在struts中实现验证码

第一步：首先写一个继承dispatchAction的类，用于产生验证码。



package userlogin;

import java.awt.Color;

import java.awt.Font;

import java.awt.Graphics;

import java.awt.image.BufferedImage;

import java.util.Random;

import javax.imageio.ImageIO;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import javax.servlet.http.HttpSession;

import org.apache.struts.action.ActionForm;

import org.apache.struts.action.ActionForward;

import org.apache.struts.action.ActionMapping;

import org.apache.struts.actions.DispatchAction;

public class ValidateCodeAction extends DispatchAction{

public ActionForward getCode(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response)throws Exception{

HttpSession session = request.getSession();

int codeLength = 6;// 验证码长度

int mixTimes = 150;// 模糊程度参数

Color bgColor = getRandColor(200, 250);// 背景颜色

Color bfColor = new Color(0, 0, 0);// 字体颜色

boolean ifRandomColor = true;// 单个字符是否颜色随机

boolean ifMixColor = true;// 模糊线是否颜色随机



// 设置页面不缓存

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

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

response.setDateHeader("Expires", 0);

// 在内存中创建图象

int width = 13 * codeLength + 6, height = 20;

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(bgColor);

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

// 设定字体

g.setFont(new Font("Arail", Font.ITALIC, 20));

// 画边框

g.setColor(new Color(33, 66, 99));

g.drawRect(120, 100, width - 1, height - 1);



g.setColor(getRandColor(160, 200));

// 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 < mixTimes * codeLength / 10; i++) {

if (ifMixColor) {

g.setColor(getRandColor(160, 200));

}

int x = random.nextInt(width);

int y = random.nextInt(height);

int xl = random.nextInt(12);

int yl = random.nextInt(12);

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

}

// 取随机产生的认证码(4位数字)



// 向图片中输出数字和字母

Random r=new Random();

char[] ch = "abcdefghijklmnopqrstyvwsyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789".toCharArray();

int index, len = ch.length;

String sRand = "";

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

index = r.nextInt(len);



String rand =String.valueOf(ch[index]);

sRand += rand;

// 将认证码显示到图象中

if (ifRandomColor)

g.setColor(getRandColor(20, 110, 0));

else

g.setColor(bfColor);

// 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.drawString(rand, 13 * i + 6, 16);

}

// 将认证码存入SESSION

// 图象生效

session.setAttribute("rand",sRand);

g.dispose();

// 输出图象到页面

ImageIO.write(image, "PNG", response.getOutputStream());

return null;

}



private static Random random = new Random();

private Color getRandColor(int fc, int bc) {

return getRandColor(fc, bc, fc);

}

private Color getRandColor(int fc, int bc, int interval) {

if (fc > 255) {

fc = 255;

}

if (bc > 255) {

bc = 255;

}

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

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

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

return new Color(r, g, b);

}

}

第二步：在jsp的表单中调用（<html:form>）：

<tr>

<td align="left" valign="middle">

<html:img page="/ValidateCode.do?method=getCode" paramName="imgValidate" border="0"

onclick="reload(this)"

style="cursor:pointer" /></td>

</tr>

第三步：在jsp页面中写一个刷新的js事件：

function reload(obj){

var timenow = new Date().getTime();

obj.src="${pageContext.request.contextPath}/ValidateCode.do?method=getCode&id="+timenow;

}



结果如此：