Java 自定义蛛网图并输出图片

要自定义蛛网图并输出图片，可以使用Java的图形库JFreeChart和Apache Batik。

首先，需要创建一个JFreeChart对象，并设置图表的类型和标题等属性。然后，创建一个SpiderWebPlot对象，并设置蛛网图的各项属性，如最大值、分类标签、数据集等。接着，将SpiderWebPlot对象添加到JFreeChart对象中，并设置图例、背景色等属性。

最后，使用Batik库将JFreeChart对象输出为PNG或SVG格式的图片。以下是示例代码：

import java.awt.Color;
import java.awt.Font;
import java.io.File;
import java.io.FileOutputStream;
import org.apache.batik.dom.GenericDOMImplementation;
import org.apache.batik.svggen.SVGGeneratorContext;
import org.apache.batik.svggen.SVGGraphics2D;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.plot.SpiderWebPlot;
import org.jfree.data.category.DefaultCategoryDataset;
import org.w3c.dom.DOMImplementation;
import org.w3c.dom.Document;

public class SpiderWebChart {

    public static void main(String[] args) {
        // create dataset
        DefaultCategoryDataset dataset = new DefaultCategoryDataset();
        dataset.addValue(5.0, "Series 1", "Factor 1");
        dataset.addValue(7.0, "Series 1", "Factor 2");
        dataset.addValue(6.0, "Series 1", "Factor 3");
        dataset.addValue(8.0, "Series 1", "Factor 4");
        dataset.addValue(4.0, "Series 1", "Factor 5");
        
        // create spider web plot
        SpiderWebPlot plot = new SpiderWebPlot(dataset);
        plot.setMaxValue(10);
        plot.setWebFilled(true);
        plot.setToolTipGenerator(null);
        plot.setOutlinePaint(Color.BLACK);
        plot.setSeriesPaint(0, Color.RED);
        plot.setLabelFont(new Font("Arial", Font.PLAIN, 12));
        
        // create chart
        JFreeChart chart = ChartFactory.createSpiderWebChart("Title", dataset, true, false, false);
        chart.setBackgroundPaint(Color.WHITE);
        chart.addSubtitle("Subtitle");
        chart.getLegend().setItemFont(new Font("Arial", Font.PLAIN, 12));
        chart.getLegend().setFrame(BlockBorder.NONE);
        chart.getPlot().setBackgroundPaint(Color.WHITE);
        chart.getPlot().setOutlinePaint(null);
        chart.getPlot().setForegroundAlpha(0.5f);
        chart.getPlot().setNoDataMessage("No data available");
        chart.getPlot().setNoDataMessageFont(new Font("Arial", Font.PLAIN, 12));
        chart.getPlot().setNoDataMessagePaint(Color.RED);
        chart.getPlot().setInsets(new RectangleInsets(10, 10, 10, 10));
        chart.getXYPlot().setDomainGridlinePaint(Color.GRAY);
        chart.getXYPlot().setRangeGridlinePaint(Color.GRAY);
        chart.getXYPlot().setDomainGridlineStroke(new BasicStroke(0.5f));
        chart.getXYPlot().setRangeGridlineStroke(new BasicStroke(0.5f));
        
        // output as PNG
        try {
            FileOutputStream fos = new FileOutputStream(new File("chart.png"));
            ChartUtilities.writeChartAsPNG(fos, chart, 500, 400);
            fos.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        
        // output as SVG
        try {
            DOMImplementation domImpl = GenericDOMImplementation.getDOMImplementation();
            Document document = domImpl.createDocument(null, "svg", null);
            SVGGeneratorContext ctx = SVGGeneratorContext.createDefault(document);
            SVGGraphics2D g2 = new SVGGraphics2D(ctx, false);
            chart.draw(g2, new Rectangle2D.Double(0, 0, 500, 400), null);
            FileOutputStream fos = new FileOutputStream(new File("chart.svg"));
            OutputStreamWriter osw = new OutputStreamWriter(fos, "UTF-8");
            g2.stream(osw, true);
            osw.flush();
            osw.close();
            fos.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}

这里创建了一个包含5个分类和1个系列的蛛网图，并输出为PNG和SVG格式的图片。你可以根据需要修改数据集和图表属性。