ResultSet rs2 = pre2.executeQuery();

        ResultSet rs3 = pre3.executeQuery();

        if(rs1.next() && rs2.next()) {

            if(rs2.getString("Pass") == Encryted.FinalEncrypted(pass) && rs3.getString("Available") == "YES") {

                flag = true;

            } else {

                flag = false;

            }

        } else {

            flag = false;

        }

        return flag;

    }

    public boolean addUser(String name,String password) throws Exception{

        boolean r = false;

        String Id = RandomString();

        String epass = Encryted.FinalEncrypted(password);

        p.load(inputs);

        String DBHost = p.getProperty("sqlhost");

        String DBName = p.getProperty("sqldata");

        String DBUser = p.getProperty("sqluser");

        String DBPass = p.getProperty("sqlpass");

        String sqlurl = "jdbc:mysql://" + DBHost + "/" + DBName;

        Connection con2 = DriverManager.getConnection(sqlurl,DBUser,DBPass);

        String regist = "insert into UserInformation values(?,?,?,?)";
        
        PreparedStatement pre = con2.prepareCall(regist);

        pre.setString(1,Id);

        pre.setString(2,name);

        pre.setString(3,epass);

        pre.setString(4,"Yes");

        if(pre.executeUpdate() > 0) {

            r = true;

        } else {

            r = false;


        }

        return r;
    }

    public String RandomString() {

        String LetterInUpperCase = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

        String LetterInLowerCase = "abcdefghijklmnopqrstuvwxyz";

        String Numbers = "0123456789";

        String All = LetterInUpperCase + LetterInLowerCase + Numbers;

        StringBuffer RandString = new StringBuffer();

        for(int g = 0;g < 10;g++) {

            Random rand = new Random();

            int RandIndex = rand.nextInt(g);

            RandString.append(All.charAt(RandIndex));

        }

        return RandString.toString();
        

    }
     

}

上面的代码可以怎么优化，让按钮点击不卡死呢

Answer 1

该回答引用自GPT-3.5, 由博主 GISer Liu 编写：

问题分析

用户遇到的问题是点击按钮后程序卡死。这种情况通常是由于在事件处理线程（Event Dispatch Thread, EDT）中执行了耗时操作，导致界面无法响应。在Java Swing中，所有与界面相关的操作都应该在EDT中进行，而耗时操作应该放在单独的线程中执行，以避免阻塞EDT。

解决方案

为了解决按钮点击后卡死的问题，我们需要将耗时的用户验证操作放在一个单独的线程中执行。可以使用Java的SwingWorker类来实现这一点。SwingWorker类允许在后台线程中执行耗时操作，并在操作完成后更新UI。

修改步骤

1. 引入SwingWorker类：在LoginWindow类中引入SwingWorker。
2. 重构actionPerformed方法：将用户验证操作放在SwingWorker中执行。

修改后的代码

package ChatExtends;

import java.awt.Color;
import java.awt.Container;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;

public class LoginWindow extends JFrame {

    User u = new User();

    public void Load() throws Exception {
        this.setName("Login");
        this.setLayout(null);
        this.setSize(600, 600);
        this.setResizable(false);
        this.setLocationRelativeTo(null);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        Container ct = this.getContentPane();

        JPanel jp1 = new JPanel();
        JPanel jp2 = new JPanel();
        JPanel jp3 = new JPanel();
        JPanel jp4 = new JPanel();

        jp1.setSize(600, 150);
        jp2.setBounds(0, 150, 500, 300);

        GridLayout gy = new GridLayout(4, 1, 5, 5);
        this.setLayout(gy);

        jp4.setLayout(new GridLayout(1, 2, 5, 5));
        jp4.setSize(600, 150);

        Font f = new Font("Blackletter", Font.ITALIC, 100);
        JLabel name = new JLabel("ChatW");
        name.setFont(f);
        name.setBounds(100, 300, 600, 300);
        name.setForeground(Color.blue);
        name.setVisible(true);
        jp1.add(name);

        JLabel l = new JLabel();
        ImageIcon ic1 = new ImageIcon("images/login.png");
        l.setIcon(ic1);
        l.setVisible(true);
        l.setHorizontalAlignment(SwingConstants.CENTER);
        l.setVerticalAlignment(SwingConstants.CENTER);

        JTextField text1 = new JTextField(15);
        u.name = text1.getText();
        text1.setBorder(null);
        text1.setVisible(true);

        JLabel l1 = new JLabel();
        ImageIcon ic2 = new ImageIcon("images/lock.png");
        l1.setIcon(ic2);
        l1.setVisible(true);
        l1.setHorizontalAlignment(SwingConstants.CENTER);
        l1.setVerticalAlignment(SwingConstants.CENTER);

        JPasswordField jf = new JPasswordField(15);
        u.pass = Encryted.FinalEncrypted(new String(jf.getPassword()));
        jf.setBorder(null);

        Font b = new Font("Arial", Font.ITALIC, 50);
        JButton jb1 = new JButton("Login");
        jb1.setFont(b);
        jb1.setBorder(null);
        jb1.setFocusPainted(false);
        jb1.setVisible(true);
        jb1.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                new LoginWorker(u.name, u.pass).execute();
            }
        });

        JButton jb2 = new JButton("Register");
        jb2.setFont(b);
        jb2.setBorder(null);
        jb2.setFocusPainted(false);
        jb2.setVisible(true);

        jp4.add(jb1);
        jp4.add(jb2);
        jp2.add(l);
        jp2.add(text1);
        jp3.add(l1);
        jp3.add(jf);
        jp2.setVisible(true);

        this.add(jp1);
        this.add(jp2);
        this.add(jp3);
        this.add(jp4);
        this.setVisible(true);

        ct.add(jp1, "North");
        ct.add(jp2, "Center");
        ct.add(jp3, "Center");
        ct.add(jp4, "South");
    }

    private class LoginWorker extends SwingWorker<Boolean, Void> {
        private String name;
        private String pass;

        public LoginWorker(String name, String pass) {
            this.name = name;
            this.pass = pass;
        }

        @Override
        protected Boolean doInBackground() throws Exception {
            UserOperation t = new UserOperation();
            return t.CheckUser(name, pass);
        }

        @Override
        protected void done() {
            try {
                boolean result = get();
                if (result) {
                    ImageIcon i1 = new ImageIcon("../images/correct.png");
                    JOptionPane.showMessageDialog(null, "Login Success!", "", JOptionPane.INFORMATION_MESSAGE, i1);
                } else {
                    ImageIcon i2 = new ImageIcon("../images/error.png");
                    JOptionPane.showMessageDialog(null, "Login Failed! The login or password is incorrect!", "", JOptionPane.INFORMATION_MESSAGE, i2);
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
}

class User {
    String id;
    String name;
    String pass;
}

解释

1. 引入SwingWorker类：在LoginWindow类中引入SwingWorker类。
2. 创建LoginWorker类：这是一个内部类，继承自SwingWorker，用于在后台线程中执行用户验证操作。
3. 重构actionPerformed方法：在按钮的ActionListener中，创建一个LoginWorker实例并调用execute()方法，这将启动后台线程执行用户验证操作。
4. 实现doInBackground方法：在LoginWorker类中，重写doInBackground方法，执行耗时的用户验证操作。
5. 实现done方法：在LoginWorker类中，重写done方法，在用户验证操作完成后更新UI。

通过这些修改，按钮点击后将不会卡死，因为耗时的用户验证操作在后台线程中执行，不会阻塞EDT。

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