验证码
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package cn.itcast.web.servlet; import javax.imageio.ImageIO; import javax.servlet.ServletException; import javax.servlet.ServletOutputStream; 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.image.BufferedImage; import java.io.IOException; import java.util.Random; @WebServlet("/checkCodeServlet") public class CheckCodeServlet extends HttpServlet { @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //设置图片的大小 int width = 100 ; int height = 50 ; //1.创建一个对象，在内存中的图片（验证码图片对象） BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB); //2.美化图片 //2.1填充背景色 Graphics g = image.getGraphics();//画笔对象 g.setColor(Color.pink); //设置画笔颜色 g.fillRect(0,0,width,height); //2.2画边框 g.setColor(Color.BLUE); g.drawRect(0,0,width-1,height-1); String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"; //生成随机角标 Random ran = new Random(); for (int i = 1; i <= 4; i++) { int index = ran.nextInt(str.length()); //获取字符 char ch = str.charAt(index); //随机字符 //2.3写验证码 g.drawString(ch+"",width/5*i,height/2); } //画干扰线 g.setColor(Color.GREEN); for (int i = 1; i <= 10 ; i++) { //随机生成坐标点 int x1 = ran.nextInt(width); int x2 = ran.nextInt(width); int y1 = ran.nextInt(height); int y2 = ran.nextInt(height); g.drawLine(x1,y1,x2,y2); } //3.将图片输出到页面上 ImageIO.write(image,"jpg",response.getOutputStream()); } @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request, response); } }
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> <script> window.onload = function () { //1.获取图片对象 var img = document.getElementById("checkcode"); //2.绑定单机事件 img.onclick = function () { //加时间戳 var date = new Date().getTime(); img.src= "/day15/checkCodeServlet?"+date; } } </script> </head> <body> <img id="checkcode" src="/day15/checkCodeServlet" > <a id="change" href="">看不清换一张?</a> </body> </html>
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