Netbeans 中 jPanel 中的 2D 图形

Question

我有一个关于一些原始图形的问题。 我对 Java 图形和 GUI 构建总体来说是新手，所以我收到了很多问题。
我正在使用 Netbeans 6.9.1。基本上，有一个主框架和一个面板。我想在面板内绘制一个图表。嗯，问题是这样做吗？下面是三个类的代码（大部分是自动生成的）：

   package graphics;

import org.jdesktop.application.Action;
import org.jdesktop.application.ResourceMap;
import org.jdesktop.application.SingleFrameApplication;
import org.jdesktop.application.FrameView;
import org.jdesktop.application.TaskMonitor;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.Timer;
import javax.swing.Icon;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JPanel;
/**
 * The application's main frame.
 */
public class GraphicsView extends FrameView {

public GraphicsView(SingleFrameApplication app) {
    super(app);

    initComponents();

    jPanel1.add(new Graph());

    // status bar initialization - message timeout, idle icon and busy animation, etc
    ResourceMap resourceMap = getResourceMap();
    int messageTimeout = resourceMap.getInteger("StatusBar.messageTimeout");
    messageTimer = new Timer(messageTimeout, new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            statusMessageLabel.setText("");
        }
    });
    messageTimer.setRepeats(false);
    int busyAnimationRate = resourceMap.getInteger("StatusBar.busyAnimationRate");
    for (int i = 0; i < busyIcons.length; i++) {
        busyIcons[i] = resourceMap.getIcon("StatusBar.busyIcons[" + i + "]");
    }
    busyIconTimer = new Timer(busyAnimationRate, new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            busyIconIndex = (busyIconIndex + 1) % busyIcons.length;
            statusAnimationLabel.setIcon(busyIcons[busyIconIndex]);
        }
    });
    idleIcon = resourceMap.getIcon("StatusBar.idleIcon");
    statusAnimationLabel.setIcon(idleIcon);
    progressBar.setVisible(false);

    // connecting action tasks to status bar via TaskMonitor
    TaskMonitor taskMonitor = new TaskMonitor(getApplication().getContext());
    taskMonitor.addPropertyChangeListener(new java.beans.PropertyChangeListener() {
        public void propertyChange(java.beans.PropertyChangeEvent evt) {
            String propertyName = evt.getPropertyName();
            if ("started".equals(propertyName)) {
                if (!busyIconTimer.isRunning()) {
                    statusAnimationLabel.setIcon(busyIcons[0]);
                    busyIconIndex = 0;
                    busyIconTimer.start();
                }
                progressBar.setVisible(true);
                progressBar.setIndeterminate(true);
            } else if ("done".equals(propertyName)) {
                busyIconTimer.stop();
                statusAnimationLabel.setIcon(idleIcon);
                progressBar.setVisible(false);
                progressBar.setValue(0);
            } else if ("message".equals(propertyName)) {
                String text = (String)(evt.getNewValue());
                statusMessageLabel.setText((text == null) ? "" : text);
                messageTimer.restart();
            } else if ("progress".equals(propertyName)) {
                int value = (Integer)(evt.getNewValue());
                progressBar.setVisible(true);
                progressBar.setIndeterminate(false);
                progressBar.setValue(value);
            }
        }
    });
}

@Action
public void showAboutBox() {
    if (aboutBox == null) {
        JFrame mainFrame = GraphicsApp.getApplication().getMainFrame();
        aboutBox = new GraphicsAboutBox(mainFrame);
        aboutBox.setLocationRelativeTo(mainFrame);
    }
    GraphicsApp.getApplication().show(aboutBox);
}

/** This method is called from within the constructor to
 * initialize the form.
 * WARNING: Do NOT modify this code. The content of this method is
 * always regenerated by the Form Editor.
 */
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {

    mainPanel = new javax.swing.JPanel();
    jPanel1 = new javax.swing.JPanel();
    menuBar = new javax.swing.JMenuBar();
    javax.swing.JMenu fileMenu = new javax.swing.JMenu();
    javax.swing.JMenuItem exitMenuItem = new javax.swing.JMenuItem();
    javax.swing.JMenu helpMenu = new javax.swing.JMenu();
    javax.swing.JMenuItem aboutMenuItem = new javax.swing.JMenuItem();
    statusPanel = new javax.swing.JPanel();
    javax.swing.JSeparator statusPanelSeparator = new javax.swing.JSeparator();
    statusMessageLabel = new javax.swing.JLabel();
    statusAnimationLabel = new javax.swing.JLabel();
    progressBar = new javax.swing.JProgressBar();

    mainPanel.setName("mainPanel"); // NOI18N

    jPanel1.setName("jPanel1"); // NOI18N

    javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
    jPanel1.setLayout(jPanel1Layout);
    jPanel1Layout.setHorizontalGroup(
        jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 380, Short.MAX_VALUE)
    );
    jPanel1Layout.setVerticalGroup(
        jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 229, Short.MAX_VALUE)
    );

    javax.swing.GroupLayout mainPanelLayout = new javax.swing.GroupLayout(mainPanel);
    mainPanel.setLayout(mainPanelLayout);
    mainPanelLayout.setHorizontalGroup(
        mainPanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(mainPanelLayout.createSequentialGroup()
            .addContainerGap()
            .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
            .addContainerGap())
    );
    mainPanelLayout.setVerticalGroup(
        mainPanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(mainPanelLayout.createSequentialGroup()
            .addContainerGap()
            .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
            .addContainerGap())
    );

    menuBar.setName("menuBar"); // NOI18N

    org.jdesktop.application.ResourceMap resourceMap = org.jdesktop.application.Application.getInstance(graphics.GraphicsApp.class).getContext().getResourceMap(GraphicsView.class);
    fileMenu.setText(resourceMap.getString("fileMenu.text")); // NOI18N
    fileMenu.setName("fileMenu"); // NOI18N

    javax.swing.ActionMap actionMap = org.jdesktop.application.Application.getInstance(graphics.GraphicsApp.class).getContext().getActionMap(GraphicsView.class, this);
    exitMenuItem.setAction(actionMap.get("quit")); // NOI18N
    exitMenuItem.setName("exitMenuItem"); // NOI18N
    fileMenu.add(exitMenuItem);

    menuBar.add(fileMenu);

    helpMenu.setText(resourceMap.getString("helpMenu.text")); // NOI18N
    helpMenu.setName("helpMenu"); // NOI18N

    aboutMenuItem.setAction(actionMap.get("showAboutBox")); // NOI18N
    aboutMenuItem.setName("aboutMenuItem"); // NOI18N
    helpMenu.add(aboutMenuItem);

    menuBar.add(helpMenu);

    statusPanel.setName("statusPanel"); // NOI18N

    statusPanelSeparator.setName("statusPanelSeparator"); // NOI18N

    statusMessageLabel.setName("statusMessageLabel"); // NOI18N

    statusAnimationLabel.setHorizontalAlignment(javax.swing.SwingConstants.LEFT);
    statusAnimationLabel.setName("statusAnimationLabel"); // NOI18N

    progressBar.setName("progressBar"); // NOI18N

    javax.swing.GroupLayout statusPanelLayout = new javax.swing.GroupLayout(statusPanel);
    statusPanel.setLayout(statusPanelLayout);
    statusPanelLayout.setHorizontalGroup(
        statusPanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addComponent(statusPanelSeparator, javax.swing.GroupLayout.DEFAULT_SIZE, 400, Short.MAX_VALUE)
        .addGroup(statusPanelLayout.createSequentialGroup()
            .addContainerGap()
            .addComponent(statusMessageLabel)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 230, Short.MAX_VALUE)
            .addComponent(progressBar, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
            .addComponent(statusAnimationLabel)
            .addContainerGap())
    );
    statusPanelLayout.setVerticalGroup(
        statusPanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(statusPanelLayout.createSequentialGroup()
            .addComponent(statusPanelSeparator, javax.swing.GroupLayout.PREFERRED_SIZE, 2, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
            .addGroup(statusPanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                .addComponent(statusMessageLabel)
                .addComponent(statusAnimationLabel)
                .addComponent(progressBar, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
            .addGap(3, 3, 3))
    );

    setComponent(mainPanel);
    setMenuBar(menuBar);
    setStatusBar(statusPanel);
}// </editor-fold>

// Variables declaration - do not modify
private javax.swing.JPanel jPanel1;
private javax.swing.JPanel mainPanel;
private javax.swing.JMenuBar menuBar;
private javax.swing.JProgressBar progressBar;
private javax.swing.JLabel statusAnimationLabel;
private javax.swing.JLabel statusMessageLabel;
private javax.swing.JPanel statusPanel;
// End of variables declaration

private final Timer messageTimer;
private final Timer busyIconTimer;
private final Icon idleIcon;
private final Icon[] busyIcons = new Icon[15];
private int busyIconIndex = 0;

private JDialog aboutBox;
}

所以，这里我只添加了

jPanel1.add(new Graph());

下一个是主类：

package graphics;

import org.jdesktop.application.Application;
import org.jdesktop.application.SingleFrameApplication;

/**
* The main class of the application.
*/
public class GraphicsApp extends SingleFrameApplication {

/**
 * At startup create and show the main frame of the application.
 */
@Override protected void startup() {
    show(new GraphicsView(this));
}

/**
 * This method is to initialize the specified window by injecting resources.
 * Windows shown in our application come fully initialized from the GUI
 * builder, so this additional configuration is not needed.
 */
@Override protected void configureWindow(java.awt.Window root) {
}

/**
 * A convenient static getter for the application instance.
 * @return the instance of GraphicsApp
 */
public static GraphicsApp getApplication() {
    return Application.getInstance(GraphicsApp.class);
}

/**
 * Main method launching the application.
 */
public static void main(String[] args) {
    launch(GraphicsApp.class, args);
}
}

最后一个类是图形本身：

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
*/

package graphics;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Line2D;
import javax.swing.JPanel;

public class Graph extends JPanel{

int[] data = {
    21, 14, 18, 03, 86, 88, 74, 87, 54, 77,
    61, 55, 48, 60, 49, 36, 38, 27, 20, 18
};
final int PAD = 20;

 protected void paintComponent(Graphics g) {
    super.paintComponent(g);
    Graphics2D g2 = (Graphics2D)g;
    g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                        RenderingHints.VALUE_ANTIALIAS_ON);
    int w = getWidth();
    int h = getHeight();
    // Draw ordinate.
    g2.draw(new Line2D.Double(PAD, PAD, PAD, h-PAD));
    // Draw abcissa.
    g2.draw(new Line2D.Double(PAD, h-PAD, w-PAD, h-PAD));
    double xInc = (double)(w - 2*PAD)/(data.length-1);
    double scale = (double)(h - 2*PAD)/getMax();
    // Mark data points.
    g2.setPaint(Color.red);
    for(int i = 0; i < data.length; i++) {
        double x = PAD + i*xInc;
        double y = h - PAD - scale*data[i];
        g2.fill(new Ellipse2D.Double(x-2, y-2, 4, 4));
    }
}

private int getMax() {
    int max = -Integer.MAX_VALUE;
    for(int i = 0; i < data.length; i++) {
        if(data[i] > max)
            max = data[i];
    }
    return max;
}
}

我有几个问题：
(a) 如何让图表出现在 jPanel1 中？
(b) 初始化图形组件有哪些好的做法？我的意思是，调用 graph() 的最佳位置在哪里？
(c) 对于不同的应用程序，我使用 jfreechart 绘制图表，然后将它们转储到 .jpeg 文件。我可以使用 jfreechart 构建图表并直接在 pagel 中显示它吗？

预先非常感谢您！

Answer 1

一些答案：

(a) 让 jPanel1 使用 BorderLayout 作为其布局管理器，并将图形 JPanel 添加到 jPanel1 的 BorderLayout.CENTER 位置。
(b) 我不清楚你在这里问什么。您可以在需要时构造一个对象。
(c) 是的。 JFreeChart 的图形组件扩展了 Swing 组件，我相信 JPanel（无论是 JPanel 还是 JComponent），因此您应该能够将它们作为组件直接添加到 GUI 中，只要（这是关键）您的组件充当容器，持有图表的人使用正确的布局管理器。如果您还没有这样做，您应该阅读有关“在容器中布局组件”的 Swing 教程，因为它的信息是成功的关键。

我的最终建议（目前）是放弃 NetBeans 代码生成并手动创建 Swing 代码。这确实是学习 Swing 的最佳方式。

运气！