Jsp表单验证码的问题

生成图片的java代码如下：

package imagevalidate;

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.http.HttpServletResponse;

public class RandImgCreater {

private static final String CODE_LIST = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890";

private HttpServletResponse response = null;

private static final int HEIGHT = 20;

private static final int FONT_NUM = 4;

private int width = 0;

private int iNum = 0;//code length

private String codeList = "";//code value range

private boolean drawBgFlag = false;

private int rBg = 0;

private int gBg = 0;

private int bBg = 0;

//could changer the image code length and code range

public RandImgCreater(HttpServletResponse response) {

this.response = response;

this.width = 13 * FONT_NUM + 12;

this.iNum = FONT_NUM;

this.codeList = CODE_LIST;

}

public RandImgCreater(HttpServletResponse response,int iNum,String codeList) {

this.response = response;

this.width = 13 * iNum + 12;

this.iNum = iNum;

this.codeList = codeList;

}

public String createRandImage(){

BufferedImage image = new BufferedImage(width, HEIGHT,

BufferedImage.TYPE_INT_RGB);

Graphics g = image.getGraphics();

Random random = new Random();//random function

if ( drawBgFlag ){

g.setColor(new Color(rBg,gBg,bBg));

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

}else{

g.setColor(getRandColor(200, 250));

g.fillrect(0, 0, width, height)。 ctx.fillrect(0,0, canvas.width,canvas.height)。 context.fillrect(0, 0, canvas.width, canvas.height)。

// random generate 155 piece jam line

for (int i = 0; i < 155; i++) {

g.setColor(getRandColor(140, 200));

//g.setColor(new Color(0x99,0x99,0x99));

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);

}

}

g.setFont(new Font("Times New Roman", Font.PLAIN, 18));

String sRand="";

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

int rand=random.nextInt(codeList.length());//from 0 to codeList.length get the value

String strRand=codeList.substring(rand,rand+1);

sRand+=strRand;

g.setcolor(new color(254, 215, 124))。 thread.sleep((new random().nextint(10)+1)*1000)。 data.set(new random().nextint(30))。

//g.setColor(new Color(0x99,0x99,0x99));

g.drawString(strRand,13*i+6,16);

}

g.dispose();

try{

imageio.write(image, "png", response.getoutputstream())。//response.contenttype = "image/jpeg"。 // response.setcontenttype("image/jpeg")。

}catch(IOException e){

}

return sRand;

}

public void setBgColor(int r,int g,int b){

drawBgFlag = true;

this.rBg = r;

this.gBg = g;

this.bBg = b;

}

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);

}

}

2.编写一个jsp文件 我命名为img.jsp

<%@ page language="java" contentType="image/jpeg; charset=gb2312" import="imagevalidate.*"

pageEncoding="gb2312"%>

<%

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

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

response.setDateHeader("Expires", 0);

//调用上面的java方法jsp表单验证jsp表单验证，绘制一张验证码，验证的数字保存在session中 rand属性

RandImgCreater rc = new RandImgCreater(response);

//RandImgCreater rc = new RandImgCreater(response,8,"abcdef");

rc.setBgColor(0xC0,0xC0,0xC0);

String rand = rc.createRandImage();

session.setAttribute("rand",rand);

//没有以下两句刷新会出现异常

out.clear();

out = pageContext.pushBody();

%>

3.在登录页面就可以这样调用

<img src="img.jsp">便可生成

2008年8月12日 11:26

感恩之云

8

000

本文来自电脑杂谈，转载请注明本文网址：
http://www.pc-fly.com/a/tongxinshuyu/article-110031-1.html