JFreeChart是老牌Java開源圖表工具包，也是JFreeReport的重要組成部分， 在業界被廣泛應用。當然，這個工具包依然有很多美中不足，確切的說，有很多 具體的應用還需要我們拓展，比如蜘蛛網圖（Spider Web）的刻度問題。
這是使用原來SpiderWebPlot時解決前的圖示：
下面是使用MySpiderWebPlot解決後的圖示：
MySpiderWebPlot代碼如下：
public class MySpiderWebPlot extends SpiderWebPlot {
private int ticks = DEFAULT_TICKS;
private static final int DEFAULT_TICKS = 5;
private NumberFormat format = NumberFormat.getInstance ();
private static final double PERPENDICULAR = 90;
private static final double TICK_SCALE = 0.015;
private int valueLabelGap = DEFAULT_GAP;
private static final int DEFAULT_GAP = 10;
private static final double THRESHOLD = 15;
MySpiderWebPlot(CategoryDataset createCategoryDataset) {
super(createCategoryDataset);
}
@Override
protected void drawLabel(final Graphics2D g2, final Rectangle2D plotArea, final double value,
final int cat, final double startAngle, final double extent) {
super.drawLabel(g2, plotArea, value, cat, startAngle, extent);
final FontRenderContext frc = g2.getFontRenderContext();
final double[] transformed = new double[2];
final double[] transformer = new double[2];
final Arc2D arc1 = new Arc2D.Double(plotArea, startAngle, 0, Arc2D.OPEN);
for (int i = 1; i <= ticks; i++) {
final Point2D point1 = arc1.getEndPoint ();
final double deltaX = plotArea.getCenterX ();
final double deltaY = plotArea.getCenterY ();
double labelX = point1.getX() - deltaX;
double labelY = point1.getY() - deltaY;
final double scale = ((double) i / (double) ticks);
final AffineTransform tx = AffineTransform.getScaleInstance(scale, scale);
final AffineTransform pointTrans = AffineTransform.getScaleInstance(scale + TICK_SCALE, scale + TICK_SCALE);
transformer[0] = labelX;
transformer[1] = labelY;
pointTrans.transform(transformer, 0, transformed, 0, 1);
final double pointX = transformed[0] + deltaX;
final double pointY = transformed[1] + deltaY;
tx.transform(transformer, 0, transformed, 0, 1);
labelX = transformed[0] + deltaX;
labelY = transformed[1] + deltaY;
double rotated = (PERPENDICULAR);
AffineTransform rotateTrans = AffineTransform.getRotateInstance(Math.toRadians(rotated), labelX, labelY);
transformer[0] = pointX;
transformer[1] = pointY;
rotateTrans.transform(transformer, 0, transformed, 0, 1);
final double x1 = transformed[0];
final double y1 = transformed[1];
rotated = (-PERPENDICULAR);
rotateTrans = AffineTransform.getRotateInstance(Math.toRadians(rotated), labelX, labelY);
rotateTrans.transform(transformer, 0, transformed, 0, 1);
final Composite saveComposite = g2.getComposite();
g2.setComposite(AlphaComposite.getInstance (AlphaComposite.SRC_OVER, 1.0f));
g2.draw(new Line2D.Double(transformed[0], transformed[1], x1, y1));
if (startAngle == this.getStartAngle()) {
final String label = format.format (((double) i / (double) ticks) * this.getMaxValue());
final Rectangle2D labelBounds = getLabelFont().getStringBounds(label, frc);
final LineMetrics lm = getLabelFont().getLineMetrics(label, frc);
final double ascent = lm.getAscent ();
if (Math.abs(labelX - plotArea.getCenterX()) < THRESHOLD) {
labelX += valueLabelGap;
labelY += ascent / (float) 2;
} else if (Math.abs(labelY - plotArea.getCenterY()) < THRESHOLD) {
labelY += valueLabelGap;
} else if (labelX >= plotArea.getCenterX()) {
if (labelY < plotArea.getCenterY()) {
labelX += valueLabelGap;
labelY += valueLabelGap;
} else {
labelX -= valueLabelGap;
labelY += valueLabelGap;
}
} else {
if (labelY > plotArea.getCenterY()) {
labelX -= valueLabelGap;
labelY -= valueLabelGap;
} else {
labelX += valueLabelGap;
labelY -= valueLabelGap;
}
}
g2.setPaint(getLabelPaint());
g2.setFont(getLabelFont());
g2.drawString(label, (float) labelX, (float) labelY);
}
g2.setComposite(saveComposite);
}
}
}
有其它需要的朋友可以參考這個思路繼續擴展。
遇到問題，不抱怨社會，不在一棵樹上吊死。
本文出自 “王傑瑞的技術博客” 博客，請務必保留此出處 http://wangjierui.blog.51cto.com/186879/116845
