Java 使用Itext8绘制蜘蛛网图

好的，我会尽力回答您的问题。

首先，需要在Java项目中引入Itext8的依赖。可以在Maven或Gradle中添加以下依赖：

<dependency>
    <groupId>com.itextpdf</groupId>
    <artifactId>itext7-core</artifactId>
    <version>7.1.14</version>
</dependency>

然后，可以使用Itext8中的Canvas类来绘制蜘蛛网图。以下是一个简单的示例代码：

import com.itextpdf.kernel.color.Color;
import com.itextpdf.kernel.pdf.canvas.PdfCanvas;
import com.itextpdf.kernel.pdf.canvas.draw.DottedLine;
import com.itextpdf.layout.Document;
import com.itextpdf.layout.element.AreaBreak;
import com.itextpdf.layout.element.Paragraph;
import com.itextpdf.layout.property.AreaBreakType;
import com.itextpdf.layout.property.TextAlignment;
import com.itextpdf.layout.property.VerticalAlignment;

import java.io.IOException;

public class SpiderChart {
    public static void main(String[] args) throws IOException {
        try (Document document = new Document()) {
            PdfCanvas canvas = new PdfCanvas(document.getPdfDocument().addNewPage());

            // 设置画布原点
            float x = 250;
            float y = 400;
            canvas.concatMatrix(1, 0, 0, 1, x, y);

            // 绘制蜘蛛网图
            int numSides = 6; // 边数
            float radius = 200; // 半径
            float angle = (float) (2 * Math.PI / numSides); // 每条边对应的角度
            float[] xPoints = new float[numSides];
            float[] yPoints = new float[numSides];
            float startAngle = (float) (-Math.PI / 2); // 起始角度
            float[] values = { 90, 70, 80, 50, 60, 75 }; // 数据值

            for (int i = 0; i < numSides; i++) {
                float currentAngle = startAngle + i * angle;
                xPoints[i] = (float) (radius * Math.cos(currentAngle));
                yPoints[i] = (float) (radius * Math.sin(currentAngle));
            }

            canvas.saveState();
            canvas.setColor(Color.BLACK, true);
            canvas.moveTo(xPoints[0], yPoints[0]);

            for (int i = 1; i < numSides; i++) {
                canvas.lineTo(xPoints[i], yPoints[i]);
            }

            canvas.closePathStroke();

            float factor = radius / values.length;
            float currentRadius = 0;

            for (int i = values.length - 1; i >= 0; i--) {
                float value = values[i];
                float currentX = xPoints[0] * value / 100;
                float currentY = yPoints[0] * value / 100;

                canvas.setLineWidth(1);
                canvas.setLineDash(8, 8);
                canvas.moveTo(0, 0);
                canvas.lineTo(currentX, currentY);
                canvas.stroke();

                canvas.setLineWidth(2);
                canvas.setLineDash(new DottedLine());
                canvas.circle(0, 0, currentRadius += factor);
                canvas.stroke();
            }

            canvas.restoreState();

            // 添加图例
            document.add(new Paragraph("图例").setTextAlignment(TextAlignment.CENTER)
                    .setVerticalAlignment(VerticalAlignment.MIDDLE).setFixedPosition(1, 50, 50, 100));

            // 添加分页符
            document.add(new AreaBreak(AreaBreakType.NEXT_PAGE));
        }
    }
}

该代码会生成一个PDF文件，其中包含一个蜘蛛网图和一个图例。您可以根据需要修改代码来调整图形的大小、颜色、边框样式等。