jsp实现生成中国国旗图片效果代码

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。