利用 Java 2D 畫曲線圖

<%@ page language="java" contentType="image/jpeg;charset=GBK"
 import="java.awt., java.awt.image., com.sun.image.codec.jpeg.*"%>
<%
 // 在內存中創建圖像
 int width  = 600;
 int height = 500;
 BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

// 繪制圖像
 Graphics g = image.getGraphics();
 Graphics2D g2d = (Graphics2D) g;
 // 背景色
 g.setColor(new Color(240, 249, 255));
g.fillRect(0, 0, width, height);
 // 字體顏色
 g.setColor(Color.BLACK);
 g.setFont(new Font("宋體", Font.PLAIN, 22));
 g.drawString("新浪網2007年上半年訪問量統計", 15, 25);
 int visit[] = new int[6];
 for (int i = 0; i < visit.length; i++) {
     visit[i] = 1 + (int) (Math.random() * 100);
 }
String mongth[] = { "1月", "2月", "3月", "4月", "5月", "6月" };
g.setFont(new Font("宋體", Font.BOLD, 16));
 g.drawString("訪問量（單位：萬次）", 20, 50);
 g.drawString("月份", 550, 465);
 g.setFont(new Font("SanSSerif", Font.PLAIN, 12));
int visitValue = 0;
 //畫橫線
 for (int i = 418; i > 0; i -= 38) {
     g.setColor(Color.BLACK);
     g.drawString("" + visitValue, 36, (i + 27));
     g.setColor(Color.LIGHT_GRAY);
     g.drawLine(80, (i + 27), 520, (i + 27));
     visitValue += 10;
 }
 g.setColor(Color.BLACK);
 g.drawLine(80, 40, 80, 445);
 g.drawLine(80, 445, 550, 445);
 int drawHigh[] = new int[mongth.length];
 int drawwidth[] = new int[mongth.length];
//折點坐標
 for (int i = 0; i < mongth.length; i++) {
     drawHigh[i] = 445 - (int) (Math.ceil(visit[i]  3.8));
     drawwidth[i] = 110 + i  80;
     g.drawString(mongth[i], 110 + i * 80, 465);
 }
//g2d.setXORMode(Color.WHITE);
 //折線粗細
 g2d.setStroke(new BasicStroke(3.0f));
 //折線的顏色
 g2d.setPaint(Color.RED);
 //畫折線
 g2d.drawPolyline(drawwidth, drawHigh, mongth.length);
 // 產生圖像
 g.dispose();
ServletOutputStream sos = response.getOutputStream();
 JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(sos);
 encoder.encode(image);
out.clear();
 out = pageContext.pushBody();
%></pre>





轉自：http://www.cnblogs.com/190196539/archive/2011/12/21/2295358.html