html:
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>驗證碼</title> <script> var code window.onload=function () { code=document.getElementById("checkCode"); code.onclick=change(); } function change() { var time=new Date().getTime(); code.src="/day07/ServletCheckCode?"+time; } </script> </head> <body> <img id="checkCode" src="/day07/ServletCheckCode"> <a onclick="change() " href="javascript:void(0)">看不清楚？點擊換一張</a> </body> </html>
servlet
@WebServlet("/ServletCheckCode") public class ServletCheckCode extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //1創建對象 int width=100; int height=50; BufferedImage img=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB); //2.美化圖片 //填充背景色 Graphics g=img.getGraphics(); g.setColor(Color.pink); g.fillRect(0,0,width,height); //畫邊框 g.setColor(Color.blue); g.drawRect(0,0,width-1,height-1); //寫驗證碼 String str="QWERTYUIOPASDFGHJKLZXCVBNMqwertyuiopasdfghjklzxcvbnm0123456789"; Random ran=new Random(); for (int i = 1; i <= 4; i++) { int index = ran.nextInt(str.length()); char c = str.charAt(index); g.drawString(c+"",width/5*i,height/2); } //畫干擾線 g.setColor(Color.green); int x1; int y1; int x2; int y2; for (int i = 0; i <10; i++) { x1=ran.nextInt(width); x2=ran.nextInt(width); y1=ran.nextInt(height); y2=ran.nextInt(height); g.drawLine(x1,y1,x2,y2); } //3.展示圖片 ImageIO.write(img,"jpg",response.getOutputStream()); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doPost(request,response); } }