以下是一个使用Java编写的生成饼图的简单示例:
import javax.swing.*;
import java.awt.*;
import java.awt.geom.*;
public class PieChart extends JPanel {
private double[] values;
private String[] labels;
private Color[] colors;
public PieChart(double[] values, String[] labels, Color[] colors) {
this.values = values;
this.labels = labels;
this.colors = colors;
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
int width = getWidth();
int height = getHeight();
int radius = Math.min(width, height) / 2;
int centerX = width / 2;
int centerY = height / 2;
double total = 0;
for (double value : values) {
total += value;
}
double startAngle = 0;
for (int i = 0; i < values.length; i++) {
double arcAngle = values[i] / total * 360;
g2d.setColor(colors[i]);
g2d.fill(new Arc2D.Double(centerX - radius, centerY - radius, 2 * radius, 2 * radius, startAngle, arcAngle, Arc2D.PIE));
startAngle += arcAngle;
}
int legendX = centerX + radius + 10;
int legendY = centerY - radius;
for (int i = 0; i < labels.length; i++) {
g2d.setColor(colors[i]);
g2d.fillRect(legendX, legendY + i * 20, 10, 10);
g2d.setColor(Color.BLACK);
g2d.drawString(labels[i], legendX + 15, legendY + i * 20 + 10);
}
}
public static void main(String[] args) {
double[] values = {30, 20, 10, 40};
String[] labels = {"Label 1", "Label 2", "Label 3", "Label 4"};
Color[] colors = {Color.RED, Color.GREEN, Color.BLUE, Color.ORANGE};
JFrame frame = new JFrame("Pie Chart");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(300, 300);
frame.setLocationRelativeTo(null);
PieChart chart = new PieChart(values, labels, colors);
frame.add(chart);
frame.setVisible(true);
}
}
在示例中,我们创建了一个继承自JPanel的类PieChart,用于绘制饼图。构造函数接受三个参数:饼图的值、标签和颜色。我们重写了paintComponent方法,在该方法中进行绘图操作。
在paintComponent方法中,我们首先获取组件的宽度、高度和半径。然后,计算出总和值total。接下来,使用Arc2D.Double类绘制每个饼块,并根据值的比例计算出饼块的角度。最后,我们绘制图例,显示每个饼块对应的标签和颜色。
在main方法中,我们创建了一个JFrame窗口,并将创建的PieChart实例添加到窗口中显示出来。
你可以根据需要修改值、标签和颜色,以及窗口的大小。运行程序后,将会显示一个饼图。