利用 Java 2D 繪制餅圖

<%@ page language="java" contentType="image/png;charset=GBK" pageEncoding="GBK"
 import="java.awt.*, javax.imageio.*,java.awt.geom.*,java.awt.image.*"%>

<%!// 繪制餅圖的說明

    public void drawTips(String tips, Color color, Arc2D.Double arc2d, Graphics2D g2d) {

        Arc2D.Double position = arc2d;

        position.setAngleExtent(arc2d.getAngleExtent() / 2);

        position.x = arc2d.x - 15;

        position.y = arc2d.y - 15;

        position.width = arc2d.getWidth() + 50;

        position.height = arc2d.getHeight() + 50;

        Point2D.Double endPoint = (Point2D.Double) position.getEndPoint();

        g2d.setPaint(color);

        int stringLength = g2d.getFontMetrics().stringWidth(tips);

        if (endPoint.x <= arc2d.getCenterX())

            g2d.drawString(tips, (float) endPoint.x - stringLength,

            (float) endPoint.y);

        else {

            g2d.drawString(tips, (float) endPoint.x, (float) endPoint.y);
        }

    }
%>

<%
    // 清空緩沖區
    response.reset();

    // 注意這里的MIME類型
    response.setContentType("image/png");

    // 創建一個 500X375 的圖像
    int width = 500, height = 375;

    BufferedImage image = new BufferedImage(width, height,

    BufferedImage.TYPE_INT_RGB);

    // 創建Java2D對象
    Graphics2D g2d = image.createGraphics();

    // 填充整個背景
    g2d.setPaint(Color.WHITE);

    g2d.fillRect(0, 0, width, height);

    // 繪制陰影，由灰色漸進圓角矩形組成
    GradientPaint grayGP = new GradientPaint(0, 0, Color.GRAY, width,

    height, new Color(218, 214, 212), false);

    g2d.setPaint(grayGP);

    RoundRectangle2D.Float bgRR = new RoundRectangle2D.Float(5, 5,

    width - 5, height - 5, 50, 50);

    g2d.fill(bgRR);

    // 繪制漸進藍色圓角矩形背景
    GradientPaint blueGP = new GradientPaint(0, 0, new Color(252, 197,

    113), width / 2, height / 2, new Color(255, 255, 169), true);

    g2d.setPaint(blueGP);

    g2d.fillRoundRect(0, 0, width - 5, height - 5, 50, 50);

    // 繪制深藍色圓角矩形輪廓
    BasicStroke bs = new BasicStroke(1.2f);

    g2d.setStroke(bs);

    g2d.setPaint(new Color(55, 71, 105));

    g2d.drawRoundRect(0, 0, width - 5, height - 5, 50, 50);

    // 繪制圖表標題
    //String chartTitle = "客戶構成分析";

    g2d.setColor(Color.BLACK);

    g2d.setFont(new Font("宋體", Font.PLAIN, 30));

    //int stringLength = g2d.getFontMetrics().stringWidth(chartTitle);

    //g2d.drawString(chartTitle, (width - stringLength) / 2, 30);

    // 定義圓弧
    Arc2D.Double arc2d = new Arc2D.Double();

    double startAngle = 30.0, arcAngle = 0.0;

    double rectWidth = 295.0, rectHeight = 245.0;

    Point2D.Double p2d = new Point2D.Double((width - rectWidth) / 2, 70.0);

    int arcType = Arc2D.PIE;

    Color color[] = new Color[5];

    color[0] = new Color(99, 99, 0);

    color[1] = new Color(255, 169, 66);

    color[2] = new Color(33, 255, 66);

    color[3] = new Color(33, 0, 255);

    color[4] = new Color(255, 0, 66);

    double bookSales[] = new double[5];

    double totalSales = 0.0;

    // 定義厚度
    int thickness = 25;

    for (int i = 0; i < bookSales.length; i++) {

        bookSales[i] = 1 + Math.random() * 99;

        totalSales += bookSales[i];

    }

    // 繪制起始角度不大于90度的圓弧
    startAngle = 30;

    for (int i = 0; i < bookSales.length; i++) {

        arcAngle = bookSales[i];

        if (startAngle >= 90) {

            break;

        }

        for (int j = thickness; j > 0; j--) {

            g2d.setColor(color[i].darker());

            arc2d = new Arc2D.Double(p2d.x, p2d.y + j, rectWidth,

            rectHeight, startAngle, arcAngle, arcType);

            // 填充圓弧
            g2d.fill(arc2d);

        }

        // 更新圓弧的起始角度
        startAngle += arcAngle;

    }

    // 繪制起始角度不小于270度的圓弧
    startAngle = 390;

    for (int i = bookSales.length - 1; i > 0; i--) {

        arcAngle = bookSales[i];

        if (startAngle <= 270) {

            break;

        }

        for (int j = thickness; j > 0; j--) {

            g2d.setColor(color[i].darker());

            arc2d = new Arc2D.Double(p2d.x, p2d.y + j, rectWidth,

            rectHeight, startAngle, -arcAngle, arcType);

            // 填充圓弧
            g2d.fill(arc2d);

        }

        // 更新圓弧的起始角度
        startAngle -= arcAngle;

    }

    // 繪制起始角度在90度到270度之間的圓弧
    startAngle = 30;

    for (int i = 0; i < bookSales.length; i++) {

        arcAngle = bookSales[i];

        if (startAngle > 90 && startAngle < 270) {

            for (int j = thickness; j > 0; j--) {

                g2d.setColor(color[i].darker());

                arc2d = new Arc2D.Double(p2d.x, p2d.y + j, rectWidth,

                rectHeight, startAngle + arcAngle, -arcAngle,

                arcType);

                // 填充圓弧
                g2d.fill(arc2d);

            }

        }

        // 更新圓弧的起始角度
        startAngle += arcAngle;

    }

    // 繪制最上面一層圓弧
    startAngle = 30;

    for (int i = 0; i < bookSales.length; i++) {

        arcAngle = bookSales[i];//item.getPercent() * 3.6;

        g2d.setColor(color[i]);

        arc2d = new Arc2D.Double(p2d.x, p2d.y, rectWidth, rectHeight,

        startAngle, arcAngle, arcType);

        // 填充圓弧
        g2d.fill(arc2d);

        // 描繪圓弧輪廓
        g2d.setStroke(new BasicStroke(1.2f));

        g2d.setPaint(Color.GRAY);

        g2d.draw(arc2d);

        // 更新圓弧的起始角度
        startAngle += arcAngle;

        g2d.setFont(new Font("宋體", Font.PLAIN, 12));

    }

    // 部署圖形
    g2d.dispose();

    // 利用ImageIO類的write方法對圖像進行編碼
    ServletOutputStream sos = response.getOutputStream();

    ImageIO.write(image, "PNG", sos);

    sos.close();

    out.clear();

 out = pageContext.pushBody();
%>