Verification code
1. 本质：图片
2. 目的：防止恶意表单注册
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<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击事件
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.绑定单击事件
img.onclick = function(){
//加时间戳
var date = new Date().getTime();
img.src = "/day15/checkCodeServlet?"+date;//如果不改变路径，那么加载的一直都是缓存在浏览器的图片
}
}
</script>
</head>
<body>
<img id="checkCode" src="/day15/checkCodeServlet" />
<a id="change" href="">看不清换一张？</a>
</body>
</html>
CheckCodeServlet.java
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 {
Random ran = new Random();
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
int width = 100;
int height = 50;
//1.创建一对象，在内存中图片(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 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghigklmnopqrstuvwxyz0123456789";
//生成随机角标
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
graphics.setColor(randomColor());//随机颜色
graphics.setFont(randomFont());//随机字体
//2.3写验证码
g.drawString(ch+"",width/5*i,height/2);
}
//2.4画干扰线
g.setColor(Color.GREEN);
//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(height);
int y2 = ran.nextInt(height);
g.drawLine(x1,y1,x2,y2);//画线
}
//画干扰点
for (int i = 0; i < 10; i++) {
graphics.setColor(randomColor());//随机颜色
int x1 = random.nextInt(width);
int y1 = random.nextInt(hight);
graphics.drawOval(x1,y1,2,2);//画点
}
//3.将图片输出到页面展示
ImageIO.write(image,"jpg",response.getOutputStream());
}
//生成随机颜色
private Color randomColor(){
int red = random.nextInt(255);
int green = random.nextInt(255);
int blue = random.nextInt(255);
return new Color(red,green,blue);
}
//生辰随机字体
private Font randomFont(){
String[] fontNames= {
"宋体", "华文楷体", "黑体", "微软雅黑", "楷体_GB2312"};
int index = random.nextInt(fontNames.length);
String fontName = fontNames[index];
int style = random.nextInt(4);
int size=random.nextInt(5)+ 24;
return new Font(fontName,style,size);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request,response);
}
}
Click on the picture to automatically switch
