java图形验证码实现

      大家在项目中肯定遇到过生成图形验证码功能，下面是我在项目中图形验证码实现代码，仅供参考：

      1.  建一个ValidateCodeServlet.java  公共类  

package com.kye.tool;

import java.awt.Color;

import java.awt.Font;

import java.awt.Graphics2D;

import java.awt.image.BufferedImage;

import java.io.IOException;

import java.util.Random;

import javax.imageio.ImageIO;

import javax.servlet.ServletConfig;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import org.apache.commons.lang.StringUtils;

import com.kye.tool.ConstantUtil;

public class ValidateCodeServlet extends HttpServlet { 

/**

* 

*/

private static final long serialVersionUID = 1L;

private final Font mFont = new Font("Arial Black", Font.PLAIN, 15); // 设置字体

private  int lineWidth = 2; // 干扰线的长度=1.414*lineWidth

private  int width = 88; // 定义图形大小

private  int height = 30; // 定义图形大小

private  int count = 200;

private  int codeCount = 4;

@Override

public void init(ServletConfig config) throws ServletException {

super.init(config);

String height = config.getInitParameter("height");

this.height = StringUtils.isEmpty(height) || !StringUtils.isNumeric(height) ?this.height:Integer.parseInt(height);

String width = config.getInitParameter("width");

this.width = StringUtils.isEmpty(width) || !StringUtils.isNumeric(width) ? this.width :Integer.parseInt(width);

String codeCount = config.getInitParameter("codeCount");

this.codeCount = StringUtils.isEmpty(codeCount) || !StringUtils.isNumeric(codeCount) ?this.codeCount:Integer.parseInt(codeCount);

}

/**

* 描述：

* 

* @param fc

*            描述：

* @param bc

*            描述：

* 

* @return 描述：

*/

private Color getRandColor(int fc, int bc) { // 取得给定范围随机颜色

final Random random = new Random();

if (fc > 255) {

fc = 255;

}

if (bc > 255) {

bc = 255;

}

final int r = fc + random.nextInt(bc - fc);

final int g = fc + random.nextInt(bc - fc);

final int b = fc + random.nextInt(bc - fc);

return new Color(r, g, b);

}

// 处理post

@Override

public void doPost(final HttpServletRequest request,

final HttpServletResponse response) throws ServletException,

IOException {

doGet(request, response);

}

/**

* 描述：

* 

* @param request

*            描述：

* @param response

*            描述：

* 

* @throws ServletException

*             描述：

* @throws IOException

*             描述：

*/

@Override

public void doGet(final HttpServletRequest request,

final HttpServletResponse response) throws ServletException,

IOException {

// response.reset();

// 设置页面不缓存

response.setHeader("Pragma", "No-cache");

response.setHeader("Cache-Control", "no-cache");

response.setDateHeader("Expires", 0);

response.setContentType("image/gif");

// 在内存中创建图象

final BufferedImage image = new BufferedImage(width, height,

BufferedImage.TYPE_INT_RGB);

// 获取图形上下文

final Graphics2D g = (Graphics2D) image.getGraphics();

// 生成随机类

final Random random = new Random();

// 设定背景色

g.setColor(getRandColor(200, 250)); // ---1

g.fillRect(0, 0, width, height);

// 设定字体

g.setFont(mFont);

// 画边框

g.setColor(getRandColor(0, 20)); // ---2

g.drawRect(0, 0, width - 1, height - 1);

// 随机产生干扰线，使图象中的认证码不易被其它程序探测到

for (int i = 0; i < count; i++) {

g.setColor(getRandColor(150, 200)); // ---3

final int x = random.nextInt(width - lineWidth - 1) + 1; // 保证画在边框之内

final int y = random.nextInt(height - lineWidth - 1) + 1;

final int xl = random.nextInt(lineWidth);

final int yl = random.nextInt(lineWidth);

g.drawLine(x, y, x + xl, y + yl);

}

// 取随机产生的认证码(4位数字)

String sRand = "";

for (int i = 0; i < codeCount; i++) {

final String rand = String.valueOf(random.nextInt(10));

sRand += rand;

// 将认证码显示到图象中,调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成

g.setColor(new Color(20 + random.nextInt(130), 20 + random

.nextInt(130), 20 + random.nextInt(130))); // --4--50-100

g.drawString(rand, (13 * i) + 6, height-8);

}

// 将认证码存入SESSION

request.getSession().setAttribute(ConstantUtil.KAPTCHA_ADMIN_SESSION_KEY, sRand);

// 图象生效

g.dispose();

final java.io.OutputStream os = response.getOutputStream();

// 输出图象到页面

ImageIO.write(image, "PNG", os);

os.flush();

os.close();

}

}

2.在web.xml中进行配置

<servlet>
<servlet-name>ValidateCodeServlet</servlet-name>
<servlet-class>com.kye.tool.ValidateCodeServlet</servlet-class>
<init-param>
<param-name>width</param-name>
<param-value>70</param-value>
</init-param>
<init-param>
<param-name>height</param-name>
<param-value>30</param-value>
</init-param>
<init-param>
<param-name>codeCount</param-name>
<param-value>4</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>ValidateCodeServlet</servlet-name>
<url-pattern>/ValidateCodeServlet</url-pattern>
</servlet-mapping>

3.jsp页面

<div class="g-row">

          <p class="">

               <label class="">验证码</label>

               <input type="text" id="validateCode"/>

              <img src="http://localhost:8080/ValidateCodeServlet" class="img-rounded" onclick="this.src='http://localhost:8080/ValidateCodeServlet?'+Math.random();" />

           </p>

</div>

END:    三步大功告成，图片验证码成功实现