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Servlet动态生成验证码

2014-10-26 15:00 381 查看

1、使用Servlet动态生成验证码

package com.xuhu.servlet;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

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;

/**
* Servlet implementation class CheckCode
*/
@WebServlet("/CheckCode")
public class CheckCode extends HttpServlet
{
private static final long serialVersionUID = 1L;

private static final int IMG_WIDTH = 100;
private static final int IMG_HEIGHT = 25;

//验证码字符
private char[] chs = new char[]
{'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E',
'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'P', 'Q', 'R', 'S',
'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
'g', 'h', 'i', 'j', 'k', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't',
'u', 'v', 'w', 'x', 'y', 'z'};

protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException
{
this.doPost(request, response);
}

protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException
{
// 1、在内存中创建图片对象
BufferedImage img = new BufferedImage(IMG_WIDTH, IMG_HEIGHT,
BufferedImage.TYPE_INT_RGB);

// 2、获取这个图像画笔
Graphics g = img.getGraphics();

// 3、设置图像的背景色
setImageBackground(g);

// 4、设置图片的边框
setImageBorder(g);

// 5、设置图片随机线
setImageRandomLine(g);

// 6、设置图片的随机数据
setImageRandomData(g);

// 7、将生成的验证码图片回传给浏览器，并通知浏览器以图片的方式打开数据
response.setContentType("image/jpeg");

//设置浏览器不缓存数据
response.setHeader("Expires", "0");
response.setHeader("Cache-Control", "no-cache");
response.setHeader("Pragma", "no-cache");

ImageIO.write(img, "jpg", response.getOutputStream());

}

/**
* 设置图片背景色
* @param g
*/
private void setImageBackground(Graphics g)
{
g.setColor(Color.WHITE);
g.fillRect(0, 0, IMG_WIDTH, IMG_HEIGHT);
}

/**
* 设置图片边框
* @param g
*/
private void setImageBorder(Graphics g)
{
g.setColor(Color.BLUE);
g.drawRect(1, 1, IMG_WIDTH - 2, IMG_HEIGHT - 2);
}

/**
* 设置干扰线
* @param g
*/
private void setImageRandomLine(Graphics g)
{
g.setColor(Color.GREEN);

for (int i = 0; i < 6; i++)
{
int x1 = new Random().nextInt(IMG_WIDTH);
int y1 = new Random().nextInt(IMG_HEIGHT);

int x2 = new Random().nextInt(IMG_WIDTH);
int y2 = new Random().nextInt(IMG_HEIGHT);

g.drawLine(x1, y1, x2, y2);
}

}

/**
* 填充数据
* @param g
*/
private void setImageRandomData(Graphics g)
{
StringBuilder sb = new StringBuilder();
for (int i = 0; i < 4; i++)
{
sb.append(chs[new Random().nextInt(chs.length)] + " ");
}

g.setColor(Color.RED);
g.setFont(new Font(null, Font.BOLD | Font.ITALIC, 20));
g.drawString(sb.toString(), 15, 20);
}

}

2、实现点击图片刷新验证码功能

<script type="text/javascript">
//点击刷新验证码图片
function refresh()
{
var r = Math.random();
var img = document.getElementById("CheckCode");
img.src = "CheckCode?r=" + r;
}
</script>

<body>
用户名：<input type="text" /><br />
密   码：<input type="password" /><br />
验证码：<input type="text" style="width: 80px;"/>
<img id="CheckCode" src="CheckCode" onclick="refresh();" style="cursor: pointer;" />
</body>

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