java实现网页验证码

package cn.bdqn.servlet; import javax.imageio.ImageIO; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.awt.*; import java.awt.font.ImageGraphicAttribute; import java.awt.image.BufferedImage; import java.io.IOException; import java.util.Random; @WebServlet(name = "Servlet",urlPatterns = "/yanCode") public class Servlet extends HttpServlet { public void doPost(javax.servlet.http.HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doGet(request,response); } public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String s="abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"; Random random = new Random(); int width=500; int height=50; BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB); Graphics graphics = image.getGraphics();//相当于画笔 //画背景 graphics.setColor(Color.gray); graphics.fillRect(0,0,width,height); graphics.setColor(Color.black); for (int i = 0; i <4 ; i++) { int index = random.nextInt(s.length()); String c = s.substring(index, index + 1); graphics.drawString(c,width/5*(i+1),15); } ImageIO.write(image,"jpg",response.getOutputStream()); } }

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