public class ResonpeRandomImgDemo extends HttpServlet {
int width=100;
int height=30;
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html;charset=utf-8");
//获取BufferedImage对象，并设置画布的大小还有类型
BufferedImage img=new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
//获取绘图对象
Graphics2D g =(Graphics2D)img.getGraphics();
//设置背景颜色
setBackgroudColor(g);
//产生随机数
getNum(g);
//把图形写给浏览器
response.setContentType("image/jpeg");
ImageIO.write(img, "jpg", response.getOutputStream());
}
private void getNum(Graphics2D g) {
String str="0123456789qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM";
g.setColor(Color.BLUE);
for (int i = 0; i < 4; i++) {
//产生随机数，%30为了产生随机数-30-30之间,这个也是旋转角度
int degee=new Random().nextInt()%30;
//进行旋转
g.rotate(degee*Math.PI/180 , 20+(i*12), 15);
g.setFont(new Font("宋体",Font.BOLD, 20));
g.drawString(str.charAt(new Random().nextInt(str.length()))+"", 20+(i*12), 15);
//旋转回来
g.rotate(-degee*Math.PI/180 , 20+(i*12), 15);
}
}
private void setBackgroudColor(Graphics2D g) {
g.setBackground(Color.WHITE);
g.fillRect(0, 0, width, height);
}
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
//jsp页面
<script type="text/javascript">
function changeImg(){
var img= document.getElementById("img");
img.src=img.src+"?";
}
</script>
验证码:<img alt="" src="/ServletTest/servlet/ResonpeRandomImgDemo" id="img" onclick="changeImg()" style="cursor: pointer;">///ServletTest/servlet/ResonpeRandomImgDemo获取servelt页面的信息