实例：验证码
Posted 超霸霸
tags:
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验证码
- Servlet：
package cn.chao.web.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 doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
int width = 100;
int height = 50;
//1.创建对象，
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.BLACK);
g.drawRect(0, 0, width - 1, height - 1);
//2.3写验证码
String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
//生成随机角标
Random random = new Random();
for (int i = 1; i <= 4; i++) {
int index = random.nextInt(str.length());
//获取字符
char ch = str.charAt(index);//随机字符
g.drawString(ch + "", width / 5 * i, height / 2);
}
//2.4画干扰线
g.setColor(Color.GREEN);
for (int i = 0; i < 10; i++) {
int x1 = random.nextInt(width);
int x2 = random.nextInt(width);
int y1 = random.nextInt(height);
int y2 = random.nextInt(height);
g.drawLine(x1, y1, x2, y2);
}
//3.输出图片
ImageIO.write(image, "jpg", response.getOutputStream());
}
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request, response);
}
}
- html：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>验证码</title>
<script>
window.onload = function () {
var img = document.getElementById("checkCode");
img.onclick = function () {
var date = new Date().getTime();
img.src = "/CheckCodeServlet?" + date;
}
}
</script>
</head>
<body>
<img id="checkCode" src="/CheckCodeServlet"/>
<a id="change" href="">看不清？换一张</a>
</body>
</html>
- 效果：
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