java验证码生成

最新推荐文章于 2022-01-28 10:59:58 发布

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<head>
<script type="text/javascript">
// 更换验证码
	function reloadcode() {
		var verify = document.getElementById("code");
		verify.setAttribute("src", "makeCertPic.jsp?it=" + Math.random());
	}
</script>
</head>
<body>
<img src="makeCertPic.jsp" id="code" onclick="reloadcode()"></img><a
					href="#" onclick="reloadcode()">换一张</a>
</body>

makeCerPic.jsp

<%@page contentType="image/jpeg"%>
<jsp:useBean id="image" scope="page"
	class="com.util.MakeCertPicUtil" />
<%
	// 验证码生成
	String str = image.getCertPic(70, 26, response.getOutputStream());
	// 将认证码存入session
	session.setAttribute("certCode", str);
	out.clear();
	out = pageContext.pushBody();
%>

MakeCertPicUtil.java

package com.util;

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

import javax.imageio.ImageIO;

/**
 * 
 * 验证码生成
 * 
 * 
 */
public class MakeCertPicUtil {

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

	/**
	 * 给定范围获得随机颜色
	 * 
	 * @param fc
	 * @param bc
	 * @return
	 */
	private Color getRandColor(int fc, int bc) {
		Random random = new Random();
		if (fc > 255)
			fc = 255;
		if (bc > 255)
			bc = 255;
		int r = fc + random.nextInt(bc - fc);
		int g = fc + random.nextInt(bc - fc);
		int b = fc + random.nextInt(bc - fc);
		return new Color(r, g, b);
	}

	/**
	 * 生成彩色验证码图片参数width为生成图片的宽度,参数height为生成图片的高度,参数os为页面的输出流
	 * 
	 * @param width
	 * @param height
	 * @param os
	 * @return
	 */
	public String getCertPic(int width, int height, OutputStream os) {
		if (width <= 0)
			width = 70;
		if (height <= 0)
			height = 22;
		BufferedImage image = new BufferedImage(width, height,
				BufferedImage.TYPE_INT_RGB);
		// 获取图形上下文
		Graphics g = image.getGraphics();
		// 设定背景色
		g.setColor(getRandColor(200, 250));
		g.fillRect(0, 0, width, height);
		// 画边框
		g.setColor(getRandColor(160, 200));
		g.drawRect(0, 0, width - 1, height - 1);
		// 取随机产生的认证码
		String strEnsure = "";
		// 4代表4位验证码,如果要生成更多位的认证码,则加大数值
		for (int i = 0; i < 4; ++i) {
			strEnsure += mapTable[(int) (mapTable.length * Math.random())];
		}
		// 将认证码显示到图像中,如果要生成更多位的认证码,增加drawString语句
		g.setColor(getRandColor(160, 200));
		g.setFont(new Font("Atlantic Inline", Font.PLAIN, 18));
		String str = strEnsure.substring(0, 1);
		g.drawString(str, 8, 17);
		str = strEnsure.substring(1, 2);
		g.drawString(str, 20, 15);
		str = strEnsure.substring(2, 3);
		g.drawString(str, 35, 18);
		str = strEnsure.substring(3, 4);
		g.drawString(str, 45, 15);
		// 随机产生100个干扰点
		Random rand = new Random();
		for (int i = 0; i < 100; i++) {
			int x = rand.nextInt(width);
			int y = rand.nextInt(height);
			g.drawOval(x, y, 1, 1);
		}
		// 释放图形上下文
		g.dispose();
		try {
			// 输出图像到页面
			ImageIO.write(image, "JPEG", os);
		} catch (IOException e) {
			return "";
		}
		return strEnsure;
	}
}