java驗證碼學習一
阿新 • • 發佈：2018-03-16
java驗證碼學習一
package com.sys.web.sesoion;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.http.HttpSession;
public class CheckCodeServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
BufferedImage image = new BufferedImage(50,25,BufferedImage.TYPE_INT_RGB);
Graphics g = image.getGraphics();
g.drawString(Token.getNum(),15,15);
ImageIO.write(image,"JPG",response.getOutputStream());
response.setHeader("expires","-1");
response.setHeader("cache-control","no-cache"); //沒有緩成
response.setHeader("pragma","no-cache");
}
}
//用於產生隨機數
class Token{
public static String getNum(){
Random r = new Random();
int num = r.nextInt(10000);
return num + "";
}
}
java驗證碼學習一