Response_案例4_验证码_分析
验证码分析
1.本质:图片
2.目的:防止恶意表单注册
package qh.xueqiang.servlet; 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.io.IOException; @WebServlet("/checkCodeServlet") public class CheckCodeServlet extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request,response); } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //1.创建一对象,在内存中图片(验证码对象) //2.美化图片 //3.将图片输出到页面展示 } }
Response_案例4_验证码_代码实现
package qh.xueqiang.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.image.BufferedImage; import java.io.IOException; import java.util.Random; @WebServlet("/checkCodeServlet") public class CheckCodeServlet extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request,response); } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { int width = 130; int heigth = 50; //1.创建一对象,在内存中图片(验证码对象) BufferedImage image = new BufferedImage(width,heigth,BufferedImage.TYPE_INT_RGB); //2.美化图片 //2.1填充背景色 Graphics graphics = image.getGraphics();//画笔对象 graphics.setColor(Color.BLUE);//设置画笔颜色 graphics.fillRect(0,0,width,heigth); //2.2画边框 graphics.setColor(Color.cyan); graphics.drawRect(0,0,width-1,heigth-1); String str ="QWERTYUIOPASDFGHJKLZXCVBNMqwertyuiopasdfghjklzxcvbnm1234567890"; //生成随机角标 Random ran = new Random(); for (int i = 0;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 graphics.drawString(ch+"",width/5*i,25); } //2.4画干扰线 graphics.setColor(Color.MAGENTA); //随机生成坐标点 for (int i = 0; i <10; i++) { int x1 = ran.nextInt(width); int x2 = ran.nextInt(width); int y1 = ran.nextInt(heigth); int y2 = ran.nextInt(heigth); graphics.drawLine(x1,x2,y1,y2 ); } //3.将图片输出到页面展示 ImageIO.write(image,"jpg",response.getOutputStream()); } }
Response_案例4_验证码_点击切换
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> <link href="favicon.ico" rel="shortcut icon"> <script> /* 分析: 点击超链接或者图片,需要换一张 1.给超链接和图片绑定单机事件 2.重新设置图片的src属性值 */ window.onload = function (){ //1.获取图片对象 var img = document.getElementById("checkCode"); //2.绑定单价事件 img.onclick = function (){ //加时间戳 var date = new Date().getTime(); img.src = "/day15/checkCodeServlet?1" } } </script> </head> <body> <img id="checkCode" src="/day15/checkCodeServlet"> <a id="change" href="">看不清,换一张</a> </body> </html>
标签:ServletException,验证码,javax,案例,import,servlet,Response From: https://www.cnblogs.com/x3449/p/17085431.html