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<div>
验证码:<input type="text" name="identified" />
<img id="codeImg" alt="验证码" src = " <%= request.getContextPath()%>/servlet/IdentifiedServlet" />
<a href="javascript:toChange();" > 看不清 </a>
</div>
function toChange(){
var time = Math.random();
document.getElementById("codeImg").src="<%= request.getContextPath()%>/servlet/IdentifiedServlet?"+time;
}
servlet:
protected void service(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//创建一个图片缓存区
BufferedImage bi = new BufferedImage(80,20,BufferedImage.TYPE_INT_RGB);
//创建制图Graphics类对象
Graphics gi = bi.getGraphics();
Color c = new Color(225,250,250);
gi.setColor(c);
gi.fillRect(0, 0, 80, 20);
char[] content = "ABCDEFGHI0123456789".toCharArray();
Random r = new Random();
int index;
for(int i=0;i<4;i++){
index = r.nextInt(content.length);
gi.setColor(new Color(r.nextInt(100),r.nextInt(188),r.nextInt(255)));
gi.drawString(content[index]+"",10+20*i,10+3*r.nextInt(4));
}
ImageIO.write(bi, "JPG", response.getOutputStream());
}