java - 从 Controller 方法更新面板

Question

我想从我的 Controller 更新我的主机上的面板(在类 GUI 中)。基本上，每个模拟步骤都应该更新面板。

    for (int step = 0; step < simSteps; step++){
         this.gui.updateGUI(this.stats, step);
    }

在我的 GUI 类中，方法 updateGUI(...) 如下所示:

 public void updateGUI(Stats stats, int step){
     this.stats = stats;
     getContentPane().remove(pollutionPanel);
     pollutionPanel = new BarPanel(settings, stats, possibleColors);
     getContentPane().add(pollutionPanel);
     validate();
     repaint();
 }

我的 BarPanel 类重写了paintComponent 方法，我只是使用图形对象来绘制一些东西。开始模拟时，面板仅在最后一个模拟步骤后更新，尽管我已经知道在每个模拟步骤中都会调用 updateGUI() 方法(我做了一些调试输出)。

有人知道为什么会发生这种情况吗？

Answer 1

所以，基本概念是，您想要生成一些动画，UI 在一段时间内更新。这并不是一个罕见的请求，有很多例子。

注意事项:

• Swing 是单线程的
• 不要做任何可能阻塞事件调度线程的事情，这将阻止 UI 更新，直到控制权传回给它为止
• 不要在 EDT 上下文之外更新 UI

好吧，这听起来有点矛盾，但是 Swing 提供了一些工具来让您的生活更轻松

你可以...

使用SwingWorker

import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.List;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingWorker;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Test {

    public static void main(String[] args) {
        new Test();
    }

    public Test() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new TestPane());
                frame.setSize(400, 400);
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public interface StepContainer {

        public void addStep(int index);
    }

    public class TestPane extends JPanel implements StepContainer {

        private int step = 0;

        public TestPane() {
            setLayout(new GridBagLayout());
            PopulateWorker worker = new PopulateWorker(10, this);
            worker.execute();
        }

        @Override
        public void addStep(int step) {
            JButton btn = new JButton(Integer.toString(step));
            GridBagConstraints gbc = new GridBagConstraints();
            gbc.gridwidth = GridBagConstraints.REMAINDER;

            add(btn, gbc);
            revalidate();
            repaint();
        }

    }

    public class PopulateWorker extends SwingWorker<Void, Integer> {

        private int steps;
        private StepContainer parent;

        public PopulateWorker(int steps, StepContainer parent) {
            this.steps = steps;
            this.parent = parent;
        }

        @Override
        protected Void doInBackground() throws Exception {
            Thread.sleep(1000);
            for (int index = 0; index < steps; index++) {
                publish(index);
                Thread.sleep(1000);
            }
            return null;
        }

        @Override
        protected void process(List<Integer> chunks) {
            for (int step : chunks) {
                parent.addStep(step);
            }
        }

    }

}

使用 Swing 计时器

import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.List;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingWorker;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Test {

    public static void main(String[] args) {
        new Test();
    }

    public Test() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new TestPane());
                frame.setSize(400, 400);
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public interface StepContainer {

        public void addStep(int index);
    }

    public class TestPane extends JPanel implements StepContainer {

        private int step = 0;

        public TestPane() {
            setLayout(new GridBagLayout());
            Timer timer = new Timer(1000, new PopulateAction(10, this));
            timer.start();
        }

        @Override
        public void addStep(int step) {
            JButton btn = new JButton(Integer.toString(step));
            GridBagConstraints gbc = new GridBagConstraints();
            gbc.gridwidth = GridBagConstraints.REMAINDER;

            add(btn, gbc);
            revalidate();
            repaint();
        }

    }

    public class PopulateAction implements ActionListener {

        private int steps;
        private StepContainer parent;
        private int step;

        public PopulateAction(int steps, StepContainer parent) {
            this.steps = steps;
            this.parent = parent;
        }

        @Override
        public void actionPerformed(ActionEvent e) {
            parent.addStep(step);
            if (step == steps - 1) {
                ((Timer) e.getSource()).stop();
                step = 0;
            }
            step++;
        }
    }
}

您使用哪个取决于问题的复杂程度，SwingWorker使用它自己的Thread来调用doInBackground，允许您处理时间消耗任务，但提供安全更新 UI 的能力。

Timer 在 EDT 上下文中触发其更新，使其保存以更新 UI，但不执行耗时的任务