本文实例讲述了jsp实现生成中国国旗图片效果代码。分享给大家供大家参考，具体如下：

图片截图如下：

具体代码如下：

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%@ page contentType="image/jpeg" import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*,java.awt.Shape.*,java.awt.geom.*,com.sun.image.codec.jpeg.*" %><% out.clear(); response.setContentType("image/jpeg"); response.setHeader("Pragma","No-cache"); response.setHeader("Cache-Control","no-cache"); response.setDateHeader("Expires", 0); int width =300; int height = width/3*2; double maxR = 0.15, minR = 0.05; double maxX = 0.50, maxY = 0.50; double[] minX = {0.75, 0.85, 0.85, 0.75}; double[] minY = {0.35, 0.45, 0.60, 0.70}; BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); java.awt.Graphics2D g=(java.awt.Graphics2D)image.createGraphics(); g.clearRect(0, 0,width,height); g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); //画棋面 g.setColor(java.awt.Color.red); g.fillRect(0, 0, width, height); //g.fillRect(50, 50, width, height); g.setColor(java.awt.Color.yellow); //画大五角星 double ox = height*maxX, oy = height*maxY; g.fill(createPentacle(ox,oy,height*maxR,-Math.PI/2)); //画小五角星 for(int idx =0;idx < 4;idx ++){ double sx = minX[idx]*height, sy = minY[idx]*height; double theta = Math.atan2(oy-sy,ox-sx); g.fill(createPentacle(sx,sy,height*minR,theta)); } g.dispose(); out.clearBuffer(); out = pageContext.pushBody(); //ImageIO.write(image, "JPEG", response.getOutputStream()); ServletOutputStream outStream = response.getOutputStream(); JPEGImageEncoder encoder =JPEGCodec.createJPEGEncoder(outStream); encoder.encode(image); outStream.close();%><%! public static java.awt.Shape createPentacle(double sx, double sy, double radius,double theta) { final double arc = Math.PI / 5; final double rad = Math.sin(Math.PI / 10) / Math.sin(3 * Math.PI / 10); GeneralPath path = new GeneralPath(); path.moveTo(1, 0); for (int idx = 0; idx < 5; idx++) { path.lineTo(rad * Math.cos((1 + 2 * idx) * arc),rad * Math.sin((1 + 2 * idx) * arc)); path.lineTo(Math.cos(2 * (idx + 1) * arc),Math.sin(2 * (idx + 1) * arc)); } path.closePath(); AffineTransform atf = AffineTransform.getScaleInstance(radius, radius); atf.translate(sx / radius, sy / radius); atf.rotate(theta); return atf.createTransformedShape(path); }%>

将代码另存为jsp文件，放在运行目录下执行即可。

代码在tomcat6.0下测试通过

希望本文所述对大家JSP程序设计有所帮助。