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